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Refactor the inline cost bonus calculation for constants to use 

a worklist rather than a recursive call.

No functionality changed.

llvm-svn: 152706
This commit is contained in:
Chandler Carruth 2012-03-14 07:32:53 +00:00
parent d7c0aae45b
commit a308955993
1 changed files with 26 additions and 20 deletions
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46
llvm/lib/Analysis/InlineCost.cpp
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@ -165,18 +165,24 @@ void CodeMetrics::analyzeBasicBlock(const BasicBlock *BB,
unsigned InlineCostAnalyzer::FunctionInfo::countCodeReductionForConstant(
const CodeMetrics &Metrics, Value *V) {
unsigned Reduction = 0;
for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;++UI){
User *U = *UI;
if (isa<BranchInst>(U) || isa<SwitchInst>(U)) {
// We will be able to eliminate all but one of the successors.
const TerminatorInst &TI = cast<TerminatorInst>(*U);
const unsigned NumSucc = TI.getNumSuccessors();
unsigned Instrs = 0;
for (unsigned I = 0; I != NumSucc; ++I)
Instrs += Metrics.NumBBInsts.lookup(TI.getSuccessor(I));
// We don't know which blocks will be eliminated, so use the average size.
Reduction += InlineConstants::InstrCost*Instrs*(NumSucc-1)/NumSucc;
} else {
SmallVector<Value *, 4> Worklist;
Worklist.push_back(V);
do {
Value *V = Worklist.pop_back_val();
for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;++UI){
User *U = *UI;
if (isa<BranchInst>(U) || isa<SwitchInst>(U)) {
// We will be able to eliminate all but one of the successors.
const TerminatorInst &TI = cast<TerminatorInst>(*U);
const unsigned NumSucc = TI.getNumSuccessors();
unsigned Instrs = 0;
for (unsigned I = 0; I != NumSucc; ++I)
Instrs += Metrics.NumBBInsts.lookup(TI.getSuccessor(I));
// We don't know which blocks will be eliminated, so use the average size.
Reduction += InlineConstants::InstrCost*Instrs*(NumSucc-1)/NumSucc;
continue;
}
// Figure out if this instruction will be removed due to simple constant
// propagation.
Instruction &Inst = cast<Instruction>(*U);
@ -198,17 +204,17 @@ unsigned InlineCostAnalyzer::FunctionInfo::countCodeReductionForConstant(
AllOperandsConstant = false;
break;
}
if (!AllOperandsConstant)
continue;
if (AllOperandsConstant) {
// We will get to remove this instruction...
Reduction += InlineConstants::InstrCost;
// We will get to remove this instruction...
Reduction += InlineConstants::InstrCost;
// And any other instructions that use it which become constants
// themselves.
Reduction += countCodeReductionForConstant(Metrics, &Inst);
}
// And any other instructions that use it which become constants
// themselves.
Worklist.push_back(&Inst);
}
}
} while (!Worklist.empty());
return Reduction;
}