Merge 6168:6800 from bleeding_edge to experimental/gc branch.

src/arm/jump-target-arm.cc

Index: src/arm/jump-target-arm.cc
===================================================================
--- src/arm/jump-target-arm.cc	(revision 6800)
+++ src/arm/jump-target-arm.cc	(working copy)
@@ -76,7 +76,7 @@
 }
 
 
-void JumpTarget::DoBranch(Condition cc, Hint ignored) {
+void JumpTarget::DoBranch(Condition cond, Hint ignored) {
   ASSERT(cgen()->has_valid_frame());
 
   if (entry_frame_set_) {
@@ -86,7 +86,7 @@
       ASSERT(entry_frame_.IsCompatibleWith(cgen()->frame()));
     }
     // We have an expected frame to merge to on the backward edge.
-    cgen()->frame()->MergeTo(&entry_frame_, cc);
+    cgen()->frame()->MergeTo(&entry_frame_, cond);
   } else {
     // Clone the current frame to use as the expected one at the target.
     set_entry_frame(cgen()->frame());
@@ -98,8 +98,8 @@
     // frame with less precise type info branches to them.
     ASSERT(direction_ != FORWARD_ONLY);
   }
-  __ b(cc, &entry_label_);
-  if (cc == al) {
+  __ b(cond, &entry_label_);
+  if (cond == al) {
     cgen()->DeleteFrame();
   }
 }
@@ -143,6 +143,16 @@
       entry_frame_set_ = true;
     } else {
       cgen()->frame()->MergeTo(&entry_frame_);
+      // On fall through we may have to merge both ways.
+      if (direction_ != FORWARD_ONLY) {
+        // This will not need to adjust the virtual frame entries that are
+        // register allocated since that was done above and they now match.
+        // But it does need to adjust the entry_frame_ of this jump target
+        // to make it potentially less optimistic.  Later code can branch back
+        // to this jump target and we need to assert that that code does not
+        // have weaker assumptions about types.
+        entry_frame_.MergeTo(cgen()->frame());
+      }
     }
   } else {
     // If there is no current frame we must have an entry frame which we can