From eb4152c192ad226a1dee825f1433277e1851edbc Mon Sep 17 00:00:00 2001 From: Dan Gohman Date: Tue, 20 Jul 2010 16:53:00 +0000 Subject: [PATCH] Add a fast path for x - x. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@108855 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Analysis/ScalarEvolution.cpp | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp index f0bc9360b16..179aa8867d6 100644 --- a/lib/Analysis/ScalarEvolution.cpp +++ b/lib/Analysis/ScalarEvolution.cpp @@ -2442,6 +2442,10 @@ const SCEV *ScalarEvolution::getNotSCEV(const SCEV *V) { /// const SCEV *ScalarEvolution::getMinusSCEV(const SCEV *LHS, const SCEV *RHS) { + // Fast path: X - X --> 0. + if (LHS == RHS) + return getConstant(LHS->getType(), 0); + // X - Y --> X + -Y return getAddExpr(LHS, getNegativeSCEV(RHS)); } -- 2.34.1