[lsan] Try to fix test failure due to compiler optimization

[Lekensteyn]

Summary

The SanitizerCommon-lsan-x86_64-Linux test failed due to the address of
the very first allocation ending up in the stack through "delete[]".
Workaround this by performing another allocation. The issue was only
present with optimization enabled, the test would pass with -O0.

[Lekensteyn]

test/sanitizer_common/TestCases/Posix/sanitizer_set_death_callback_test.cc

3 ↗

(On Diff #145955)

Renato, this line was added in r249398, "[LSAN] Mark death callback as unstable while we investigate the cause in AArch64". If the issue was also caused by pointers on the stack, perhaps this line can be removed?

To investigate what is leaking, try env var LSAN_OPTIONS=log_pointers=1

[vitalybuka]

test/sanitizer_common/TestCases/Posix/sanitizer_set_death_callback_test.cc

28 ↗

(On Diff #145955)

This stack cleanup looks unreliable.
Maybe just leak twice?

__attribute__((noinline))
void Leak() {
  sink = new char[100];
  sink = new char[100];
}

[Lekensteyn]

Done, it still passes my tests.

compiler-rt/trunk/test/sanitizer_common/TestCases/Posix/sanitizer_set_death_callback_test.cc

 // RUN: %clangxx -O2 %s -o %t && not %run %t 2>&1 | FileCheck %s
 
 // REQUIRES: stable-runtime
 
-// For standalone LSan on x86 we have a problem: compiler spills the address
-// of allocated at line 42 memory thus memory block allocated in Leak() function
-// ends up to be classified as reachable despite the fact we zero out 'sink' at
-// the last line of main function. The problem doesn't reproduce with ASan because
-// quarantine prohibits memory block reuse for different allocations.
-// XFAIL: lsan-x86
 // XFAIL: ubsan
 
 #include <sanitizer/common_interface_defs.h>
 #include <stdio.h>
 
 volatile char *zero = 0;
 
 void Death() {
   fprintf(stderr, "DEATH CALLBACK EXECUTED\n");
 }
 // CHECK: DEATH CALLBACK EXECUTED
 
 char global;
 volatile char *sink;
 
 __attribute__((noinline))
 void MaybeInit(int *uninitialized) {
   if (zero)
     *uninitialized = 1;
 }
 
 __attribute__((noinline))
 void Leak() {
-  sink = new char[100];  // trigger lsan report.
+  // Trigger lsan report. Two attempts in case the address of the first
+  // allocation remained on the stack.
+  sink = new char[100];
+  sink = new char[100];
 }
 
 int main(int argc, char **argv) {
   int uninitialized;
   __sanitizer_set_death_callback(Death);
   MaybeInit(&uninitialized);
   if (uninitialized)  // trigger msan report.
     global = 77;
   sink = new char[100];
   delete[] sink;
   global = sink[0];  // use-after-free: trigger asan/tsan report.
   Leak();
   sink = 0;
 }