https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63627
Bug ID: 63627
Summary: thread sanitizer does not instrument
__atomic_test_and_set or __atomic_clear
Product: gcc
Version: 4.9.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: sanitizer
Assignee: unassigned at gcc dot gnu.org
Reporter: rogero at howzatt dot demon.co.uk
CC: dodji at gcc dot gnu.org, dvyukov at gcc dot gnu.org,
jakub at gcc dot gnu.org, kcc at gcc dot gnu.org
Created attachment 33791
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33791&action=edit
EXample using __atomic_test_and_set that causes tsan positives
When compiling code using atomic instrinsics with -fsanitize=thread some of the
functions - in particular __atomic_test_and_set and __atomic_clear are not
instrumented.
Hence tsan reports false positives when spin-locking with
__atomic_test_and_set/__atomic_clear but not when using
__atomic_exchange_n/__atomic_store_n.
(This also affects std:atomic_flag as it uses the problematic operations in its
implementation.)
