Subzero: Allow delaying Phi lowering until after register allocation.

src/IceInstX8632.cpp

Index: src/IceInstX8632.cpp
diff --git a/src/IceInstX8632.cpp b/src/IceInstX8632.cpp
index 23948e47707eb53db45fcb7159c31d1ca9ce9eb1..5b77a37d2f4ef9a9f52eb644ea19b7452ae0c827 100644
--- a/src/IceInstX8632.cpp
+++ b/src/IceInstX8632.cpp
@@ -184,6 +184,17 @@ bool InstX8632Br::optimizeBranch(const CfgNode *NextNode) {
   return false;
 }
 
+bool InstX8632Br::repointEdge(CfgNode *OldNode, CfgNode *NewNode) {
+  if (TargetFalse == OldNode) {
+    TargetFalse = NewNode;
+    return true;
+  } else if (TargetTrue == OldNode) {
+    TargetTrue = NewNode;
+    return true;
+  }
+  return false;
+}
+
 InstX8632Call::InstX8632Call(Cfg *Func, Variable *Dest, Operand *CallTarget)
     : InstX8632(Func, InstX8632::Call, 1, Dest) {
   HasSideEffects = true;