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MdePkg/BaseSynchronizationLib GCC: simplify IA32 InternalSyncCompareExchange64()

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The IA32 variant of InternalSyncCompareExchange64() is correct, but we can
simplify it. We don't need to load the lower 32 bits of ExchangeValue into
EBX in two steps (first into a general register, then into EBX); we can
ask GCC to populate EBX like that itself.

Cc: Liming Gao <liming.gao@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1208
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Acked-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
This commit is contained in:
Laszlo Ersek
2018-09-29 23:13:47 +02:00
parent e5d4e7500f
commit 3a0329bed2
1 changed files with 1 additions and 4 deletions
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5
MdePkg/Library/BaseSynchronizationLib/Ia32/GccInline.c
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@@ -193,14 +193,11 @@ InternalSyncCompareExchange64 (
)
{
__asm__ __volatile__ (
"push %%ebx \n\t"
"movl %2,%%ebx \n\t"
"lock \n\t"
"cmpxchg8b (%1) \n\t"
"pop %%ebx \n\t"
: "+A" (CompareValue) // %0
: "S" (Value), // %1
"r" ((UINT32) ExchangeValue), // %2
"b" ((UINT32) ExchangeValue), // %2
"c" ((UINT32) (ExchangeValue >> 32)) // %3
: "memory",
"cc"