From 7a2ed26563512149ea03e56d8ecd92c884c32f8f Mon Sep 17 00:00:00 2001 From: David Majnemer Date: Fri, 16 May 2014 16:57:04 +0000 Subject: InstSimplify: Optimize using dividend in sdiv Summary: The dividend in an sdiv tells us the largest and smallest possible results. Use this fact to optimize comparisons against an sdiv with a constant dividend. Reviewers: nicholas Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D3795 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208999 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Analysis/InstructionSimplify.cpp | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'lib/Analysis') diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp index 5421a39922..4cad81b139 100644 --- a/lib/Analysis/InstructionSimplify.cpp +++ b/lib/Analysis/InstructionSimplify.cpp @@ -2020,6 +2020,10 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, APInt NegOne = APInt::getAllOnesValue(Width); if (!CI2->isZero()) Upper = NegOne.udiv(CI2->getValue()) + 1; + } else if (match(LHS, m_SDiv(m_ConstantInt(CI2), m_Value()))) { + // 'sdiv CI2, x' produces [-|CI2|, |CI2|]. + Upper = CI2->getValue().abs() + 1; + Lower = (-Upper) + 1; } else if (match(LHS, m_SDiv(m_Value(), m_ConstantInt(CI2)))) { // 'sdiv x, CI2' produces [INT_MIN / CI2, INT_MAX / CI2]. APInt IntMin = APInt::getSignedMinValue(Width); -- cgit v1.2.3