> You can even promise a func is pure without even implementing it in the same t... | Hacker News

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einpoklum on Aug 20, 2019 | parent | context | favorite | on: Why Const Doesn't Make C Code Faster

> 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.

dmitrygr on Aug 20, 2019 [–]

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

einpoklum on Aug 20, 2019 | [–]

Well, fair point, but - compilers shouldn't be that lazy :-)

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