Optimize yasm even in debug builds

build/config/win/BUILD.gn

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/clang/clang.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 import("//build/config/win/visual_studio_version.gni")
 import("//build/toolchain/toolchain.gni")
 
@@ skipping 276 matching lines @@
     if (current_os != "win") {
       # WindowsRT: use the dynamic CRT.
       configs = [ ":dynamic_crt" ]
     } else {
       # Desktop Windows: static CRT.
       configs = [ ":static_crt" ]
     }
   }
 }
 
+# Use this to force the debug CRT for when building perf-critical build tools
+# that need to be fully optimized even in debug builds, for those times when the
+# debug CRT is part of the bottleneck. This also avoids *implicitly* defining
+# _DEBUG.
+config("release_crt") {
+  if (is_component_build) {
+    cflags = [ "/MD" ]
+  } else {
+    cflags = [ "/MT" ]
+  }
+}
+
 config("dynamic_crt") {
   if (is_debug) {
+    # This pulls in the DLL debug CRT and defines _DEBUG
     cflags = [ "/MDd" ]
   } else {
     cflags = [ "/MD" ]
   }
 }
 
 config("static_crt") {
   if (is_debug) {
+    # This pulls in the static debug CRT and defines _DEBUG
     cflags = [ "/MTd" ]
   } else {
     cflags = [ "/MT" ]
   }
 }
 
 # Subsystem --------------------------------------------------------------------
 
 # This is appended to the subsystem to specify a minimum version.
 if (current_cpu == "x64") {
@@ skipping 98 matching lines @@
 
 # Internal stuff --------------------------------------------------------------
 
 # Config used by the MIDL template to disable warnings.
 config("midl_warnings") {
   if (is_clang) {
     # MIDL generates code like "#endif !_MIDL_USE_GUIDDEF_".
     cflags = [ "-Wno-extra-tokens" ]
   }
 }