[PATCH] D74950: GlobalISel: Fix narrowing of (G_ASHR i64:x, 32)

[Jay Foad via Phabricator via llvm-commits]

foad created this revision.
foad added a reviewer: arsenm.
Herald added subscribers: llvm-commits, kerbowa, volkan, hiraditya, rovka, nhaehnle, wdng, jvesely.
Herald added a project: LLVM.

Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D74950

Files:
  llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
  llvm/test/CodeGen/AMDGPU/GlobalISel/combine-ashr-narrow.mir


Index: llvm/test/CodeGen/AMDGPU/GlobalISel/combine-ashr-narrow.mir
===================================================================
--- llvm/test/CodeGen/AMDGPU/GlobalISel/combine-ashr-narrow.mir
+++ llvm/test/CodeGen/AMDGPU/GlobalISel/combine-ashr-narrow.mir
@@ -14,7 +14,7 @@
     ; CHECK: [[UV:%[0-9]+]]:_(s32), [[UV1:%[0-9]+]]:_(s32) = G_UNMERGE_VALUES [[COPY]](s64)
     ; CHECK: [[C:%[0-9]+]]:_(s32) = G_CONSTANT i32 31
     ; CHECK: [[ASHR:%[0-9]+]]:_(s32) = G_ASHR [[UV1]], [[C]](s32)
-    ; CHECK: [[MV:%[0-9]+]]:_(s64) = G_MERGE_VALUES [[UV]](s32), [[ASHR]](s32)
+    ; CHECK: [[MV:%[0-9]+]]:_(s64) = G_MERGE_VALUES [[UV1]](s32), [[ASHR]](s32)
     ; CHECK: $vgpr0_vgpr1 = COPY [[MV]](s64)
     %0:_(s64) = COPY $vgpr0_vgpr1
     %1:_(s64) = G_CONSTANT i64 32
@@ -35,7 +35,7 @@
     ; CHECK: [[UV:%[0-9]+]]:_(s32), [[UV1:%[0-9]+]]:_(s32) = G_UNMERGE_VALUES [[COPY]](s64)
     ; CHECK: [[C:%[0-9]+]]:_(s32) = G_CONSTANT i32 31
     ; CHECK: [[ASHR:%[0-9]+]]:_(s32) = G_ASHR [[UV1]], [[C]](s32)
-    ; CHECK: [[MV:%[0-9]+]]:_(s64) = G_MERGE_VALUES [[UV]](s32), [[ASHR]](s32)
+    ; CHECK: [[MV:%[0-9]+]]:_(s64) = G_MERGE_VALUES [[UV1]](s32), [[ASHR]](s32)
     ; CHECK: $vgpr0_vgpr1 = COPY [[MV]](s64)
     %0:_(s64) = COPY $vgpr0_vgpr1
     %1:_(s32) = G_CONSTANT i32 32
Index: llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
===================================================================
--- llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
+++ llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
@@ -1449,8 +1449,8 @@
 
     if (ShiftVal == HalfSize) {
       // (G_ASHR i64:x, 32) ->
-      //   G_MERGE_VALUES lo_32(x), (G_ASHR hi_32(x), 31)
-      Builder.buildMerge(DstReg, { Unmerge.getReg(0), Hi });
+      //   G_MERGE_VALUES hi_32(x), (G_ASHR hi_32(x), 31)
+      Builder.buildMerge(DstReg, { Unmerge.getReg(1), Hi });
     } else if (ShiftVal == Size - 1) {
       // Don't need a second shift.
       // (G_ASHR i64:x, 63) ->


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