simoll marked an inline comment as done. simoll added inline comments.
================ Comment at: llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp:2137 + if (match(&I, m_FNeg(m_Value(Op)))) + return UnaryOperator::CreateFNegFMF(Op, &I); ---------------- cameron.mcinally wrote: > Just noticed that this is a bug -- it needs a guard for denormal flushing. > > When FTZ or DAZ: > fsub -0.0, Denorm ==> +-0 > fneg Denorm ==> -Denorm > > Handling denormals correctly is an ongoing project. If you'd like to leave > this for later, we'll get to it. I see that it's currently broken, so no harm > in continuing that way for now. > > Could you add a brief FIXME here? Added a FIXME for now. I suppose this should be fixed in PatternMatch.h by making `m_FNeg` refuse to match the fsub idiom for FTZ/DAZ if fneg does not preserve denormal semantics under those settings. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D75467/new/ https://reviews.llvm.org/D75467 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
