cyb70289 commented on issue #12681:
URL: https://github.com/apache/arrow/issues/12681#issuecomment-2490386237
I cannot find an example.
I dumped the operands of error case, as shown in below test code.
Build with gcc -O3.
On Arm server, it outputs mismatch:
```
f=0.071641, a=86.263564, b=82.135635
r1 = 82.43136555356123551519
r2 = 82.43136555356122130434
!!!!!! MISMATCH !!!!!!
r1 register = 40549b9b7e444aa7
r2 register = 40549b9b7e444aa6
```
On x86 server, no error:
```
f=0.071641, a=86.263564, b=82.135635
r1 = 82.43136555356123551519
r2 = 82.43136555356123551519
```
test code
```
#include <stdio.h>
// 64bit double register dumped from error case
volatile long fl=0x3fb257174cbebc00, al=0x405590de3a8ef93d,
bl=0x405488ae3e2af9f6;
int main() {
volatile double f = *(volatile double*)&fl;
volatile double a = *(volatile double*)&al;
volatile double b = *(volatile double*)&bl;
printf("f=%f, a=%f, b=%f\n", f, a, b);
double r1 = f * a + (1 - f) * b;
double r2 = (1 - f) * b + f * a;
printf("r1 = %.20f\n", r1);
printf("r2 = %.20f\n", r2);
if (r1 != r2) {
printf("!!!!!! MISMATCH !!!!!!\n");
printf("r1 register = %lx\n", *(long*)&r1);
printf("r2 register = %lx\n", *(long*)&r2);
}
return 0;
}
```
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