Refactor load forwarding pass to use a Place abstraction.

runtime/vm/intermediate_language.cc

Index: runtime/vm/intermediate_language.cc
diff --git a/runtime/vm/intermediate_language.cc b/runtime/vm/intermediate_language.cc
index 87e5407ce22e6968396bfe23f4293e389e4d84c9..58823144b9e2d87b3e1fb0d527a363f4944b90d0 100644
--- a/runtime/vm/intermediate_language.cc
+++ b/runtime/vm/intermediate_language.cc
@@ -937,6 +937,20 @@ void JoinEntryInstr::InsertPhi(PhiInstr* phi) {
   phis_->Add(phi);
 }
 
+void JoinEntryInstr::RemovePhi(PhiInstr* phi) {
+  ASSERT(phis_ != NULL);
+  intptr_t to_index = 0;
+  for (intptr_t from_index = 0; from_index < phis_->length(); ++from_index) {

[Kevin Millikin (Google), 2013/06/25 09:18:29]

Is this better than searching for the phi and replacing it with the last
element, unless it is the last element?

[Vyacheslav Egorov (Google), 2013/06/25 18:02:39]

Done.

+    PhiInstr* current = (*phis_)[from_index];
+    if (phi != current) {
+      if (to_index != from_index) {
+        (*phis_)[to_index] = current;
+      }
+      to_index++;
+    }
+  }
+  phis_->RemoveLast();
+}
 
 void JoinEntryInstr::RemoveDeadPhis(Definition* replacement) {
   if (phis_ == NULL) return;