#define mb() do { \
int __dummy; \
asm volatile("movl %%eax,%0":"=m" (&dummy): :"memory"); \
} while (0)
which instead of using a read-modify-write cycle and a long immediate just
uses a single write-cycle. It makes gcc allocate a word on the stack, and
sometimes that might be unnecessary, but it should be smaller and faster.
You might want to check out code generation..
Linus
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