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From: "sebastian.huber@embedded-brains.de" <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 12:36:40 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D99151

--- Comment #6 from Sebastian Huber <sebastian.huber@embedded-brains.de> ---
(In reply to Eric Botcazou from comment #5)
> static void
> sparc_asm_function_epilogue (FILE *file)
> {
>   /* If the last two instructions of a function are "call foo; dslot;"
>      the return address might point to the first instruction in the next
>      function and we have to output a dummy nop for the sake of sane
>      backtraces in such cases.  This is pointless for sibling calls since
>      the return address is explicitly adjusted.  */

This nop behaviour could be a bit inconsistent across architectures. For
example, arm and powerpc don't generate a nop here.

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