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From: "bergner at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug target/100799] Stackoverflow in optimized code on PPC
Date: Tue, 01 Jun 2021 19:08:13 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D100799

Peter Bergner <bergner at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2021-06-01

--- Comment #2 from Peter Bergner <bergner at gcc dot gnu.org> ---
(In reply to Alexander Grund from comment #1)
> Confirmed to also break with GCC 7.3, 8.2, 8.3 but works with 6.3, 6.4, 6=
.5

The failure with GCC 7 and later coincides with the PPC port starting to
default to LRA instead of reload.  If I look at the debug dumps compiling
dgebal.f, the 440 offset to the stack is created by an LRA spill.  No probl=
em
there that I can see.  The problem seems to come later when we generate the
prologue/epilogue and we only update the stack pointer by the smaller 368 b=
yte
offset.

Either LRA isn't telling us it needs that extra stack space or the ppc back=
end
didn't notice.  I'll keep digging.=