| Issue |
157874
|
| Summary |
x86 optimization: Missed merging comparison of isunordered() and islessgreater()
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
Explorer09
|
```c
#include <limits.h>
#include <math.h>
#include <stdlib.h>
int func(double x, double y) {
if (isunordered(x, y))
return INT_MIN;
if (islessgreater(x, y))
return x > y ? 1 : -1;
return 0;
}
```
https://godbolt.org/z/fPxT3qfPG
x86-64 clang 21.1.0 with `-Os` option produces:
```assembly
func:
ucomisd xmm0, xmm1
jp .LBB0_1
ucomisd xmm0, xmm1
je .LBB0_3
seta al
movzx eax, al
lea eax, [2*rax - 1]
ret
.LBB0_3:
xor eax, eax
ret
.LBB0_1:
mov eax, -2147483648
ret
```
Note the duplicate UCOMISD instructions.
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