1 files changed, 51 insertions, 0 deletions
diff --git a/compiler-rt/test/msan/unpoison_param.cc b/compiler-rt/test/msan/unpoison_param.cc
new file mode 100644
index 00000000000..f59d2cbe231
--- /dev/null
+++ b/compiler-rt/test/msan/unpoison_param.cc
@@ -0,0 +1,51 @@
+// Tests that __msan_unpoison_param() works as specified.  To prevent MSan
+// instrumentation from modifying parameter shadow before each call to foo(), we
+// compile main() without MSan.
+
+// RUN: %clangxx_msan -fno-sanitize=memory -c %s -o %t-main.o
+// RUN: %clangxx_msan %t-main.o %s -o %t
+// RUN: %run %t
+
+#include <assert.h>
+#include <sanitizer/msan_interface.h>
+
+#if __has_feature(memory_sanitizer)
+
+__attribute__((noinline)) int bar(int a, int b) {
+  volatile int zero = 0;
+  return zero;
+}
+
+int foo(int a, int b, int unpoisoned_params) {
+  if (unpoisoned_params == 0) {
+    assert(__msan_test_shadow(&a, sizeof(a)) == 0);
+    assert(__msan_test_shadow(&b, sizeof(b)) == 0);
+  } else if (unpoisoned_params == 1) {
+    assert(__msan_test_shadow(&a, sizeof(a)) == -1);
+    assert(__msan_test_shadow(&b, sizeof(b)) == 0);
+  } else if (unpoisoned_params == 2) {
+    assert(__msan_test_shadow(&a, sizeof(a)) == -1);
+    assert(__msan_test_shadow(&b, sizeof(b)) == -1);
+  }
+
+  // Poisons parameter shadow in TLS so that the next call from uninstrumented
+  // main has params 1 and 2 poisoned no matter what.
+  int x, y;
+  return bar(x, y);
+}
+
+#else
+
+int foo(int, int, int);
+
+int main() {
+  foo(0, 0, 2); // Poison parameters for next call.
+  foo(0, 0, 0); // Check that both params are poisoned.
+  __msan_unpoison_param(1);
+  foo(0, 0, 1); // Check that only first param is unpoisoned.
+  __msan_unpoison_param(2);
+  foo(0, 0, 2); // Check that first and second params are unpoisoned.
+  return 0;
+}
+
+#endif