diff options
Diffstat (limited to 'runtime/arch/x86/quick_entrypoints_x86.S')
| -rw-r--r-- | runtime/arch/x86/quick_entrypoints_x86.S | 73 |
1 files changed, 53 insertions, 20 deletions
diff --git a/runtime/arch/x86/quick_entrypoints_x86.S b/runtime/arch/x86/quick_entrypoints_x86.S index c2acdd1668..c4374284b0 100644 --- a/runtime/arch/x86/quick_entrypoints_x86.S +++ b/runtime/arch/x86/quick_entrypoints_x86.S @@ -922,29 +922,39 @@ DEFINE_FUNCTION art_quick_lock_object jz .Lslow_lock .Lretry_lock: movl MIRROR_OBJECT_LOCK_WORD_OFFSET(%eax), %ecx // ecx := lock word - test LITERAL(0xC0000000), %ecx // test the 2 high bits. + test LITERAL(LOCK_WORD_STATE_MASK), %ecx // test the 2 high bits. jne .Lslow_lock // slow path if either of the two high bits are set. - movl %fs:THREAD_ID_OFFSET, %edx // edx := thread id + movl %ecx, %edx // save lock word (edx) to keep read barrier bits. + andl LITERAL(LOCK_WORD_READ_BARRIER_STATE_MASK_TOGGLED), %ecx // zero the read barrier bits. test %ecx, %ecx jnz .Lalready_thin // lock word contains a thin lock - // unlocked case - %edx holds thread id with count of 0 + // unlocked case - edx: original lock word, eax: obj. movl %eax, %ecx // remember object in case of retry - xor %eax, %eax // eax == 0 for comparison with lock word in cmpxchg - lock cmpxchg %edx, MIRROR_OBJECT_LOCK_WORD_OFFSET(%ecx) - jnz .Lcmpxchg_fail // cmpxchg failed retry + movl %edx, %eax // eax: lock word zero except for read barrier bits. + movl %fs:THREAD_ID_OFFSET, %edx // load thread id. + or %eax, %edx // edx: thread id with count of 0 + read barrier bits. + lock cmpxchg %edx, MIRROR_OBJECT_LOCK_WORD_OFFSET(%ecx) // eax: old val, edx: new val. + jnz .Llock_cmpxchg_fail // cmpxchg failed retry ret -.Lcmpxchg_fail: - movl %ecx, %eax // restore eax - jmp .Lretry_lock -.Lalready_thin: +.Lalready_thin: // edx: lock word (with high 2 bits zero and original rb bits), eax: obj. + movl %fs:THREAD_ID_OFFSET, %ecx // ecx := thread id cmpw %cx, %dx // do we hold the lock already? jne .Lslow_lock - addl LITERAL(65536), %ecx // increment recursion count - test LITERAL(0xC0000000), %ecx // overflowed if either of top two bits are set + movl %edx, %ecx // copy the lock word to check count overflow. + andl LITERAL(LOCK_WORD_READ_BARRIER_STATE_MASK_TOGGLED), %ecx // zero the read barrier bits. + addl LITERAL(LOCK_WORD_THIN_LOCK_COUNT_ONE), %ecx // increment recursion count for overflow check. + test LITERAL(LOCK_WORD_READ_BARRIER_STATE_MASK), %ecx // overflowed if either of the upper two bits (28-29) are set. jne .Lslow_lock // count overflowed so go slow - // update lockword, cmpxchg not necessary as we hold lock - movl %ecx, MIRROR_OBJECT_LOCK_WORD_OFFSET(%eax) + movl %eax, %ecx // save obj to use eax for cmpxchg. + movl %edx, %eax // copy the lock word as the old val for cmpxchg. + addl LITERAL(LOCK_WORD_THIN_LOCK_COUNT_ONE), %edx // increment recursion count again for real. + // update lockword, cmpxchg necessary for read barrier bits. + lock cmpxchg %edx, MIRROR_OBJECT_LOCK_WORD_OFFSET(%ecx) // eax: old val, edx: new val. + jnz .Llock_cmpxchg_fail // cmpxchg failed retry ret +.Llock_cmpxchg_fail: + movl %ecx, %eax // restore eax + jmp .Lretry_lock .Lslow_lock: SETUP_REFS_ONLY_CALLEE_SAVE_FRAME ebx, ebx // save ref containing registers for GC // Outgoing argument set up @@ -963,20 +973,43 @@ END_FUNCTION art_quick_lock_object DEFINE_FUNCTION art_quick_unlock_object testl %eax, %eax // null check object/eax jz .Lslow_unlock +.Lretry_unlock: movl MIRROR_OBJECT_LOCK_WORD_OFFSET(%eax), %ecx // ecx := lock word movl %fs:THREAD_ID_OFFSET, %edx // edx := thread id - test LITERAL(0xC0000000), %ecx + test LITERAL(LOCK_WORD_STATE_MASK), %ecx jnz .Lslow_unlock // lock word contains a monitor cmpw %cx, %dx // does the thread id match? jne .Lslow_unlock - cmpl LITERAL(65536), %ecx + movl %ecx, %edx // copy the lock word to detect new count of 0. + andl LITERAL(LOCK_WORD_READ_BARRIER_STATE_MASK_TOGGLED), %edx // zero the read barrier bits. + cmpl LITERAL(LOCK_WORD_THIN_LOCK_COUNT_ONE), %edx jae .Lrecursive_thin_unlock - movl LITERAL(0), MIRROR_OBJECT_LOCK_WORD_OFFSET(%eax) + // update lockword, cmpxchg necessary for read barrier bits. + movl %eax, %edx // edx: obj + movl %ecx, %eax // eax: old lock word. + andl LITERAL(LOCK_WORD_READ_BARRIER_STATE_MASK), %ecx // ecx: new lock word zero except original rb bits. +#ifndef USE_READ_BARRIER + movl %ecx, MIRROR_OBJECT_LOCK_WORD_OFFSET(%edx) +#else + lock cmpxchg %ecx, MIRROR_OBJECT_LOCK_WORD_OFFSET(%edx) // eax: old val, ecx: new val. + jnz .Lunlock_cmpxchg_fail // cmpxchg failed retry +#endif ret -.Lrecursive_thin_unlock: - subl LITERAL(65536), %ecx - mov %ecx, MIRROR_OBJECT_LOCK_WORD_OFFSET(%eax) +.Lrecursive_thin_unlock: // ecx: original lock word, eax: obj + // update lockword, cmpxchg necessary for read barrier bits. + movl %eax, %edx // edx: obj + movl %ecx, %eax // eax: old lock word. + subl LITERAL(LOCK_WORD_THIN_LOCK_COUNT_ONE), %ecx // ecx: new lock word with decremented count. +#ifndef USE_READ_BARRIER + mov %ecx, MIRROR_OBJECT_LOCK_WORD_OFFSET(%edx) +#else + lock cmpxchg %ecx, MIRROR_OBJECT_LOCK_WORD_OFFSET(%edx) // eax: old val, ecx: new val. + jnz .Lunlock_cmpxchg_fail // cmpxchg failed retry +#endif ret +.Lunlock_cmpxchg_fail: // edx: obj + movl %edx, %eax // restore eax + jmp .Lretry_unlock .Lslow_unlock: SETUP_REFS_ONLY_CALLEE_SAVE_FRAME ebx, ebx // save ref containing registers for GC // Outgoing argument set up |