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From 3c819146751bedbca46f5f089a786d7b5595baa8 Mon Sep 17 00:00:00 2001
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From: "H.J. Lu" <hjl.tools@gmail.com>
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Date: Wed, 2 Mar 2022 16:30:33 -0800
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Subject: [PATCH] x86-64: Use notl in EVEX strcmp [BZ #28646]
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Must use notl %edi here as lower bits are for CHAR comparisons
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potentially out of range thus can be 0 without indicating mismatch.
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This fixes BZ #28646.
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Co-Authored-By: H.J. Lu <hjl.tools@gmail.com>
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(cherry picked from commit 4df1fa6ddc8925a75f3da644d5da3bb16eb33f02)
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---
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sysdeps/x86_64/multiarch/strcmp-evex.S | 14 ++++++++------
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1 file changed, 8 insertions(+), 6 deletions(-)
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diff --git a/sysdeps/x86_64/multiarch/strcmp-evex.S b/sysdeps/x86_64/multiarch/strcmp-evex.S
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index 82f12ac8..6f5c4bf9 100644
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--- a/sysdeps/x86_64/multiarch/strcmp-evex.S
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+++ b/sysdeps/x86_64/multiarch/strcmp-evex.S
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@@ -656,12 +656,13 @@ L(loop_cross_page):
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in YMM3 and 32 bytes at VEC_SIZE(%rdx, %r10). */
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VPCMP $0, VEC_SIZE(%rdx, %r10), %YMM3, %k3{%k4}
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kmovd %k3, %edi
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+ /* Must use notl %edi here as lower bits are for CHAR
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+ comparisons potentially out of range thus can be 0 without
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+ indicating mismatch. */
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+ notl %edi
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# ifdef USE_AS_WCSCMP
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/* Don't use subl since it is the upper 8 bits of EDI below. */
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- notl %edi
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andl $0xff, %edi
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-# else
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- incl %edi
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# endif
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# ifdef USE_AS_WCSCMP
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@@ -743,12 +744,13 @@ L(loop_cross_page_2_vec):
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in YMM1 and 32 bytes at (VEC_SIZE * 3)(%rdx, %r10). */
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VPCMP $0, (VEC_SIZE * 3)(%rdx, %r10), %YMM1, %k3{%k4}
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kmovd %k3, %edi
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+ /* Must use notl %edi here as lower bits are for CHAR
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+ comparisons potentially out of range thus can be 0 without
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+ indicating mismatch. */
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+ notl %edi
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# ifdef USE_AS_WCSCMP
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/* Don't use subl since it is the upper 8 bits of EDI below. */
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- notl %edi
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andl $0xff, %edi
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-# else
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- incl %edi
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# endif
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# ifdef USE_AS_WCSCMP
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--
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GitLab
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