From 9b8d2c26bce15d47a54718a50b44dd0a65eb88f4 Mon Sep 17 00:00:00 2001 From: Nick Lewycky Date: Sat, 22 Jan 2011 22:06:21 +0000 Subject: [PATCH] Have SCEV turn sext(x) into zext(x) when x is s>= 0. This applies many times in "make check" alone. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124046 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 424f74427be..63602ffaa78 100644 --- a/lib/Analysis/ScalarEvolution.cpp +++ b/lib/Analysis/ScalarEvolution.cpp @@ -1035,6 +1035,10 @@ const SCEV *ScalarEvolution::getSignExtendExpr(const SCEV *Op, void *IP = 0; if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; + // If the input value is provably positive, build a zext instead. + if (isKnownNonNegative(Op)) + return getZeroExtendExpr(Op, Ty); + // If the input value is a chrec scev, and we can prove that the value // did not overflow the old, smaller, value, we can sign extend all of the // operands (often constants). This allows analysis of something like -- 2.34.1