On Tue, Feb 10, 2009 at 06:18:43PM -0500, Matt Turner wrote:
> Your code fixes the problem. Thanks!
Great news!
> I had to make one minor change though: moved 'old' from an output to
> an input. That is,
>
> > "=m"(__drm_dummy_lock(lock)), \
> > "=&r"(old) \
> > : "r"(new) \
>
> becomes
>
> > "=m"(__drm_dummy_lock(lock)) \
> > : "r"(old), "r"(new) \
Yes, you are right. But strictly speaking, "old" should be both input
and output operand.
> Please let me know if this change is acceptable. If so, please submit
> a patch to the bug report so that proper credit is given to you.
Well, I've got slightly improved version, which saves one instruction
for register-register move. Another instruction can be saved if we
define DRM_CAS_RESULT(_result) as "long" (no need for sign extending then).
Can you test this please?
Ivan.
--- libdrm-2.4.4/libdrm/xf86drm.h.orig Wed Dec 17 21:28:24 2008
+++ libdrm-2.4.4/libdrm/xf86drm.h Wed Feb 11 03:07:05 2009
@@ -325,28 +325,28 @@ typedef struct _drmSetVersion {
#elif defined(__alpha__)
-#define DRM_CAS(lock, old, new, ret) \
- do { \
- int old32; \
- int cur32; \
- __asm__ __volatile__( \
- " mb\n" \
- " zap %4, 0xF0, %0\n" \
- " ldl_l %1, %2\n" \
- " zap %1, 0xF0, %1\n" \
- " cmpeq %0, %1, %1\n" \
- " beq %1, 1f\n" \
- " bis %5, %5, %1\n" \
- " stl_c %1, %2\n" \
- "1: xor %1, 1, %1\n" \
- " stl %1, %3" \
- : "=r" (old32), \
- "=&r" (cur32), \
- "=m" (__drm_dummy_lock(lock)),\
- "=m" (ret) \
- : "r" (old), \
- "r" (new)); \
- } while(0)
+#define DRM_CAS(lock, old, new, ret) \
+ do { \
+ int tmp, old32; \
+ __asm__ __volatile__( \
+ " addl $31, %5, %3\n" \
+ "1: ldl_l %0, %2\n" \
+ " cmpeq %0, %3, %1\n" \
+ " beq %1, 2f\n" \
+ " mov %4, %0\n" \
+ " stl_c %0, %2\n" \
+ " beq %0, 3f\n" \
+ " mb\n" \
+ "2: cmpeq %1, 0, %1\n" \
+ ".subsection 2\n" \
+ "3: br 1b\n" \
+ ".previous" \
+ : "=&r"(tmp), "=&r"(ret), \
+ "=m"(__drm_dummy_lock(lock)), \
+ "=&r"(old32) \
+ : "r"(new), "r"(old) \
+ : "memory"); \
+ } while (0)
#elif defined(__sparc__)
@@ -429,7 +429,9 @@ do { register unsigned int __old __asm("
#define DRM_CAS(lock,old,new,ret) do { ret=1; } while (0) /* FAST LOCK FAILS */
#endif
-#if defined(__alpha__) || defined(__powerpc__)
+#if defined(__alpha__)
+#define DRM_CAS_RESULT(_result) long _result
+#elif defined(__powerpc__)
#define DRM_CAS_RESULT(_result) int _result
#else
#define DRM_CAS_RESULT(_result) char _result
--
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