I'm aware of the recent curve25519-donna on 32-bit MSVC research, but PHP uses a different instruction than llmul (smull), so I'm not sure if that particular re

I'm aware of the recent curve25519-donna on 32-bit MSVC research, but PHP uses a different instruction than llmul (smull), so I'm not sure if that particular research is a concern here. I don't have any tools to objectively measure the timing differences to detect leaks on-hand. I'm not sure if any even exist for measuring PHP software. So, the answer to your question is "No, but open to suggestions on how to measure and possibly mitigate".