From 8c5c6f0e090f91b6555cdd9d2eea238fff3befe6 Mon Sep 17 00:00:00 2001 From: David Majnemer Date: Tue, 9 Jul 2013 22:01:22 +0000 Subject: InstSimplify: X >> X -> 0 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185973 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Analysis/InstructionSimplify.cpp | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'lib/Analysis/InstructionSimplify.cpp') diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp index bf7745143d..d66ecca928 100644 --- a/lib/Analysis/InstructionSimplify.cpp +++ b/lib/Analysis/InstructionSimplify.cpp @@ -1363,6 +1363,10 @@ static Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact, if (Value *V = SimplifyShift(Instruction::LShr, Op0, Op1, Q, MaxRecurse)) return V; + // X >> X -> 0 + if (Op0 == Op1) + return Constant::getNullValue(Op0->getType()); + // undef >>l X -> 0 if (match(Op0, m_Undef())) return Constant::getNullValue(Op0->getType()); @@ -1391,6 +1395,10 @@ static Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact, if (Value *V = SimplifyShift(Instruction::AShr, Op0, Op1, Q, MaxRecurse)) return V; + // X >> X -> 0 + if (Op0 == Op1) + return Constant::getNullValue(Op0->getType()); + // all ones >>a X -> all ones if (match(Op0, m_AllOnes())) return Op0; -- cgit v1.2.3