[llvm] AMDGPU/GlobalISel: Fix inst-selection of ballot (PR #109986)

[Matt Arsenault via llvm-commits]

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@@ -132,7 +132,8 @@ define amdgpu_ps void @struct_ptr_buffer_store_format_f32__sgpr_val__vgpr_rsrc__
   ; CHECK-NEXT:   [[V_READFIRSTLANE_B32_4:%[0-9]+]]:sreg_32 = V_READFIRSTLANE_B32 [[COPY7]], implicit $exec
   ; CHECK-NEXT:   [[V_CMP_EQ_U32_e64_:%[0-9]+]]:sreg_64_xexec = V_CMP_EQ_U32_e64 [[V_READFIRSTLANE_B32_4]], [[COPY7]], implicit $exec
   ; CHECK-NEXT:   [[S_AND_B64_1:%[0-9]+]]:sreg_64_xexec = S_AND_B64 [[S_AND_B64_]], [[V_CMP_EQ_U32_e64_]], implicit-def dead $scc
-  ; CHECK-NEXT:   [[S_AND_SAVEEXEC_B64_:%[0-9]+]]:sreg_64_xexec = S_AND_SAVEEXEC_B64 killed [[S_AND_B64_1]], implicit-def $exec, implicit-def $scc, implicit $exec
+  ; CHECK-NEXT:   [[S_AND_B64_2:%[0-9]+]]:sreg_64_xexec = S_AND_B64 [[S_AND_B64_1]], $exec, implicit-def dead $scc
+  ; CHECK-NEXT:   [[S_AND_SAVEEXEC_B64_:%[0-9]+]]:sreg_64_xexec = S_AND_SAVEEXEC_B64 killed [[S_AND_B64_2]], implicit-def $exec, implicit-def $scc, implicit $exec
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arsenm wrote:

Nearly all of the test changes are regressing the waterfall loop case, for the ballot from regbankselect. Can we do anything about that? Intuitively we should be able to use the raw value 

https://github.com/llvm/llvm-project/pull/109986