[TTI] Make the cost APIs in TargetTransformInfo consistently use 'int'

rather than 'unsigned' for their costs.

For something like costs in particular there is a natural "negative"
value, that of savings or saved cost. As a consequence, there is a lot
of code that subtracts or creates negative values based on cost, all of
which is prone to awkwardness or bugs when dealing with an unsigned
type. Similarly, we *never* want these values to wrap, as that would
cause Very Bad code generation (likely percieved as an infinite loop as
we try to emit over 2^32 instructions or some such insanity).

All around 'int' seems a much better fit for these basic metrics. I've
added asserts to ensure that at least the TTI interface never returns
negative numbers here. If we ever have a use case for negative numbers,
we can remove this, but this way a bug where someone used '-1' to
produce a 'very large' cost will be caught by the assert.

This passes all tests, and is also UBSan clean.

No functional change intended.

Differential Revision: http://reviews.llvm.org/D11741

llvm-svn: 244080

1 files changed, 17 insertions, 19 deletions

diff --git a/llvm/lib/Target/X86/X86TargetTransformInfo.h b/llvm/lib/Target/X86/X86TargetTransformInfo.h
index 23efcade51d..3bb98b5bfcb 100644
--- a/llvm/lib/Target/X86/X86TargetTransformInfo.h
+++ b/llvm/lib/Target/X86/X86TargetTransformInfo.h
@@ -33,7 +33,7 @@ class X86TTIImpl : public BasicTTIImplBase<X86TTIImpl> {
   const X86Subtarget *ST;
   const X86TargetLowering *TLI;
 
-  unsigned getScalarizationOverhead(Type *Ty, bool Insert, bool Extract);
+  int getScalarizationOverhead(Type *Ty, bool Insert, bool Extract);
 
   const X86Subtarget *getST() const { return ST; }
   const X86TargetLowering *getTLI() const { return TLI; }
@@ -62,34 +62,32 @@ public:
   unsigned getNumberOfRegisters(bool Vector);
   unsigned getRegisterBitWidth(bool Vector);
   unsigned getMaxInterleaveFactor(unsigned VF);
-  unsigned getArithmeticInstrCost(
+  int getArithmeticInstrCost(
       unsigned Opcode, Type *Ty,
       TTI::OperandValueKind Opd1Info = TTI::OK_AnyValue,
       TTI::OperandValueKind Opd2Info = TTI::OK_AnyValue,
       TTI::OperandValueProperties Opd1PropInfo = TTI::OP_None,
       TTI::OperandValueProperties Opd2PropInfo = TTI::OP_None);
-  unsigned getShuffleCost(TTI::ShuffleKind Kind, Type *Tp, int Index,
-                          Type *SubTp);
-  unsigned getCastInstrCost(unsigned Opcode, Type *Dst, Type *Src);
-  unsigned getCmpSelInstrCost(unsigned Opcode, Type *ValTy, Type *CondTy);
-  unsigned getVectorInstrCost(unsigned Opcode, Type *Val, unsigned Index);
-  unsigned getMemoryOpCost(unsigned Opcode, Type *Src, unsigned Alignment,
-                           unsigned AddressSpace);
-  unsigned getMaskedMemoryOpCost(unsigned Opcode, Type *Src, unsigned Alignment,
-                                 unsigned AddressSpace);
+  int getShuffleCost(TTI::ShuffleKind Kind, Type *Tp, int Index, Type *SubTp);
+  int getCastInstrCost(unsigned Opcode, Type *Dst, Type *Src);
+  int getCmpSelInstrCost(unsigned Opcode, Type *ValTy, Type *CondTy);
+  int getVectorInstrCost(unsigned Opcode, Type *Val, unsigned Index);
+  int getMemoryOpCost(unsigned Opcode, Type *Src, unsigned Alignment,
+                      unsigned AddressSpace);
+  int getMaskedMemoryOpCost(unsigned Opcode, Type *Src, unsigned Alignment,
+                            unsigned AddressSpace);
 
-  unsigned getAddressComputationCost(Type *PtrTy, bool IsComplex);
+  int getAddressComputationCost(Type *PtrTy, bool IsComplex);
 
-  unsigned getReductionCost(unsigned Opcode, Type *Ty, bool IsPairwiseForm);
+  int getReductionCost(unsigned Opcode, Type *Ty, bool IsPairwiseForm);
 
-  unsigned getIntImmCost(int64_t);
+  int getIntImmCost(int64_t);
 
-  unsigned getIntImmCost(const APInt &Imm, Type *Ty);
+  int getIntImmCost(const APInt &Imm, Type *Ty);
 
-  unsigned getIntImmCost(unsigned Opcode, unsigned Idx, const APInt &Imm,
-                         Type *Ty);
-  unsigned getIntImmCost(Intrinsic::ID IID, unsigned Idx, const APInt &Imm,
-                         Type *Ty);
+  int getIntImmCost(unsigned Opcode, unsigned Idx, const APInt &Imm, Type *Ty);
+  int getIntImmCost(Intrinsic::ID IID, unsigned Idx, const APInt &Imm,
+                    Type *Ty);
   bool isLegalMaskedLoad(Type *DataType, int Consecutive);
   bool isLegalMaskedStore(Type *DataType, int Consecutive);
   bool areInlineCompatible(const Function *Caller,