[nit.git] / src / compiler / abstract_compiler.nit

# This file is part of NIT ( http://www.nitlanguage.org ).
#
# Copyright 2012 Jean Privat <jean@pryen.org>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# Abstract compiler
module abstract_compiler

import literal
import semantize
import platform
import c_tools
private import annotation
import mixin

# Add compiling options
redef class ToolContext
        # --output
        var opt_output = new OptionString("Output file", "-o", "--output")
        # --dir
        var opt_dir = new OptionString("Output directory", "--dir")
        # --no-cc
        var opt_no_cc = new OptionBool("Do not invoke C compiler", "--no-cc")
        # --no-main
        var opt_no_main = new OptionBool("Do not generate main entry point", "--no-main")
        # --make-flags
        var opt_make_flags = new OptionString("Additional options to make", "--make-flags")
        # --max-c-lines
        var opt_max_c_lines = new OptionInt("Maximum number of lines in generated C files. Use 0 for unlimited", 10000, "--max-c-lines")
        # --group-c-files
        var opt_group_c_files = new OptionBool("Group all generated code in the same series of files", "--group-c-files")
        # --compile-dir
        var opt_compile_dir = new OptionString("Directory used to generate temporary files", "--compile-dir")
        # --hardening
        var opt_hardening = new OptionBool("Generate contracts in the C code against bugs in the compiler", "--hardening")
        # --no-check-covariance
        var opt_no_check_covariance = new OptionBool("Disable type tests of covariant parameters (dangerous)", "--no-check-covariance")
        # --no-check-attr-isset
        var opt_no_check_attr_isset = new OptionBool("Disable isset tests before each attribute access (dangerous)", "--no-check-attr-isset")
        # --no-check-assert
        var opt_no_check_assert = new OptionBool("Disable the evaluation of explicit 'assert' and 'as' (dangerous)", "--no-check-assert")
        # --no-check-autocast
        var opt_no_check_autocast = new OptionBool("Disable implicit casts on unsafe expression usage (dangerous)", "--no-check-autocast")
        # --no-check-null
        var opt_no_check_null = new OptionBool("Disable tests of null receiver (dangerous)", "--no-check-null")
        # --no-check-all
        var opt_no_check_all = new OptionBool("Disable all tests (dangerous)", "--no-check-all")
        # --typing-test-metrics
        var opt_typing_test_metrics = new OptionBool("Enable static and dynamic count of all type tests", "--typing-test-metrics")
        # --invocation-metrics
        var opt_invocation_metrics = new OptionBool("Enable static and dynamic count of all method invocations", "--invocation-metrics")
        # --isset-checks-metrics
        var opt_isset_checks_metrics = new OptionBool("Enable static and dynamic count of isset checks before attributes access", "--isset-checks-metrics")
        # --stacktrace
        var opt_stacktrace = new OptionString("Control the generation of stack traces", "--stacktrace")
        # --no-gcc-directives
        var opt_no_gcc_directive = new OptionArray("Disable a advanced gcc directives for optimization", "--no-gcc-directive")
        # --release
        var opt_release = new OptionBool("Compile in release mode and finalize application", "--release")

        redef init
        do
                super
                self.option_context.add_option(self.opt_output, self.opt_dir, self.opt_no_cc, self.opt_no_main, self.opt_make_flags, self.opt_compile_dir, self.opt_hardening)
                self.option_context.add_option(self.opt_no_check_covariance, self.opt_no_check_attr_isset, self.opt_no_check_assert, self.opt_no_check_autocast, self.opt_no_check_null, self.opt_no_check_all)
                self.option_context.add_option(self.opt_typing_test_metrics, self.opt_invocation_metrics, self.opt_isset_checks_metrics)
                self.option_context.add_option(self.opt_stacktrace)
                self.option_context.add_option(self.opt_no_gcc_directive)
                self.option_context.add_option(self.opt_release)
                self.option_context.add_option(self.opt_max_c_lines, self.opt_group_c_files)

                opt_no_main.hidden = true
        end

        redef fun process_options(args)
        do
                super

                var st = opt_stacktrace.value
                if st == "none" or st == "libunwind" or st == "nitstack" then
                        # Fine, do nothing
                else if st == "auto" or st == null then
                        # Default is nitstack
                        opt_stacktrace.value = "nitstack"
                else
                        print "Error: unknown value `{st}` for --stacktrace. Use `none`, `libunwind`, `nitstack` or `auto`."
                        exit(1)
                end

                if opt_output.value != null and opt_dir.value != null then
                        print "Error: cannot use both --dir and --output"
                        exit(1)
                end

                if opt_no_check_all.value then
                        opt_no_check_covariance.value = true
                        opt_no_check_attr_isset.value = true
                        opt_no_check_assert.value = true
                        opt_no_check_autocast.value = true
                        opt_no_check_null.value = true
                end
        end
end

redef class ModelBuilder
        # The compilation directory
        var compile_dir: String

        # Simple indirection to `Toolchain::write_and_make`
        protected fun write_and_make(compiler: AbstractCompiler)
        do
                var platform = compiler.mainmodule.target_platform
                var toolchain
                if platform == null then
                        toolchain = new MakefileToolchain(toolcontext)
                else
                        toolchain = platform.toolchain(toolcontext)
                end
                compile_dir = toolchain.compile_dir
                toolchain.write_and_make compiler
        end
end

redef class Platform
        fun toolchain(toolcontext: ToolContext): Toolchain is abstract
end

class Toolchain
        var toolcontext: ToolContext

        fun compile_dir: String
        do
                var compile_dir = toolcontext.opt_compile_dir.value
                if compile_dir == null then compile_dir = ".nit_compile"
                return compile_dir
        end

        fun write_and_make(compiler: AbstractCompiler) is abstract
end

class MakefileToolchain
        super Toolchain

        redef fun write_and_make(compiler)
        do
                var compile_dir = compile_dir

                # Generate the .h and .c files
                # A single C file regroups many compiled rumtime functions
                # Note that we do not try to be clever an a small change in a Nit source file may change the content of all the generated .c files
                var time0 = get_time
                self.toolcontext.info("*** WRITING C ***", 1)

                compile_dir.mkdir

                var cfiles = new Array[String]
                write_files(compiler, compile_dir, cfiles)

                # Generate the Makefile

                write_makefile(compiler, compile_dir, cfiles)

                var time1 = get_time
                self.toolcontext.info("*** END WRITING C: {time1-time0} ***", 2)

                # Execute the Makefile

                if self.toolcontext.opt_no_cc.value then return

                time0 = time1
                self.toolcontext.info("*** COMPILING C ***", 1)

                compile_c_code(compiler, compile_dir)

                time1 = get_time
                self.toolcontext.info("*** END COMPILING C: {time1-time0} ***", 2)
        end

        fun write_files(compiler: AbstractCompiler, compile_dir: String, cfiles: Array[String])
        do
                var platform = compiler.mainmodule.target_platform
                if self.toolcontext.opt_stacktrace.value == "nitstack" and (platform == null or platform.supports_libunwind) then compiler.build_c_to_nit_bindings
                var cc_opt_with_libgc = "-DWITH_LIBGC"
                if platform != null and not platform.supports_libgc then cc_opt_with_libgc = ""

                # Add gc_choser.h to aditionnal bodies
                var gc_chooser = new ExternCFile("gc_chooser.c", cc_opt_with_libgc)
                if cc_opt_with_libgc != "" then gc_chooser.pkgconfigs.add "bdw-gc"
                compiler.extern_bodies.add(gc_chooser)
                var clib = toolcontext.nit_dir / "clib"
                compiler.files_to_copy.add "{clib}/gc_chooser.c"
                compiler.files_to_copy.add "{clib}/gc_chooser.h"

                # FFI
                for m in compiler.mainmodule.in_importation.greaters do
                        compiler.finalize_ffi_for_module(m)
                end

                # Copy original .[ch] files to compile_dir
                for src in compiler.files_to_copy do
                        var basename = src.basename("")
                        var dst = "{compile_dir}/{basename}"
                        src.file_copy_to dst
                end

                var hfilename = compiler.header.file.name + ".h"
                var hfilepath = "{compile_dir}/{hfilename}"
                var h = new OFStream.open(hfilepath)
                for l in compiler.header.decl_lines do
                        h.write l
                        h.write "\n"
                end
                for l in compiler.header.lines do
                        h.write l
                        h.write "\n"
                end
                h.close

                var max_c_lines = toolcontext.opt_max_c_lines.value
                for f in compiler.files do
                        var i = 0
                        var count = 0
                        var file: nullable OFStream = null
                        for vis in f.writers do
                                if vis == compiler.header then continue
                                var total_lines = vis.lines.length + vis.decl_lines.length
                                if total_lines == 0 then continue
                                count += total_lines
                                if file == null or (count > max_c_lines and max_c_lines > 0) then
                                        i += 1
                                        if file != null then file.close
                                        var cfilename = "{f.name}.{i}.c"
                                        var cfilepath = "{compile_dir}/{cfilename}"
                                        self.toolcontext.info("new C source files to compile: {cfilepath}", 3)
                                        cfiles.add(cfilename)
                                        file = new OFStream.open(cfilepath)
                                        file.write "#include \"{f.name}.0.h\"\n"
                                        count = total_lines
                                end
                                for l in vis.decl_lines do
                                        file.write l
                                        file.write "\n"
                                end
                                for l in vis.lines do
                                        file.write l
                                        file.write "\n"
                                end
                        end
                        if file == null then continue
                        file.close

                        var cfilename = "{f.name}.0.h"
                        var cfilepath = "{compile_dir}/{cfilename}"
                        var hfile: nullable OFStream = null
                        hfile = new OFStream.open(cfilepath)
                        hfile.write "#include \"{hfilename}\"\n"
                        for key in f.required_declarations do
                                if not compiler.provided_declarations.has_key(key) then
                                        var node = compiler.requirers_of_declarations.get_or_null(key)
                                        if node != null then
                                                node.debug "No provided declaration for {key}"
                                        else
                                                print "No provided declaration for {key}"
                                        end
                                        abort
                                end
                                hfile.write compiler.provided_declarations[key]
                                hfile.write "\n"
                        end
                        hfile.close
                end

                self.toolcontext.info("Total C source files to compile: {cfiles.length}", 2)
        end

        fun makefile_name(mainmodule: MModule): String do return "{mainmodule.c_name}.mk"

        fun default_outname(mainmodule: MModule): String
        do
                # Search a non fictive module
                var res = mainmodule.name
                while mainmodule.is_fictive do
                        mainmodule = mainmodule.in_importation.direct_greaters.first
                        res = mainmodule.name
                end
                return res
        end

        # Combine options and platform informations to get the final path of the outfile
        fun outfile(mainmodule: MModule): String
        do
                var res = self.toolcontext.opt_output.value
                if res != null then return res
                res = default_outname(mainmodule)
                var dir = self.toolcontext.opt_dir.value
                if dir != null then return dir.join_path(res)
                return res
        end

        fun write_makefile(compiler: AbstractCompiler, compile_dir: String, cfiles: Array[String])
        do
                var mainmodule = compiler.mainmodule
                var platform = compiler.mainmodule.target_platform

                var outname = outfile(mainmodule)

                var real_outpath = compile_dir.relpath(outname)
                var outpath = real_outpath.escape_to_mk
                if outpath != real_outpath then
                        # If the name is crazy and need escaping, we will do an indirection
                        # 1. generate the binary in the .nit_compile dir under an escaped name
                        # 2. copy the binary at the right place in the `all` goal.
                        outpath = mainmodule.c_name
                end
                var makename = makefile_name(mainmodule)
                var makepath = "{compile_dir}/{makename}"
                var makefile = new OFStream.open(makepath)

                var linker_options = new HashSet[String]
                for m in mainmodule.in_importation.greaters do
                        var libs = m.collect_linker_libs
                        if libs != null then linker_options.add_all(libs)
                end

                makefile.write("CC = ccache cc\nCXX = ccache c++\nCFLAGS = -g -O2 -Wno-unused-value -Wno-switch -Wno-attributes\nCINCL =\nLDFLAGS ?= \nLDLIBS  ?= -lm {linker_options.join(" ")}\n\n")

                var ost = toolcontext.opt_stacktrace.value
                if (ost == "libunwind" or ost == "nitstack") and (platform == null or platform.supports_libunwind) then makefile.write("NEED_LIBUNWIND := YesPlease\n")

                # Dynamic adaptations
                # While `platform` enable complex toolchains, they are statically applied
                # For a dynamic adaptsation of the compilation, the generated Makefile should check and adapt things itself

                # Check and adapt the targeted system
                makefile.write("uname_S := $(shell sh -c 'uname -s 2>/dev/null || echo not')\n")
                makefile.write("ifeq ($(uname_S),Darwin)\n")
                # remove -lunwind since it is already included on macosx
                makefile.write("\tNEED_LIBUNWIND :=\n")
                makefile.write("endif\n\n")

                # Check and adapt for the compiler used
                # clang need an additionnal `-Qunused-arguments`
                makefile.write("clang_check := $(shell sh -c '$(CC) -v 2>&1 | grep -q clang; echo $$?')\nifeq ($(clang_check), 0)\n\tCFLAGS += -Qunused-arguments\nendif\n")

                makefile.write("ifdef NEED_LIBUNWIND\n\tLDLIBS += -lunwind\nendif\n")

                makefile.write("all: {outpath}\n")
                if outpath != real_outpath then
                        makefile.write("\tcp -- {outpath.escape_to_sh} {real_outpath.escape_to_sh.replace("$","$$")}")
                end
                makefile.write("\n")

                var ofiles = new Array[String]
                var dep_rules = new Array[String]
                # Compile each generated file
                for f in cfiles do
                        var o = f.strip_extension(".c") + ".o"
                        makefile.write("{o}: {f}\n\t$(CC) $(CFLAGS) $(CINCL) -c -o {o} {f}\n\n")
                        ofiles.add(o)
                        dep_rules.add(o)
                end

                var java_files = new Array[ExternFile]

                var pkgconfigs = new Array[String]
                for f in compiler.extern_bodies do
                        pkgconfigs.add_all f.pkgconfigs
                end
                # Protect pkg-config
                if not pkgconfigs.is_empty then
                        makefile.write """
# does pkg-config exists?
ifneq ($(shell which pkg-config >/dev/null; echo $$?), 0)
$(error "Command `pkg-config` not found. Please install it")
endif
"""
                        for p in pkgconfigs do
                                makefile.write """
# Check for library {{{p}}}
ifneq ($(shell pkg-config --exists '{{{p}}}'; echo $$?), 0)
$(error "pkg-config: package {{{p}}} is not found.")
endif
"""
                        end
                end

                # Compile each required extern body into a specific .o
                for f in compiler.extern_bodies do
                        var o = f.makefile_rule_name
                        var ff = f.filename.basename("")
                        makefile.write("{o}: {ff}\n")
                        makefile.write("\t{f.makefile_rule_content}\n\n")
                        dep_rules.add(f.makefile_rule_name)

                        if f.compiles_to_o_file then ofiles.add(o)
                        if f.add_to_jar then java_files.add(f)
                end

                if not java_files.is_empty then
                        var jar_file = "{outpath}.jar"

                        var class_files_array = new Array[String]
                        for f in java_files do class_files_array.add(f.makefile_rule_name)
                        var class_files = class_files_array.join(" ")

                        makefile.write("{jar_file}: {class_files}\n")
                        makefile.write("\tjar cf {jar_file} {class_files}\n\n")
                        dep_rules.add jar_file
                end

                # Link edition
                var pkg = ""
                if not pkgconfigs.is_empty then
                        pkg = "`pkg-config --libs {pkgconfigs.join(" ")}`"
                end
                makefile.write("{outpath}: {dep_rules.join(" ")}\n\t$(CC) $(LDFLAGS) -o {outpath.escape_to_sh} {ofiles.join(" ")} $(LDLIBS) {pkg}\n\n")
                # Clean
                makefile.write("clean:\n\trm {ofiles.join(" ")} 2>/dev/null\n")
                if outpath != real_outpath then
                        makefile.write("\trm -- {outpath.escape_to_sh} 2>/dev/null\n")
                end
                makefile.close
                self.toolcontext.info("Generated makefile: {makepath}", 2)

                makepath.file_copy_to "{compile_dir}/Makefile"
        end

        fun compile_c_code(compiler: AbstractCompiler, compile_dir: String)
        do
                var makename = makefile_name(compiler.mainmodule)

                var makeflags = self.toolcontext.opt_make_flags.value
                if makeflags == null then makeflags = ""
                self.toolcontext.info("make -B -C {compile_dir} -f {makename} -j 4 {makeflags}", 2)

                var res
                if self.toolcontext.verbose_level >= 3 then
                        res = sys.system("make -B -C {compile_dir} -f {makename} -j 4 {makeflags} 2>&1")
                else
                        res = sys.system("make -B -C {compile_dir} -f {makename} -j 4 {makeflags} 2>&1 >/dev/null")
                end
                if res != 0 then
                        toolcontext.error(null, "make failed! Error code: {res}.")
                end
        end
end

# Singleton that store the knowledge about the compilation process
abstract class AbstractCompiler
        type VISITOR: AbstractCompilerVisitor

        # Table corresponding c_names to nit names (methods)
        var names = new HashMap[String, String]

        # The main module of the program currently compiled
        # Is assigned during the separate compilation
        var mainmodule: MModule is writable

        # The real main module of the program
        var realmainmodule: MModule is noinit

        # The modelbuilder used to know the model and the AST
        var modelbuilder: ModelBuilder is protected writable

        # Is hardening asked? (see --hardening)
        fun hardening: Bool do return self.modelbuilder.toolcontext.opt_hardening.value

        init
        do
                self.realmainmodule = mainmodule
        end

        # Force the creation of a new file
        # The point is to avoid contamination between must-be-compiled-separately files
        fun new_file(name: String): CodeFile
        do
                if modelbuilder.toolcontext.opt_group_c_files.value then
                        if self.files.is_empty then
                                var f = new CodeFile(mainmodule.c_name)
                                self.files.add(f)
                        end
                        return self.files.first
                end
                var f = new CodeFile(name)
                self.files.add(f)
                return f
        end

        # The list of all associated files
        # Used to generate .c files
        var files = new List[CodeFile]

        # Initialize a visitor specific for a compiler engine
        fun new_visitor: VISITOR is abstract

        # Where global declaration are stored (the main .h)
        var header: CodeWriter is writable, noinit

        # Provide a declaration that can be requested (before or latter) by a visitor
        fun provide_declaration(key: String, s: String)
        do
                if self.provided_declarations.has_key(key) then
                        assert self.provided_declarations[key] == s
                end
                self.provided_declarations[key] = s
        end

        private var provided_declarations = new HashMap[String, String]

        private var requirers_of_declarations = new HashMap[String, ANode]

        # Builds the .c and .h files to be used when generating a Stack Trace
        # Binds the generated C function names to Nit function names
        fun build_c_to_nit_bindings
        do
                var compile_dir = modelbuilder.compile_dir

                var stream = new OFStream.open("{compile_dir}/c_functions_hash.c")
                stream.write("#include <string.h>\n")
                stream.write("#include <stdlib.h>\n")
                stream.write("#include \"c_functions_hash.h\"\n")
                stream.write("typedef struct C_Nit_Names\{char* name; char* nit_name;\}C_Nit_Names;\n")
                stream.write("const char* get_nit_name(register const char* procproc, register unsigned int len)\{\n")
                stream.write("char* procname = malloc(len+1);")
                stream.write("memcpy(procname, procproc, len);")
                stream.write("procname[len] = '\\0';")
                stream.write("static const C_Nit_Names map[{names.length}] = \{\n")
                for i in names.keys do
                        stream.write("\{\"")
                        stream.write(i.escape_to_c)
                        stream.write("\",\"")
                        stream.write(names[i].escape_to_c)
                        stream.write("\"\},\n")
                end
                stream.write("\};\n")
                stream.write("int i;")
                stream.write("for(i = 0; i < {names.length}; i++)\{")
                stream.write("if(strcmp(procname,map[i].name) == 0)\{")
                stream.write("free(procname);")
                stream.write("return map[i].nit_name;")
                stream.write("\}")
                stream.write("\}")
                stream.write("free(procname);")
                stream.write("return NULL;")
                stream.write("\}\n")
                stream.close

                stream = new OFStream.open("{compile_dir}/c_functions_hash.h")
                stream.write("const char* get_nit_name(register const char* procname, register unsigned int len);\n")
                stream.close

                extern_bodies.add(new ExternCFile("{compile_dir}/c_functions_hash.c", ""))
        end

        # Compile C headers
        # This method call compile_header_strucs method that has to be refined
        fun compile_header do
                self.header.add_decl("#include <stdlib.h>")
                self.header.add_decl("#include <stdio.h>")
                self.header.add_decl("#include <string.h>")
                self.header.add_decl("#include \"gc_chooser.h\"")
                self.header.add_decl("#ifdef ANDROID")
                self.header.add_decl("  #include <android/log.h>")
                self.header.add_decl("  #define PRINT_ERROR(...) (void)__android_log_print(ANDROID_LOG_WARN, \"Nit\", __VA_ARGS__)")
                self.header.add_decl("#else")
                self.header.add_decl("  #define PRINT_ERROR(...) fprintf(stderr, __VA_ARGS__)")
                self.header.add_decl("#endif")

                compile_header_structs
                compile_nitni_structs

                var gccd_disable = modelbuilder.toolcontext.opt_no_gcc_directive.value
                if gccd_disable.has("noreturn") or gccd_disable.has("all") then
                        # Signal handler function prototype
                        self.header.add_decl("void show_backtrace(int);")
                else
                        self.header.add_decl("void show_backtrace(int) __attribute__ ((noreturn));")
                end

                if gccd_disable.has("likely") or gccd_disable.has("all") then
                        self.header.add_decl("#define likely(x)       (x)")
                        self.header.add_decl("#define unlikely(x)     (x)")
                else if gccd_disable.has("correct-likely") then
                        # invert the `likely` definition
                        # Used by masochists to bench the worst case
                        self.header.add_decl("#define likely(x)       __builtin_expect((x),0)")
                        self.header.add_decl("#define unlikely(x)     __builtin_expect((x),1)")
                else
                        self.header.add_decl("#define likely(x)       __builtin_expect((x),1)")
                        self.header.add_decl("#define unlikely(x)     __builtin_expect((x),0)")
                end

                # Global variable used by intern methods
                self.header.add_decl("extern int glob_argc;")
                self.header.add_decl("extern char **glob_argv;")
                self.header.add_decl("extern val *glob_sys;")
        end

        # Declaration of structures for live Nit types
        protected fun compile_header_structs is abstract

        # Declaration of structures for nitni undelying the FFI
        protected fun compile_nitni_structs
        do
                self.header.add_decl """
/* Native reference to Nit objects */
/* This structure is used to represent every Nit type in extern methods and custom C code. */
struct nitni_ref {
        struct nitni_ref *next,
                *prev; /* adjacent global references in global list */
        int count; /* number of time this global reference has been marked */
};

/* List of global references from C code to Nit objects */
/* Instanciated empty at init of Nit system and filled explicitly by user in C code */
struct nitni_global_ref_list_t {
        struct nitni_ref *head, *tail;
};
extern struct nitni_global_ref_list_t *nitni_global_ref_list;

/* Initializer of global reference list */
extern void nitni_global_ref_list_init();

/* Intern function to add a global reference to the list */
extern void nitni_global_ref_add( struct nitni_ref *ref );

/* Intern function to remove a global reference from the list */
extern void nitni_global_ref_remove( struct nitni_ref *ref );

/* Increase count on an existing global reference */
extern void nitni_global_ref_incr( struct nitni_ref *ref );

/* Decrease count on an existing global reference */
extern void nitni_global_ref_decr( struct nitni_ref *ref );
"""
        end

        fun compile_finalizer_function
        do
                var finalizable_type = mainmodule.finalizable_type
                if finalizable_type == null then return

                var finalize_meth = mainmodule.try_get_primitive_method("finalize", finalizable_type.mclass)

                if finalize_meth == null then
                        modelbuilder.toolcontext.error(null, "The `Finalizable` class doesn't declare the `finalize` method.")
                        return
                end

                var v = self.new_visitor
                v.add_decl "void gc_finalize (void *obj, void *client_data) \{"
                var recv = v.new_expr("obj", finalizable_type)
                v.send(finalize_meth, [recv])
                v.add "\}"
        end

        # Generate the main C function.
        #
        # This function:
        #
        # * allocate the Sys object if it exists
        # * call init if is exists
        # * call main if it exists
        fun compile_main_function
        do
                var v = self.new_visitor
                v.add_decl("#include <signal.h>")
                var ost = modelbuilder.toolcontext.opt_stacktrace.value
                var platform = mainmodule.target_platform

                if platform != null and not platform.supports_libunwind then ost = "none"

                var no_main = (platform != null and platform.no_main) or modelbuilder.toolcontext.opt_no_main.value

                if ost == "nitstack" or ost == "libunwind" then
                        v.add_decl("#define UNW_LOCAL_ONLY")
                        v.add_decl("#include <libunwind.h>")
                        if ost == "nitstack" then
                                v.add_decl("#include \"c_functions_hash.h\"")
                        end
                end
                v.add_decl("int glob_argc;")
                v.add_decl("char **glob_argv;")
                v.add_decl("val *glob_sys;")

                if self.modelbuilder.toolcontext.opt_typing_test_metrics.value then
                        for tag in count_type_test_tags do
                                v.add_decl("long count_type_test_resolved_{tag};")
                                v.add_decl("long count_type_test_unresolved_{tag};")
                                v.add_decl("long count_type_test_skipped_{tag};")
                                v.compiler.header.add_decl("extern long count_type_test_resolved_{tag};")
                                v.compiler.header.add_decl("extern long count_type_test_unresolved_{tag};")
                                v.compiler.header.add_decl("extern long count_type_test_skipped_{tag};")
                        end
                end

                if self.modelbuilder.toolcontext.opt_invocation_metrics.value then
                        v.add_decl("long count_invoke_by_tables;")
                        v.add_decl("long count_invoke_by_direct;")
                        v.add_decl("long count_invoke_by_inline;")
                        v.compiler.header.add_decl("extern long count_invoke_by_tables;")
                        v.compiler.header.add_decl("extern long count_invoke_by_direct;")
                        v.compiler.header.add_decl("extern long count_invoke_by_inline;")
                end

                if self.modelbuilder.toolcontext.opt_isset_checks_metrics.value then
                        v.add_decl("long count_attr_reads = 0;")
                        v.add_decl("long count_isset_checks = 0;")
                        v.compiler.header.add_decl("extern long count_attr_reads;")
                        v.compiler.header.add_decl("extern long count_isset_checks;")
                end

                v.add_decl("void sig_handler(int signo)\{")
                v.add_decl("PRINT_ERROR(\"Caught signal : %s\\n\", strsignal(signo));")
                v.add_decl("show_backtrace(signo);")
                v.add_decl("\}")

                v.add_decl("void show_backtrace (int signo) \{")
                if ost == "nitstack" or ost == "libunwind" then
                        v.add_decl("char* opt = getenv(\"NIT_NO_STACK\");")
                        v.add_decl("unw_cursor_t cursor;")
                        v.add_decl("if(opt==NULL)\{")
                        v.add_decl("unw_context_t uc;")
                        v.add_decl("unw_word_t ip;")
                        v.add_decl("char* procname = malloc(sizeof(char) * 100);")
                        v.add_decl("unw_getcontext(&uc);")
                        v.add_decl("unw_init_local(&cursor, &uc);")
                        v.add_decl("PRINT_ERROR(\"-------------------------------------------------\\n\");")
                        v.add_decl("PRINT_ERROR(\"--   Stack Trace   ------------------------------\\n\");")
                        v.add_decl("PRINT_ERROR(\"-------------------------------------------------\\n\");")
                        v.add_decl("while (unw_step(&cursor) > 0) \{")
                        v.add_decl("    unw_get_proc_name(&cursor, procname, 100, &ip);")
                        if ost == "nitstack" then
                        v.add_decl("    const char* recv = get_nit_name(procname, strlen(procname));")
                        v.add_decl("    if (recv != NULL)\{")
                        v.add_decl("            PRINT_ERROR(\"` %s\\n\", recv);")
                        v.add_decl("    \}else\{")
                        v.add_decl("            PRINT_ERROR(\"` %s\\n\", procname);")
                        v.add_decl("    \}")
                        else
                        v.add_decl("    PRINT_ERROR(\"` %s \\n\",procname);")
                        end
                        v.add_decl("\}")
                        v.add_decl("PRINT_ERROR(\"-------------------------------------------------\\n\");")
                        v.add_decl("free(procname);")
                        v.add_decl("\}")
                end
                v.add_decl("exit(signo);")
                v.add_decl("\}")

                if no_main then
                        v.add_decl("int nit_main(int argc, char** argv) \{")
                else
                        v.add_decl("int main(int argc, char** argv) \{")
                end

                v.add("signal(SIGABRT, sig_handler);")
                v.add("signal(SIGFPE, sig_handler);")
                v.add("signal(SIGILL, sig_handler);")
                v.add("signal(SIGINT, sig_handler);")
                v.add("signal(SIGTERM, sig_handler);")
                v.add("signal(SIGSEGV, sig_handler);")
                v.add("signal(SIGPIPE, sig_handler);")

                v.add("glob_argc = argc; glob_argv = argv;")
                v.add("initialize_gc_option();")

                v.add "initialize_nitni_global_refs();"

                var main_type = mainmodule.sys_type
                if main_type != null then
                        var mainmodule = v.compiler.mainmodule
                        var glob_sys = v.init_instance(main_type)
                        v.add("glob_sys = {glob_sys};")
                        var main_init = mainmodule.try_get_primitive_method("init", main_type.mclass)
                        if main_init != null then
                                v.send(main_init, [glob_sys])
                        end
                        var main_method = mainmodule.try_get_primitive_method("run", main_type.mclass) or else
                                mainmodule.try_get_primitive_method("main", main_type.mclass)
                        if main_method != null then
                                v.send(main_method, [glob_sys])
                        end
                end

                if self.modelbuilder.toolcontext.opt_typing_test_metrics.value then
                        v.add_decl("long count_type_test_resolved_total = 0;")
                        v.add_decl("long count_type_test_unresolved_total = 0;")
                        v.add_decl("long count_type_test_skipped_total = 0;")
                        v.add_decl("long count_type_test_total_total = 0;")
                        for tag in count_type_test_tags do
                                v.add_decl("long count_type_test_total_{tag};")
                                v.add("count_type_test_total_{tag} = count_type_test_resolved_{tag} + count_type_test_unresolved_{tag} + count_type_test_skipped_{tag};")
                                v.add("count_type_test_resolved_total += count_type_test_resolved_{tag};")
                                v.add("count_type_test_unresolved_total += count_type_test_unresolved_{tag};")
                                v.add("count_type_test_skipped_total += count_type_test_skipped_{tag};")
                                v.add("count_type_test_total_total += count_type_test_total_{tag};")
                        end
                        v.add("printf(\"# dynamic count_type_test: total %l\\n\");")
                        v.add("printf(\"\\tresolved\\tunresolved\\tskipped\\ttotal\\n\");")
                        var tags = count_type_test_tags.to_a
                        tags.add("total")
                        for tag in tags do
                                v.add("printf(\"{tag}\");")
                                v.add("printf(\"\\t%ld (%.2f%%)\", count_type_test_resolved_{tag}, 100.0*count_type_test_resolved_{tag}/count_type_test_total_total);")
                                v.add("printf(\"\\t%ld (%.2f%%)\", count_type_test_unresolved_{tag}, 100.0*count_type_test_unresolved_{tag}/count_type_test_total_total);")
                                v.add("printf(\"\\t%ld (%.2f%%)\", count_type_test_skipped_{tag}, 100.0*count_type_test_skipped_{tag}/count_type_test_total_total);")
                                v.add("printf(\"\\t%ld (%.2f%%)\\n\", count_type_test_total_{tag}, 100.0*count_type_test_total_{tag}/count_type_test_total_total);")
                        end
                end

                if self.modelbuilder.toolcontext.opt_invocation_metrics.value then
                        v.add_decl("long count_invoke_total;")
                        v.add("count_invoke_total = count_invoke_by_tables + count_invoke_by_direct + count_invoke_by_inline;")
                        v.add("printf(\"# dynamic count_invocation: total %ld\\n\", count_invoke_total);")
                        v.add("printf(\"by table: %ld (%.2f%%)\\n\", count_invoke_by_tables, 100.0*count_invoke_by_tables/count_invoke_total);")
                        v.add("printf(\"direct:   %ld (%.2f%%)\\n\", count_invoke_by_direct, 100.0*count_invoke_by_direct/count_invoke_total);")
                        v.add("printf(\"inlined:  %ld (%.2f%%)\\n\", count_invoke_by_inline, 100.0*count_invoke_by_inline/count_invoke_total);")
                end

                if self.modelbuilder.toolcontext.opt_isset_checks_metrics.value then
                        v.add("printf(\"# dynamic attribute reads: %ld\\n\", count_attr_reads);")
                        v.add("printf(\"# dynamic isset checks: %ld\\n\", count_isset_checks);")
                end

                v.add("return 0;")
                v.add("\}")
        end

        # Copile all C functions related to the [incr|decr]_ref features of the FFI
        fun compile_nitni_global_ref_functions
        do
                var v = self.new_visitor
                v.add """
struct nitni_global_ref_list_t *nitni_global_ref_list;
void initialize_nitni_global_refs() {
        nitni_global_ref_list = (struct nitni_global_ref_list_t*)nit_alloc(sizeof(struct nitni_global_ref_list_t));
        nitni_global_ref_list->head = NULL;
        nitni_global_ref_list->tail = NULL;
}

void nitni_global_ref_add( struct nitni_ref *ref ) {
        if ( nitni_global_ref_list->head == NULL ) {
                nitni_global_ref_list->head = ref;
                ref->prev = NULL;
        } else {
                nitni_global_ref_list->tail->next = ref;
                ref->prev = nitni_global_ref_list->tail;
        }
        nitni_global_ref_list->tail = ref;

        ref->next = NULL;
}

void nitni_global_ref_remove( struct nitni_ref *ref ) {
        if ( ref->prev == NULL ) {
                nitni_global_ref_list->head = ref->next;
        } else {
                ref->prev->next = ref->next;
        }

        if ( ref->next == NULL ) {
                nitni_global_ref_list->tail = ref->prev;
        } else {
                ref->next->prev = ref->prev;
        }
}

extern void nitni_global_ref_incr( struct nitni_ref *ref ) {
        if ( ref->count == 0 ) /* not registered */
        {
                /* add to list */
                nitni_global_ref_add( ref );
        }

        ref->count ++;
}

extern void nitni_global_ref_decr( struct nitni_ref *ref ) {
        if ( ref->count == 1 ) /* was last reference */
        {
                /* remove from list */
                nitni_global_ref_remove( ref );
        }

        ref->count --;
}
"""
        end

        # List of additional files required to compile (FFI)
        var extern_bodies = new Array[ExternFile]

        # List of source files to copy over to the compile dir
        var files_to_copy = new Array[String]

        # This is used to avoid adding an extern file more than once
        private var seen_extern = new ArraySet[String]

        # Generate code that initialize the attributes on a new instance
        fun generate_init_attr(v: VISITOR, recv: RuntimeVariable, mtype: MClassType)
        do
                var cds = mtype.collect_mclassdefs(self.mainmodule).to_a
                self.mainmodule.linearize_mclassdefs(cds)
                for cd in cds do
                        for npropdef in modelbuilder.collect_attr_propdef(cd) do
                                npropdef.init_expr(v, recv)
                        end
                end
        end

        # Generate code that check if an attribute is correctly initialized
        fun generate_check_attr(v: VISITOR, recv: RuntimeVariable, mtype: MClassType)
        do
                var cds = mtype.collect_mclassdefs(self.mainmodule).to_a
                self.mainmodule.linearize_mclassdefs(cds)
                for cd in cds do
                        for npropdef in modelbuilder.collect_attr_propdef(cd) do
                                npropdef.check_expr(v, recv)
                        end
                end
        end

        # stats

        var count_type_test_tags: Array[String] = ["isa", "as", "auto", "covariance", "erasure"]
        var count_type_test_resolved: HashMap[String, Int] = init_count_type_test_tags
        var count_type_test_unresolved: HashMap[String, Int] = init_count_type_test_tags
        var count_type_test_skipped: HashMap[String, Int] = init_count_type_test_tags

        protected fun init_count_type_test_tags: HashMap[String, Int]
        do
                var res = new HashMap[String, Int]
                for tag in count_type_test_tags do
                        res[tag] = 0
                end
                return res
        end

        # Display stats about compilation process
        #
        # Metrics used:
        #
        # * type tests against resolved types (`x isa Collection[Animal]`)
        # * type tests against unresolved types (`x isa Collection[E]`)
        # * type tests skipped
        # * type tests total
        fun display_stats
        do
                if self.modelbuilder.toolcontext.opt_typing_test_metrics.value then
                        print "# static count_type_test"
                        print "\tresolved:\tunresolved\tskipped\ttotal"
                        var count_type_test_total = init_count_type_test_tags
                        count_type_test_resolved["total"] = 0
                        count_type_test_unresolved["total"] = 0
                        count_type_test_skipped["total"] = 0
                        count_type_test_total["total"] = 0
                        for tag in count_type_test_tags do
                                count_type_test_total[tag] = count_type_test_resolved[tag] + count_type_test_unresolved[tag] + count_type_test_skipped[tag]
                                count_type_test_resolved["total"] += count_type_test_resolved[tag]
                                count_type_test_unresolved["total"] += count_type_test_unresolved[tag]
                                count_type_test_skipped["total"] += count_type_test_skipped[tag]
                                count_type_test_total["total"] += count_type_test_total[tag]
                        end
                        var count_type_test = count_type_test_total["total"]
                        var tags = count_type_test_tags.to_a
                        tags.add("total")
                        for tag in tags do
                                printn tag
                                printn "\t{count_type_test_resolved[tag]} ({div(count_type_test_resolved[tag],count_type_test)}%)"
                                printn "\t{count_type_test_unresolved[tag]} ({div(count_type_test_unresolved[tag],count_type_test)}%)"
                                printn "\t{count_type_test_skipped[tag]} ({div(count_type_test_skipped[tag],count_type_test)}%)"
                                printn "\t{count_type_test_total[tag]} ({div(count_type_test_total[tag],count_type_test)}%)"
                                print ""
                        end
                end
        end

        fun finalize_ffi_for_module(mmodule: MModule) do mmodule.finalize_ffi(self)

        # Division facility
        # Avoid division by zero by returning the string "n/a"
        fun div(a,b:Int):String
        do
                if b == 0 then return "n/a"
                return ((a*10000/b).to_f / 100.0).to_precision(2)
        end
end

# A file unit (may be more than one file if
# A file unit aim to be autonomous and is made or one or more `CodeWriter`s
class CodeFile
        var name: String
        var writers = new Array[CodeWriter]
        var required_declarations = new HashSet[String]
end

# Where to store generated lines
class CodeWriter
        var file: CodeFile
        var lines: List[String] = new List[String]
        var decl_lines: List[String] = new List[String]

        # Add a line in the main part of the generated C
        fun add(s: String) do self.lines.add(s)

        # Add a line in the
        # (used for local or global declaration)
        fun add_decl(s: String) do self.decl_lines.add(s)

        init
        do
                file.writers.add(self)
        end
end

# A visitor on the AST of property definition that generate the C code.
abstract class AbstractCompilerVisitor

        type COMPILER: AbstractCompiler

        # The associated compiler
        var compiler: COMPILER

        # The current visited AST node
        var current_node: nullable ANode = null is writable

        # The current `Frame`
        var frame: nullable Frame = null is writable

        # Alias for self.compiler.mainmodule.object_type
        fun object_type: MClassType do return self.compiler.mainmodule.object_type

        # Alias for self.compiler.mainmodule.bool_type
        fun bool_type: MClassType do return self.compiler.mainmodule.bool_type

        var writer: CodeWriter is noinit

        init
        do
                self.writer = new CodeWriter(compiler.files.last)
        end

        # Force to get the primitive class named `name` or abort
        fun get_class(name: String): MClass do return self.compiler.mainmodule.get_primitive_class(name)

        # Force to get the primitive property named `name` in the instance `recv` or abort
        fun get_property(name: String, recv: MType): MMethod
        do
                assert recv isa MClassType
                return self.compiler.modelbuilder.force_get_primitive_method(self.current_node, name, recv.mclass, self.compiler.mainmodule)
        end

        fun compile_callsite(callsite: CallSite, arguments: Array[RuntimeVariable]): nullable RuntimeVariable
        do
                var initializers = callsite.mpropdef.initializers
                if not initializers.is_empty then
                        var recv = arguments.first

                        var i = 1
                        for p in initializers do
                                if p isa MMethod then
                                        var args = [recv]
                                        for x in p.intro.msignature.mparameters do
                                                args.add arguments[i]
                                                i += 1
                                        end
                                        self.send(p, args)
                                else if p isa MAttribute then
                                        self.write_attribute(p, recv, arguments[i])
                                        i += 1
                                else abort
                        end
                        assert i == arguments.length

                        return self.send(callsite.mproperty, [recv])
                end

                return self.send(callsite.mproperty, arguments)
        end

        fun native_array_instance(elttype: MType, length: RuntimeVariable): RuntimeVariable is abstract

        fun calloc_array(ret_type: MType, arguments: Array[RuntimeVariable]) is abstract

        fun native_array_def(pname: String, ret_type: nullable MType, arguments: Array[RuntimeVariable]) is abstract

        # Evaluate `args` as expressions in the call of `mpropdef` on `recv`.
        # This method is used to manage varargs in signatures and returns the real array
        # of runtime variables to use in the call.
        fun varargize(mpropdef: MMethodDef, recv: RuntimeVariable, args: SequenceRead[AExpr]): Array[RuntimeVariable]
        do
                var msignature = mpropdef.new_msignature or else mpropdef.msignature.as(not null)
                var res = new Array[RuntimeVariable]
                res.add(recv)

                if args.is_empty then return res

                var vararg_rank = msignature.vararg_rank
                var vararg_len = args.length - msignature.arity
                if vararg_len < 0 then vararg_len = 0

                for i in [0..msignature.arity[ do
                        if i == vararg_rank then
                                var ne = args[i]
                                if ne isa AVarargExpr then
                                        var e = self.expr(ne.n_expr, null)
                                        res.add(e)
                                        continue
                                end
                                var vararg = new Array[RuntimeVariable]
                                for j in [vararg_rank..vararg_rank+vararg_len] do
                                        var e = self.expr(args[j], null)
                                        vararg.add(e)
                                end
                                var elttype = msignature.mparameters[vararg_rank].mtype
                                var arg = self.vararg_instance(mpropdef, recv, vararg, elttype)
                                res.add(arg)
                        else
                                var j = i
                                if i > vararg_rank then j += vararg_len
                                var e = self.expr(args[j], null)
                                res.add(e)
                        end
                end
                return res
        end

        # Type handling

        # Anchor a type to the main module and the current receiver
        fun anchor(mtype: MType): MType
        do
                if not mtype.need_anchor then return mtype
                return mtype.anchor_to(self.compiler.mainmodule, self.frame.receiver)
        end

        fun resolve_for(mtype: MType, recv: RuntimeVariable): MType
        do
                if not mtype.need_anchor then return mtype
                return mtype.resolve_for(recv.mcasttype, self.frame.receiver, self.compiler.mainmodule, true)
        end

        # Unsafely cast a value to a new type
        # ie the result share the same C variable but my have a different mcasttype
        # NOTE: if the adaptation is useless then `value` is returned as it.
        # ENSURE: `result.name == value.name`
        fun autoadapt(value: RuntimeVariable, mtype: MType): RuntimeVariable
        do
                mtype = self.anchor(mtype)
                var valmtype = value.mcasttype
                if valmtype.is_subtype(self.compiler.mainmodule, null, mtype) then
                        return value
                end

                if valmtype isa MNullableType and valmtype.mtype.is_subtype(self.compiler.mainmodule, null, mtype) then
                        var res = new RuntimeVariable(value.name, valmtype, valmtype.mtype)
                        return res
                else
                        var res = new RuntimeVariable(value.name, valmtype, mtype)
                        return res
                end
        end

        # Generate a super call from a method definition
        fun supercall(m: MMethodDef, recvtype: MClassType, args: Array[RuntimeVariable]): nullable RuntimeVariable is abstract

        # Adapt the arguments of a method according to targetted `MMethodDef`
        fun adapt_signature(m: MMethodDef, args: Array[RuntimeVariable]) is abstract

        # Unbox all the arguments of a method when implemented `extern` or `intern`
        fun unbox_signature_extern(m: MMethodDef, args: Array[RuntimeVariable]) is abstract

        # Box or unbox a value to another type iff a C type conversion is needed
        # ENSURE: `result.mtype.ctype == mtype.ctype`
        fun autobox(value: RuntimeVariable, mtype: MType): RuntimeVariable is abstract

        # Box extern classes to be used in the generated code
        fun box_extern(value: RuntimeVariable, mtype: MType): RuntimeVariable is abstract

        # Unbox extern classes to be used in extern code (legacy NI and FFI)
        fun unbox_extern(value: RuntimeVariable, mtype: MType): RuntimeVariable is abstract

        #  Generate a polymorphic subtype test
        fun type_test(value: RuntimeVariable, mtype: MType, tag: String): RuntimeVariable is abstract

        #  Generate the code required to dynamically check if 2 objects share the same runtime type
        fun is_same_type_test(value1, value2: RuntimeVariable): RuntimeVariable is abstract

        #  Generate a Nit "is" for two runtime_variables
        fun equal_test(value1, value2: RuntimeVariable): RuntimeVariable is abstract

        # Sends

        #  Generate a static call on a method definition
        fun call(m: MMethodDef, recvtype: MClassType, args: Array[RuntimeVariable]): nullable RuntimeVariable is abstract

        #  Generate a polymorphic send for the method `m` and the arguments `args`
        fun send(m: MMethod, args: Array[RuntimeVariable]): nullable RuntimeVariable is abstract

        # Generate a monomorphic send for the method `m`, the type `t` and the arguments `args`
        fun monomorphic_send(m: MMethod, t: MType, args: Array[RuntimeVariable]): nullable RuntimeVariable
        do
                assert t isa MClassType
                var propdef = m.lookup_first_definition(self.compiler.mainmodule, t)
                return self.call(propdef, t, args)
        end

        # Generate a monomorphic super send from the method `m`, the type `t` and the arguments `args`
        fun monomorphic_super_send(m: MMethodDef, t: MType, args: Array[RuntimeVariable]): nullable RuntimeVariable
        do
                assert t isa MClassType
                m = m.lookup_next_definition(self.compiler.mainmodule, t)
                return self.call(m, t, args)
        end

        # Attributes handling

        # Generate a polymorphic attribute is_set test
        fun isset_attribute(a: MAttribute, recv: RuntimeVariable): RuntimeVariable is abstract

        # Generate a polymorphic attribute read
        fun read_attribute(a: MAttribute, recv: RuntimeVariable): RuntimeVariable is abstract

        # Generate a polymorphic attribute write
        fun write_attribute(a: MAttribute, recv: RuntimeVariable, value: RuntimeVariable) is abstract

        # Checks

        # Add a check and an abort for a null receiver if needed
        fun check_recv_notnull(recv: RuntimeVariable)
        do
                if self.compiler.modelbuilder.toolcontext.opt_no_check_null.value then return

                var maybenull = recv.mcasttype isa MNullableType or recv.mcasttype isa MNullType
                if maybenull then
                        self.add("if (unlikely({recv} == NULL)) \{")
                        self.add_abort("Receiver is null")
                        self.add("\}")
                end
        end

        # Names handling

        private var names = new HashSet[String]
        private var last: Int = 0

        # Return a new name based on `s` and unique in the visitor
        fun get_name(s: String): String
        do
                if not self.names.has(s) then
                        self.names.add(s)
                        return s
                end
                var i = self.last + 1
                loop
                        var s2 = s + i.to_s
                        if not self.names.has(s2) then
                                self.last = i
                                self.names.add(s2)
                                return s2
                        end
                        i = i + 1
                end
        end

        # Return an unique and stable identifier associated with an escapemark
        fun escapemark_name(e: nullable EscapeMark): String
        do
                assert e != null
                if frame.escapemark_names.has_key(e) then return frame.escapemark_names[e]
                var name = e.name
                if name == null then name = "label"
                name = get_name(name)
                frame.escapemark_names[e] = name
                return name
        end

        # Insert a C label for associated with an escapemark
        fun add_escape_label(e: nullable EscapeMark)
        do
                if e == null then return
                if e.escapes.is_empty then return
                add("BREAK_{escapemark_name(e)}: (void)0;")
        end

        # Return a "const char*" variable associated to the classname of the dynamic type of an object
        # NOTE: we do not return a `RuntimeVariable` "NativeString" as the class may not exist in the module/program
        fun class_name_string(value: RuntimeVariable): String is abstract

        # Variables handling

        protected var variables = new HashMap[Variable, RuntimeVariable]

        # Return the local runtime_variable associated to a Nit local variable
        fun variable(variable: Variable): RuntimeVariable
        do
                if self.variables.has_key(variable) then
                        return self.variables[variable]
                else
                        var name = self.get_name("var_{variable.name}")
                        var mtype = variable.declared_type.as(not null)
                        mtype = self.anchor(mtype)
                        var res = new RuntimeVariable(name, mtype, mtype)
                        self.add_decl("{mtype.ctype} {name} /* var {variable}: {mtype} */;")
                        self.variables[variable] = res
                        return res
                end
        end

        # Return a new uninitialized local runtime_variable
        fun new_var(mtype: MType): RuntimeVariable
        do
                mtype = self.anchor(mtype)
                var name = self.get_name("var")
                var res = new RuntimeVariable(name, mtype, mtype)
                self.add_decl("{mtype.ctype} {name} /* : {mtype} */;")
                return res
        end

        # The difference with `new_var` is the C static type of the local variable
        fun new_var_extern(mtype: MType): RuntimeVariable
        do
                mtype = self.anchor(mtype)
                var name = self.get_name("var")
                var res = new RuntimeVariable(name, mtype, mtype)
                self.add_decl("{mtype.ctype_extern} {name} /* : {mtype} for extern */;")
                return res
        end

        # Return a new uninitialized named runtime_variable
        fun new_named_var(mtype: MType, name: String): RuntimeVariable
        do
                mtype = self.anchor(mtype)
                var res = new RuntimeVariable(name, mtype, mtype)
                self.add_decl("{mtype.ctype} {name} /* : {mtype} */;")
                return res
        end

        # Correctly assign a left and a right value
        # Boxing and unboxing is performed if required
        fun assign(left, right: RuntimeVariable)
        do
                right = self.autobox(right, left.mtype)
                self.add("{left} = {right};")
        end

        # Generate instances

        # Generate a alloc-instance + init-attributes
        fun init_instance(mtype: MClassType): RuntimeVariable is abstract

        # Set a GC finalizer on `recv`, only if `recv` isa Finalizable
        fun set_finalizer(recv: RuntimeVariable)
        do
                var mtype = recv.mtype
                var finalizable_type = compiler.mainmodule.finalizable_type
                if finalizable_type != null and not mtype.need_anchor and
                                mtype.is_subtype(compiler.mainmodule, null, finalizable_type) then
                        add "gc_register_finalizer({recv});"
                end
        end

        # Generate an integer value
        fun int_instance(value: Int): RuntimeVariable
        do
                var res = self.new_var(self.get_class("Int").mclass_type)
                self.add("{res} = {value};")
                return res
        end

        # Generate an integer value
        fun bool_instance(value: Bool): RuntimeVariable
        do
                var res = self.new_var(self.get_class("Bool").mclass_type)
                if value then
                        self.add("{res} = 1;")
                else
                        self.add("{res} = 0;")
                end
                return res
        end

        # Generate a string value
        fun string_instance(string: String): RuntimeVariable
        do
                var mtype = self.get_class("String").mclass_type
                var name = self.get_name("varonce")
                self.add_decl("static {mtype.ctype} {name};")
                var res = self.new_var(mtype)
                self.add("if ({name}) \{")
                self.add("{res} = {name};")
                self.add("\} else \{")
                var native_mtype = self.get_class("NativeString").mclass_type
                var nat = self.new_var(native_mtype)
                self.add("{nat} = \"{string.escape_to_c}\";")
                var length = self.int_instance(string.length)
                self.add("{res} = {self.send(self.get_property("to_s_with_length", native_mtype), [nat, length]).as(not null)};")
                self.add("{name} = {res};")
                self.add("\}")
                return res
        end

        fun value_instance(object: Object): RuntimeVariable
        do
                if object isa Int then
                        return int_instance(object)
                else if object isa Bool then
                        return bool_instance(object)
                else if object isa String then
                        return string_instance(object)
                else
                        abort
                end
        end

        # Generate an array value
        fun array_instance(array: Array[RuntimeVariable], elttype: MType): RuntimeVariable is abstract

        # Get an instance of a array for a vararg
        fun vararg_instance(mpropdef: MPropDef, recv: RuntimeVariable, varargs: Array[RuntimeVariable], elttype: MType): RuntimeVariable is abstract

        # Code generation

        # Add a line in the main part of the generated C
        fun add(s: String) do self.writer.lines.add(s)

        # Add a line in the
        # (used for local or global declaration)
        fun add_decl(s: String) do self.writer.decl_lines.add(s)

        # Request the presence of a global declaration
        fun require_declaration(key: String)
        do
                var reqs = self.writer.file.required_declarations
                if reqs.has(key) then return
                reqs.add(key)
                var node = current_node
                if node != null then compiler.requirers_of_declarations[key] = node
        end

        # Add a declaration in the local-header
        # The declaration is ensured to be present once
        fun declare_once(s: String)
        do
                self.compiler.provide_declaration(s, s)
                self.require_declaration(s)
        end

        # look for a needed .h and .c file for a given .nit source-file
        # FIXME: bad API, parameter should be a `MModule`, not its source-file
        fun add_extern(file: String)
        do
                file = file.strip_extension(".nit")
                var tryfile = file + ".nit.h"
                if tryfile.file_exists then
                        self.declare_once("#include \"{tryfile.basename("")}\"")
                        self.compiler.files_to_copy.add(tryfile)
                end
                tryfile = file + "_nit.h"
                if tryfile.file_exists then
                        self.declare_once("#include \"{tryfile.basename("")}\"")
                        self.compiler.files_to_copy.add(tryfile)
                end

                if self.compiler.seen_extern.has(file) then return
                self.compiler.seen_extern.add(file)
                tryfile = file + ".nit.c"
                if not tryfile.file_exists then
                        tryfile = file + "_nit.c"
                        if not tryfile.file_exists then return
                end
                var f = new ExternCFile(tryfile.basename(""), "")
                self.compiler.extern_bodies.add(f)
                self.compiler.files_to_copy.add(tryfile)
        end

        # Return a new local runtime_variable initialized with the C expression `cexpr`.
        fun new_expr(cexpr: String, mtype: MType): RuntimeVariable
        do
                var res = new_var(mtype)
                self.add("{res} = {cexpr};")
                return res
        end

        # Generate generic abort
        # used by aborts, asserts, casts, etc.
        fun add_abort(message: String)
        do
                self.add("PRINT_ERROR(\"Runtime error: %s\", \"{message.escape_to_c}\");")
                add_raw_abort
        end

        fun add_raw_abort
        do
                if self.current_node != null and self.current_node.location.file != null then
                        self.add("PRINT_ERROR(\" (%s:%d)\\n\", \"{self.current_node.location.file.filename.escape_to_c}\", {current_node.location.line_start});")
                else
                        self.add("PRINT_ERROR(\"\\n\");")
                end
                self.add("show_backtrace(1);")
        end

        # Add a dynamic cast
        fun add_cast(value: RuntimeVariable, mtype: MType, tag: String)
        do
                var res = self.type_test(value, mtype, tag)
                self.add("if (unlikely(!{res})) \{")
                var cn = self.class_name_string(value)
                self.add("PRINT_ERROR(\"Runtime error: Cast failed. Expected `%s`, got `%s`\", \"{mtype.to_s.escape_to_c}\", {cn});")
                self.add_raw_abort
                self.add("\}")
        end

        # Generate a return with the value `s`
        fun ret(s: RuntimeVariable)
        do
                self.assign(self.frame.returnvar.as(not null), s)
                self.add("goto {self.frame.returnlabel.as(not null)};")
        end

        # Compile a statement (if any)
        fun stmt(nexpr: nullable AExpr)
        do
                if nexpr == null then return

                var narray = nexpr.comprehension
                if narray != null then
                        var recv = frame.comprehension.as(not null)
                        var val = expr(nexpr, narray.element_mtype)
                        compile_callsite(narray.push_callsite.as(not null), [recv, val])
                        return
                end

                var old = self.current_node
                self.current_node = nexpr
                nexpr.stmt(self)
                self.current_node = old
        end

        # Compile an expression an return its result
        # `mtype` is the expected return type, pass null if no specific type is expected.
        fun expr(nexpr: AExpr, mtype: nullable MType): RuntimeVariable
        do
                var old = self.current_node
                self.current_node = nexpr
                var res = nexpr.expr(self).as(not null)
                if mtype != null then
                        mtype = self.anchor(mtype)
                        res = self.autobox(res, mtype)
                end
                res = autoadapt(res, nexpr.mtype.as(not null))
                var implicit_cast_to = nexpr.implicit_cast_to
                if implicit_cast_to != null and not self.compiler.modelbuilder.toolcontext.opt_no_check_autocast.value then
                        add_cast(res, implicit_cast_to, "auto")
                        res = autoadapt(res, implicit_cast_to)
                end
                self.current_node = old
                return res
        end

        # Alias for `self.expr(nexpr, self.bool_type)`
        fun expr_bool(nexpr: AExpr): RuntimeVariable do return expr(nexpr, bool_type)

        # Safely show a debug message on the current node and repeat the message in the C code as a comment
        fun debug(message: String)
        do
                var node = self.current_node
                if node == null then
                        print "?: {message}"
                else
                        node.debug(message)
                end
                self.add("/* DEBUG: {message} */")
        end
end

# A C function associated to a Nit method
# Because of customization, a given Nit method can be compiler more that once
abstract class AbstractRuntimeFunction

        type COMPILER: AbstractCompiler
        type VISITOR: AbstractCompilerVisitor

        # The associated Nit method
        var mmethoddef: MMethodDef

        # The mangled c name of the runtime_function
        # Subclasses should redefine `build_c_name` instead
        fun c_name: String
        do
                var res = self.c_name_cache
                if res != null then return res
                res = self.build_c_name
                self.c_name_cache = res
                return res
        end

        # Non cached version of `c_name`
        protected fun build_c_name: String is abstract

        protected var c_name_cache: nullable String = null is writable

        # Implements a call of the runtime_function
        # May inline the body or generate a C function call
        fun call(v: VISITOR, arguments: Array[RuntimeVariable]): nullable RuntimeVariable is abstract

        # Generate the code for the `AbstractRuntimeFunction`
        # Warning: compile more than once compilation makes CC unhappy
        fun compile_to_c(compiler: COMPILER) is abstract
end

# A runtime variable hold a runtime value in C.
# Runtime variables are associated to Nit local variables and intermediate results in Nit expressions.
#
# The tricky point is that a single C variable can be associated to more than one `RuntimeVariable` because the static knowledge of the type of an expression can vary in the C code.
class RuntimeVariable
        # The name of the variable in the C code
        var name: String

        # The static type of the variable (as declard in C)
        var mtype: MType

        # The current casted type of the variable (as known in Nit)
        var mcasttype: MType is writable

        # If the variable exaclty a mcasttype?
        # false (usual value) means that the variable is a mcasttype or a subtype.
        var is_exact: Bool = false is writable

        init
        do
                assert not mtype.need_anchor
                assert not mcasttype.need_anchor
        end

        redef fun to_s do return name

        redef fun inspect
        do
                var exact_str
                if self.is_exact then
                        exact_str = " exact"
                else
                        exact_str = ""
                end
                var type_str
                if self.mtype == self.mcasttype then
                        type_str = "{mtype}{exact_str}"
                else
                        type_str = "{mtype}({mcasttype}{exact_str})"
                end
                return "<{name}:{type_str}>"
        end
end

# A frame correspond to a visited property in a `GlobalCompilerVisitor`
class Frame

        type VISITOR: AbstractCompilerVisitor

        # The associated visitor
        var visitor: VISITOR

        # The executed property.
        # A Method in case of a call, an attribute in case of a default initialization.
        var mpropdef: MPropDef

        # The static type of the receiver
        var receiver: MClassType

        # Arguments of the method (the first is the receiver)
        var arguments: Array[RuntimeVariable]

        # The runtime_variable associated to the return (in a function)
        var returnvar: nullable RuntimeVariable = null is writable

        # The label at the end of the property
        var returnlabel: nullable String = null is writable

        # Labels associated to a each escapemarks.
        # Because of inlinings, escape-marks must be associated to their context (the frame)
        private var escapemark_names = new HashMap[EscapeMark, String]

        # The array comprehension currently filled, if any
        private var comprehension: nullable RuntimeVariable = null
end

redef class MType
        # Return the C type associated to a given Nit static type
        fun ctype: String do return "val*"

        # C type outside of the compiler code and in boxes
        fun ctype_extern: String do return "val*"

        # Short name of the `ctype` to use in unions
        fun ctypename: String do return "val"
end

redef class MClassType

        redef fun ctype: String
        do
                if mclass.name == "Int" then
                        return "long"
                else if mclass.name == "Bool" then
                        return "short int"
                else if mclass.name == "Char" then
                        return "char"
                else if mclass.name == "Float" then
                        return "double"
                else if mclass.name == "NativeString" then
                        return "char*"
                else if mclass.name == "NativeArray" then
                        return "val*"
                else
                        return "val*"
                end
        end

        redef fun ctype_extern: String
        do
                if mclass.kind == extern_kind then
                        return "void*"
                else
                        return ctype
                end
        end

        redef fun ctypename: String
        do
                if mclass.name == "Int" then
                        return "l"
                else if mclass.name == "Bool" then
                        return "s"
                else if mclass.name == "Char" then
                        return "c"
                else if mclass.name == "Float" then
                        return "d"
                else if mclass.name == "NativeString" then
                        return "str"
                else if mclass.name == "NativeArray" then
                        #return "{self.arguments.first.ctype}*"
                        return "val"
                else
                        return "val"
                end
        end
end

redef class MPropDef
        type VISITOR: AbstractCompilerVisitor
end

redef class MMethodDef
        # Can the body be inlined?
        fun can_inline(v: VISITOR): Bool
        do
                if is_abstract then return true
                var modelbuilder = v.compiler.modelbuilder
                var node = modelbuilder.mpropdef2node(self)
                if node isa APropdef then
                        return node.can_inline
                else if node isa AClassdef then
                        # Automatic free init is always inlined since it is empty or contains only attribtes assigments
                        return true
                else
                        abort
                end
        end

        # Inline the body in another visitor
        fun compile_inside_to_c(v: VISITOR, arguments: Array[RuntimeVariable]): nullable RuntimeVariable
        do
                var modelbuilder = v.compiler.modelbuilder
                var val = constant_value
                var node = modelbuilder.mpropdef2node(self)
                if node isa APropdef then
                        var oldnode = v.current_node
                        v.current_node = node
                        self.compile_parameter_check(v, arguments)
                        node.compile_to_c(v, self, arguments)
                        v.current_node = oldnode
                else if node isa AClassdef then
                        var oldnode = v.current_node
                        v.current_node = node
                        self.compile_parameter_check(v, arguments)
                        node.compile_to_c(v, self, arguments)
                        v.current_node = oldnode
                else if val != null then
                        v.ret(v.value_instance(val))
                else
                        abort
                end
                return null
        end

        # Generate type checks in the C code to check covariant parameters
        fun compile_parameter_check(v: VISITOR, arguments: Array[RuntimeVariable])
        do
                if v.compiler.modelbuilder.toolcontext.opt_no_check_covariance.value then return

                for i in [0..msignature.arity[ do
                        # skip test for vararg since the array is instantiated with the correct polymorphic type
                        if msignature.vararg_rank == i then continue

                        # skip if the cast is not required
                        var origmtype =  self.mproperty.intro.msignature.mparameters[i].mtype
                        if not origmtype.need_anchor then continue

                        # get the parameter type
                        var mtype = self.msignature.mparameters[i].mtype

                        # generate the cast
                        # note that v decides if and how to implements the cast
                        v.add("/* Covariant cast for argument {i} ({self.msignature.mparameters[i].name}) {arguments[i+1].inspect} isa {mtype} */")
                        v.add_cast(arguments[i+1], mtype, "covariance")
                end
        end
end

# Node visit

redef class APropdef
        fun compile_to_c(v: AbstractCompilerVisitor, mpropdef: MMethodDef, arguments: Array[RuntimeVariable])
        do
                v.add("PRINT_ERROR(\"NOT YET IMPLEMENTED {class_name} {mpropdef} at {location.to_s}\\n\");")
                debug("Not yet implemented")
        end

        fun can_inline: Bool do return true
end

redef class AMethPropdef
        redef fun compile_to_c(v, mpropdef, arguments)
        do
                if mpropdef.is_abstract then
                        var cn = v.class_name_string(arguments.first)
                        v.add("PRINT_ERROR(\"Runtime error: Abstract method `%s` called on `%s`\", \"{mpropdef.mproperty.name.escape_to_c}\", {cn});")
                        v.add_raw_abort
                        return
                end

                # Call the implicit super-init
                var auto_super_inits = self.auto_super_inits
                if auto_super_inits != null then
                        var args = [arguments.first]
                        for auto_super_init in auto_super_inits do
                                assert auto_super_init.mproperty != mpropdef.mproperty
                                args.clear
                                for i in [0..auto_super_init.msignature.arity+1[ do
                                        args.add(arguments[i])
                                end
                                assert auto_super_init.mproperty != mpropdef.mproperty
                                v.compile_callsite(auto_super_init, args)
                        end
                end
                if auto_super_call then
                        v.supercall(mpropdef, arguments.first.mtype.as(MClassType), arguments)
                end

                # Try special compilation
                if mpropdef.is_intern then
                        if compile_intern_to_c(v, mpropdef, arguments) then return
                else if mpropdef.is_extern then
                        if mpropdef.mproperty.is_init then
                                if compile_externinit_to_c(v, mpropdef, arguments) then return
                        else
                                if compile_externmeth_to_c(v, mpropdef, arguments) then return
                        end
                end

                # Compile block if any
                var n_block = n_block
                if n_block != null then
                        for i in [0..mpropdef.msignature.arity[ do
                                var variable = self.n_signature.n_params[i].variable.as(not null)
                                v.assign(v.variable(variable), arguments[i+1])
                        end
                        v.stmt(n_block)
                        return
                end

                # We have a problem
                var cn = v.class_name_string(arguments.first)
                v.add("PRINT_ERROR(\"Runtime error: uncompiled method `%s` called on `%s`. NOT YET IMPLEMENTED\", \"{mpropdef.mproperty.name.escape_to_c}\", {cn});")
                v.add_raw_abort
        end

        redef fun can_inline
        do
                if self.auto_super_inits != null then return false
                var nblock = self.n_block
                if nblock == null then return true
                if (mpropdef.mproperty.name == "==" or mpropdef.mproperty.name == "!=") and mpropdef.mclassdef.mclass.name == "Object" then return true
                if nblock isa ABlockExpr and nblock.n_expr.length == 0 then return true
                return false
        end

        fun compile_intern_to_c(v: AbstractCompilerVisitor, mpropdef: MMethodDef, arguments: Array[RuntimeVariable]): Bool
        do
                var pname = mpropdef.mproperty.name
                var cname = mpropdef.mclassdef.mclass.name
                var ret = mpropdef.msignature.return_mtype
                if ret != null then
                        ret = v.resolve_for(ret, arguments.first)
                end
                if pname != "==" and pname != "!=" then
                        v.adapt_signature(mpropdef, arguments)
                        v.unbox_signature_extern(mpropdef, arguments)
                end
                if cname == "Int" then
                        if pname == "output" then
                                v.add("printf(\"%ld\\n\", {arguments.first});")
                                return true
                        else if pname == "object_id" then
                                v.ret(arguments.first)
                                return true
                        else if pname == "+" then
                                v.ret(v.new_expr("{arguments[0]} + {arguments[1]}", ret.as(not null)))
                                return true
                        else if pname == "-" then
                                v.ret(v.new_expr("{arguments[0]} - {arguments[1]}", ret.as(not null)))
                                return true
                        else if pname == "unary -" then
                                v.ret(v.new_expr("-{arguments[0]}", ret.as(not null)))
                                return true
                        else if pname == "*" then
                                v.ret(v.new_expr("{arguments[0]} * {arguments[1]}", ret.as(not null)))
                                return true
                        else if pname == "/" then
                                v.ret(v.new_expr("{arguments[0]} / {arguments[1]}", ret.as(not null)))
                                return true
                        else if pname == "%" then
                                v.ret(v.new_expr("{arguments[0]} % {arguments[1]}", ret.as(not null)))
                                return true
                        else if pname == "lshift" then
                                v.ret(v.new_expr("{arguments[0]} << {arguments[1]}", ret.as(not null)))
                                return true
                        else if pname == "rshift" then
                                v.ret(v.new_expr("{arguments[0]} >> {arguments[1]}", ret.as(not null)))
                                return true
                        else if pname == "==" then
                                v.ret(v.equal_test(arguments[0], arguments[1]))
                                return true
                        else if pname == "!=" then
                                var res = v.equal_test(arguments[0], arguments[1])
                                v.ret(v.new_expr("!{res}", ret.as(not null)))
                                return true
                        else if pname == "<" then
                                v.ret(v.new_expr("{arguments[0]} < {arguments[1]}", ret.as(not null)))
                                return true
                        else if pname == ">" then
                                v.ret(v.new_expr("{arguments[0]} > {arguments[1]}", ret.as(not null)))
                                return true
                        else if pname == "<=" then
                                v.ret(v.new_expr("{arguments[0]} <= {arguments[1]}", ret.as(not null)))
                                return true
                        else if pname == ">=" then
                                v.ret(v.new_expr("{arguments[0]} >= {arguments[1]}", ret.as(not null)))
                                return true
                        else if pname == "to_f" then
                                v.ret(v.new_expr("(double){arguments[0]}", ret.as(not null)))
                                return true
                        else if pname == "ascii" then
                                v.ret(v.new_expr("{arguments[0]}", ret.as(not null)))
                                return true
                        end
                else if cname == "Char" then
                        if pname == "output" then
                                v.add("printf(\"%c\", {arguments.first});")
                                return true
                        else if pname == "object_id" then
                                v.ret(v.new_expr("(long){arguments.first}", ret.as(not null)))
                                return true
                        else if pname == "successor" then
                                v.ret(v.new_expr("{arguments[0]} + {arguments[1]}", ret.as(not null)))
                                return true
                        else if pname == "predecessor" then
                                v.ret(v.new_expr("{arguments[0]} - {arguments[1]}", ret.as(not null)))
                                return true
                        else if pname == "==" then
                                v.ret(v.equal_test(arguments[0], arguments[1]))
                                return true
                        else if pname == "!=" then
                                var res = v.equal_test(arguments[0], arguments[1])
                                v.ret(v.new_expr("!{res}", ret.as(not null)))
                                return true
                        else if pname == "<" then
                                v.ret(v.new_expr("{arguments[0]} < {arguments[1]}", ret.as(not null)))
                                return true
                        else if pname == ">" then
                                v.ret(v.new_expr("{arguments[0]} > {arguments[1]}", ret.as(not null)))
                                return true
                        else if pname == "<=" then
                                v.ret(v.new_expr("{arguments[0]} <= {arguments[1]}", ret.as(not null)))
                                return true
                        else if pname == ">=" then
                                v.ret(v.new_expr("{arguments[0]} >= {arguments[1]}", ret.as(not null)))
                                return true
                        else if pname == "to_i" then
                                v.ret(v.new_expr("{arguments[0]}-'0'", ret.as(not null)))
                                return true
                        else if pname == "ascii" then
                                v.ret(v.new_expr("(unsigned char){arguments[0]}", ret.as(not null)))
                                return true
                        end
                else if cname == "Bool" then
                        if pname == "output" then
                                v.add("printf({arguments.first}?\"true\\n\":\"false\\n\");")
                                return true
                        else if pname == "object_id" then
                                v.ret(v.new_expr("(long){arguments.first}", ret.as(not null)))
                                return true
                        else if pname == "==" then
                                v.ret(v.equal_test(arguments[0], arguments[1]))
                                return true
                        else if pname == "!=" then
                                var res = v.equal_test(arguments[0], arguments[1])
                                v.ret(v.new_expr("!{res}", ret.as(not null)))
                                return true
                        end
                else if cname == "Float" then
                        if pname == "output" then
                                v.add("printf(\"%f\\n\", {arguments.first});")
                                return true
                        else if pname == "object_id" then
                                v.ret(v.new_expr("(double){arguments.first}", ret.as(not null)))
                                return true
                        else if pname == "+" then
                                v.ret(v.new_expr("{arguments[0]} + {arguments[1]}", ret.as(not null)))
                                return true
                        else if pname == "-" then
                                v.ret(v.new_expr("{arguments[0]} - {arguments[1]}", ret.as(not null)))
                                return true
                        else if pname == "unary -" then
                                v.ret(v.new_expr("-{arguments[0]}", ret.as(not null)))
                                return true
                        else if pname == "succ" then
                                v.ret(v.new_expr("{arguments[0]}+1", ret.as(not null)))
                                return true
                        else if pname == "prec" then
                                v.ret(v.new_expr("{arguments[0]}-1", ret.as(not null)))
                                return true
                        else if pname == "*" then
                                v.ret(v.new_expr("{arguments[0]} * {arguments[1]}", ret.as(not null)))
                                return true
                        else if pname == "/" then
                                v.ret(v.new_expr("{arguments[0]} / {arguments[1]}", ret.as(not null)))
                                return true
                        else if pname == "==" then
                                v.ret(v.equal_test(arguments[0], arguments[1]))
                                return true
                        else if pname == "!=" then
                                var res = v.equal_test(arguments[0], arguments[1])
                                v.ret(v.new_expr("!{res}", ret.as(not null)))
                                return true
                        else if pname == "<" then
                                v.ret(v.new_expr("{arguments[0]} < {arguments[1]}", ret.as(not null)))
                                return true
                        else if pname == ">" then
                                v.ret(v.new_expr("{arguments[0]} > {arguments[1]}", ret.as(not null)))
                                return true
                        else if pname == "<=" then
                                v.ret(v.new_expr("{arguments[0]} <= {arguments[1]}", ret.as(not null)))
                                return true
                        else if pname == ">=" then
                                v.ret(v.new_expr("{arguments[0]} >= {arguments[1]}", ret.as(not null)))
                                return true
                        else if pname == "to_i" then
                                v.ret(v.new_expr("(long){arguments[0]}", ret.as(not null)))
                                return true
                        end
                else if cname == "NativeString" then
                        if pname == "[]" then
                                v.ret(v.new_expr("{arguments[0]}[{arguments[1]}]", ret.as(not null)))
                                return true
                        else if pname == "[]=" then
                                v.add("{arguments[0]}[{arguments[1]}]={arguments[2]};")
                                return true
                        else if pname == "copy_to" then
                                v.add("memmove({arguments[1]}+{arguments[4]},{arguments[0]}+{arguments[3]},{arguments[2]});")
                                return true
                        else if pname == "atoi" then
                                v.ret(v.new_expr("atoi({arguments[0]});", ret.as(not null)))
                                return true
                        else if pname == "new" then
                                v.ret(v.new_expr("(char*)nit_alloc({arguments[1]})", ret.as(not null)))
                                return true
                        end
                else if cname == "NativeArray" then
                        v.native_array_def(pname, ret, arguments)
                        return true
                end
                if pname == "exit" then
                        v.add("exit({arguments[1]});")
                        return true
                else if pname == "sys" then
                        v.ret(v.new_expr("glob_sys", ret.as(not null)))
                        return true
                else if pname == "calloc_string" then
                        v.ret(v.new_expr("(char*)nit_alloc({arguments[1]})", ret.as(not null)))
                        return true
                else if pname == "calloc_array" then
                        v.calloc_array(ret.as(not null), arguments)
                        return true
                else if pname == "object_id" then
                        v.ret(v.new_expr("(long){arguments.first}", ret.as(not null)))
                        return true
                else if pname == "is_same_type" then
                        v.ret(v.is_same_type_test(arguments[0], arguments[1]))
                        return true
                else if pname == "is_same_instance" then
                        v.ret(v.equal_test(arguments[0], arguments[1]))
                        return true
                else if pname == "output_class_name" then
                        var nat = v.class_name_string(arguments.first)
                        v.add("printf(\"%s\\n\", {nat});")
                        return true
                else if pname == "native_class_name" then
                        var nat = v.class_name_string(arguments.first)
                        v.ret(v.new_expr("(char*){nat}", ret.as(not null)))
                        return true
                else if pname == "force_garbage_collection" then
                        v.add("nit_gcollect();")
                        return true
                else if pname == "native_argc" then
                        v.ret(v.new_expr("glob_argc", ret.as(not null)))
                        return true
                else if pname == "native_argv" then
                        v.ret(v.new_expr("glob_argv[{arguments[1]}]", ret.as(not null)))
                        return true
                end
                return false
        end

        # Compile an extern method
        # Return `true` if the compilation was successful, `false` if a fall-back is needed
        fun compile_externmeth_to_c(v: AbstractCompilerVisitor, mpropdef: MMethodDef, arguments: Array[RuntimeVariable]): Bool
        do
                var externname
                var at = self.get_single_annotation("extern", v.compiler.modelbuilder)
                if at != null and at.n_args.length == 1 then
                        externname = at.arg_as_string(v.compiler.modelbuilder)
                        if externname == null then return false
                else
                        return false
                end
                if location.file != null then
                        var file = location.file.filename
                        v.add_extern(file)
                end
                var res: nullable RuntimeVariable = null
                var ret = mpropdef.msignature.return_mtype
                if ret != null then
                        ret = v.resolve_for(ret, arguments.first)
                        res = v.new_var_extern(ret)
                end
                v.adapt_signature(mpropdef, arguments)
                v.unbox_signature_extern(mpropdef, arguments)

                if res == null then
                        v.add("{externname}({arguments.join(", ")});")
                else
                        v.add("{res} = {externname}({arguments.join(", ")});")
                        res = v.box_extern(res, ret.as(not null))
                        v.ret(res)
                end
                return true
        end

        # Compile an extern factory
        # Return `true` if the compilation was successful, `false` if a fall-back is needed
        fun compile_externinit_to_c(v: AbstractCompilerVisitor, mpropdef: MMethodDef, arguments: Array[RuntimeVariable]): Bool
        do
                var externname
                var at = self.get_single_annotation("extern", v.compiler.modelbuilder)
                if at != null then
                        externname = at.arg_as_string(v.compiler.modelbuilder)
                        if externname == null then return false
                else
                        return false
                end
                if location.file != null then
                        var file = location.file.filename
                        v.add_extern(file)
                end
                v.adapt_signature(mpropdef, arguments)
                v.unbox_signature_extern(mpropdef, arguments)
                var ret = arguments.first.mtype
                var res = v.new_var_extern(ret)

                arguments.shift

                v.add("{res} = {externname}({arguments.join(", ")});")
                res = v.box_extern(res, ret)
                v.ret(res)
                return true
        end
end

redef class AAttrPropdef
        redef fun can_inline: Bool do return not is_lazy

        redef fun compile_to_c(v, mpropdef, arguments)
        do
                if mpropdef == mreadpropdef then
                        assert arguments.length == 1
                        var recv = arguments.first
                        var res
                        if is_lazy then
                                var set
                                var ret = self.mpropdef.static_mtype
                                var useiset = ret.ctype == "val*" and not ret isa MNullableType
                                var guard = self.mlazypropdef.mproperty
                                if useiset then
                                        set = v.isset_attribute(self.mpropdef.mproperty, recv)
                                else
                                        set = v.read_attribute(guard, recv)
                                end
                                v.add("if(likely({set})) \{")
                                res = v.read_attribute(self.mpropdef.mproperty, recv)
                                v.add("\} else \{")

                                var value = evaluate_expr(v, recv)

                                v.assign(res, value)
                                if not useiset then
                                        var true_v = v.new_expr("1", v.bool_type)
                                        v.write_attribute(guard, arguments.first, true_v)
                                end
                                v.add("\}")
                        else
                                res = v.read_attribute(self.mpropdef.mproperty, arguments.first)
                        end
                        v.assign(v.frame.returnvar.as(not null), res)
                else if mpropdef == mwritepropdef then
                        assert arguments.length == 2
                        v.write_attribute(self.mpropdef.mproperty, arguments.first, arguments[1])
                        if is_lazy then
                                var ret = self.mpropdef.static_mtype
                                var useiset = ret.ctype == "val*" and not ret isa MNullableType
                                if not useiset then
                                        v.write_attribute(self.mlazypropdef.mproperty, arguments.first, v.new_expr("1", v.bool_type))
                                end
                        end
                else
                        abort
                end
        end

        fun init_expr(v: AbstractCompilerVisitor, recv: RuntimeVariable)
        do
                if has_value and not is_lazy then evaluate_expr(v, recv)
        end

        # Evaluate, store and return the default value of the attribute
        private fun evaluate_expr(v: AbstractCompilerVisitor, recv: RuntimeVariable): RuntimeVariable
        do
                var oldnode = v.current_node
                v.current_node = self
                var old_frame = v.frame
                var frame = new Frame(v, self.mpropdef.as(not null), recv.mcasttype.as_notnullable.as(MClassType), [recv])
                v.frame = frame

                var value
                var mtype = self.mpropdef.static_mtype
                assert mtype != null

                var nexpr = self.n_expr
                var nblock = self.n_block
                if nexpr != null then
                        value = v.expr(nexpr, mtype)
                else if nblock != null then
                        value = v.new_var(mtype)
                        frame.returnvar = value
                        frame.returnlabel = v.get_name("RET_LABEL")
                        v.add("\{")
                        v.stmt(nblock)
                        v.add("{frame.returnlabel.as(not null)}:(void)0;")
                        v.add("\}")
                else
                        abort
                end

                v.write_attribute(self.mpropdef.mproperty, recv, value)

                v.frame = old_frame
                v.current_node = oldnode

                return value
        end

        fun check_expr(v: AbstractCompilerVisitor, recv: RuntimeVariable)
        do
                var nexpr = self.n_expr
                if nexpr != null then return

                var oldnode = v.current_node
                v.current_node = self
                var old_frame = v.frame
                var frame = new Frame(v, self.mpropdef.as(not null), recv.mtype.as(MClassType), [recv])
                v.frame = frame
                # Force read to check the initialization
                v.read_attribute(self.mpropdef.mproperty, recv)
                v.frame = old_frame
                v.current_node = oldnode
        end
end

redef class AClassdef
        private fun compile_to_c(v: AbstractCompilerVisitor, mpropdef: MMethodDef, arguments: Array[RuntimeVariable])
        do
                if mpropdef == self.mfree_init then
                        assert mpropdef.mproperty.is_root_init
                        assert arguments.length == 1
                        if not mpropdef.is_intro then
                                v.supercall(mpropdef, arguments.first.mtype.as(MClassType), arguments)
                        end
                        return
                else
                        abort
                end
        end
end

redef class AExpr
        # Try to compile self as an expression
        # Do not call this method directly, use `v.expr` instead
        private fun expr(v: AbstractCompilerVisitor): nullable RuntimeVariable
        do
                v.add("PRINT_ERROR(\"NOT YET IMPLEMENTED {class_name}:{location.to_s}\\n\");")
                var mtype = self.mtype
                if mtype == null then
                        return null
                else
                        var res = v.new_var(mtype)
                        v.add("/* {res} = NOT YET {class_name} */")
                        return res
                end
        end

        # Try to compile self as a statement
        # Do not call this method directly, use `v.stmt` instead
        private fun stmt(v: AbstractCompilerVisitor)
        do
                expr(v)
        end
end

redef class ABlockExpr
        redef fun stmt(v)
        do
                for e in self.n_expr do v.stmt(e)
        end
        redef fun expr(v)
        do
                var last = self.n_expr.last
                for e in self.n_expr do
                        if e == last then break
                        v.stmt(e)
                end
                return v.expr(last, null)
        end
end

redef class AVardeclExpr
        redef fun stmt(v)
        do
                var variable = self.variable.as(not null)
                var ne = self.n_expr
                if ne != null then
                        var i = v.expr(ne, variable.declared_type)
                        v.assign(v.variable(variable), i)
                end
        end
end

redef class AVarExpr
        redef fun expr(v)
        do
                var res = v.variable(self.variable.as(not null))
                var mtype = self.mtype.as(not null)
                return v.autoadapt(res, mtype)
        end
end

redef class AVarAssignExpr
        redef fun expr(v)
        do
                var variable = self.variable.as(not null)
                var i = v.expr(self.n_value, variable.declared_type)
                v.assign(v.variable(variable), i)
                return i
        end
end

redef class AVarReassignExpr
        redef fun stmt(v)
        do
                var variable = self.variable.as(not null)
                var vari = v.variable(variable)
                var value = v.expr(self.n_value, variable.declared_type)
                var res = v.compile_callsite(self.reassign_callsite.as(not null), [vari, value])
                assert res != null
                v.assign(v.variable(variable), res)
        end
end

redef class ASelfExpr
        redef fun expr(v) do return v.frame.arguments.first
end

redef class AEscapeExpr
        redef fun stmt(v) do v.add("goto BREAK_{v.escapemark_name(self.escapemark)};")
end

redef class AReturnExpr
        redef fun stmt(v)
        do
                var nexpr = self.n_expr
                if nexpr != null then
                        var returnvar = v.frame.returnvar.as(not null)
                        var i = v.expr(nexpr, returnvar.mtype)
                        v.assign(returnvar, i)
                end
                v.add("goto {v.frame.returnlabel.as(not null)};")
        end
end

redef class AAbortExpr
        redef fun stmt(v) do v.add_abort("Aborted")
end

redef class AIfExpr
        redef fun stmt(v)
        do
                var cond = v.expr_bool(self.n_expr)
                v.add("if ({cond})\{")
                v.stmt(self.n_then)
                v.add("\} else \{")
                v.stmt(self.n_else)
                v.add("\}")
        end

        redef fun expr(v)
        do
                var res = v.new_var(self.mtype.as(not null))
                var cond = v.expr_bool(self.n_expr)
                v.add("if ({cond})\{")
                v.assign(res, v.expr(self.n_then.as(not null), null))
                v.add("\} else \{")
                v.assign(res, v.expr(self.n_else.as(not null), null))
                v.add("\}")
                return res
        end
end

redef class AIfexprExpr
        redef fun expr(v)
        do
                var res = v.new_var(self.mtype.as(not null))
                var cond = v.expr_bool(self.n_expr)
                v.add("if ({cond})\{")
                v.assign(res, v.expr(self.n_then, null))
                v.add("\} else \{")
                v.assign(res, v.expr(self.n_else, null))
                v.add("\}")
                return res
        end
end

redef class ADoExpr
        redef fun stmt(v)
        do
                v.stmt(self.n_block)
                v.add_escape_label(break_mark)
        end
end

redef class AWhileExpr
        redef fun stmt(v)
        do
                v.add("for(;;) \{")
                var cond = v.expr_bool(self.n_expr)
                v.add("if (!{cond}) break;")
                v.stmt(self.n_block)
                v.add_escape_label(continue_mark)
                v.add("\}")
                v.add_escape_label(break_mark)
        end
end

redef class ALoopExpr
        redef fun stmt(v)
        do
                v.add("for(;;) \{")
                v.stmt(self.n_block)
                v.add_escape_label(continue_mark)
                v.add("\}")
                v.add_escape_label(break_mark)
        end
end

redef class AForExpr
        redef fun stmt(v)
        do
                var cl = v.expr(self.n_expr, null)
                var it_meth = self.method_iterator
                assert it_meth != null
                var it = v.compile_callsite(it_meth, [cl])
                assert it != null
                v.add("for(;;) \{")
                var isok_meth = self.method_is_ok
                assert isok_meth != null
                var ok = v.compile_callsite(isok_meth, [it])
                assert ok != null
                v.add("if(!{ok}) break;")
                if self.variables.length == 1 then
                        var item_meth = self.method_item
                        assert item_meth != null
                        var i = v.compile_callsite(item_meth, [it])
                        assert i != null
                        v.assign(v.variable(variables.first), i)
                else if self.variables.length == 2 then
                        var key_meth = self.method_key
                        assert key_meth != null
                        var i = v.compile_callsite(key_meth, [it])
                        assert i != null
                        v.assign(v.variable(variables[0]), i)
                        var item_meth = self.method_item
                        assert item_meth != null
                        i = v.compile_callsite(item_meth, [it])
                        assert i != null
                        v.assign(v.variable(variables[1]), i)
                else
                        abort
                end
                v.stmt(self.n_block)
                v.add_escape_label(continue_mark)
                var next_meth = self.method_next
                assert next_meth != null
                v.compile_callsite(next_meth, [it])
                v.add("\}")
                v.add_escape_label(break_mark)

                var method_finish = self.method_finish
                if method_finish != null then
                        # TODO: Find a way to call this also in long escape (e.g. return)
                        v.compile_callsite(method_finish, [it])
                end
        end
end

redef class AAssertExpr
        redef fun stmt(v)
        do
                if v.compiler.modelbuilder.toolcontext.opt_no_check_assert.value then return

                var cond = v.expr_bool(self.n_expr)
                v.add("if (unlikely(!{cond})) \{")
                v.stmt(self.n_else)
                var nid = self.n_id
                if nid != null then
                        v.add_abort("Assert '{nid.text}' failed")
                else
                        v.add_abort("Assert failed")
                end
                v.add("\}")
        end
end

redef class AOrExpr
        redef fun expr(v)
        do
                var res = v.new_var(self.mtype.as(not null))
                var i1 = v.expr_bool(self.n_expr)
                v.add("if ({i1}) \{")
                v.add("{res} = 1;")
                v.add("\} else \{")
                var i2 = v.expr_bool(self.n_expr2)
                v.add("{res} = {i2};")
                v.add("\}")
                return res
        end
end

redef class AImpliesExpr
        redef fun expr(v)
        do
                var res = v.new_var(self.mtype.as(not null))
                var i1 = v.expr_bool(self.n_expr)
                v.add("if (!{i1}) \{")
                v.add("{res} = 1;")
                v.add("\} else \{")
                var i2 = v.expr_bool(self.n_expr2)
                v.add("{res} = {i2};")
                v.add("\}")
                return res
        end
end

redef class AAndExpr
        redef fun expr(v)
        do
                var res = v.new_var(self.mtype.as(not null))
                var i1 = v.expr_bool(self.n_expr)
                v.add("if (!{i1}) \{")
                v.add("{res} = 0;")
                v.add("\} else \{")
                var i2 = v.expr_bool(self.n_expr2)
                v.add("{res} = {i2};")
                v.add("\}")
                return res
        end
end

redef class ANotExpr
        redef fun expr(v)
        do
                var cond = v.expr_bool(self.n_expr)
                return v.new_expr("!{cond}", self.mtype.as(not null))
        end
end

redef class AOrElseExpr
        redef fun expr(v)
        do
                var res = v.new_var(self.mtype.as(not null))
                var i1 = v.expr(self.n_expr, null)
                v.add("if ({i1}!=NULL) \{")
                v.assign(res, i1)
                v.add("\} else \{")
                var i2 = v.expr(self.n_expr2, null)
                v.assign(res, i2)
                v.add("\}")
                return res
        end
end

redef class AIntExpr
        redef fun expr(v) do return v.new_expr("{self.value.to_s}", self.mtype.as(not null))
end

redef class AFloatExpr
        redef fun expr(v) do return v.new_expr("{self.n_float.text}", self.mtype.as(not null)) # FIXME use value, not n_float
end

redef class ACharExpr
        redef fun expr(v) do return v.new_expr("'{self.value.to_s.escape_to_c}'", self.mtype.as(not null))
end

redef class AArrayExpr
        redef fun expr(v)
        do
                var mtype = self.element_mtype.as(not null)
                var array = new Array[RuntimeVariable]
                var res = v.array_instance(array, mtype)

                var old_comprehension = v.frame.comprehension
                v.frame.comprehension = res
                for nexpr in self.n_exprs do
                        v.stmt(nexpr)
                end
                v.frame.comprehension = old_comprehension

                return res
        end
end

redef class AStringFormExpr
        redef fun expr(v) do return v.string_instance(self.value.as(not null))
end

redef class ASuperstringExpr
        redef fun expr(v)
        do
                var array = new Array[RuntimeVariable]
                for ne in self.n_exprs do
                        if ne isa AStringFormExpr and ne.value == "" then continue # skip empty sub-strings
                        var i = v.expr(ne, null)
                        array.add(i)
                end
                var a = v.array_instance(array, v.object_type)
                var res = v.send(v.get_property("to_s", a.mtype), [a])
                return res
        end
end

redef class ACrangeExpr
        redef fun expr(v)
        do
                var i1 = v.expr(self.n_expr, null)
                var i2 = v.expr(self.n_expr2, null)
                var mtype = self.mtype.as(MClassType)
                var res = v.init_instance(mtype)
                v.compile_callsite(init_callsite.as(not null), [res, i1, i2])
                return res
        end
end

redef class AOrangeExpr
        redef fun expr(v)
        do
                var i1 = v.expr(self.n_expr, null)
                var i2 = v.expr(self.n_expr2, null)
                var mtype = self.mtype.as(MClassType)
                var res = v.init_instance(mtype)
                v.compile_callsite(init_callsite.as(not null), [res, i1, i2])
                return res
        end
end

redef class ATrueExpr
        redef fun expr(v) do return v.new_expr("1", self.mtype.as(not null))
end

redef class AFalseExpr
        redef fun expr(v) do return v.new_expr("0", self.mtype.as(not null))
end

redef class ANullExpr
        redef fun expr(v) do return v.new_expr("NULL", self.mtype.as(not null))
end

redef class AIsaExpr
        redef fun expr(v)
        do
                var i = v.expr(self.n_expr, null)
                return v.type_test(i, self.cast_type.as(not null), "isa")
        end
end

redef class AAsCastExpr
        redef fun expr(v)
        do
                var i = v.expr(self.n_expr, null)
                if v.compiler.modelbuilder.toolcontext.opt_no_check_assert.value then return i

                v.add_cast(i, self.mtype.as(not null), "as")
                return i
        end
end

redef class AAsNotnullExpr
        redef fun expr(v)
        do
                var i = v.expr(self.n_expr, null)
                if v.compiler.modelbuilder.toolcontext.opt_no_check_assert.value then return i

                if i.mtype.ctype != "val*" then return i

                v.add("if (unlikely({i} == NULL)) \{")
                v.add_abort("Cast failed")
                v.add("\}")
                return i
        end
end

redef class AParExpr
        redef fun expr(v) do return v.expr(self.n_expr, null)
end

redef class AOnceExpr
        redef fun expr(v)
        do
                var mtype = self.mtype.as(not null)
                var name = v.get_name("varonce")
                var guard = v.get_name(name + "_guard")
                v.add_decl("static {mtype.ctype} {name};")
                v.add_decl("static int {guard};")
                var res = v.new_var(mtype)
                v.add("if ({guard}) \{")
                v.add("{res} = {name};")
                v.add("\} else \{")
                var i = v.expr(self.n_expr, mtype)
                v.add("{res} = {i};")
                v.add("{name} = {res};")
                v.add("{guard} = 1;")
                v.add("\}")
                return res
        end
end

redef class ASendExpr
        redef fun expr(v)
        do
                var recv = v.expr(self.n_expr, null)
                var callsite = self.callsite.as(not null)
                var args = v.varargize(callsite.mpropdef, recv, self.raw_arguments)
                return v.compile_callsite(callsite, args)
        end
end

redef class ASendReassignFormExpr
        redef fun stmt(v)
        do
                var recv = v.expr(self.n_expr, null)
                var callsite = self.callsite.as(not null)
                var args = v.varargize(callsite.mpropdef, recv, self.raw_arguments)

                var value = v.expr(self.n_value, null)

                var left = v.compile_callsite(callsite, args)
                assert left != null

                var res = v.compile_callsite(self.reassign_callsite.as(not null), [left, value])
                assert res != null

                args.add(res)
                v.compile_callsite(self.write_callsite.as(not null), args)
        end
end

redef class ASuperExpr
        redef fun expr(v)
        do
                var recv = v.frame.arguments.first

                var callsite = self.callsite
                if callsite != null then
                        var args = v.varargize(callsite.mpropdef, recv, self.n_args.n_exprs)

                        # Add additional arguments for the super init call
                        if args.length == 1 then
                                for i in [0..callsite.msignature.arity[ do
                                        args.add(v.frame.arguments[i+1])
                                end
                        end
                        # Super init call
                        var res = v.compile_callsite(callsite, args)
                        return res
                end

                var mpropdef = self.mpropdef.as(not null)
                var args = v.varargize(mpropdef, recv, self.n_args.n_exprs)
                if args.length == 1 then
                        args = v.frame.arguments
                end

                # stantard call-next-method
                return v.supercall(mpropdef, recv.mtype.as(MClassType), args)
        end
end

redef class ANewExpr
        redef fun expr(v)
        do
                var mtype = self.recvtype
                assert mtype != null
                var recv
                var ctype = mtype.ctype
                if mtype.mclass.name == "NativeArray" then
                        assert self.n_args.n_exprs.length == 1
                        var l = v.expr(self.n_args.n_exprs.first, null)
                        assert mtype isa MGenericType
                        var elttype = mtype.arguments.first
                        return v.native_array_instance(elttype, l)
                else if ctype == "val*" then
                        recv = v.init_instance(mtype)
                else if ctype == "char*" then
                        recv = v.new_expr("NULL/*special!*/", mtype)
                else
                        recv = v.new_expr("({ctype})0/*special!*/", mtype)
                end

                var callsite = self.callsite.as(not null)
                var args = v.varargize(callsite.mpropdef, recv, self.n_args.n_exprs)
                var res2 = v.compile_callsite(callsite, args)
                if res2 != null then
                        #self.debug("got {res2} from {mproperty}. drop {recv}")
                        return res2
                end
                return recv
        end
end

redef class AAttrExpr
        redef fun expr(v)
        do
                var recv = v.expr(self.n_expr, null)
                var mproperty = self.mproperty.as(not null)
                return v.read_attribute(mproperty, recv)
        end
end

redef class AAttrAssignExpr
        redef fun expr(v)
        do
                var recv = v.expr(self.n_expr, null)
                var i = v.expr(self.n_value, null)
                var mproperty = self.mproperty.as(not null)
                v.write_attribute(mproperty, recv, i)
                return i
        end
end

redef class AAttrReassignExpr
        redef fun stmt(v)
        do
                var recv = v.expr(self.n_expr, null)
                var value = v.expr(self.n_value, null)
                var mproperty = self.mproperty.as(not null)
                var attr = v.read_attribute(mproperty, recv)
                var res = v.compile_callsite(self.reassign_callsite.as(not null), [attr, value])
                assert res != null
                v.write_attribute(mproperty, recv, res)
        end
end

redef class AIssetAttrExpr
        redef fun expr(v)
        do
                var recv = v.expr(self.n_expr, null)
                var mproperty = self.mproperty.as(not null)
                return v.isset_attribute(mproperty, recv)
        end
end

redef class ADebugTypeExpr
        redef fun stmt(v)
        do
                # do nothing
        end
end

# Utils

redef class Array[E]
        # Return a new `Array` with the elements only contened in self and not in `o`
        fun -(o: Array[E]): Array[E] do
                var res = new Array[E]
                for e in self do if not o.has(e) then res.add(e)
                return res
        end
end

redef class MModule
        # All `MProperty` associated to all `MClassDef` of `mclass`
        fun properties(mclass: MClass): Set[MProperty] do
                if not self.properties_cache.has_key(mclass) then
                        var properties = new HashSet[MProperty]
                        var parents = new Array[MClass]
                        if self.flatten_mclass_hierarchy.has(mclass) then
                                parents.add_all(mclass.in_hierarchy(self).direct_greaters)
                        end
                        for parent in parents do
                                properties.add_all(self.properties(parent))
                        end
                        for mclassdef in mclass.mclassdefs do
                                if not self.in_importation <= mclassdef.mmodule then continue
                                for mprop in mclassdef.intro_mproperties do
                                        properties.add(mprop)
                                end
                        end
                        self.properties_cache[mclass] = properties
                end
                return properties_cache[mclass]
        end
        private var properties_cache: Map[MClass, Set[MProperty]] = new HashMap[MClass, Set[MProperty]]

        # Write FFI and nitni results to file
        fun finalize_ffi(c: AbstractCompiler) do end

        # Give requided addinional system libraries (as given to LD_LIBS)
        # Note: can return null instead of an empty set
        fun collect_linker_libs: nullable Set[String] do return null
end

# Create a tool context to handle options and paths
var toolcontext = new ToolContext

toolcontext.tooldescription = "Usage: nitc [OPTION]... file.nit...\nCompiles Nit programs."

# We do not add other options, so process them now!
toolcontext.process_options(args)

# We need a model to collect stufs
var model = new Model
# An a model builder to parse files
var modelbuilder = new ModelBuilder(model, toolcontext)

var arguments = toolcontext.option_context.rest
if arguments.length > 1 and toolcontext.opt_output.value != null then
        print "Error: --output needs a single source file. Do you prefer --dir?"
        exit 1
end

# Here we load an process all modules passed on the command line
var mmodules = modelbuilder.parse(arguments)

if mmodules.is_empty then return
modelbuilder.run_phases

for mmodule in mmodules do
        toolcontext.info("*** PROCESS {mmodule} ***", 1)
        var ms = [mmodule]
        toolcontext.run_global_phases(ms)
end