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From: "jason at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/102586] [12 Regression] ICE in
 clear_padding_type, at gimple-fold.c:4798 since r12-3433-ga25e0b5e6ac8a77a
Date: Sat, 12 Mar 2022 04:40:38 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D102586

--- Comment #28 from Jason Merrill <jason at gcc dot gnu.org> ---
(In reply to Qing Zhao from comment #27)
> Does this issue only exist with -flifetime-dse=3D2?
> When -flifetime-dse=3D2, the call to __builtin_clear_padding should be
> inserted AFTER the start point of the constructor of the object, otherwise
> it=E2=80=99s dead and will be eliminated by DSE.=20
> And with -flifetime-dse=3D2, the padding initialization should be done by=
 C++
> FE instead of middle end.
> Is this understanding correct?

Yes, -flifetime-dse=3D2 conflicts with -ftrivial-auto-var-init in that both=
 are
trying to define the initial state of the variable.

Perhaps -ftrivial-auto-var-init should lower to -flifetime-dse=3D1.

Or change build_clobber_this to do the specified initialization instead of a
clobber, though that would mean doing the initialization for any object of =
that
type, not just automatics.=