[llvm] [AMDGPU] Preserve old MSBs when handling SETREG (PR #191352)

[Stanislav Mekhanoshin via llvm-commits]

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@@ -21,7 +21,7 @@ body: |
     ; CHECK-NEXT: $vgpr256 = V_MOV_B32_e32 undef $sgpr0, implicit $exec
     ; CHECK-NEXT: S_SETREG_IMM32_B32 146108, 30721, implicit-def $mode, implicit $mode
     ; CHECK-NEXT: S_NOP 0
-    ; CHECK-NEXT: S_SET_VGPR_MSB 64, implicit-def $mode
+    ; CHECK-NEXT: S_SET_VGPR_MSB 16448, implicit-def $mode
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rampitec wrote:

Then technically it is not absolutely needed because previous instruction is SALU. I have already seen users' confusion though that high bits are zero. IMHO it is easier to always set it.

https://github.com/llvm/llvm-project/pull/191352