Subzero: Allow delaying Phi lowering until after register allocation.

src/IceTargetLowering.cpp

Index: src/IceTargetLowering.cpp
diff --git a/src/IceTargetLowering.cpp b/src/IceTargetLowering.cpp
index b18999f67ebb6e7013bd5cf3153bf4121f79e938..2ff5162413728873ce100c2fedda9b0009a6d0f5 100644
--- a/src/IceTargetLowering.cpp
+++ b/src/IceTargetLowering.cpp
@@ -52,6 +52,11 @@ void LoweringContext::init(CfgNode *N) {
   advanceForward(Next);
 }
 
+void LoweringContext::rewind() {
+  Begin = getNode()->getInsts().begin();

[jvoung (off chromium), 2014/10/27 22:12:21]

It seems a bit unexpected that this isn't like init() in that it doesn't
skipDeleted(Cur).

[Jim Stichnoth, 2014/10/28 01:20:14]

Refactored init() to call rewind() - and added the skipDeleted() call to
rewind().

+  Cur = Next = Begin;
+}
+
 void LoweringContext::insert(Inst *Inst) {
   getNode()->getInsts().insert(Next, Inst);
   LastInserted = Inst;