diff options
| author | Ralf Baechle <ralf@linux-mips.org> | 2006-09-28 01:45:21 +0100 |
|---|---|---|
| committer | Ralf Baechle <ralf@linux-mips.org> | 2007-02-13 22:40:50 +0000 |
| commit | f65e4fa8e0c6022ad58dc88d1b11b12589ed7f9f (patch) | |
| tree | 2405e012e079693e0fcfde9ff981c549d6c68a21 /include/asm-mips/system.h | |
| parent | 509cb37e173d4e39cec47238397e91b718730794 (diff) | |
[MIPS] Improve branch prediction in ll/sc atomic operations.
Now that finally all supported versions of binutils have functioning
support for .subsection use .subsection to tweak the branch prediction
I did not modify the R10000 errata variants because it seems unclear if
this will invalidate the workaround which actually relies on the cheesy
prediction of branch likely to cause a misspredict if the sc was
successful.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'include/asm-mips/system.h')
| -rw-r--r-- | include/asm-mips/system.h | 20 |
1 files changed, 16 insertions, 4 deletions
diff --git a/include/asm-mips/system.h b/include/asm-mips/system.h index 5e1289c85ed9..597a3743f6a1 100644 --- a/include/asm-mips/system.h +++ b/include/asm-mips/system.h @@ -110,7 +110,10 @@ static inline unsigned long __xchg_u32(volatile int * m, unsigned int val) " move %2, %z4 \n" " .set mips3 \n" " sc %2, %1 \n" - " beqz %2, 1b \n" + " beqz %2, 2f \n" + " .subsection 2 \n" + "2: b 1b \n" + " .previous \n" " .set mips0 \n" : "=&r" (retval), "=m" (*m), "=&r" (dummy) : "R" (*m), "Jr" (val) @@ -155,7 +158,10 @@ static inline __u64 __xchg_u64(volatile __u64 * m, __u64 val) "1: lld %0, %3 # xchg_u64 \n" " move %2, %z4 \n" " scd %2, %1 \n" - " beqz %2, 1b \n" + " beqz %2, 2f \n" + " .subsection 2 \n" + "2: b 1b \n" + " .previous \n" " .set mips0 \n" : "=&r" (retval), "=m" (*m), "=&r" (dummy) : "R" (*m), "Jr" (val) @@ -232,8 +238,11 @@ static inline unsigned long __cmpxchg_u32(volatile int * m, unsigned long old, " move $1, %z4 \n" " .set mips3 \n" " sc $1, %1 \n" - " beqz $1, 1b \n" + " beqz $1, 3f \n" "2: \n" + " .subsection 2 \n" + "3: b 1b \n" + " .previous \n" " .set pop \n" : "=&r" (retval), "=R" (*m) : "R" (*m), "Jr" (old), "Jr" (new) @@ -283,8 +292,11 @@ static inline unsigned long __cmpxchg_u64(volatile int * m, unsigned long old, " bne %0, %z3, 2f \n" " move $1, %z4 \n" " scd $1, %1 \n" - " beqz $1, 1b \n" + " beqz $1, 3f \n" "2: \n" + " .subsection 2 \n" + "3: b 1b \n" + " .previous \n" " .set pop \n" : "=&r" (retval), "=R" (*m) : "R" (*m), "Jr" (old), "Jr" (new) |