[asan] Regression test for PR33372

[eugenis]

Please add a comment to the test case with the PR number at least.

[vitalybuka]

Comment in the test

compiler-rt/trunk/test/asan/TestCases/pr33372.cc

+// RUN: %clangxx_asan -O0 -std=c++11 %s -o %t && %run %t 2>&1 | FileCheck %s
+// RUN: %clangxx_asan -O1 -std=c++11 %s -o %t && %run %t 2>&1 | FileCheck %s
+// RUN: %clangxx_asan -O2 -std=c++11 %s -o %t && %run %t 2>&1 | FileCheck %s
+
+// Test that we do not detect false buffer overflows cased by optimization when
+// when local variable replaced by a smaller global constant.
+// https://bugs.llvm.org/show_bug.cgi?id=33372
+
+#include <stdio.h>
+#include <string.h>
+
+struct A { int x, y, z; };
+struct B { A a; /*gap*/ long b; };
+B *bb;
+
+void test1() {
+  A a1 = {1, 1, 2};
+  B b1 = {a1, 6};
+  bb = new B(b1);
+}
+
+const char KKK[] = {1, 1, 2};
+char bbb[100000];
+
+void test2() {
+  char cc[sizeof(bbb)];
+  memcpy(cc, KKK , sizeof(KKK));
+  memcpy(bbb, cc, sizeof(bbb));
+}
+
+int main(int argc, char *argv[]) {
+  test1();
+  test2();
+  printf("PASSED");
+  return 0;
+}
+
+// CHECK-NOT: ERROR: AddressSanitizer
+// CHECK: PASSED