From a23b141cd2120232ef0a7088fa9bc480773dcfe1 Mon Sep 17 00:00:00 2001 From: Sanjay Patel Date: Mon, 15 May 2017 19:16:49 +0000 Subject: [PATCH] [InstSimplify] restrict icmp fold with 2 sdiv exact operands (PR32949) These folds were introduced with https://reviews.llvm.org/rL127064 as part of solving: https://bugs.llvm.org/show_bug.cgi?id=9343 As shown here: http://rise4fun.com/Alive/C8 ...however, the sdiv exact case needs a stronger predicate. I opted for duplicated code instead of adding another fallthrough because I think that's easier to read (and edit in case we need/want to restrict/loosen the predicates any more). This should fix: https://bugs.llvm.org/show_bug.cgi?id=32949 https://bugs.llvm.org/show_bug.cgi?id=32948 Differential Revision: https://reviews.llvm.org/D32954 llvm-svn: 303104 --- llvm/lib/Analysis/InstructionSimplify.cpp | 13 +++++++++++-- llvm/test/Transforms/InstSimplify/compare.ll | 7 +++++-- 2 files changed, 16 insertions(+), 4 deletions(-) diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp index 6293c2a..5728887 100644 --- a/llvm/lib/Analysis/InstructionSimplify.cpp +++ b/llvm/lib/Analysis/InstructionSimplify.cpp @@ -2827,10 +2827,19 @@ static Value *simplifyICmpWithBinOp(CmpInst::Predicate Pred, Value *LHS, break; case Instruction::UDiv: case Instruction::LShr: - if (ICmpInst::isSigned(Pred)) + if (ICmpInst::isSigned(Pred) || !LBO->isExact() || !RBO->isExact()) break; - LLVM_FALLTHROUGH; + if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0), + RBO->getOperand(0), Q, MaxRecurse - 1)) + return V; + break; case Instruction::SDiv: + if (!ICmpInst::isEquality(Pred) || !LBO->isExact() || !RBO->isExact()) + break; + if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0), + RBO->getOperand(0), Q, MaxRecurse - 1)) + return V; + break; case Instruction::AShr: if (!LBO->isExact() || !RBO->isExact()) break; diff --git a/llvm/test/Transforms/InstSimplify/compare.ll b/llvm/test/Transforms/InstSimplify/compare.ll index 883bf31..d6f1b63 100644 --- a/llvm/test/Transforms/InstSimplify/compare.ll +++ b/llvm/test/Transforms/InstSimplify/compare.ll @@ -598,11 +598,14 @@ define i1 @sdiv_exact_equality(i32 %Z) { ret i1 %C } -; FIXME: But not other preds: PR32949 - https://bugs.llvm.org/show_bug.cgi?id=32949 +; But not other preds: PR32949 - https://bugs.llvm.org/show_bug.cgi?id=32949 define i1 @sdiv_exact_not_equality(i32 %Z) { ; CHECK-LABEL: @sdiv_exact_not_equality( -; CHECK-NEXT: ret i1 true +; CHECK-NEXT: [[A:%.*]] = sdiv exact i32 10, %Z +; CHECK-NEXT: [[B:%.*]] = sdiv exact i32 20, %Z +; CHECK-NEXT: [[C:%.*]] = icmp ult i32 [[A]], [[B]] +; CHECK-NEXT: ret i1 [[C]] ; %A = sdiv exact i32 10, %Z %B = sdiv exact i32 20, %Z -- 2.7.4