X87: Introduce intrinsic to expose debug state to generated code.

port r21908.

original commit message:

BUG=
R=weiliang.lin@intel.com

Review URL: https://codereview.chromium.org/349183002

Patch from Chunyang Dai <chunyang.dai@intel.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21923 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/x87/full-codegen-x87.cc

@@ -3989,6 +3989,16 @@ void FullCodeGenerator::EmitFastAsciiArrayJoin(CallRuntime* expr) {
 }
 
 
+void FullCodeGenerator::EmitDebugIsActive(CallRuntime* expr) {
+  ASSERT(expr->arguments()->length() == 0);
+  ExternalReference debug_is_active =
+      ExternalReference::debug_is_active_address(isolate());
+  __ movzx_b(eax, Operand::StaticVariable(debug_is_active));
+  __ SmiTag(eax);
+  context()->Plug(eax);
+}
+
+
 void FullCodeGenerator::VisitCallRuntime(CallRuntime* expr) {
   if (expr->function() != NULL &&
       expr->function()->intrinsic_type == Runtime::INLINE) {