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...) are not the same operation. They are *very* similar, but still different at an edge case(s). The current transformations that occur in LLVM are unsafe. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20180926/0e96dd1f/attachment.html>

Do we really want to have fneg be the only instruction with guaranteed no side effects? That just sounds like a gotcha waiting to happen. Or it could result in horrible code depending on the architecture. I’m still leaning towards having both an intrinsic and an instruction, and if they happen to have the same behavior then that’s fine. If fneg is to be a special instruction with extra promises