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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/109945] Escape analysis hates copy elision:
 different result with -O1 vs -O2
Date: Wed, 24 May 2023 08:16:11 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D109945

--- Comment #14 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #13)
> with the former for -m64 and the latter for -m32 only seems to be the
> only fallout here.

It will penalize C and other languages without mandatory NRV in the FEs,
without that I think the address can't escape (taking address then would ei=
ther
prevent tree-nrv.cc or
even if not, would be still considered taking address of a local variable).
Perhaps we could remember in some FUNCTION_DECL bit whether mandatory NRV w=
as
done and
least for the cases where we know the callee, we know it hasn't done NRV and
!TREE_ADDRESSABLE (TREE_TYPE (gimple_call_lhs (stmt)))) we could avoid this.
But perhaps it is an overkill.=