From b632a516a0448818a25f35e15a4bf0a3187af359 Mon Sep 17 00:00:00 2001
From: Richard Sandiford <richard.sandiford@arm.com>
Date: Tue, 24 Oct 2023 10:58:40 +0100
Subject: [PATCH] aarch64: Avoid bogus atomics match
The non-LSE pattern aarch64_atomic_exchange<mode> comes before the
LSE pattern aarch64_atomic_exchange<mode>_lse. From a recog
perspective, the only difference between the patterns is that
the non-LSE one clobbers CC and needs a scratch.
However, combine and RTL-SSA can both add clobbers to make a
pattern match. This means that if they try to rerecognise an
LSE pattern, they could end up turning it into a non-LSE pattern.
This patch adds a !TARGET_LSE test to avoid that.
This is needed to avoid a regression with later patches.
gcc/
* config/aarch64/atomics.md (aarch64_atomic_exchange<mode>): Require
!TARGET_LSE.
---
gcc/config/aarch64/atomics.md | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/gcc/config/aarch64/atomics.md b/gcc/config/aarch64/atomics.md
index 2b6f04efa6c9..055a87320caa 100644
--- a/gcc/config/aarch64/atomics.md
+++ b/gcc/config/aarch64/atomics.md
@@ -224,7 +224,7 @@
UNSPECV_ATOMIC_EXCHG))
(clobber (reg:CC CC_REGNUM))
(clobber (match_scratch:SI 4 "=&r"))]
- ""
+ "!TARGET_LSE"
"#"
"&& epilogue_completed"
[(const_int 0)]
--
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