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authorJan Beulich <JBeulich@suse.com>2012-01-20 16:22:04 (GMT)
committerH. Peter Anvin <hpa@linux.intel.com>2012-01-21 01:29:49 (GMT)
commitcb8095bba6d24118135a5683a956f4f4fb5f17bb (patch)
tree25eff3732e8471e314591d0bc6ea41d96857c18b /arch/x86/lib/atomic64_386_32.S
parent819165fb34b9777f852429f2c6d6f79fbb71b9eb (diff)
x86: atomic64 assembly improvements
In the "xchg" implementation, %ebx and %ecx don't need to be copied into %eax and %edx respectively (this is only necessary when desiring to only read the stored value). In the "add_unless" implementation, swapping the use of %ecx and %esi for passing arguments allows %esi to become an input only (i.e. permitting the register to be re-used to address the same object without reload). In "{add,sub}_return", doing the initial read64 through the passed in %ecx decreases a register dependency. In "inc_not_zero", a branch can be eliminated by or-ing together the two halves of the current (64-bit) value, and code size can be further reduced by adjusting the arithmetic slightly. v2: Undo the folding of "xchg" and "set". Signed-off-by: Jan Beulich <jbeulich@suse.com> Link: http://lkml.kernel.org/r/4F19A2BC020000780006E0DC@nat28.tlf.novell.com Cc: Luca Barbieri <luca@luca-barbieri.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch/x86/lib/atomic64_386_32.S')
-rw-r--r--arch/x86/lib/atomic64_386_32.S6
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/x86/lib/atomic64_386_32.S b/arch/x86/lib/atomic64_386_32.S
index e8e7e0d..00933d5 100644
--- a/arch/x86/lib/atomic64_386_32.S
+++ b/arch/x86/lib/atomic64_386_32.S
@@ -137,13 +137,13 @@ BEGIN(dec_return)
RET_ENDP
#undef v
-#define v %ecx
+#define v %esi
BEGIN(add_unless)
- addl %eax, %esi
+ addl %eax, %ecx
adcl %edx, %edi
addl (v), %eax
adcl 4(v), %edx
- cmpl %eax, %esi
+ cmpl %eax, %ecx
je 3f
1:
movl %eax, (v)

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