Initial real implementation of simple merge for frames. Does not yet...

src/jump-target-ia32.cc

Index: src/jump-target-ia32.cc
===================================================================
--- src/jump-target-ia32.cc	(revision 894)
+++ src/jump-target-ia32.cc	(working copy)
@@ -69,11 +69,13 @@
 
   if (expected_frame_ == NULL) {
     expected_frame_ = current_frame;
-    expected_frame_->EnsureMergable();
     // The frame at the actual function return will always have height zero.
     if (code_generator_->IsActualFunctionReturn(this)) {
       expected_frame_->Forget(expected_frame_->height());
     }
+    if (!expected_frame_->IsMergable()) {
+      expected_frame_->MakeMergable();
+    }
     code_generator_->set_frame(NULL);
   } else {
     // No code needs to be emitted to merge to the expected frame at the
@@ -101,11 +103,13 @@
 
   if (expected_frame_ == NULL) {
     expected_frame_ = new VirtualFrame(current_frame);
-    expected_frame_->EnsureMergable();
     // The frame at the actual function return will always have height zero.
     if (code_generator_->IsActualFunctionReturn(this)) {
       expected_frame_->Forget(expected_frame_->height());
     }
+    if (!expected_frame_->IsMergable()) {
+      expected_frame_->MakeMergable();
+    }
   } else {
     // No code needs to be emitted to merge to the expected frame at the
     // actual function return.
@@ -132,7 +136,9 @@
   ASSERT(expected_frame_ == NULL);
 
   expected_frame_ = new VirtualFrame(current_frame);
-  expected_frame_->EnsureMergable();
+  if (!expected_frame_->IsMergable()) {
+    expected_frame_->MakeMergable();
+  }
   // Adjust the expected frame's height to account for the return address
   // pushed by the call instruction.
   expected_frame_->Adjust(1);
@@ -156,11 +162,13 @@
 
   if (expected_frame_ == NULL) {
     expected_frame_ = new VirtualFrame(current_frame);
-    expected_frame_->EnsureMergable();
     // The frame at the actual function return will always have height zero.
     if (code_generator_->IsActualFunctionReturn(this)) {
       expected_frame_->Forget(expected_frame_->height());
     }
+    if (!expected_frame_->IsMergable()) {
+      expected_frame_->MakeMergable();
+    }
   } else if (current_frame == NULL) {
     code_generator_->set_frame(new VirtualFrame(expected_frame_));
   } else {