release/21.x: [scudo] Make Ptr volatile so that the malloc and free calls are not optimized out (#149944)

[llvmbot]

Backport fcdcc4e

Requested by: @mgorny

[llvmbot]

@cferris1000 What do you think about merging this PR to the release branch?

[llvmbot]

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

Author: None (llvmbot)

Changes

Backport fcdcc4e

Requested by: @mgorny

---

Full diff: https://github.com/llvm/llvm-project/pull/151201.diff

1 Files Affected:

• (modified) compiler-rt/lib/scudo/standalone/tests/wrappers_c_test.cpp (+2-1)

diff --git a/compiler-rt/lib/scudo/standalone/tests/wrappers_c_test.cpp b/compiler-rt/lib/scudo/standalone/tests/wrappers_c_test.cpp
index 05065444a70c5..612317b3c3293 100644
--- a/compiler-rt/lib/scudo/standalone/tests/wrappers_c_test.cpp
+++ b/compiler-rt/lib/scudo/standalone/tests/wrappers_c_test.cpp
@@ -183,7 +183,8 @@ TEST_F(ScudoWrappersCDeathTest, Malloc) {
   // process doing free(P) is not a double free.
   EXPECT_DEATH(
       {
-        void *Ptr = malloc(Size);
+        // Note: volatile here prevents the calls from being optimized out.
+        void *volatile Ptr = malloc(Size);
         free(Ptr);
         free(Ptr);
       },

[cferris1000]

That seems fine to me.

[github-actions]

@mgorny (or anyone else). If you would like to add a note about this fix in the release notes (completely optional). Please reply to this comment with a one or two sentence description of the fix. When you are done, please add the release:note label to this PR.