From: Daniel King <dmking@adacore.com>
Date: Fri, 13 Sep 2024 15:16:52 +0000 (+0100)
Subject: ada: Fix alignment of pthread_mutex_t
X-Git-Tag: basepoints/gcc-16~4650
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=758a95db8a9ee0048a5de5334b59027535e2ecbc;p=thirdparty%2Fgcc.git

ada: Fix alignment of pthread_mutex_t

On most targets the alignment of unsigned long is the same as pointer
alignment, but on CHERI targets pointers have larger alignment (16 bytes
compared to 8 bytes). pthread_mutex_t needs the same alignment as
System.Address to account for CHERI targets.

gcc/ada/ChangeLog:

	* libgnat/s-oslock__posix.ads: Fix alignment of pthread_mutex_t
	for CHERI targets.
---

diff --git a/gcc/ada/libgnat/s-oslock__posix.ads b/gcc/ada/libgnat/s-oslock__posix.ads
index e2c237f26981..cde92e5f23a3 100644
--- a/gcc/ada/libgnat/s-oslock__posix.ads
+++ b/gcc/ada/libgnat/s-oslock__posix.ads
@@ -52,6 +52,11 @@ private
       Data : char_array (1 .. OS_Constants.PTHREAD_MUTEX_SIZE);
    end record;
    pragma Convention (C, pthread_mutex_t);
-   for pthread_mutex_t'Alignment use Interfaces.C.unsigned_long'Alignment;
+   for pthread_mutex_t'Alignment use
+     Integer'Max (Interfaces.C.unsigned_long'Alignment,
+                  System.Address'Alignment);
+   --  On some targets (e.g. CHERI), pointers have larger alignment than
+   --  unsigned_long. On other targets (e.g. some 16-bit targets) long is
+   --  larger than a pointer. Choose the largest to err on the side of caution.
 
 end System.OS_Locks;