[Bug target/103882] Register corruption in ASM only functions when optization is -O2/-Os/-O3

["krystalgamer at protonmail dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103882

Jose Silva <krystalgamer at protonmail dot com> changed:

           What    |Removed                     |Added
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         Resolution|INVALID                     |WONTFIX

--- Comment #11 from Jose Silva <krystalgamer at protonmail dot com> ---
> much more important is that it needs to know what the inline asm does for code generation within the function, it needs to know in which registers or memory it can spill values live across the inline asm etc.
> if you are unable or not willing to tell the compiler how it behaves

Read the title of issue. This problem only manifests with O2/Os/O3, O0 and O1
don't exhibit it because IPA RA doesn't kick in. So no, the compiler doesn't
need to be told how it behaves if it takes precautions. The only reason to tell
a compiler something is to further optimize something, in any other
circumstance it should treat the piece of code as a black-box as you said.

What we're arguing here is about sensible compiler defaults. By default a
compiler should be cautious about asm statements and protect the surrounding
code by respecting the ABI. The programmer should be able to override this
behavior, not the other way around like GCC does.

There is absolutely no need to tell the compiler something he could've easily
accounted for.

> Don't use inline asm 

Wish I didn't need to, but there's no way of doing syscalls without it.



On the other hand, since you avoided answering my question regarding modifying
GCC I suppose you're not familiar with the codebase. Please refrain from
polluting this discussion with unnecessary noise if you don't wish to help.