[PowerPC] Update MemorySanitizer test to cater for number of CPUs > 1024

[saghir]

Summary

MemorySanitizer test fails on systems with more than 1024 CPUs.
This patch updates the test to make it work for machines that
have more than 1024 CPUs. This helps to fix errors on the PowerPC
sanitizer bot.

[nemanjai]

LGTM. Thanks for fixing this.

compiler-rt/lib/msan/tests/msan_test.cpp

TEST(MemorySanitizer, dlopenFailed) {
   ASSERT_TRUE(lib == NULL);
 }
 
 #endif // MSAN_TEST_DISABLE_DLOPEN
 
 #if !defined(__FreeBSD__) && !defined(__NetBSD__)
 TEST(MemorySanitizer, sched_getaffinity) {
   cpu_set_t mask;
-  int res = sched_getaffinity(getpid(), sizeof(mask), &mask);
-  ASSERT_EQ(0, res);
+  if (sched_getaffinity(getpid(), sizeof(mask), &mask) == 0)
     EXPECT_NOT_POISONED(mask);
+  else {
+    // The call to sched_getaffinity() may have failed because the Affinity
+    // mask is too small for the number of CPUs on the system (i.e. the
+    // system has more than 1024 CPUs). Allocate a mask large enough for
+    // twice as many CPUs.
+    cpu_set_t *DynAffinity;
+    DynAffinity = CPU_ALLOC(2048);
+    int res = sched_getaffinity(getpid(), CPU_ALLOC_SIZE(2048), DynAffinity);
+    ASSERT_EQ(0, res);
+    EXPECT_NOT_POISONED(*DynAffinity);
+  }
 }
 #endif
 
 TEST(MemorySanitizer, scanf) {
   const char *input = "42 hello";
   int* d = new int;
   char* s = new char[7];
   int res = sscanf(input, "%d %5s", d, s);