From bfb705e21d24b65da515ad59a902ec279335aaa0 Mon Sep 17 00:00:00 2001
From: Yingwei Zheng <dtcxzyw2333@gmail.com>
Date: Tue, 5 Mar 2024 22:34:04 +0800
Subject: [PATCH] [InstCombine] Fix miscompilation in PR83947 (#83993)

https://github.com/llvm/llvm-project/blob/762f762504967efbe159db5c737154b989afc9bb/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp#L394-L407

Comment from @topperc:
> This transforms assumes the mask is a non-zero splat. We only know its
a splat and not provably all 0s. The mask is a constexpr that includes
the address of the global variable. We can't resolve the constant
expression to an exact value.

Fixes #83947.
---
 llvm/test/Transforms/InstCombine/masked_intrinsics.ll | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/llvm/test/Transforms/InstCombine/masked_intrinsics.ll b/llvm/test/Transforms/InstCombine/masked_intrinsics.ll
index 15ffc881b5731b..e49984d9211a3e 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: