Subzero: Allow delaying Phi lowering until after register allocation.

src/IceInstX8632.h

 //===- subzero/src/IceInstX8632.h - Low-level x86 instructions --*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file declares the InstX8632 and OperandX8632 classes and
@@ skipping 369 matching lines @@
   uint32_t getEmitInstCount() const override {
     uint32_t Sum = 0;
     if (Label)
       ++Sum;
     if (getTargetTrue())
       ++Sum;
     if (getTargetFalse())
       ++Sum;
     return Sum;
   }
+  bool isUnconditionalBranch() const override {
+    return !Label && Condition == CondX86::Br_None;
+  }
+  bool repointEdge(CfgNode *OldNode, CfgNode *NewNode) override;
   void emit(const Cfg *Func) const override;
   void emitIAS(const Cfg *Func) const override;
   void dump(const Cfg *Func) const override;
   static bool classof(const Inst *Inst) { return isClassof(Inst, Br); }
 
 private:
   InstX8632Br(Cfg *Func, const CfgNode *TargetTrue, const CfgNode *TargetFalse,
               const InstX8632Label *Label, CondX86::BrCond Condition);
   ~InstX8632Br() override {}
   CondX86::BrCond Condition;
@@ skipping 1146 matching lines @@
 template <> void InstX8632Pinsr::emitIAS(const Cfg *Func) const;
 template <> void InstX8632Movsx::emitIAS(const Cfg *Func) const;
 template <> void InstX8632Movzx::emitIAS(const Cfg *Func) const;
 template <> void InstX8632Pmull::emitIAS(const Cfg *Func) const;
 template <> void InstX8632Pshufd::emitIAS(const Cfg *Func) const;
 template <> void InstX8632Shufps::emitIAS(const Cfg *Func) const;
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICEINSTX8632_H