[PATCH] aarch64: Avoid bogus atomics match

[PATCH] aarch64: Avoid bogus atomics match

[Richard Sandiford]

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.

Tested on aarch64-linux-gnu & pushed.

Richard


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 2b6f04efa6c..055a87320ca 100644
--- a/gcc/config/aarch64/atomics.md
+++ b/gcc/config/aarch64/atomics.md
@@ -224,7 +224,7 @@ (define_insn_and_split "aarch64_atomic_exchange<mode>"
       UNSPECV_ATOMIC_EXCHG))
    (clobber (reg:CC CC_REGNUM))
    (clobber (match_scratch:SI 4 "=&r"))]
-  ""
+  "!TARGET_LSE"
   "#"
   "&& epilogue_completed"
   [(const_int 0)]
-- 
2.25.1