| Issue |
180456
|
| Summary |
[SLP] Binary combines with MUL and AND may use the wrong identity value
|
| Labels |
llvm:SLPVectorizer
|
| Assignees |
bababuck
|
| Reporter |
bababuck
|
The following lowering currently occurs:
`opt -S --passes=slp-vectorizer -mtriple=aarch64-unknown-linux-gnu -slp-threshold=-50`
```
define void @sub_mul(ptr %p, ptr %s) {
entry:
%p1 = getelementptr i16, ptr %p, i64 1
%p2 = getelementptr i16, ptr %p, i64 2
%p3 = getelementptr i16, ptr %p, i64 3
%l0 = load i16, ptr %p
%l1 = load i16, ptr %p1
%l2 = load i16, ptr %p2
%l3 = load i16, ptr %p3
%mul0 = sub i16 %l0, 0
%mul1 = mul i16 %l1, 5
%mul2 = mul i16 %l2, 2
%mul3 = mul i16 %l3, 3
%s1 = getelementptr i16, ptr %s, i64 1
%s2 = getelementptr i16, ptr %s, i64 2
%s3 = getelementptr i16, ptr %s, i64 3
store i16 %mul0, ptr %s
store i16 %mul1, ptr %s1
store i16 %mul2, ptr %s2
store i16 %mul3, ptr %s3
ret void
}
```
to
```
define void @sub_mul(ptr %p, ptr %s) {
entry:
%tmp0 = load <4 x i16>, ptr %p, align 2
%tmp1 = mul <4 x i16> %tmp0, <i16 0, i16 5, i16 2, i16 3>
store <4 x i16> %tmp1, ptr %s, align 2
ret void
}
```
Which is an incorrect transformation: https://alive2.llvm.org/ce/z/BgqGWV
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