[clang] [lld] [llvm] [WIP][IR][Constants] Change the semantic of `ConstantPointerNull` to represent an actual `nullptr` instead of a zero-value pointer (PR #166667)

[Shilei Tian via llvm-commits]

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@@ -42,7 +42,7 @@ define amdgpu_kernel void @addrspacecast_flat_null_to_local(ptr addrspace(1) %ou
 ; CHECK-NEXT:    PAD
 ; CHECK-NEXT:    ALU clause starting at 4:
 ; CHECK-NEXT:     MOV * T0.X, literal.x,
-; CHECK-NEXT:    -1(nan), 0(0.000000e+00)
+; CHECK-NEXT:    0(0.000000e+00), 0(0.000000e+00)
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shiltian wrote:

Does R600 even have multiple address spaces? It doesn't look like the case from the data layout string.

https://github.com/llvm/llvm-project/pull/166667