k0kubun	2018-02-07 22:48:48 +0900 (Wed, 07 Feb 2018)

  New Revision: 62285

  https://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=62285

  Log:
    transform_mjit_header.rb: ignore unsupported cc
    
    to generate MJIT header.
    
    Even if we can't build MJIT header, Ruby's build should success. And
    compilers which are not explicitly supported are likely to fail to
    transform MJIT header.
    
    Also you can pass only gcc or clang to --jit-cc=xxx for now. Thus
    generating header does never make sense.
    
    So I decided to conservatively give up MJIT header generation.
    But please feel free to add your favorite compiler's macro if you think
    it's working. (Another workaround is passing -D__GNUC__ :p)
    
    [Bug #14447] [Bug #14446]

  Modified files:
    trunk/tool/transform_mjit_header.rb
Index: tool/transform_mjit_header.rb
===================================================================
--- tool/transform_mjit_header.rb	(revision 62284)
+++ tool/transform_mjit_header.rb	(revision 62285)
@@ -13,6 +13,13 @@ module MJITHeader https://github.com/ruby/ruby/blob/trunk/tool/transform_mjit_header.rb#L13
   FUNC_HEADER_REGEXP = /\A(\s*#{ATTR_REGEXP})*[^\[{(]*\((#{ATTR_REGEXP}|[^()])*\)(\s*#{ATTR_REGEXP})*\s*/
   TARGET_NAME_REGEXP = /\A(rb|ruby|vm|insn|attr)_/
 
+  # Predefined macros for compilers which are already supported by MJIT.
+  # We're going to support cl.exe too (WIP) but `cl.exe -E` can't produce macro.
+  SUPPORTED_CC_MACROS = [
+    '__GNUC__', # gcc
+    '__clang__', # clang
+  ]
+
   # For MinGW's ras.h. Those macros have its name in its definition and can't be preprocessed multiple times.
   RECURSIVE_MACROS = %w[
     RASCTRYINFO
@@ -121,6 +128,15 @@ module MJITHeader https://github.com/ruby/ruby/blob/trunk/tool/transform_mjit_header.rb#L128
   def self.windows?
     RUBY_PLATFORM =~ /mswin|mingw|msys/
   end
+
+  def self.cl_exe?(cc)
+    cc =~ /\Acl(\z| |\.exe)/
+  end
+
+  # If code has macro which only supported compilers predefine, return true.
+  def self.supported_header?(code)
+    SUPPORTED_CC_MACROS.any? { |macro| code =~ /^#\s*define\s+#{macro}\b/ }
+  end
 end
 
 if ARGV.size != 3
@@ -130,12 +146,18 @@ end https://github.com/ruby/ruby/blob/trunk/tool/transform_mjit_header.rb#L146
 cc      = ARGV[0]
 code    = File.binread(ARGV[1]) # Current version of the header file.
 outfile = ARGV[2]
-if cc =~ /\Acl(\z| |\.exe)/
+if MJITHeader.cl_exe?(cc)
   cflags = '-DMJIT_HEADER -Zs'
 else
   cflags = '-S -DMJIT_HEADER -fsyntax-only -Werror=implicit-function-declaration -Werror=implicit-int -Wfatal-errors'
 end
 
+if !MJITHeader.cl_exe?(cc) && !MJITHeader.supported_header?(code)
+  puts "This compiler (#{cc}) looks not supported for MJIT. Giving up to generate MJIT header."
+  MJITHeader.write("#error MJIT does not support '#{cc}' yet", outfile)
+  exit
+end
+
 if MJITHeader.windows?
   MJITHeader.remove_harmful_macros!(code)
 end

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