Subzero: Randomize register assignment.

src/IceTargetLowering.h

Index: src/IceTargetLowering.h
diff --git a/src/IceTargetLowering.h b/src/IceTargetLowering.h
index 91512a9fb47189ad7f322bb1d18e8c08816f076b..8694695efef42f7c42309c7186e5cacb23b6bc31 100644
--- a/src/IceTargetLowering.h
+++ b/src/IceTargetLowering.h
@@ -156,6 +156,10 @@ public:
   virtual const llvm::SmallBitVector &getRegisterSetForType(Type Ty) const = 0;
   void regAlloc();
 
+  typedef std::vector<int32_t> RegisterPermutation;

[JF, 2014/08/12 05:27:00]

What's the expected size of this vector? Shouldn't it be ~ number of registers?
If so the that should be a SmallVector.

[wala, 2014/08/15 03:37:23]

Done.

+  virtual void makeRandomRegisterPermutation(RegisterPermutation &Permutation,

[Jim Stichnoth, 2014/08/14 01:10:29]

Can this method be const?

[wala, 2014/08/15 03:37:23]

It changes the state of the RNG, so I wouldn't make it const.

+      const llvm::SmallBitVector &ExcludeRegisters) = 0;
+
   virtual void emitVariable(const Variable *Var, const Cfg *Func) const = 0;
 
   // Performs target-specific argument lowering.