void ShortestPathAnalysis::analyzeLoopsRecursively(SILLoop *Loop, int LoopDepth) {
if (LoopDepth >= MaxNumLoopLevels)
return;
// First dive into the inner loops.
for (SILLoop *SubLoop : Loop->getSubLoops()) {
analyzeLoopsRecursively(SubLoop, LoopDepth + 1);
}
BlockInfo *HeaderInfo = getBlockInfo(Loop->getHeader());
Distances &HeaderDists = HeaderInfo->getDistances(LoopDepth);
// Initial values for the entry (== header) and exit-predecessor (== header as
// well).
HeaderDists.DistFromEntry = 0;
HeaderDists.DistToExit = 0;
solveDataFlow(Loop->getBlocks(), LoopDepth);
int LoopLength = getExitDistFromSuccs(Loop->getHeader(), LoopDepth) +
HeaderInfo->getLength(LoopDepth);
HeaderDists.DistToExit = LoopLength;
// If there is a loop bypass edge, add the loop length to the loop pre-pre-
// header instead to the header. This actually let us ignore the loop bypass
// edge in the length calculation for the loop's parent scope.
if (SILBasicBlock *Bypass = detectLoopBypassPreheader(Loop))
HeaderInfo = getBlockInfo(Bypass);
// Add the full loop length (= assumed-iteration-count * length) to the loop
// header so that it is considered in the parent scope.
HeaderInfo->getDistances(LoopDepth - 1).LoopHeaderLength =
LoopCount * LoopLength;
}
void ShortestPathAnalysis::printBlockInfo(llvm::raw_ostream &OS,
SILBasicBlock *BB, int LoopDepth) {
BlockInfo *BBInfo = getBlockInfo(BB);
Distances &D = BBInfo->getDistances(LoopDepth);
OS << " bb" << BB->getDebugID() << ": length=" << BBInfo->Length << '+'
<< D.LoopHeaderLength << ", d-entry=" << D.DistFromEntry
<< ", d-exit=" << D.DistToExit << '\n';
}
int ShortestPathAnalysis::getExitDistFromSuccs(const SILBasicBlock *BB,
int LoopDepth) {
int MinDist = InitialDist;
for (const SILSuccessor &Succ : BB->getSuccessors()) {
BlockInfo *SuccInfo = getBlockInfo(Succ);
Distances &SDists = SuccInfo->getDistances(LoopDepth);
if (SDists.DistToExit < MinDist)
MinDist = SDists.DistToExit;
}
return MinDist;
}
int ShortestPathAnalysis::getEntryDistFromPreds(const SILBasicBlock *BB,
int LoopDepth) {
int MinDist = InitialDist;
for (SILBasicBlock *Pred : BB->getPreds()) {
BlockInfo *PredInfo = getBlockInfo(Pred);
Distances &PDists = PredInfo->getDistances(LoopDepth);
int DistFromEntry = PDists.DistFromEntry + PredInfo->Length +
PDists.LoopHeaderLength;
assert(DistFromEntry >= 0);
if (DistFromEntry < MinDist)
MinDist = DistFromEntry;
}
return MinDist;
}
