[patch] DirectFB-1.7.1-atomic-fix-compiler-error-when-building-for-thumb2.patch

DirectFB-1.7.1-atomic-fix-compiler-error-when-building-for-thumb2.patch (text/plain), 1.63 KB, created by Julian Ospald on 2013-12-29 13:05:32 UTC

From 253e1d0d10bdece158f8f68dc48c19ab57d2da29 Mon Sep 17 00:00:00 2001
From: Mandeep Singh Baines <[e-mail]>
Date: Mon, 18 Mar 2013 19:03:36 -0700
Subject: [PATCH] atomic: fix compiler error when building for thumb2

Fixed the following error:

{standard input}: Assembler messages:
{standard input}:179: Error: thumb conditional instruction should be in IT block
-- `strexeq r4,r1,[r2]'
{standard input}:283: Error: thumb conditional instruction should be in IT block
-- `strexeq r1,r4,[r2]'
{standard input}:379: Error: thumb conditional instruction should be in IT block
-- `strexeq r1,r2,[r0]'
make[4]: *** [fifo.lo] Error 1

Fix was to add the appropriate it block.

While I was at it, I optimized the code a bit by:

1) Moved the mov instruction above the ldrex to minimize the number
of instructions between the ldex and strex as recommeded here:
http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0552a/BABFFBJB.html
2) Saved 4 bytes by replacing mov with movs and teq with cmp.

Signed-off-by: Mandeep Singh Baines <[e-mail]>
---
 lib/direct/atomic.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib/direct/atomic.h b/lib/direct/atomic.h
index 94cb0c9..8dc0dfb 100644
--- a/lib/direct/atomic.h
+++ b/lib/direct/atomic.h
@@ -191,9 +191,10 @@ static inline int _D__atomic_cmpxchg(volatile int *ptr, int old, int _new)
 
 	do {
 		__asm__ __volatile__("@ atomic_cmpxchg\n"
+		"movs	%0, #0\n"
 		"ldrex	%1, [%2]\n"
-		"mov	%0, #0\n"
-		"teq	%1, %3\n"
+		"cmp	%1, %3\n"
+		"it	eq\n"
 		"strexeq %0, %4, [%2]\n"
 		    : "=&r" (res), "=&r" (oldval)
 		    : "r" (ptr), "Ir" (old), "r" (_new)
-- 
1.7.12.4