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| author | Mathieu Chartier <mathieuc@google.com> | 2013-10-25 10:05:23 -0700 |
|---|---|---|
| committer | Mathieu Chartier <mathieuc@google.com> | 2013-10-29 12:14:36 -0700 |
| commit | ad2541a59c00c2c69e8973088891a2b5257c9780 (patch) | |
| tree | 523898cf039c5185352978e71a54fa3a2657a04c /runtime/arch/arm | |
| parent | 9780099e445884d8bc9444c8c1261b02d80a26c7 (diff) | |
| download | art-ad2541a59c00c2c69e8973088891a2b5257c9780.zip art-ad2541a59c00c2c69e8973088891a2b5257c9780.tar.gz art-ad2541a59c00c2c69e8973088891a2b5257c9780.tar.bz2 | |
Fix object identity hash.
The object identity hash is now stored in the monitor word after
being computed. Hashes are computed by a pseudo random number
generator.
When we write the image, we eagerly compute object hashes to
prevent pages getting dirtied.
Bug: 8981901
Change-Id: Ic8edacbacb0afc7055fd740a52444929f88ed564
Diffstat (limited to 'runtime/arch/arm')
| -rw-r--r-- | runtime/arch/arm/quick_entrypoints_arm.S | 19 |
1 files changed, 10 insertions, 9 deletions
diff --git a/runtime/arch/arm/quick_entrypoints_arm.S b/runtime/arch/arm/quick_entrypoints_arm.S index 736ce2f..c11349802 100644 --- a/runtime/arch/arm/quick_entrypoints_arm.S +++ b/runtime/arch/arm/quick_entrypoints_arm.S @@ -325,24 +325,25 @@ END art_quick_handle_fill_data ENTRY art_quick_lock_object cbz r0, slow_lock retry_lock: - ldrex r1, [r0, #LOCK_WORD_OFFSET] ldrt r2, [r9, #THREAD_ID_OFFSET] - cmp r1, #0 - bmi slow_lock @ lock word contains a monitor - bne already_thin + ldrex r1, [r0, #LOCK_WORD_OFFSET] + cbnz r1, not_unlocked @ already thin locked @ unlocked case - r2 holds thread id with count of 0 strex r3, r2, [r0, #LOCK_WORD_OFFSET] cbnz r3, strex_fail @ store failed, retry bx lr strex_fail: b retry_lock @ unlikely forward branch, need to reload and recheck r1/r2 -already_thin: +not_unlocked: + lsr r3, r1, 30 + cbnz r3, slow_lock @ if either of the top two bits are set, go slow path eor r2, r1, r2 @ lock_word.ThreadId() ^ self->ThreadId() uxth r2, r2 @ zero top 16 bits cbnz r2, slow_lock @ lock word and self thread id's match -> recursive lock @ else contention, go to slow path - adds r2, r1, #65536 @ increment count in lock word placing in r2 for storing - bmi slow_lock @ if we overflow the count go slow + add r2, r1, #65536 @ increment count in lock word placing in r2 for storing + lsr r1, r2, 30 @ if either of the top two bits are set, we overflowed. + cbnz r1, slow_lock @ if we overflow the count go slow path str r2, [r0, #LOCK_WORD_OFFSET] @ no need for strex as we hold the lock bx lr slow_lock: @@ -363,9 +364,9 @@ END art_quick_lock_object ENTRY art_quick_unlock_object cbz r0, slow_unlock ldr r1, [r0, #LOCK_WORD_OFFSET] + lsr r2, r1, 30 + cbnz r2, slow_unlock @ if either of the top two bits are set, go slow path ldr r2, [r9, #THREAD_ID_OFFSET] - cmp r1, #0 - bmi slow_unlock @ lock word contains a monitor eor r3, r1, r2 @ lock_word.ThreadId() ^ self->ThreadId() uxth r3, r3 @ zero top 16 bits cbnz r3, slow_unlock @ do lock word and self thread id's match? |