Subzero: Randomize register assignment.

src/IceTargetLowering.h

 //===- subzero/src/IceTargetLowering.h - Lowering interface -----*- 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 TargetLowering and LoweringContext
@@ skipping 173 matching lines @@
     RegSet_FramePointer = 1 << 3,
     RegSet_All = ~RegSet_None
   };
   typedef uint32_t RegSetMask;
 
   virtual llvm::SmallBitVector getRegisterSet(RegSetMask Include,
                                               RegSetMask Exclude) const = 0;
   virtual const llvm::SmallBitVector &getRegisterSetForType(Type Ty) const = 0;
   void regAlloc(RegAllocKind Kind);
 
+  virtual void makeRandomRegisterPermutation(
+      llvm::SmallVectorImpl<int32_t> &Permutation,
+      const llvm::SmallBitVector &ExcludeRegisters) const = 0;
+
   virtual void emitVariable(const Variable *Var) const = 0;
 
   // Performs target-specific argument lowering.
   virtual void lowerArguments() = 0;
 
   virtual void addProlog(CfgNode *Node) = 0;
   virtual void addEpilog(CfgNode *Node) = 0;
 
   virtual void emitConstants() const = 0;
 
   virtual ~TargetLowering() {}
 
 protected:
-  TargetLowering(Cfg *Func)
-      : Func(Func), Ctx(Func->getContext()), HasComputedFrame(false),
-        CallsReturnsTwice(false), StackAdjustment(0) {}
+  TargetLowering(Cfg *Func);
   virtual void lowerAlloca(const InstAlloca *Inst) = 0;
   virtual void lowerArithmetic(const InstArithmetic *Inst) = 0;
   virtual void lowerAssign(const InstAssign *Inst) = 0;
   virtual void lowerBr(const InstBr *Inst) = 0;
   virtual void lowerCall(const InstCall *Inst) = 0;
   virtual void lowerCast(const InstCast *Inst) = 0;
   virtual void lowerFcmp(const InstFcmp *Inst) = 0;
   virtual void lowerExtractElement(const InstExtractElement *Inst) = 0;
   virtual void lowerIcmp(const InstIcmp *Inst) = 0;
   virtual void lowerInsertElement(const InstInsertElement *Inst) = 0;
@@ skipping 14 matching lines @@
   virtual void postLower() {}
 
   Cfg *Func;
   GlobalContext *Ctx;
   bool HasComputedFrame;
   bool CallsReturnsTwice;
   // StackAdjustment keeps track of the current stack offset from its
   // natural location, as arguments are pushed for a function call.
   int32_t StackAdjustment;
   LoweringContext Context;
+  const bool RandomizeRegisterAllocation;

[jvoung (off chromium), 2014/12/17 19:53:34]

Maybe keep the bools together.

[Jim Stichnoth, 2014/12/18 18:52:03]

Done.

 };
 
 // TargetGlobalInitLowering is used for "lowering" global
 // initializers.  It is separated out from TargetLowering because it
 // does not require a Cfg.
 class TargetGlobalInitLowering {
   TargetGlobalInitLowering(const TargetGlobalInitLowering &) = delete;
   TargetGlobalInitLowering &operator=(const TargetGlobalInitLowering &) =
       delete;
 
 public:
   static TargetGlobalInitLowering *createLowering(TargetArch Target,
                                                   GlobalContext *Ctx);
   virtual ~TargetGlobalInitLowering();
 
   virtual void lower(const VariableDeclaration &Var) = 0;
 
 protected:
   TargetGlobalInitLowering(GlobalContext *Ctx) : Ctx(Ctx) {}
   GlobalContext *Ctx;
 };
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICETARGETLOWERING_H