From 5b281946c4b51132caf5e5b64c730fef92dd6123 Mon Sep 17 00:00:00 2001
From: Richard Biener <rguenther@suse.de>
Date: Thu, 1 Feb 2024 13:54:11 +0100
Subject: [PATCH] target/113255 - avoid REG_POINTER on a pointer difference
The following avoids re-using a register holding a pointer (and
thus might be REG_POINTER) for the result of a pointer difference
computation. That might confuse heuristics in (broken) RTL alias
analysis which relies on REG_POINTER indicating that we're
dealing with one.
This alone doesn't fix anything.
PR target/113255
* config/i386/i386-expand.cc
(expand_set_or_cpymem_prologue_epilogue_by_misaligned_moves):
Use a new pseudo for the skipped number of bytes.
---
gcc/config/i386/i386-expand.cc | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/gcc/config/i386/i386-expand.cc b/gcc/config/i386/i386-expand.cc
index 5706220823ab..50f9fe2c0d73 100644
--- a/gcc/config/i386/i386-expand.cc
+++ b/gcc/config/i386/i386-expand.cc
@@ -8429,7 +8429,7 @@ expand_set_or_cpymem_prologue_epilogue_by_misaligned_moves (rtx destmem, rtx src
/* See how many bytes we skipped. */
saveddest = expand_simple_binop (GET_MODE (*destptr), MINUS, saveddest,
*destptr,
- saveddest, 1, OPTAB_DIRECT);
+ NULL_RTX, 1, OPTAB_DIRECT);
/* Adjust srcptr and count. */
if (!issetmem)
*srcptr = expand_simple_binop (GET_MODE (*srcptr), MINUS, *srcptr,
--
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