[llvm-branch-commits] [llvm] release/18.x: [InstCombine] Fix miscompilation in PR83947 (#83993) (PR #84021)

[Yingwei Zheng via llvm-branch-commits]

dtcxzyw wrote:

@nikic Do you know how to add a commit to this PR?
```
diff --git a/llvm/test/Transforms/InstCombine/masked_intrinsics.ll b/llvm/test/Transforms/InstCombine/masked_intrinsics.ll
index 2704905f7a35..c87c1199f727 100644
--- a/llvm/test/Transforms/InstCombine/masked_intrinsics.ll
+++ b/llvm/test/Transforms/InstCombine/masked_intrinsics.ll
@@ -292,7 +292,11 @@ entry:
 define void @scatter_nxv4i16_uniform_vals_uniform_ptrs_all_active_mask(ptr %dst, i16 %val) {
 ; CHECK-LABEL: @scatter_nxv4i16_uniform_vals_uniform_ptrs_all_active_mask(
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    store i16 [[VAL:%.*]], ptr [[DST:%.*]], align 2
+; CHECK-NEXT:    [[BROADCAST_SPLATINSERT:%.*]] = insertelement <vscale x 4 x ptr> poison, ptr [[DST:%.*]], i64 0
+; CHECK-NEXT:    [[BROADCAST_SPLAT:%.*]] = shufflevector <vscale x 4 x ptr> [[BROADCAST_SPLATINSERT]], <vscale x 4 x ptr> poison, <vscale x 4 x i32> zeroinitializer
+; CHECK-NEXT:    [[BROADCAST_VALUE:%.*]] = insertelement <vscale x 4 x i16> poison, i16 [[VAL:%.*]], i64 0
+; CHECK-NEXT:    [[BROADCAST_SPLATVALUE:%.*]] = shufflevector <vscale x 4 x i16> [[BROADCAST_VALUE]], <vscale x 4 x i16> poison, <vscale x 4 x i32> zeroinitializer
+; CHECK-NEXT:    call void @llvm.masked.scatter.nxv4i16.nxv4p0(<vscale x 4 x i16> [[BROADCAST_SPLATVALUE]], <vscale x 4 x ptr> [[BROADCAST_SPLAT]], i32 2, <vscale x 4 x i1> shufflevector (<vscale x 4 x i1> insertelement (<vscale x 4 x i1> zeroinitializer, i1 true, i32 0), <vscale x 4 x i1> zeroinitializer, <vscale x 4 x i32> zeroinitializer))
 ; CHECK-NEXT:    ret void
 ;
 entry:
```

It is a regression. But I think it should be fixed by https://github.com/llvm/llvm-project/commit/fd07b8f809eb64af9b29331ff6b94904b3159f84.


https://github.com/llvm/llvm-project/pull/84021