From 14ab9170b8026b24a7d88bbab33e6e4494d55fa7 Mon Sep 17 00:00:00 2001 From: Sanjay Patel Date: Tue, 20 Nov 2018 17:34:59 +0000 Subject: [InstSimplify] fold funnel shifts with undef operands Splitting these off from the D54666. Patch by: nikic (Nikita Popov) llvm-svn: 347332 --- llvm/lib/Analysis/InstructionSimplify.cpp | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'llvm/lib/Analysis') diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp index 599a2f2ce4c..9fc10af9668 100644 --- a/llvm/lib/Analysis/InstructionSimplify.cpp +++ b/llvm/lib/Analysis/InstructionSimplify.cpp @@ -5042,7 +5042,16 @@ static Value *simplifyIntrinsic(Function *F, IterTy ArgBegin, IterTy ArgEnd, } case Intrinsic::fshl: case Intrinsic::fshr: { - Value *ShAmtArg = ArgBegin[2]; + Value *Op0 = ArgBegin[0], *Op1 = ArgBegin[1], *ShAmtArg = ArgBegin[2]; + + // If both operands are undef, the result is undef. + if (match(Op0, m_Undef()) && match(Op1, m_Undef())) + return UndefValue::get(F->getReturnType()); + + // If shift amount is undef, assume it is zero. + if (match(ShAmtArg, m_Undef())) + return ArgBegin[IID == Intrinsic::fshl ? 0 : 1]; + const APInt *ShAmtC; if (match(ShAmtArg, m_APInt(ShAmtC))) { // If there's effectively no shift, return the 1st arg or 2nd arg. -- cgit v1.2.3