[X86] Remove different address space check in isNoopAddrSpaceCast

[wenju]

Summary

SrcAS and DestAS could be the same.

[arsenm]

What context is this from? addrspacecast is required to change the address space

[wenju]

isNoopPtrIntCastPair in lib/Transforms/Scalar/InferAddressSpaces.cpp calls isNoopAddrSpaceCast, but the two arguments might be the same. I notice isNoopAddrSpaceCast in other targets don't have such assert, so I remove this assert in X86 target.
Do you think we should check address spaces are not the same prior to isNoopAddrSpaceCast callsite in isNoopPtrIntCastPair?

[arsenm]

In D123368#3441750, @wenju wrote:

isNoopPtrIntCastPair in lib/Transforms/Scalar/InferAddressSpaces.cpp calls isNoopAddrSpaceCast, but the two arguments might be the same. I notice isNoopAddrSpaceCast in other targets don't have such assert, so I remove this assert in X86 target.
Do you think we should check address spaces are not the same prior to isNoopAddrSpaceCast callsite in isNoopPtrIntCastPair?

So you're claiming InferAddressSpaces asserts for x86? Can you add a test?

[wenju]

So you're claiming InferAddressSpaces asserts for x86? Can you add a test?

Test is added in https://reviews.llvm.org/D123573, please review.
Abandon this revision.

llvm/lib/Target/X86/X86TargetMachine.cpp

I = std::make_unique<X86Subtarget>(
         MaybeAlign(F.getParent()->getOverrideStackAlignment()),
         PreferVectorWidthOverride, RequiredVectorWidth);
   }
   return I.get();
 }
 
 bool X86TargetMachine::isNoopAddrSpaceCast(unsigned SrcAS,
                                            unsigned DestAS) const {
-  assert(SrcAS != DestAS && "Expected different address spaces!");
   if (getPointerSize(SrcAS) != getPointerSize(DestAS))
     return false;
   return SrcAS < 256 && DestAS < 256;
 }
 
 //===----------------------------------------------------------------------===//
 // X86 TTI query.
 //===----------------------------------------------------------------------===//