[llvm] [AMDGPU] Allocate AVRegClass last (PR #146606)

[Matt Arsenault via llvm-commits]

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@@ -307,13 +307,13 @@ define amdgpu_kernel void @build_v2i32_from_v4i16_shuffle(ptr addrspace(1) %out,
 ; GFX942-LABEL: build_v2i32_from_v4i16_shuffle:
 ; GFX942:       ; %bb.0: ; %entry
 ; GFX942-NEXT:    s_load_dwordx4 s[0:3], s[4:5], 0x24
-; GFX942-NEXT:    v_mov_b32_e32 v2, 0
+; GFX942-NEXT:    v_mov_b32_e32 v0, 0
 ; GFX942-NEXT:    s_waitcnt lgkmcnt(0)
 ; GFX942-NEXT:    s_lshl_b32 s3, s3, 16
 ; GFX942-NEXT:    s_lshl_b32 s2, s2, 16
-; GFX942-NEXT:    v_mov_b32_e32 v0, s2
-; GFX942-NEXT:    v_mov_b32_e32 v1, s3
-; GFX942-NEXT:    global_store_dwordx2 v2, v[0:1], s[0:1]
+; GFX942-NEXT:    v_mov_b32_e32 v2, s2
+; GFX942-NEXT:    v_mov_b32_e32 v3, s3
+; GFX942-NEXT:    global_store_dwordx2 v0, v[2:3], s[0:1]
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arsenm wrote:

On my list of things to do is to allow inflating to the unaligned register classes. We currently hackily applied the new-in-mi200 alignment restriction by overly conservatively always using aligned classes even in contexts where it's unnecessary 

https://github.com/llvm/llvm-project/pull/146606