News for hackers. Stuff that matters.

A comment on Why Const Doesn't Make C Code Faster. Parent comment

Re:Why Const Doesn't Make C Code Faster by einpoklum on Tuesday August 20, 2019 @02:38AM (#20744342)
> You can even promise a func is pure without even implementing it in the same translation unit!

Actually that's the main point, as if it's in the same TU, the compiler can probably figure out a function is pure.

[ Parent | on HN ]
Re:Why Const Doesn't Make C Code Faster by dmitrygr on Tuesday August 20, 2019 @04:38PM (#20751830)
often but not always, for example a function using asm() to access, say, some AES intrinsics is pure (const even) since the output only depends on input, but oftentimes compiler by itself will not declare a function with an asm() block pure or const
[ Parent | on HN ]
Re:Why Const Doesn't Make C Code Faster by einpoklum on Tuesday August 20, 2019 @05:22PM (#20752329)
Well, fair point, but - compilers shouldn't be that lazy :-)
[ Parent | on HN ]