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Corrected register usage in x86 DCAS asm blocks.

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In some of the asm blocks eax was modified as a result of cmpxchg8b but that
was not reflected in the register constraints. This could cause incorrect code
being generated.
This commit is contained in:
Andrey Semashev
2017-01-08 18:09:12 +03:00
parent 2b6ef06b57
commit a67cc1b055
1 changed files with 8 additions and 6 deletions
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14
include/boost/atomic/detail/ops_gcc_x86_dcas.hpp
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@@ -73,6 +73,7 @@ struct gcc_dcas_x86
{
#if !defined(BOOST_ATOMIC_DETAIL_NO_ASM_IMPLIED_ZERO_DISPLACEMENTS)
#if defined(__PIC__)
uint32_t v_lo = (uint32_t)v;
uint32_t scratch;
__asm__ __volatile__
(
@@ -84,8 +85,8 @@ struct gcc_dcas_x86
"1: lock; cmpxchg8b %[dest]\n\t"
"jne 1b\n\t"
"movl %[scratch], %%ebx\n\t"
: [scratch] "=m" (scratch), [dest] "=o" (storage)
: [value_lo] "a" ((uint32_t)v), "c" ((uint32_t)(v >> 32))
: [scratch] "=m" (scratch), [dest] "=o" (storage), [value_lo] "+a" (v_lo)
: "c" ((uint32_t)(v >> 32))
: BOOST_ATOMIC_DETAIL_ASM_CLOBBER_CC_COMMA "edx", "memory"
);
#else // defined(__PIC__)
@@ -103,6 +104,7 @@ struct gcc_dcas_x86
#endif // defined(__PIC__)
#else // !defined(BOOST_ATOMIC_DETAIL_NO_ASM_IMPLIED_ZERO_DISPLACEMENTS)
#if defined(__PIC__)
uint32_t v_lo = (uint32_t)v;
uint32_t scratch;
__asm__ __volatile__
(
@@ -115,11 +117,11 @@ struct gcc_dcas_x86
"jne 1b\n\t"
"movl %[scratch], %%ebx\n\t"
#if !defined(BOOST_ATOMIC_DETAIL_NO_ASM_CONSTRAINT_ALTERNATIVES)
: [scratch] "=m,m" (scratch)
: [value_lo] "a,a" ((uint32_t)v), "c,c" ((uint32_t)(v >> 32)), [dest] "D,S" (&storage)
: [scratch] "=m,m" (scratch), [value_lo] "+a,a" (v_lo)
: "c,c" ((uint32_t)(v >> 32)), [dest] "D,S" (&storage)
#else
: [scratch] "=m" (scratch)
: [value_lo] "a" ((uint32_t)v), "c" ((uint32_t)(v >> 32)), [dest] "D" (&storage)
: [scratch] "=m" (scratch), [value_lo] "+a" (v_lo)
: "c" ((uint32_t)(v >> 32)), [dest] "D" (&storage)
#endif
: BOOST_ATOMIC_DETAIL_ASM_CLOBBER_CC_COMMA "edx", "memory"
);