[llvm] [AMDGPU][GISel] Use datalayout alignment for buffer-load legalization (PR #95578)

[Matt Arsenault via llvm-commits]

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@@ -272,7 +272,7 @@ body:             |
     ; GFX67-NEXT: {{  $}}
     ; GFX67-NEXT: [[COPY:%[0-9]+]]:_(<4 x s32>) = COPY $sgpr0_sgpr1_sgpr2_sgpr3
     ; GFX67-NEXT: [[C:%[0-9]+]]:_(s32) = G_CONSTANT i32 0
-    ; GFX67-NEXT: [[AMDGPU_S_BUFFER_LOAD:%[0-9]+]]:_(<4 x s32>) = G_AMDGPU_S_BUFFER_LOAD [[COPY]](<4 x s32>), [[C]](s32), 0 :: (dereferenceable invariant load (s96), align 4)
+    ; GFX67-NEXT: [[AMDGPU_S_BUFFER_LOAD:%[0-9]+]]:_(<4 x s32>) = G_AMDGPU_S_BUFFER_LOAD [[COPY]](<4 x s32>), [[C]](s32), 0 :: (dereferenceable invariant load (s96), align 16)
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arsenm wrote:

We might be setting the wrong alignment field, I thought the MMO didn't print the align when it was the same as the size 

https://github.com/llvm/llvm-project/pull/95578