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Revert X + X --> X * 2 optz'n which pessimizes heavily on x86.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@51474 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nick Lewycky 2008-05-23 04:34:58 +00:00
parent 3adaa93700
commit 02d639fcc0
2 changed files with 5 additions and 19 deletions
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18
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -2292,22 +2292,14 @@ static Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) {
namespace {
// AddRHS - Implements: X + X --> X << 1 and X + X --> X * 2 for vectors
// AddRHS - Implements: X + X --> X << 1
struct AddRHS {
Value *RHS;
AddRHS(Value *rhs) : RHS(rhs) {}
bool shouldApply(Value *LHS) const { return LHS == RHS; }
Instruction *apply(BinaryOperator &Add) const {
if (Add.getType()->getTypeID() == Type::VectorTyID) {
const VectorType *VTy = cast<VectorType>(Add.getType());
ConstantInt *CI = ConstantInt::get(VTy->getElementType(), 2);
std::vector<Constant*> Elts(VTy->getNumElements(), CI);
return BinaryOperator::CreateMul(Add.getOperand(0),
ConstantVector::get(Elts));
} else {
return BinaryOperator::CreateShl(Add.getOperand(0),
ConstantInt::get(Add.getType(), 1));
}
return BinaryOperator::CreateShl(Add.getOperand(0),
ConstantInt::get(Add.getType(), 1));
}
};
@ -2635,8 +2627,8 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
}
}
// X + X --> X << 1 and X + X --> X * 2 for vectors
if (I.getType()->isIntOrIntVector() && I.getType() != Type::Int1Ty) {
// X + X --> X
if (I.getType()->isInteger() && I.getType() != Type::Int1Ty) {
if (Instruction *Result = AssociativeOpt(I, AddRHS(RHS))) return Result;
if (Instruction *RHSI = dyn_cast<Instruction>(RHS)) {

6
test/Transforms/InstCombine/2008-05-22-FoldAddIVec.ll
View File

@ -1,6 +0,0 @@
; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep mul
define <3 x i8> @f(<3 x i8> %i) {
%A = add <3 x i8> %i, %i
ret <3 x i8> %A
}