compiler: use linker symbols to encode colors

Signed-off-by: Jean Privat <jean@pryen.org>

diff --git a/src/compiler/separate_compiler.nit b/src/compiler/separate_compiler.nit
index 5c33ad4..cf6a516 100644 (file)
--- a/src/compiler/separate_compiler.nit
+++ b/src/compiler/separate_compiler.nit
@@ -29,6 +29,9 @@ redef class ToolContext
        var opt_no_union_attribute = new OptionBool("Put primitive attibutes in a box instead of an union", "--no-union-attribute")
        # --no-shortcut-equate
        var opt_no_shortcut_equate = new OptionBool("Always call == in a polymorphic way", "--no-shortcut-equal")
+       # --colors-are-symbols
+       var opt_colors_are_symbols = new OptionBool("Store colors as symbols (faster)", "--colors-are-symbols")
+
        # --inline-coloring-numbers
        var opt_inline_coloring_numbers = new OptionBool("Inline colors and ids (semi-global)", "--inline-coloring-numbers")
        # --inline-some-methods
@@ -50,7 +53,7 @@ redef class ToolContext
                self.option_context.add_option(self.opt_separate)
                self.option_context.add_option(self.opt_no_inline_intern)
                self.option_context.add_option(self.opt_no_union_attribute)
-               self.option_context.add_option(self.opt_no_shortcut_equate)
+               self.option_context.add_option(self.opt_no_shortcut_equate, opt_colors_are_symbols)
                self.option_context.add_option(self.opt_inline_coloring_numbers, opt_inline_some_methods, opt_direct_call_monomorph, opt_skip_dead_methods, opt_semi_global)
                self.option_context.add_option(self.opt_colo_dead_methods)
                self.option_context.add_option(self.opt_tables_metrics)
@@ -255,9 +258,15 @@ class SeparateCompiler
                if m isa MEntity then
                        if modelbuilder.toolcontext.opt_inline_coloring_numbers.value then
                                self.provide_declaration(m.const_color, "#define {m.const_color} {color}")
-                       else
+                       else if not modelbuilder.toolcontext.opt_colors_are_symbols.value then
                                self.provide_declaration(m.const_color, "extern const int {m.const_color};")
                                v.add("const int {m.const_color} = {color};")
+                       else
+                               # The color 'C' is the ``address'' of a false static variable 'XC'
+                               self.provide_declaration(m.const_color, "#define {m.const_color} ((long)&X{m.const_color})\nextern const void X{m.const_color};")
+                               if color == -1 then color = 0 # Symbols cannot be negative, so just use 0 for dead things
+                               # Teach the linker that the address of 'XC' is `color`.
+                               linker_script.add("X{m.const_color} = {color};")
                        end
                else
                        abort