}
// Return Heuristics
- void calcReturnHeuristics(BasicBlock *BB);
+ bool calcReturnHeuristics(BasicBlock *BB);
// Pointer Heuristics
- void calcPointerHeuristics(BasicBlock *BB);
+ bool calcPointerHeuristics(BasicBlock *BB);
// Loop Branch Heuristics
- void calcLoopBranchHeuristics(BasicBlock *BB);
+ bool calcLoopBranchHeuristics(BasicBlock *BB);
bool runOnFunction(Function &F);
};
// Calculate Edge Weights using "Return Heuristics". Predict a successor which
// leads directly to Return Instruction will not be taken.
-void BranchProbabilityAnalysis::calcReturnHeuristics(BasicBlock *BB){
+bool BranchProbabilityAnalysis::calcReturnHeuristics(BasicBlock *BB){
if (BB->getTerminator()->getNumSuccessors() == 1)
- return;
+ return false;
+ bool Any = false;
for (succ_iterator I = succ_begin(BB), E = succ_end(BB); I != E; ++I) {
BasicBlock *Succ = *I;
if (isReturningBlock(Succ)) {
decEdgeWeight(BB, Succ);
+ Any = true;
}
}
+
+ return Any;
}
// Calculate Edge Weights using "Pointer Heuristics". Predict a comparsion
// between two pointer or pointer and NULL will fail.
-void BranchProbabilityAnalysis::calcPointerHeuristics(BasicBlock *BB) {
+bool BranchProbabilityAnalysis::calcPointerHeuristics(BasicBlock *BB) {
BranchInst * BI = dyn_cast<BranchInst>(BB->getTerminator());
if (!BI || !BI->isConditional())
- return;
+ return false;
Value *Cond = BI->getCondition();
ICmpInst *CI = dyn_cast<ICmpInst>(Cond);
if (!CI || !CI->isEquality())
- return;
+ return false;
Value *LHS = CI->getOperand(0);
if (!LHS->getType()->isPointerTy())
- return;
+ return false;
assert(CI->getOperand(1)->getType()->isPointerTy());
incEdgeWeight(BB, Taken);
decEdgeWeight(BB, NonTaken);
+ return true;
}
// Calculate Edge Weights using "Loop Branch Heuristics". Predict backedges
// as taken, exiting edges as not-taken.
-void BranchProbabilityAnalysis::calcLoopBranchHeuristics(BasicBlock *BB) {
+bool BranchProbabilityAnalysis::calcLoopBranchHeuristics(BasicBlock *BB) {
uint32_t numSuccs = BB->getTerminator()->getNumSuccessors();
Loop *L = LI->getLoopFor(BB);
if (!L)
- return;
+ return false;
SmallVector<BasicBlock *, 8> BackEdges;
SmallVector<BasicBlock *, 8> ExitingEdges;
BP->setEdgeWeight(BB, Exiting, exitWeight);
}
}
+
+ return true;
}
bool BranchProbabilityAnalysis::runOnFunction(Function &F) {
BasicBlock *BB = I++;
// Only LBH uses setEdgeWeight method.
- calcLoopBranchHeuristics(BB);
+ if (calcLoopBranchHeuristics(BB))
+ continue;
// PH and RH use only incEdgeWeight and decEwdgeWeight methods to
// not efface LBH results.
+ if (calcReturnHeuristics(BB))
+ continue;
+
calcPointerHeuristics(BB);
- calcReturnHeuristics(BB);
}
return false;