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Make one getAddExpr call when analyzing a+b+c+d+e+... instead of one

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for each add instruction. Ditto for Mul.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@111136 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2010-08-16 16:03:49 +00:00
parent 57560da3f5
commit d3f171d66f
1 changed files with 31 additions and 6 deletions
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37
lib/Analysis/ScalarEvolution.cpp
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@ -3244,12 +3244,37 @@ const SCEV *ScalarEvolution::createSCEV(Value *V) {
Operator *U = cast<Operator>(V);
switch (Opcode) {
case Instruction::Add:
return getAddExpr(getSCEV(U->getOperand(0)),
getSCEV(U->getOperand(1)));
case Instruction::Mul:
return getMulExpr(getSCEV(U->getOperand(0)),
getSCEV(U->getOperand(1)));
case Instruction::Add: {
// The simple thing to do would be to just call getSCEV on both operands
// and call getAddExpr with the result. However if we're looking at a
// bunch of things all added together, this can be quite inefficient,
// because it leads to N-1 getAddExpr calls for N ultimate operands.
// Instead, gather up all the operands and make a single getAddExpr call.
// LLVM IR canonical form means we need only traverse the left operands.
SmallVector<const SCEV *, 4> AddOps;
AddOps.push_back(getSCEV(U->getOperand(1)));
for (Value *Op = U->getOperand(0);
Op->getValueID() == Instruction::Add + Value::InstructionVal;
Op = U->getOperand(0)) {
U = cast<Operator>(Op);
AddOps.push_back(getSCEV(U->getOperand(1)));
}
AddOps.push_back(getSCEV(U->getOperand(0)));
return getAddExpr(AddOps);
}
case Instruction::Mul: {
// See the Add code above.
SmallVector<const SCEV *, 4> MulOps;
MulOps.push_back(getSCEV(U->getOperand(1)));
for (Value *Op = U->getOperand(0);
Op->getValueID() == Instruction::Mul + Value::InstructionVal;
Op = U->getOperand(0)) {
U = cast<Operator>(Op);
MulOps.push_back(getSCEV(U->getOperand(1)));
}
MulOps.push_back(getSCEV(U->getOperand(0)));
return getMulExpr(MulOps);
}
case Instruction::UDiv:
return getUDivExpr(getSCEV(U->getOperand(0)),
getSCEV(U->getOperand(1)));