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Use file static variables in WEBP_DSP_INIT_FUNC()

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Function static variables are initialized on the first call to the
function. In C the initialization of function static variables is not
thread-safe. Use file static variables instead in the
WEBP_DSP_INIT_FUNC() macro.

Remove the volatile qualifier for the pthread version of the
func##_last_cpuinfo_used variable because the variable is only accessed
while holding the mutex.

Change-Id: I1237904a49d2467d7ce79fc53f9e7f966aa7a5c1
This commit is contained in:
Wan-Teh Chang
2025-08-01 19:07:41 -07:00
parent 484991ce3f
commit 313692d51e
1 changed files with 14 additions and 11 deletions
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13
src/dsp/cpu.h
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@@ -193,11 +193,12 @@
#include <pthread.h> // NOLINT
// clang-format off
#define WEBP_DSP_INIT_VARS(func) \
static VP8CPUInfo func##_last_cpuinfo_used = \
(VP8CPUInfo)&func##_last_cpuinfo_used; \
static pthread_mutex_t func##_lock = PTHREAD_MUTEX_INITIALIZER
#define WEBP_DSP_INIT(func) \
do { \
static volatile VP8CPUInfo func##_last_cpuinfo_used = \
(VP8CPUInfo)&func##_last_cpuinfo_used; \
static pthread_mutex_t func##_lock = PTHREAD_MUTEX_INITIALIZER; \
if (pthread_mutex_lock(&func##_lock)) break; \
if (func##_last_cpuinfo_used != VP8GetCPUInfo) func(); \
func##_last_cpuinfo_used = VP8GetCPUInfo; \
@@ -206,10 +207,11 @@
// clang-format on
#else // !(defined(WEBP_USE_THREAD) && !defined(_WIN32))
// clang-format off
#define WEBP_DSP_INIT_VARS(func) \
static volatile VP8CPUInfo func##_last_cpuinfo_used = \
(VP8CPUInfo)&func##_last_cpuinfo_used
#define WEBP_DSP_INIT(func) \
do { \
static volatile VP8CPUInfo func##_last_cpuinfo_used = \
(VP8CPUInfo)&func##_last_cpuinfo_used; \
if (func##_last_cpuinfo_used == VP8GetCPUInfo) break; \
func(); \
func##_last_cpuinfo_used = VP8GetCPUInfo; \
@@ -225,6 +227,7 @@
}
*/
#define WEBP_DSP_INIT_FUNC(name) \
WEBP_DSP_INIT_VARS(name##_body); \
static WEBP_TSAN_IGNORE_FUNCTION void name##_body(void); \
WEBP_TSAN_IGNORE_FUNCTION void name(void) { WEBP_DSP_INIT(name##_body); } \
static WEBP_TSAN_IGNORE_FUNCTION void name##_body(void)