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From: "ebotcazou at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug middle-end/99151] Missed optimization: Superfluous stack frame
 and code with noreturn or __builtin_unreachable()
Date: Mon, 01 Mar 2021 12:53:03 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D99151

--- Comment #7 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
> This nop behaviour could be a bit inconsistent across architectures. For
> example, arm and powerpc don't generate a nop here.

Well, it's low-level trickery so architecture-dependent by definition.

> I still think that the profiling counter increment in the
> __builtin_unreachable() path is a bug.

How so?  I only see a missed optimization, but with -fprofile-arcs
-ftest-coverage you're splitting hairs IMO.=