From 6d4ea22e70924da411998edcbdb321bfd3f17545 Mon Sep 17 00:00:00 2001 From: Sanjay Patel Date: Wed, 25 Sep 2019 14:35:02 +0000 Subject: [IR] allow fast-math-flags on phi of FP values (2nd try) The changes here are based on the corresponding diffs for allowing FMF on 'select': D61917 As discussed there, we want to have fast-math-flags be a property of an FP value because the alternative (having them on things like fcmp) leads to logical inconsistency such as: https://bugs.llvm.org/show_bug.cgi?id=38086 The earlier patch for select made almost no practical difference because most unoptimized conditional code begins life as a phi (based on what I see in clang). Similarly, I don't expect this patch to do much on its own either because SimplifyCFG promptly drops the flags when converting to select on a minimal example like: https://bugs.llvm.org/show_bug.cgi?id=39535 But once we have this plumbing in place, we should be able to wire up the FMF propagation and start solving cases like that. The change to RecurrenceDescriptor::AddReductionVar() is required to prevent a regression in a LoopVectorize test. We are intersecting the FMF of any FPMathOperator there, so if a phi is not properly annotated, new math instructions may not be either. Once we fix the propagation in SimplifyCFG, it may be safe to remove that hack. Differential Revision: https://reviews.llvm.org/D67564 llvm-svn: 372878 --- llvm/lib/Bitcode/Writer/BitcodeWriter.cpp | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'llvm/lib/Bitcode/Writer/BitcodeWriter.cpp') diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp index 0eea6dc..2818e84 100644 --- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp +++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp @@ -2880,6 +2880,11 @@ void ModuleBitcodeWriter::writeInstruction(const Instruction &I, pushValueSigned(PN.getIncomingValue(i), InstID, Vals64); Vals64.push_back(VE.getValueID(PN.getIncomingBlock(i))); } + + uint64_t Flags = getOptimizationFlags(&I); + if (Flags != 0) + Vals64.push_back(Flags); + // Emit a Vals64 vector and exit. Stream.EmitRecord(Code, Vals64, AbbrevToUse); Vals64.clear(); -- cgit v1.1