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[asan] more compaction: don't use the next field while the chunk is in allocated state 

llvm-svn: 158083
This commit is contained in:
Kostya Serebryany 2012-06-06 16:58:21 +00:00
parent c0bbfbfba2
commit 112ac68d52
1 changed files with 9 additions and 7 deletions
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16
compiler-rt/lib/asan/asan_allocator.cc
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@ -145,8 +145,8 @@ static u8 *MmapNewPagesAndPoisonShadow(uptr size) {
// CHUNK_QUARANTINE: the chunk was freed and put into quarantine zone.
//
// The pseudo state CHUNK_MEMALIGN is used to mark that the address is not
// the beginning of a AsanChunk (in which case 'next' contains the address
// of the AsanChunk).
// the beginning of a AsanChunk (in which the actual chunk resides at
// this - this->used_size).
//
// The magic numbers for the enum values are taken randomly.
enum {
@ -167,7 +167,8 @@ struct ChunkBase {
uptr alignment_log : 8;
uptr used_size : FIRST_32_SECOND_64(32, 56); // Size requested by the user.
// The rest.
// This field may overlap with the user area and thus should not
// be used while the chunk is in CHUNK_ALLOCATED state.
AsanChunk *next;
// Typically the beginning of the user-accessible memory is 'this'+REDZONE
@ -246,7 +247,7 @@ struct AsanChunk: public ChunkBase {
static AsanChunk *PtrToChunk(uptr ptr) {
AsanChunk *m = (AsanChunk*)(ptr - REDZONE);
if (m->chunk_state == CHUNK_MEMALIGN) {
m = m->next;
m = (AsanChunk*)((uptr)m - m->used_size);
}
return m;
}
@ -686,7 +687,7 @@ static u8 *Allocate(uptr alignment, uptr size, AsanStackTrace *stack) {
CHECK((addr & (alignment - 1)) == 0);
AsanChunk *p = (AsanChunk*)(addr - REDZONE);
p->chunk_state = CHUNK_MEMALIGN;
p->next = m;
p->used_size = (uptr)p - (uptr)m;
m->alignment_log = Log2(alignment);
CHECK(m->Beg() == addr);
} else {
@ -736,6 +737,8 @@ static void Deallocate(u8 *ptr, AsanStackTrace *stack) {
ShowStatsAndAbort();
}
CHECK(old_chunk_state == CHUNK_ALLOCATED);
// With REDZONE==16 m->next is in the user area, otherwise it should be 0.
CHECK(REDZONE <= 16 || !m->next);
CHECK(m->free_tid == kInvalidTid);
CHECK(m->alloc_tid >= 0);
AsanThread *t = asanThreadRegistry().GetCurrent();
@ -752,16 +755,15 @@ static void Deallocate(u8 *ptr, AsanStackTrace *stack) {
thread_stats.freed_by_size[m->SizeClass()]++;
CHECK(m->chunk_state == CHUNK_QUARANTINE);
if (t) {
AsanThreadLocalMallocStorage *ms = &t->malloc_storage();
CHECK(!m->next);
ms->quarantine_.Push(m);
if (ms->quarantine_.size() > kMaxThreadLocalQuarantine) {
malloc_info.SwallowThreadLocalMallocStorage(ms, false);
}
} else {
CHECK(!m->next);
malloc_info.BypassThreadLocalQuarantine(m);
}
}