RKSimon added inline comments.
================
Comment at: clang/lib/Headers/immintrin.h:301
+ unsigned long long tmp;
+ if (__builtin_ia32_rdrand32_step((unsigned int *)&tmp) &
+ __builtin_ia32_rdrand32_step(((unsigned int *)&tmp) + 1)) {
----------------
RKSimon wrote:
> craig.topper wrote:
> > craig.topper wrote:
> > > Should `&` be `&&`?
> > Can we avoid the pointer cast here? Use two unsigned ints and manually
> > concatenate them to a 64-bit value.
> +1
> ```
> unsigned int lo, hi;
> if (__builtin_ia32_rdrand32_step(&lo) &&
> __builtin_ia32_rdrand32_step(&hi)) {
> *p = ((unsigned long)hi << 32) | lo;
> return 1;
> }
> ```
Are there any sideeffects that we might encounter by not always performing both
__builtin_ia32_rdrand32_step calls?
```
unsigned int __lo, __hi;
int __res_lo = __builtin_ia32_rdrand32_step(&__lo);
int __res_hi = __builtin_ia32_rdrand32_step(&__hi);
if (__res_lo && __res_hi) {
*__p = ((unsigned long long)__hi << 32) | (unsigned long long)__lo;
return 1;
} else {
*__p = 0;
return 0;
}
```
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D132141/new/
https://reviews.llvm.org/D132141
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
