Optimize %IsConstructCall() on IA-32.

src/ia32/codegen-ia32.cc

Index: src/ia32/codegen-ia32.cc
===================================================================
--- src/ia32/codegen-ia32.cc	(revision 2285)
+++ src/ia32/codegen-ia32.cc	(working copy)
@@ -4987,6 +4987,29 @@
 }
 
 
+void CodeGenerator::GenerateIsConstructCall(ZoneList<Expression*>* args) {
+  ASSERT(args->length() == 0);
+
+  // Get the frame pointer for the calling frame.
+  Result fp = allocator()->Allocate();
+  __ mov(fp.reg(), Operand(ebp, StandardFrameConstants::kCallerFPOffset));
+
+  // Skip the arguments adaptor frame if it exists.
+  Label check_frame_marker;
+  __ cmp(Operand(fp.reg(), StandardFrameConstants::kContextOffset),
+         Immediate(ArgumentsAdaptorFrame::SENTINEL));
+  __ j(not_equal, &check_frame_marker);
+  __ mov(fp.reg(), Operand(fp.reg(), StandardFrameConstants::kCallerFPOffset));
+
+  // Check the marker in the calling frame.
+  __ bind(&check_frame_marker);
+  __ cmp(Operand(fp.reg(), StandardFrameConstants::kMarkerOffset),
+         Immediate(Smi::FromInt(StackFrame::CONSTRUCT)));
+  fp.Unuse();
+  destination()->Split(equal);
+}
+
+
 void CodeGenerator::GenerateArgumentsLength(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 0);
   // ArgumentsAccessStub takes the parameter count as an input argument