| Issue |
113988
|
| Summary |
Wrong simplification of nested `select` using an implied condition
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
bongjunj
|
https://github.com/llvm/llvm-project/blob/1ceccbb0dd9d8539fec2213566fe6cc2a05b7993/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp#L2785-L2798
```llvm
----------------------------------------
define float @fmin_fmin_zero_mismatch.2(float %x) {
#0:
%cmp1 = fcmp olt float %x, -0.000000
%#1 = fmul float %x, 1.000000
%min1 = select i1 %cmp1, float %#1, float 0.000000
%cmp2 = fcmp olt float %min1, 0.000000
%min2 = select i1 %cmp2, float %min1, float 0.000000
ret float %min2
}
=>
define float @fmin_fmin_zero_mismatch.2(float %x) {
#0:
%cmp1 = fcmp olt float %x, 0.000000
%min2 = select i1 %cmp1, float %x, float 0.000000
ret float %min2
}
Transformation doesn't verify!
ERROR: Value mismatch
Example:
float %x = undef
Source:
i1 %cmp1 = #x0 (0) [based on undef value]
float %#1 = #x00000000 (+0.0) [based on undef value]
float %min1 = #x00000000 (+0.0)
i1 %cmp2 = #x0 (0)
float %min2 = #x00000000 (+0.0)
Target:
i1 %cmp1 = #x1 (1)
float %min2 = #x7f801090 (SNaN)
Source value: #x00000000 (+0.0)
Target value: #x7f801090 (SNaN)
Summary:
0 correct transformations
1 incorrect transformations
0 failed-to-prove transformations
0 Alive2 errors
```
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