[Pixman] [PATCH] Use "=a" and "=d" constraints for rdtsc inline assembly
Søren Sandmann
sandmann at cs.au.dk
Wed Mar 14 14:29:50 PDT 2012
From: Søren Sandmann Pedersen <ssp at redhat.com>
In 32 bit mode the "=A" constraint refers to the register pair
edx:eax, but according to GCC developers this is not the case in 64
bit mode, where it refers to "rax".
Hence, using "=A" for rdtsc is incorrect in 64 bit mode.
See http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21249
---
pixman/pixman-private.h | 7 ++++---
1 files changed, 4 insertions(+), 3 deletions(-)
diff --git a/pixman/pixman-private.h b/pixman/pixman-private.h
index 9d96a93..0cba2e9 100644
--- a/pixman/pixman-private.h
+++ b/pixman/pixman-private.h
@@ -936,10 +936,11 @@ _pixman_log_error (const char *function, const char *message);
static inline uint64_t
oil_profile_stamp_rdtsc (void)
{
- uint64_t ts;
+ uint32_t hi, lo;
- __asm__ __volatile__ ("rdtsc\n" : "=A" (ts));
- return ts;
+ __asm__ __volatile__ ("rdtsc\n" : "=a" (lo), "=d" (hi));
+
+ return lo | (((uint64_t)hi) << 32);
}
#define OIL_STAMP oil_profile_stamp_rdtsc
--
1.6.0.6
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