From c7cef4bcc4400673ffb86be04c006790577f7f56 Mon Sep 17 00:00:00 2001 From: Tim Shen Date: Mon, 2 Jul 2018 20:01:54 +0000 Subject: [SCEV] Strengthen StrengthenNoWrapFlags (reapply r334428). Summary: Comment on Transforms/LoopVersioning/incorrect-phi.ll: With the change SCEV is able to prove that the loop doesn't wrap-self (due to zext i16 to i64), disabling the entire loop versioning pass. Removed the zext and just use i64. Reviewers: sanjoy Subscribers: jlebar, hiraditya, javed.absar, bixia, llvm-commits Differential Revision: https://reviews.llvm.org/D48409 llvm-svn: 336140 --- llvm/lib/Analysis/ScalarEvolution.cpp | 27 ++++++++++++++++++++------- 1 file changed, 20 insertions(+), 7 deletions(-) (limited to 'llvm/lib/Analysis/ScalarEvolution.cpp') diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp index d52c5b0276a..a39ac9b9fb9 100644 --- a/llvm/lib/Analysis/ScalarEvolution.cpp +++ b/llvm/lib/Analysis/ScalarEvolution.cpp @@ -2247,22 +2247,35 @@ StrengthenNoWrapFlags(ScalarEvolution *SE, SCEVTypes Type, SignOrUnsignWrap = ScalarEvolution::maskFlags(Flags, SignOrUnsignMask); - if (SignOrUnsignWrap != SignOrUnsignMask && Type == scAddExpr && - Ops.size() == 2 && isa(Ops[0])) { - - // (A + C) --> (A + C) if the addition does not sign overflow - // (A + C) --> (A + C) if the addition does not unsign overflow + if (SignOrUnsignWrap != SignOrUnsignMask && + (Type == scAddExpr || Type == scMulExpr) && Ops.size() == 2 && + isa(Ops[0])) { + + auto Opcode = [&] { + switch (Type) { + case scAddExpr: + return Instruction::Add; + case scMulExpr: + return Instruction::Mul; + default: + llvm_unreachable("Unexpected SCEV op."); + } + }(); const APInt &C = cast(Ops[0])->getAPInt(); + + // (A C) --> (A C) if the op doesn't sign overflow. if (!(SignOrUnsignWrap & SCEV::FlagNSW)) { auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion( - Instruction::Add, C, OBO::NoSignedWrap); + Opcode, C, OBO::NoSignedWrap); if (NSWRegion.contains(SE->getSignedRange(Ops[1]))) Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW); } + + // (A C) --> (A C) if the op doesn't unsign overflow. if (!(SignOrUnsignWrap & SCEV::FlagNUW)) { auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion( - Instruction::Add, C, OBO::NoUnsignedWrap); + Opcode, C, OBO::NoUnsignedWrap); if (NUWRegion.contains(SE->getUnsignedRange(Ops[1]))) Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW); } -- cgit v1.2.3