tsan: don't write to meta shadow unnecessarily
If user does malloc(1<<30), the write to meta shadow
can cause excessive memory consumption.
llvm-svn: 233373
diff --git a/compiler-rt/lib/tsan/rtl/tsan_sync.cc b/compiler-rt/lib/tsan/rtl/tsan_sync.cc
index 49c4d15..4202d30 100644
--- a/compiler-rt/lib/tsan/rtl/tsan_sync.cc
+++ b/compiler-rt/lib/tsan/rtl/tsan_sync.cc
@@ -88,11 +88,13 @@
end++;
for (; meta < end; meta++) {
u32 idx = *meta;
+ if (idx == 0) {
+ // Note: don't write to meta in this case -- the block can be huge.
+ continue;
+ }
*meta = 0;
- for (;;) {
- if (idx == 0)
- break;
- has_something = true;
+ has_something = true;
+ while (idx != 0) {
if (idx & kFlagBlock) {
block_alloc_.Free(&thr->block_cache, idx & ~kFlagMask);
break;