[nit.git] / src / interpreter / dynamic_loading_ffi / on_demand_compiler.nit

# This file is part of NIT ( http://www.nitlanguage.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.

# Compiles extern code within a module to a static library, as needed
module on_demand_compiler

import modelbuilder
import c_tools
import nitni
import ffi
import naive_interpreter

redef class AMethPropdef
        # Does this method definition use the FFI and is it supported by the interpreter?
        #
        # * Must use the nested foreign code block of the FFI.
        # * Must not have callbacks.
        # * Must be implemented in C.
        fun supported_by_dynamic_ffi: Bool
        do
                var n_extern_code_block = n_extern_code_block
                if not (n_extern_calls == null and n_extern_code_block != null and
                        n_extern_code_block.is_c) then return false

                for mparam in mpropdef.msignature.mparameters do
                        var mtype = mparam.mtype
                        if not mtype.is_cprimitive then
                                return false
                        end
                end

                return true
        end
end

redef class NaiveInterpreter
        # Where to store generated C and extracted code
        #
        # TODO make customizable and delete when execution completes
        private var compile_dir = "nit_compile"

        # Path of the compiled foreign code library
        #
        # TODO change the ".so" extension per platform.
        fun foreign_code_lib_path(mmodule: MModule): String
        do
                return compile_dir / mmodule.c_name + ".so"
        end

        # External compiler used to generate the foreign code library
        private var c_compiler = "gcc"
end

redef class AModule

        # Compile user FFI code and a standardized API into a `.so` file
        #
        # Returns `true` on success.
        fun compile_foreign_lib(v: NaiveInterpreter): Bool
        do
                var mmodule = mmodule
                assert mmodule != null

                var compile_dir = v.compile_dir
                var foreign_code_lib_path = v.foreign_code_lib_path(mmodule)

                if not compile_dir.file_exists then compile_dir.mkdir

                # Compile the common FFI part
                ensure_compile_ffi_wrapper
                for mclassdef in mmodule.mclassdefs do for mpropdef in mclassdef.mpropdefs do
                        var anode = v.modelbuilder.mpropdef2node(mpropdef)
                        if mpropdef isa MMethodDef and anode isa AMethPropdef and anode.supported_by_dynamic_ffi then
                                anode.compile_ffi_method(mmodule)
                        end
                end
                mmodule.finalize_ffi_wrapper(compile_dir, mmodule)

                # Compile the standard API and its implementation for the .so file
                var ccu = compile_foreign_lib_api(compile_dir)

                var srcs = [for file in ccu.files do new ExternCFile(file, ""): ExternFile]
                srcs.add_all mmodule.ffi_files

                if mmodule.pkgconfigs.not_empty then
                        fatal(v, "NOT YET IMPLEMENTED annotation `pkgconfig`")
                        return false
                end

                var ldflags = mmodule.ldflags[""].join(" ")
                # TODO pkgconfig

                # Compile each source file to an object file (or equivalent)
                var object_files = new Array[String]
                for f in srcs do
                        f.compile(v, mmodule, object_files)
                end

                # Link everything in a shared library
                # TODO customize the compiler
                var cmd = "{v.c_compiler} -Wall -shared -Wl,-soname,{mmodule.name}.so -g -o {foreign_code_lib_path} {object_files.join(" ")} {ldflags}"
                if sys.system(cmd) != 0 then
                        v.fatal "FFI Error: Failed to link native code using `{cmd}`"
                        return false
                end

                return true
        end

        # Compile the standard API of the `.so` file
        #
        # * The shared structure `nit_call_arg`.
        # * Standardized implementation functions entrypoints that relay calls
        #   to the FFI implementation functions.
        private fun compile_foreign_lib_api(compdir: String): CCompilationUnit
        do
                var mmodule = mmodule
                assert mmodule != null

                # ready extern code compiler
                var ecc = new CCompilationUnit

                ecc.body_decl.add """

#include <string.h>
#include <stdio.h>
#include <inttypes.h>

// C structure behind `CallArg` from the interpreter
typedef union nit_call_arg {
        long value_Int;
        int value_Bool;
        uint32_t value_Char;
        uint8_t value_Byte;
        double value_Float;
        void* value_Pointer;
} nit_call_arg;

"""

                # types
                var used_types = collect_mtypes
                for t in used_types do
                        if not t.is_cprimitive then
                                ecc.header_c_types.add "typedef void* {t.cname};\n"
                        end
                end

                # TODO callbacks & casts

                for nclassdef in n_classdefs do for npropdef in nclassdef.n_propdefs do
                        if npropdef isa AMethPropdef and npropdef.supported_by_dynamic_ffi then
                                npropdef.mpropdef.compile_foreign_code_entry ecc
                        end
                end

                ecc.write_as_foreign_lib_api(mmodule, compdir)

                return ecc
        end

        # Collect all `MType` use in extern methods within this module
        private fun collect_mtypes: Set[MType]
        do
                var used_types = new HashSet[MType]

                # collect callbacks
                for nclassdef in n_classdefs do for npropdef in nclassdef.n_propdefs do
                        if npropdef isa AMethPropdef and npropdef.supported_by_dynamic_ffi then
                                var fcs = npropdef.foreign_callbacks
                                used_types.add_all fcs.types
                        end
                end

                return used_types
        end
end

redef class CCompilationUnit
        # Write this compilation unit as the API of a foreign code library
        private fun write_as_foreign_lib_api(mmodule: MModule, compdir: String)
        do
                # The FFI expects the support header to end with `._nitni.h`
                var base_name = mmodule.c_name + "._nitni"
                var guard = mmodule.c_name.to_s.to_upper + "_API_H"
                var header_comment = """
/*
        Public API to foreign code of the Nit module {{{mmodule.name}}}
*/
"""

                # Header file
                var h_file = base_name+".h"
                var stream = new FileWriter.open(compdir/h_file)
                stream.write header_comment
                stream.write """
#ifndef {{{guard}}}
#define {{{guard}}}
"""
                compile_header_core stream
                stream.write """

#endif
"""
                stream.close

                # Body file
                var c_file = base_name+".c"
                stream = new FileWriter.open(compdir/c_file)
                stream.write header_comment
                stream.write """
#include "{{{h_file}}}"
"""
                compile_body_core stream
                stream.close

                # Only the C files needs compiling
                files.add compdir / c_file
        end
end

redef class MMethodDef
        # Name of the entry point to the implementation function in the foreign lib
        fun foreign_lib_entry_cname: String do return "entry__{cname}"

        # Compile the standardized entry point as part of the foreign lib API
        private fun compile_foreign_code_entry(ecc: CCompilationUnit)
        do
                var msignature = msignature
                if msignature == null then return

                # Return type
                var return_mtype = msignature.return_mtype
                if mproperty.is_init then return_mtype = mclassdef.mclass.mclass_type

                var c_return_type
                if return_mtype != null then
                        c_return_type = return_mtype.cname_blind
                else c_return_type = "void"

                var is_init = mproperty.is_init

                # Params
                var params = new Array[String]
                if not is_init then params.add mclassdef.mclass.mclass_type.cname_blind
                for param in msignature.mparameters do params.add param.mtype.cname_blind

                # Declare the implementation function as extern
                var impl_cname = mproperty.build_cname(mclassdef.mclass.mclass_type,
                        mclassdef.mmodule, "___impl", long_signature)
                ecc.body_decl.add "extern {c_return_type} {impl_cname}({params.join(", ")});\n"

                # Declare the entry function
                var foreign_lib_entry_cname = "int {foreign_lib_entry_cname}(int argc, nit_call_arg *argv, nit_call_arg *result)"
                var fc = new CFunction(foreign_lib_entry_cname)

                # Check argument count on the library side
                #
                # This may detect inconsistencies between the interpreter and the generated code.
                var expected_argc = msignature.arity
                if not is_init then expected_argc += 1

                fc.exprs.add """
        if (argc != {{{expected_argc}}}) {
                printf("Invalid argument count in `{{{mproperty.full_name}}}`, expected %d, got %d.\\n",
                        argc, {{{expected_argc}}});
                return 1;
        }
"""

                # Unpack and prepare args for the user code
                var k = 0
                var args_for_call = new Array[String]
                if not is_init then
                        var mtype = mclassdef.mclass.mclass_type
                        var arg_name = "arg___self"

                        fc.decls.add "  {mtype.cname_blind} {arg_name};\n"
                        fc.exprs.add "  {arg_name} = argv[{k}].{mtype.call_arg_field};\n"
                        args_for_call.add arg_name

                        k += 1
                end
                for param in msignature.mparameters do
                        var mtype = param.mtype
                        var arg_name = "arg__"+param.name

                        fc.decls.add "  {mtype.cname_blind} {arg_name};\n"
                        fc.exprs.add "  {arg_name} = argv[{k}].{mtype.call_arg_field};\n"
                        args_for_call.add arg_name

                        k += 1
                end

                # Call implementation function
                var args_compressed = args_for_call.join(", ")
                var method_call = "{impl_cname}({args_compressed})"
                if return_mtype != null then
                        fc.decls.add """
        {{{return_mtype.cname_blind}}} return_value;
"""
                        fc.exprs.add """
        return_value = {{{method_call}}};
        result->{{{return_mtype.call_arg_field}}} = return_value;
"""
                else
                        fc.exprs.add "  {method_call};\n"
                end

                fc.exprs.add "  return 0;\n"

                ecc.add_exported_function fc
        end
end

redef class MType
        # The interpreter FFI use `void*` to represent intern data types
        redef fun cname_blind do return "void*"

        # Field to store this type in the C structure `nit_call_arg`
        private fun call_arg_field: String do return "value_Pointer"
end

redef class MClassType
        redef fun call_arg_field
        do
                if is_cprimitive and mclass.kind != extern_kind then
                        return "value_{name}"
                else return super
        end
end

redef class ExternFile
        # Compile this source file
        private fun compile(v: NaiveInterpreter, mmodule: MModule,
                object_files: Array[String]): Bool is abstract
end

redef class ExternCFile
        redef fun compile(v, mmodule, object_files)
        do
                var compile_dir = v.compile_dir
                var cflags = mmodule.cflags[""].join(" ")
                var obj = compile_dir / filename.basename(".c") + ".o"

                var cmd = "{v.c_compiler} -Wall -c -fPIC -I {compile_dir} -g -o {obj} {filename} {cflags}"
                if sys.system(cmd) != 0 then
                         v.fatal "FFI Error: Failed to compile C code using `{cmd}`"
                         return false
                end

                object_files.add obj
                return true
        end
end