How the GNU C Compiler became the Clippy of cryptography

At FOSDEM 2026, René Meusel (Botan) warned that modern compilers like GCC can optimize away constant-time cryptographic code, reintroducing timing side-channel leaks in operations such as password checks; he demonstrated how Boolean logic transformations cause this and recommended mitigations including bitwise masking, obfuscation, no-op inline assembly barriers, selectively disabling optimizations, and using tools like valgrind—urging security developers to understand compiler behavior and collaborate rather than roll their own.