[tsan] Implement a 'ignore_noninstrumented_modules' flag to better suppress false positive races

On Darwin, we currently use 'ignore_interceptors_accesses', which is a heavy-weight solution that simply turns of race detection in all interceptors. This was done to suppress false positives coming from system libraries (non-instrumented code), but it also silences a lot of real races. This patch implements an alternative approach that should allow us to enable interceptors and report races coming from them, but only if they are called directly from instrumented code.

The patch matches the caller PC in each interceptors. For non-instrumented code, we call ThreadIgnoreBegin.

The assumption here is that the number of instrumented modules is low. Most likely there's only one (the instrumented main executable) and all the other modules are system libraries (non-instrumented).

Differential Revision: https://reviews.llvm.org/D28264



git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@291631 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 53 insertions, 0 deletions

diff --git a/test/tsan/Darwin/ignore-noninstrumented.mm b/test/tsan/Darwin/ignore-noninstrumented.mm
new file mode 100644
index 000000000..5e4453102
--- /dev/null
+++ b/test/tsan/Darwin/ignore-noninstrumented.mm
@@ -0,0 +1,53 @@
+// Check that ignore_noninstrumented_modules=1 supresses races from system libraries on OS X.
+
+// RUN: %clang_tsan %s -o %t -framework Foundation
+
+// Check that without the flag, there are false positives.
+// RUN: %deflake %run %t 2>&1 | FileCheck %s --check-prefix=CHECK-RACE
+
+// With ignore_noninstrumented_modules=1, no races are reported.
+// RUN: %env_tsan_opts=ignore_noninstrumented_modules=1 %run %t 2>&1 | FileCheck %s
+
+// With ignore_noninstrumented_modules=1, races in user's code are still reported.
+// RUN: %env_tsan_opts=ignore_noninstrumented_modules=1 %deflake %run %t race 2>&1 | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-RACE
+
+#import <Foundation/Foundation.h>
+
+#import "../test.h"
+
+char global_buf[64];
+
+void *Thread1(void *x) {
+  barrier_wait(&barrier);
+  strcpy(global_buf, "hello world");
+  return NULL;
+}
+
+void *Thread2(void *x) {
+  strcpy(global_buf, "world hello");
+  barrier_wait(&barrier);
+  return NULL;
+}
+
+int main(int argc, char *argv[]) {
+  fprintf(stderr, "Hello world.\n");
+  
+  // NSUserDefaults uses XPC which triggers the false positive.
+  NSDictionary *d = [[NSUserDefaults standardUserDefaults] dictionaryRepresentation];
+  fprintf(stderr, "d = %p\n", d);
+
+  if (argc > 1 && strcmp(argv[1], "race") == 0) {
+    barrier_init(&barrier, 2);
+    pthread_t t[2];
+    pthread_create(&t[0], NULL, Thread1, NULL);
+    pthread_create(&t[1], NULL, Thread2, NULL);
+    pthread_join(t[0], NULL);
+    pthread_join(t[1], NULL);
+  }
+
+  fprintf(stderr, "Done.\n");
+}
+
+// CHECK: Hello world.
+// CHECK-RACE: SUMMARY: ThreadSanitizer: data race
+// CHECK: Done.