[PATCH 5/5] MdePkg/BaseSynchronizationLib GCC: simplify IA32 InternalSyncCompareExchange64()

[Laszlo Ersek <lersek@redhat.com>]

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>
---
 MdePkg/Library/BaseSynchronizationLib/Ia32/GccInline.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/MdePkg/Library/BaseSynchronizationLib/Ia32/GccInline.c b/MdePkg/Library/BaseSynchronizationLib/Ia32/GccInline.c
index 44188e265af2..af39bdeb516c 100644
--- a/MdePkg/Library/BaseSynchronizationLib/Ia32/GccInline.c
+++ b/MdePkg/Library/BaseSynchronizationLib/Ia32/GccInline.c
@@ -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"
-- 
2.14.1.3.gb7cf6e02401b