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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug target/103882] Register corruption in ASM only functions when
 optization is -O2/-Os/-O3
Date: Sat, 01 Jan 2022 20:34:12 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D103882

--- Comment #12 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
That is solely because you didn't write anything else in the function, try =
to
put some code around the inline asm and you'll see how it will misbehave ev=
en
with noipa attribute.
Your code is invalid as documented in GCC documentation, the behavior is
undefined, it can do anything, break with different optimization levels,
different compiler versions or revisions, it can appear to work in some cas=
es
the way you intended, but it is still broken.=