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Small improvement to InterlockedExchange on ARM

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Use movs instead of mov when setting the result in r0. This way the Z
flag will be set for the calling function which might allow some smaller
optimizations later on. It does not affect current code in any way,
because flags are not expected to be used across function calls.

git-svn-id: trunk@22033 -
This commit is contained in:
masta 2012-08-08 06:44:26 +00:00
parent aa21845cd9
commit 25e2f5f3fa
1 changed files with 5 additions and 3 deletions
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8
rtl/arm/arm.inc
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@ -511,7 +511,7 @@ asm
strex r2, r1, [r0] strex r2, r1, [r0]
cmp r2, #0 cmp r2, #0
bne .Lloop bne .Lloop
mov r0, r1 movs r0, r1
bx lr bx lr
{$else} {$else}
{$if defined(LINUX) and defined(CPUARMEL)} {$if defined(LINUX) and defined(CPUARMEL)}
@ -535,7 +535,9 @@ asm
sub r1, r0, #1 // Decrement value sub r1, r0, #1 // Decrement value
blx r3 // Call kuser_cmpxchg, sets C-Flag on success blx r3 // Call kuser_cmpxchg, sets C-Flag on success
movcs r0, r1 // We expect that to work most of the time so keep it pipeline friendly // MOVS sets the Z flag when the result reaches zero, this can be used later on
// The C-Flag will not be modified by this because we're not doing any shifting
movcss r0, r1 // We expect that to work most of the time so keep it pipeline friendly
ldmcsfd r13!, {pc} ldmcsfd r13!, {pc}
b .Latomic_dec_loop // kuser_cmpxchg sets C flag on error b .Latomic_dec_loop // kuser_cmpxchg sets C flag on error
@ -551,7 +553,7 @@ asm
ldr r1, [r0] ldr r1, [r0]
sub r1, r1, #1 sub r1, r1, #1
str r1, [r0] str r1, [r0]
mov r0, r1 movs r0, r1
// unlock and return // unlock and return
str r2, [r3] str r2, [r3]
bx lr bx lr