[PATCH] D68706: [InstCombine] don't assume 'inbounds' for bitcast deref or null pointer in non-default address space

[Johannes Doerfert via Phabricator via llvm-commits]

jdoerfert added a comment.

In D68706#1701551 <https://reviews.llvm.org/D68706#1701551>, @lebedev.ri wrote:

> You want `llvm::NullPointerIsDefined()`, which also checks for `"null-pointer-is-valid"` attribute.


`getPointerDereferenceableBytes` should do the above. The tests in the file show it works except there is one missing:

  define float @matching_scalar_smallest_deref_addrspace(<4 x float> addrspace(4)* dereferenceable(1) %p) {
  ; CHECK-LABEL: @matching_scalar_smallest_deref_addrspace(
  ; CHECK-NEXT:    [[BC:%.*]] = getelementptr inbounds <4 x float>, <4 x float> addrspace(4)* [[P:%.*]], i64 0, i64 0
  ; CHECK-NEXT:    [[R:%.*]] = load float, float addrspace(4)* [[BC]], align 16
  ; CHECK-NEXT:    ret float [[R]]
  ;
    %bc = bitcast <4 x float> addrspace(4)* %p to float addrspace(4)*
    %r = load float, float addrspace(4)* %bc, align 16
    ret float %r
  }

I think this is fine but I want to hear if people agree.


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