| Issue |
115575
|
| Summary |
[VectorCombine] UB triggered after optimization
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
bongjunj
|
https://github.com/llvm/llvm-project/blob/c93e001ca695e905cb965b36d63f7a348d1dd809/llvm/lib/Transforms/Vectorize/VectorCombine.cpp#L1013-L1031
Alive2 report: https://alive2.llvm.org/ce/z/78CM4x
```llvm
----------------------------------------
define <2 x i8> @sdiv_constant_op1_not_undef_lane.2(i8 %x) {
#0:
%ins = insertelement <2 x i8> poison, i8 %x, i32 3
%bo = sdiv <2 x i8> %ins, { 5, 2 }
ret <2 x i8> %bo
}
=>
define <2 x i8> @sdiv_constant_op1_not_undef_lane.2(i8 %x) {
#0:
%bo.scalar = sdiv i8 %x, poison
%bo = insertelement <2 x i8> poison, i8 %bo.scalar, i64 3
ret <2 x i8> %bo
}
Transformation doesn't verify!
ERROR: Source is more defined than target
Example:
i8 %x = poison
Source:
<2 x i8> %ins = < poison, poison >
<2 x i8> %bo = < poison, poison >
Target:
i8 %bo.scalar = UB triggered!
----------------------------------------
define <2 x i64> @urem_constant_op1_not_undef_lane.2(i64 %x) {
#0:
%ins = insertelement <2 x i64> poison, i64 %x, i32 4294967295
%bo = urem <2 x i64> %ins, { 5, 2 }
ret <2 x i64> %bo
}
=>
define <2 x i64> @urem_constant_op1_not_undef_lane.2(i64 %x) {
#0:
%bo.scalar = urem i64 %x, poison
%bo = insertelement <2 x i64> poison, i64 %bo.scalar, i64 4294967295
ret <2 x i64> %bo
}
Transformation doesn't verify!
ERROR: Source is more defined than target
Example:
i64 %x = poison
Source:
<2 x i64> %ins = < poison, poison >
<2 x i64> %bo = < poison, poison >
Target:
i64 %bo.scalar = UB triggered!
Summary:
0 correct transformations
2 incorrect transformations
0 failed-to-prove transformations
0 Alive2 errors
```
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