Remove instructions properly (stack check elimination was leaving "dangling uses" around).

BUG=

Review URL: https://codereview.chromium.org/12224090

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13647 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/hydrogen-instructions.cc

@@ -790,6 +790,13 @@ void HInstruction::Verify() {
   // HValue::DataEquals.  The default implementation is UNREACHABLE.  We
   // don't actually care whether DataEquals returns true or false here.
   if (CheckFlag(kUseGVN)) DataEquals(this);
+
+  // Verify that all uses are in the graph.
+  for (HUseIterator use = uses(); !use.Done(); use.Advance()) {
+    if (use.value()->IsInstruction()) {
+      ASSERT(HInstruction::cast(use.value())->IsLinked());
+    }
+  }
 }
 #endif
 

src/hydrogen-instructions.h

@@ -1546,7 +1546,7 @@ class HStackCheck: public HTemplateInstruction<1> {
     // The stack check eliminator might try to eliminate the same stack
     // check instruction multiple times.
     if (IsLinked()) {
-      DeleteFromGraph();
+      DeleteAndReplaceWith(NULL);
     }
   }