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From: "liuhongt at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/115517] Fix x86 regressions after dropping uses of
 vcond{,u,eq}_optab
Date: Tue, 18 Jun 2024 08:39:33 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D115517

--- Comment #2 from Hongtao Liu <liuhongt at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #1)
> Btw, I had opened PR115490 with my results for this already.  Some mitiga=
tion
> should be from optimizing ISEL expansion to vcond_mask and I'd start with
> looking at some of the fallout from that side (note that might require
> the backend reject not natively implemented vec_cmp via its operand 1
> predicate)

w/o AVX512, vector integer comparison only supports EQ/GT, others comparison
rtx_cost is transformed to that. (.i.e GTU is emulated with us_minus + eq +
negative the vector mask)
If we restrict the predicate of operand 1, would middle-end reject
vectorization (or lower it to scalar version)?=