[GN]: Add asmflags

tools/gn/ninja_binary_target_writer.cc

Index: tools/gn/ninja_binary_target_writer.cc
diff --git a/tools/gn/ninja_binary_target_writer.cc b/tools/gn/ninja_binary_target_writer.cc
index 3a08e57964e9cbb367cfaa2e820fdb100a1fbbe2..ae46760059fff7fbb1e7dadb27351a3af1188ccd 100644
--- a/tools/gn/ninja_binary_target_writer.cc
+++ b/tools/gn/ninja_binary_target_writer.cc
@@ -351,12 +351,7 @@ void NinjaBinaryTargetWriter::Run() {
       &pch_obj_files : &pch_other_files;
 
   // Treat all pch output files as explicit dependencies of all
-  // compiles. Some notes:
-  //
-  //  - Only the language-specific one is required for any specific compile, but
-  //    that's more difficult to express and the additional logic doesn't buy
-  //    much reduced parallelism. Just list them all (there's usually only one
-  //    anyway).
+  // compiles that support them. Some notes:
   //
   //  - On Windows, the .pch file is the input to the compile, not the
   //    precompiled header's corresponding object file that we're using here.
@@ -420,16 +415,17 @@ void NinjaBinaryTargetWriter::WriteCompilerVars(
   bool has_precompiled_headers =
       target_->config_values().has_precompiled_headers();
 
-  // Some toolchains pass cflags to the assembler since it's the same command.
   EscapeOptions opts = GetFlagOptions();
+  if (used_types.Get(SOURCE_S) || used_types.Get(SOURCE_ASM)) {
+    WriteOneFlag(SUBSTITUTION_ASMFLAGS, false, Toolchain::TYPE_NONE,
+                 &ConfigValues::asmflags, opts);
+  }
   if (used_types.Get(SOURCE_C) || used_types.Get(SOURCE_CPP) ||
-      used_types.Get(SOURCE_M) || used_types.Get(SOURCE_MM) ||
-      used_types.Get(SOURCE_S) || used_types.Get(SOURCE_ASM)) {

[brettw, 2015/09/24 18:30:09]

Can you leave the S/ASM check in here and below with a TODO to remove? In
between the time that we roll these GN binary deps and the time we update the
toolchain definition to use asmflags, we won't necessarily write cflags for
targets that have only assembly files. Once we start using asmflags, we can
remove these lines.

[Bons, 2015/09/24 19:41:54]

Done.

+      used_types.Get(SOURCE_M) || used_types.Get(SOURCE_MM)) {
     WriteOneFlag(SUBSTITUTION_CFLAGS, false, Toolchain::TYPE_NONE,
                  &ConfigValues::cflags, opts);
   }
-  if (used_types.Get(SOURCE_C) || used_types.Get(SOURCE_S) ||
-      used_types.Get(SOURCE_ASM)) {
+  if (used_types.Get(SOURCE_C)) {
     WriteOneFlag(SUBSTITUTION_CFLAGS_C, has_precompiled_headers,
                  Toolchain::TYPE_CC, &ConfigValues::cflags_c, opts);
   }
@@ -678,17 +674,20 @@ void NinjaBinaryTargetWriter::WriteSources(
       // with the naming scheme specified in GetWindowsPCHObjectExtension or
       // GetGCCPCHOutputExtension.
       const Tool* tool = target_->toolchain()->GetTool(tool_type);
-      for (const auto& dep : pch_deps) {
-        const std::string& output_value = dep.value();
-        std::string output_extension;
-        if (tool->precompiled_header_type() == Tool::PCH_MSVC) {
-          output_extension = GetWindowsPCHObjectExtension(tool_type);
-        } else if (tool->precompiled_header_type() == Tool::PCH_GCC) {
-          output_extension = GetGCCPCHOutputExtension(tool_type);
-        }
-        if (output_value.compare(output_value.size() - output_extension.size(),
-            output_extension.size(), output_extension) == 0) {
-          deps.push_back(dep);
+      if (tool->precompiled_header_type() != Tool::PCH_NONE) {
+        for (const auto& dep : pch_deps) {
+          const std::string& output_value = dep.value();
+          std::string output_extension;
+          if (tool->precompiled_header_type() == Tool::PCH_MSVC) {
+            output_extension = GetWindowsPCHObjectExtension(tool_type);
+          } else if (tool->precompiled_header_type() == Tool::PCH_GCC) {
+            output_extension = GetGCCPCHOutputExtension(tool_type);
+          }
+          if (output_value.compare(output_value.size() -
+              output_extension.size(), output_extension.size(),
+              output_extension) == 0) {
+            deps.push_back(dep);
+          }
         }
       }
       WriteCompilerBuildLine(source, deps, order_only_dep, tool_type,