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fix riscv64 atomic asm constraints 

most egregious problem was the lack of memory clobber and lack of
volatile asm; this made the atomics memory barriers but not compiler
barriers. use of "+r" rather than "=r" for a clobbered temp was also
wrong, since the initial value is indeterminate.
This commit is contained in:
Rich Felker 2019-07-17 18:53:26 -04:00
parent 8eb49e0485
commit 2dcbeabd91
1 changed files with 10 additions and 6 deletions
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16
arch/riscv64/atomic_arch.h
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@ -8,13 +8,15 @@ static inline void a_barrier()
static inline int a_cas(volatile int *p, int t, int s)
{
int old, tmp;
__asm__("\n1: lr.w.aqrl %0, %2\n"
__asm__ __volatile__ (
"\n1: lr.w.aqrl %0, %2\n"
" bne %0, %3, 1f\n"
" sc.w.aqrl %1, %4, %2\n"
" bnez %1, 1b\n"
"1:"
: "=&r"(old), "+r"(tmp), "+A"(*p)
: "r"(t), "r"(s));
: "=&r"(old), "=r"(tmp), "+A"(*p)
: "r"(t), "r"(s)
: "memory");
return old;
}
@ -23,12 +25,14 @@ static inline void *a_cas_p(volatile void *p, void *t, void *s)
{
void *old;
int tmp;
__asm__("\n1: lr.d.aqrl %0, %2\n"
__asm__ __volatile__ (
"\n1: lr.d.aqrl %0, %2\n"
" bne %0, %3, 1f\n"
" sc.d.aqrl %1, %4, %2\n"
" bnez %1, 1b\n"
"1:"
: "=&r"(old), "+r"(tmp), "+A"(*(long *)p)
: "r"(t), "r"(s));
: "=&r"(old), "=r"(tmp), "+A"(*(long *)p)
: "r"(t), "r"(s)
: "memory");
return old;
}