From: Wilco Dijkstra <wilco.dijkstra@arm.com>
Date: Wed, 17 Sep 2025 16:36:33 +0000 (+0000)
Subject: AArch64: Use dmb ishld+ishst for release fence
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=a3d141316c413256adc59f49cb9094d3f76a017f;p=thirdparty%2Fgcc.git

AArch64: Use dmb ishld+ishst for release fence

Use dmb ishld and dmb ishst for a release fence since this is less
restrictive than dmb ish.

gcc:
	* config/aarch64/atomics.md (*dmb): Expand release fence into dmb ishld
	and dmb ishst.
---

diff --git a/gcc/config/aarch64/atomics.md b/gcc/config/aarch64/atomics.md
index ea4a9367fc8..d4b4afb5815 100644
--- a/gcc/config/aarch64/atomics.md
+++ b/gcc/config/aarch64/atomics.md
@@ -870,7 +870,13 @@
     enum memmodel model = memmodel_from_int (INTVAL (operands[1]));
     if (is_mm_acquire (model))
       return "dmb\\tishld";
+    else if (is_mm_release (model))
+      return "dmb\\tishld\;dmb\\tishst";
     else
       return "dmb\\tish";
   }
+  [(set (attr "length")
+    (if_then_else
+     (match_test "is_mm_release (memmodel_from_int (INTVAL (operands[1])))")
+      (const_int 8) (const_int 4)))]
 )