Author: Marco Elver Date: 2026-01-31T13:36:05+01:00 New Revision: b6d6af98feb6850e6402d4bbee21cab970d74b4f
URL: https://github.com/llvm/llvm-project/commit/b6d6af98feb6850e6402d4bbee21cab970d74b4f DIFF: https://github.com/llvm/llvm-project/commit/b6d6af98feb6850e6402d4bbee21cab970d74b4f.diff LOG: Thread Safety Analysis: Add test for alias reassignment through pointer-to-pointer (#179028) Alias reassignment through pointer-to-pointer (nor ptr-to-ptr-to-ptr...) does not invalidate an alias for now. While this may result in either false positives or negatives, there's rarely a good reason not to just do direct assignment within the same scope. For the time being, we retain this as a deliberate "escape hatch": specifically, this may be used to help the alias analysis to "see through" complex helper macros that e.g. read a value (such as a pointer) via inline assembly or other opaque helpers [1]. Add a test to document the current behaviour. NFC. [1] https://lore.kernel.org/all/[email protected]/ Added: Modified: clang/test/SemaCXX/warn-thread-safety-analysis.cpp Removed: ################################################################################ diff --git a/clang/test/SemaCXX/warn-thread-safety-analysis.cpp b/clang/test/SemaCXX/warn-thread-safety-analysis.cpp index d9efa745b7d59..466135a1d9cef 100644 --- a/clang/test/SemaCXX/warn-thread-safety-analysis.cpp +++ b/clang/test/SemaCXX/warn-thread-safety-analysis.cpp @@ -7498,6 +7498,27 @@ void testReassignment() { ptr->mu.Unlock(); } +// Alias reassignment through pointer-to-pointer (nor ptr-to-ptr-to-ptr...) does +// not invalidate aliases for now. +// +// While this may result in either false positives or negatives, there's rarely +// a good reason not to just do direct assignment within the same scope. For the +// time being, we retain this as a deliberate "escape hatch": specifically, this +// may be used to help the alias analysis to "see through" complex helper macros +// that e.g. read a value (such as a pointer) via inline assembly or other +// opaque helpers. +void testReassignmentPointerToAlias(Foo *f) { + Mutex *mu = &f->mu; + // Escape hatch. + Mutex **mu_p = μ + Mutex *actual_mu = [&] { /* ... */ return mu; }(); + *mu_p = actual_mu; + + mu->Lock(); + f->data = 42; + mu->Unlock(); +} + // Nested field access through pointer struct Container { Foo foo; _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
