Windows GN build flag fixes.

BUILD.gn

 # Copyright 2014 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/android/config.gni")
 import("//build/config/arm.gni")
 import("//build/config/dcheck_always_on.gni")
 import("//build/config/mips.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 
@@ skipping 146 matching lines @@
   if (v8_use_external_startup_data) {
     defines += [ "V8_USE_EXTERNAL_STARTUP_DATA" ]
   }
 }
 
 config("toolchain") {
   visibility = [ ":*" ]  # Only targets in this file can depend on this.
 
   defines = []
   cflags = []
+  ldflags = []
 
   if (v8_target_cpu == "arm") {
     defines += [ "V8_TARGET_ARCH_ARM" ]
     if (arm_version == 7) {
       defines += [ "CAN_USE_ARMV7_INSTRUCTIONS" ]
     }
     if (arm_fpu == "vfpv3-d16") {
       defines += [ "CAN_USE_VFP3_INSTRUCTIONS" ]
     } else if (arm_fpu == "vfpv3") {
       defines += [
@@ skipping 85 matching lines @@
     defines += [ "V8_TARGET_ARCH_S390" ]
     if (v8_target_cpu == "s390x") {
       defines += [ "V8_TARGET_ARCH_S390X" ]
     }
     if (host_cpu == "x64" || host_cpu == "x86") {
       defines += [ "V8_TARGET_ARCH_S390_LE_SIM" ]
     }
   }
   if (v8_target_cpu == "x86") {
     defines += [ "V8_TARGET_ARCH_IA32" ]
+    if (is_win) {
+      # Ensure no surprising artifacts from 80bit double math with x86.
+      cflags += [ "/arch:SSE2" ]
+    }
   }
   if (v8_target_cpu == "x64") {
     defines += [ "V8_TARGET_ARCH_X64" ]
+    if (is_win) {
+      # Increase the initial stack size. The default is 1MB, this is 2MB. This
+      # applies only to executables and shared libraries produced by V8 since
+      # ldflags are not pushed to dependants.
+      ldflags += [ "/STACK:2097152" ]
+    }
   }
 
-  if (is_win) {
-    defines += [ "WIN32" ]
-    # TODO(jochen): Support v8_enable_prof.
-  }
-
+  # TODO(jochen): Support v8_enable_prof on Windows.
   # TODO(jochen): Add support for compiling with simulators.
 
   if (is_debug) {
     # TODO(jochen): Add support for different debug optimization levels.
     defines += [
       "ENABLE_DISASSEMBLER",
       "V8_ENABLE_CHECKS",
       "OBJECT_PRINT",
       "VERIFY_HEAP",
       "DEBUG",
@@ skipping 1957 matching lines @@
 
   deps = [
     ":fuzzer_support",
   ]
 
   configs = [ ":internal_config" ]
 }
 
 v8_fuzzer("wasm_asmjs_fuzzer") {
 }