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

src/x87/full-codegen-x87.cc

Index: src/x87/full-codegen-x87.cc
diff --git a/src/x87/full-codegen-x87.cc b/src/x87/full-codegen-x87.cc
index 7006e7bdabc64343b1a519f7a0f5bf826fe937ec..9259f39738c7975408750c1ea859c583f49e4337 100644
--- a/src/x87/full-codegen-x87.cc
+++ b/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) {