[PATCH] Teach ValueTracking about address spaces

[Matt Arsenault]

On Aug 2, 2013, at 16:51 , Eli Friedman <eli.friedman at gmail.com> wrote:

> On Thu, Aug 1, 2013 at 2:22 PM, Matt Arsenault
> <Matthew.Arsenault at amd.com> wrote:
>> This is required for
>> 
>> http://llvm-reviews.chandlerc.com/D1250
>> 
>> I don't have a test for this using different address spaces until some other pieces are also in.
>> 
>> http://llvm-reviews.chandlerc.com/D1262
>> 
>> Files:
>>  lib/Analysis/ValueTracking.cpp
>> 
>> Index: lib/Analysis/ValueTracking.cpp
>> ===================================================================
>> --- lib/Analysis/ValueTracking.cpp
>> +++ lib/Analysis/ValueTracking.cpp
>> @@ -39,8 +39,8 @@
>> static unsigned getBitWidth(Type *Ty, const DataLayout *TD) {
>>   if (unsigned BitWidth = Ty->getScalarSizeInBits())
>>     return BitWidth;
>> -  assert(isa<PointerType>(Ty) && "Expected a pointer type!");
>> -  return TD ? TD->getPointerSizeInBits() : 0;
>> +
>> +  return TD ? TD->getPointerTypeSizeInBits(Ty) : 0;
>> }
>> 
>> static void ComputeMaskedBitsAddSub(bool Add, Value *Op0, Value *Op1, bool NSW,
>> @@ -1704,20 +1704,25 @@
>> /// it can be expressed as a base pointer plus a constant offset.  Return the
>> /// base and offset to the caller.
>> Value *llvm::GetPointerBaseWithConstantOffset(Value *Ptr, int64_t &Offset,
>> -                                              const DataLayout *TD) {
>> +                                              const DataLayout *DL) {
>>   // Without DataLayout, conservatively assume 64-bit offsets, which is
>>   // the widest we support.
>> -  unsigned BitWidth = TD ? TD->getPointerSizeInBits() : 64;
>> +  unsigned BitWidth = DL ? DL->getPointerTypeSizeInBits(Ptr->getType()) : 64;
>>   APInt ByteOffset(BitWidth, 0);
>>   while (1) {
>>     if (Ptr->getType()->isVectorTy())
>>       break;
>> 
>>     if (GEPOperator *GEP = dyn_cast<GEPOperator>(Ptr)) {
>> -      APInt GEPOffset(BitWidth, 0);
>> -      if (TD && !GEP->accumulateConstantOffset(*TD, GEPOffset))
>> -        break;
>> -      ByteOffset += GEPOffset;
>> +      if (DL) {
>> +        BitWidth = DL->getPointerTypeSizeInBits(Ptr->getType());
> 
> Why do you need to reset BitWidth every iteration of the loop?  Didn't
> you already commit the verifier patches which guarantee BitWidth will
> be the same for every iteration of the loop?

It doesn't, I'll remove it. I don't know why it's there.