commit 78661f52b532737cff85a502d129e815b093fb77
author Hans Boehm <hboehm@google.com> Tue Apr 04 17:34:59 2017 -0700
committer Elliott Hughes <enh@google.com> Wed Apr 05 18:34:03 2017 -0700
tree 02901d89a6b36d15b38a48747ad7f0d65129aba0
parent 61e05392a9b755f01cc9da68b3ea71012aa920e7

Fix compare_exchange_weak tests to allow spurious failure

Test: Ran bionic unit tests on angler.

Bug: 36869788

(cherry picked from commit 590a410d29978016b2a01e8fbedaf17154743b76)

Change-Id: I22c280baa6bc50334765dae043307d21e1e9c930

tests/stdatomic_test.cpp

diff --git a/tests/stdatomic_test.cpp b/tests/stdatomic_test.cpp
index 22e0c50..389b251 100644
--- a/tests/stdatomic_test.cpp
+++ b/tests/stdatomic_test.cpp
@@ -116,20 +116,34 @@
 
   atomic_store(&i, 123);
   expected = 123;
-  ASSERT_TRUE(atomic_compare_exchange_strong_explicit(&i, &expected, 456, memory_order_relaxed, memory_order_relaxed));
-  ASSERT_FALSE(atomic_compare_exchange_strong_explicit(&i, &expected, 456, memory_order_relaxed, memory_order_relaxed));
+  ASSERT_TRUE(atomic_compare_exchange_strong_explicit(&i, &expected, 456, memory_order_relaxed,
+          memory_order_relaxed));
+  ASSERT_FALSE(atomic_compare_exchange_strong_explicit(&i, &expected, 456, memory_order_relaxed,
+          memory_order_relaxed));
   ASSERT_EQ(456, expected);
 
   atomic_store(&i, 123);
   expected = 123;
-  ASSERT_TRUE(atomic_compare_exchange_weak(&i, &expected, 456));
+  int iter_count = 0;
+  do {
+    ++iter_count;
+    ASSERT_LT(iter_count, 100);  // Arbitrary limit on spurious compare_exchange failures.
+    ASSERT_EQ(expected, 123);
+  } while(!atomic_compare_exchange_weak(&i, &expected, 456));
   ASSERT_FALSE(atomic_compare_exchange_weak(&i, &expected, 456));
   ASSERT_EQ(456, expected);
 
   atomic_store(&i, 123);
   expected = 123;
-  ASSERT_TRUE(atomic_compare_exchange_weak_explicit(&i, &expected, 456, memory_order_relaxed, memory_order_relaxed));
-  ASSERT_FALSE(atomic_compare_exchange_weak_explicit(&i, &expected, 456, memory_order_relaxed, memory_order_relaxed));
+  iter_count = 0;
+  do {
+    ++iter_count;
+    ASSERT_LT(iter_count, 100);
+    ASSERT_EQ(expected, 123);
+  } while(!atomic_compare_exchange_weak_explicit(&i, &expected, 456, memory_order_relaxed,
+          memory_order_relaxed));
+  ASSERT_FALSE(atomic_compare_exchange_weak_explicit(&i, &expected, 456, memory_order_relaxed,
+          memory_order_relaxed));
   ASSERT_EQ(456, expected);
 }