4 ms·
> it is legal to optimize out any code paths that rely on this, even if they occur earlier in program order. I don't think this is true. The compiler cannot re
by teo_zero 6mo ago
> it is legal to optimize out any code paths that rely on this, even if they occur earlier in program order.
I don't think this is true. The compiler cannot remove or reorder instructions that have a visible effect.
if (p == 0)
printf("Ready?\n");
*p++;
The printf() can't be omitted.
- aw1621107 6mo ago> The compiler cannot remove or reorder instructions that have a visible effect. You might be surprised! When it comes to UB compilers can and do reorder/eliminate instructions with side effects, resulting in "time travel" [0]. IIRC the upcoming version of the C standard bans this behavior, but the C++ standard still allows it (for now, at least). [0]: https://devblogs.microsoft.com/oldnewthing/20140627-00/?p=633 https://devblogs.microsoft.com/oldnewthing/20140627-00/?p=63...
- saagarjha 6mo agoNo, this is explicitly legal. Most compilers will shy away from it these days since it made a lot of people upset, but it's definitely allowed.