| Issue |
143123
|
| Summary |
[InstCombine] fcmp is incorrectly inverted
|
| Labels |
miscompilation,
llvm:instcombine,
floating-point,
generated by fuzzer
|
| Assignees |
dtcxzyw
|
| Reporter |
dtcxzyw
|
Reproducer: https://alive2.llvm.org/ce/z/yVw9wM
```
define float @src(float %x) {
%cmp = fcmp olt float %x, 0.000000e+00
%sel = select nnan nsz i1 %cmp, float %x, float -0.000000e+00
ret float %sel
}
define float @tgt(float %x) {
%.inv = fcmp oge float %x, 0.000000e+00
%sel1 = select i1 %.inv, float -0.000000e+00, float %x
ret float %sel1
}
```
```
----------------------------------------
define float @src(float %x) {
#0:
%cmp = fcmp olt float %x, 0.000000
%sel = select nnan nsz i1 %cmp, float %x, float -0.000000
ret float %sel
}
=>
define float @tgt(float %x) {
#0:
%.inv = fcmp oge float %x, 0.000000
%sel1 = select i1 %.inv, float -0.000000, float %x
ret float %sel1
}
Transformation doesn't verify!
ERROR: Value mismatch
Example:
float %x = #x7f800002 (SNaN)
Source:
i1 %cmp = #x0 (0)
float %sel = #x80000000 (-0.0)
Target:
i1 %.inv = #x0 (0)
float %sel1 = #x7f800002 (SNaN)
Source value: #x80000000 (-0.0)
Target value: #x7f800002 (SNaN)
```
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