-#define __build_read_lock(rw, helper) \
- asm volatile(LOCK_PREFIX " subl $1,(%0)\n\t" \
- "jns 1f\n" \
- "call " helper "\n\t" \
- "1:\n" \
- ::"a" (rw) : "memory")
-
-#define __build_write_lock(rw, helper) \
- asm volatile(LOCK_PREFIX " subl $" RW_LOCK_BIAS_STR ",(%0)\n\t" \
- "jz 1f\n" \
- "call " helper "\n\t" \
- "1:\n" \
- ::"a" (rw) : "memory")
+#define __build_read_lock_ptr(rw, helper) \
+ asm volatile(LOCK "subl $1,(%0)\n\t" \
+ "jns 1f\n" \
+ "call " helper "\n\t" \
+ "1:\n" \
+ ::"a" (rw) : "memory")
+
+#define __build_read_lock_const(rw, helper) \
+ asm volatile(LOCK "subl $1,%0\n\t" \
+ "jns 1f\n" \
+ "pushl %%eax\n\t" \
+ "leal %0,%%eax\n\t" \
+ "call " helper "\n\t" \
+ "popl %%eax\n\t" \
+ "1:\n" \
+ :"=m" (*(volatile int *)rw) : : "memory")
+
+#define __build_read_lock(rw, helper) do { \
+ if (__builtin_constant_p(rw)) \
+ __build_read_lock_const(rw, helper); \
+ else \
+ __build_read_lock_ptr(rw, helper); \
+ } while (0)
+
+#define __build_write_lock_ptr(rw, helper) \
+ asm volatile(LOCK "subl $" RW_LOCK_BIAS_STR ",(%0)\n\t" \
+ "jz 1f\n" \
+ "call " helper "\n\t" \
+ "1:\n" \
+ ::"a" (rw) : "memory")
+
+#define __build_write_lock_const(rw, helper) \
+ asm volatile(LOCK "subl $" RW_LOCK_BIAS_STR ",%0\n\t" \
+ "jz 1f\n" \
+ "pushl %%eax\n\t" \
+ "leal %0,%%eax\n\t" \
+ "call " helper "\n\t" \
+ "popl %%eax\n\t" \
+ "1:\n" \
+ :"=m" (*(volatile int *)rw) : : "memory")
+
+#define __build_write_lock(rw, helper) do { \
+ if (__builtin_constant_p(rw)) \
+ __build_write_lock_const(rw, helper); \
+ else \
+ __build_write_lock_ptr(rw, helper); \
+ } while (0)