[ASan][Test-Only] Allow read of size 2 in strcmp.c test

[DanBlackwell]

Occasionally this test fails on Darwin due to CHECK: READ of size 1 not matching the actual output CHECK: READ of size 2. This can happen when the memory before the string s1 happens to match the first character of s2.

This patch allows for READ of size 2 to pass in order to account for the above circumstances.

rdar://151317947

[llvmbot]

@llvm/pr-subscribers-compiler-rt-sanitizer

Author: Dan Blackwell (DanBlackwell)

Changes

Occasionally this test fails on Darwin due to CHECK: READ of size 1 not matching the actual output CHECK: READ of size 2. This can happen when the memory before the string s1 happens to match the first character of s2.

This patch allows for READ of size 2 to pass in order to account for the above circumstances.

rdar://151317947

---

Full diff: https://github.com/llvm/llvm-project/pull/166179.diff

1 Files Affected:

• (modified) compiler-rt/test/asan/TestCases/strcmp.c (+3-1)

diff --git a/compiler-rt/test/asan/TestCases/strcmp.c b/compiler-rt/test/asan/TestCases/strcmp.c
index 417bd491ebe02..2b31e64768c42 100644
--- a/compiler-rt/test/asan/TestCases/strcmp.c
+++ b/compiler-rt/test/asan/TestCases/strcmp.c
@@ -14,6 +14,8 @@ int main(int argc, char **argv) {
   assert(strcmp(s1 - 1, s2));
 
   // CHECK: {{.*ERROR: AddressSanitizer: stack-buffer-underflow on address}}
-  // CHECK: READ of size 1
+  // Very rarely `s1[-1]` happens to be '1', resulting in `strcmp` needing to
+  // check 2 bytes before failing, rather than 1 - this should still pass
+  // CHECK: READ of size {{[12]}}
   return 0;
 }

[thurstond]

Thanks!