From e0f15f8b7aa9e838964ded92bb81d1134358ffd6 Mon Sep 17 00:00:00 2001 From: Matt Arsenault Date: Wed, 23 Apr 2014 16:48:40 +0000 Subject: [PATCH] Remove dead code in instcombine. Don't replace shifts greater than the type with the maximum shift. This isn't hit anywhere in the tests, and somewhere else is replacing these with undef. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207000 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/InstCombine/InstCombineShifts.cpp | 13 ++----------- 1 file changed, 2 insertions(+), 11 deletions(-) diff --git a/lib/Transforms/InstCombine/InstCombineShifts.cpp b/lib/Transforms/InstCombine/InstCombineShifts.cpp index 1eaff16c593..1f98a0d22e1 100644 --- a/lib/Transforms/InstCombine/InstCombineShifts.cpp +++ b/lib/Transforms/InstCombine/InstCombineShifts.cpp @@ -337,21 +337,12 @@ Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, Constant *Op1, GetShiftedValue(Op0, COp1->getZExtValue(), isLeftShift, *this)); } - // See if we can simplify any instructions used by the instruction whose sole // purpose is to compute bits we don't care about. uint32_t TypeBits = Op0->getType()->getScalarSizeInBits(); - // shl i32 X, 32 = 0 and srl i8 Y, 9 = 0, ... just don't eliminate - // a signed shift. - // - if (COp1->uge(TypeBits)) { - if (I.getOpcode() != Instruction::AShr) - return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType())); - // ashr i32 X, 32 --> ashr i32 X, 31 - I.setOperand(1, ConstantInt::get(I.getType(), TypeBits-1)); - return &I; - } + assert(!COp1->uge(TypeBits) && + "Shift over the type width should have been removed already"); // ((X*C1) << C2) == (X * (C1 << C2)) if (BinaryOperator *BO = dyn_cast(Op0)) -- 2.34.1