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[MachineSink] add threshold in machinesink pass to reduce compiling time.

This commit is contained in:
Chen Zheng 2020-12-27 20:39:13 -05:00
parent d76c1d2247
commit 31c2b93d83
1 changed files with 36 additions and 0 deletions
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36
llvm/lib/CodeGen/MachineSink.cpp
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@ -79,6 +79,18 @@ static cl::opt<unsigned> SplitEdgeProbabilityThreshold(
"splitted critical edge"),
cl::init(40), cl::Hidden);
static cl::opt<unsigned> SinkLoadInstsPerBlockThreshold(
"machine-sink-load-instrs-threshold",
cl::desc("Do not try to find alias store for a load if there is a in-path "
"block whose instruction number is higher than this threshold."),
cl::init(2000), cl::Hidden);
static cl::opt<unsigned> SinkLoadBlocksThreshold(
"machine-sink-load-blocks-threshold",
cl::desc("Do not try to find alias store for a load if the block number in "
"the straight line is higher than this threshold."),
cl::init(20), cl::Hidden);
STATISTIC(NumSunk, "Number of machine instructions sunk");
STATISTIC(NumSplit, "Number of critical edges split");
STATISTIC(NumCoalesces, "Number of copies coalesced");
@ -1020,6 +1032,7 @@ bool MachineSinking::hasStoreBetween(MachineBasicBlock *From,
bool SawStore = false;
bool HasAliasedStore = false;
DenseSet<MachineBasicBlock *> HandledBlocks;
DenseSet<MachineBasicBlock *> HandledDomBlocks;
// Go through all reachable blocks from From.
for (MachineBasicBlock *BB : depth_first(From)) {
// We insert the instruction at the start of block To, so no need to worry
@ -1036,10 +1049,33 @@ bool MachineSinking::hasStoreBetween(MachineBasicBlock *From,
HandledBlocks.insert(BB);
// To post dominates BB, it must be a path from block From.
if (PDT->dominates(To, BB)) {
if (!HandledDomBlocks.count(BB))
HandledDomBlocks.insert(BB);
// If this BB is too big or the block number in straight line between From
// and To is too big, stop searching to save compiling time.
if (BB->size() > SinkLoadInstsPerBlockThreshold ||
HandledDomBlocks.size() > SinkLoadBlocksThreshold) {
for (auto *DomBB : HandledDomBlocks) {
if (DomBB != BB && DT->dominates(DomBB, BB))
HasStoreCache[std::make_pair(DomBB, To)] = true;
else if(DomBB != BB && DT->dominates(BB, DomBB))
HasStoreCache[std::make_pair(From, DomBB)] = true;
}
HasStoreCache[BlockPair] = true;
return true;
}
for (MachineInstr &I : *BB) {
// Treat as alias conservatively for a call or an ordered memory
// operation.
if (I.isCall() || I.hasOrderedMemoryRef()) {
for (auto *DomBB : HandledDomBlocks) {
if (DomBB != BB && DT->dominates(DomBB, BB))
HasStoreCache[std::make_pair(DomBB, To)] = true;
else if(DomBB != BB && DT->dominates(BB, DomBB))
HasStoreCache[std::make_pair(From, DomBB)] = true;
}
HasStoreCache[BlockPair] = true;
return true;
}