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[DAGCombiner] Limit number of nodes explored as store candidates. 

To find the candidates to merge stores we iterate over all nodes in a chain
for each store, which leads to quadratic compile times for large basic blocks
with a large number of stores.

Reviewers: niravd, spatel, craig.topper

Reviewed By: niravd

Differential Revision: https://reviews.llvm.org/D61511

llvm-svn: 360357
This commit is contained in:
Florian Hahn 2019-05-09 17:05:52 +00:00
parent 0b68fc3f59
commit be10bc71f9
1 changed files with 5 additions and 2 deletions
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7
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -14857,9 +14857,11 @@ void DAGCombiner::getStoreMergeCandidates(
RootNode = St->getChain().getNode(); RootNode = St->getChain().getNode();
unsigned NumNodesExplored = 0;
if (LoadSDNode *Ldn = dyn_cast<LoadSDNode>(RootNode)) { if (LoadSDNode *Ldn = dyn_cast<LoadSDNode>(RootNode)) {
RootNode = Ldn->getChain().getNode(); RootNode = Ldn->getChain().getNode();
for (auto I = RootNode->use_begin(), E = RootNode->use_end(); I != E; ++I) for (auto I = RootNode->use_begin(), E = RootNode->use_end();
I != E && NumNodesExplored < 1024; ++I, ++NumNodesExplored)
if (I.getOperandNo() == 0 && isa<LoadSDNode>(*I)) // walk down chain if (I.getOperandNo() == 0 && isa<LoadSDNode>(*I)) // walk down chain
for (auto I2 = (*I)->use_begin(), E2 = (*I)->use_end(); I2 != E2; ++I2) for (auto I2 = (*I)->use_begin(), E2 = (*I)->use_end(); I2 != E2; ++I2)
if (I2.getOperandNo() == 0) if (I2.getOperandNo() == 0)
@ -14870,7 +14872,8 @@ void DAGCombiner::getStoreMergeCandidates(
StoreNodes.push_back(MemOpLink(OtherST, PtrDiff)); StoreNodes.push_back(MemOpLink(OtherST, PtrDiff));
} }
} else } else
for (auto I = RootNode->use_begin(), E = RootNode->use_end(); I != E; ++I) for (auto I = RootNode->use_begin(), E = RootNode->use_end();
I != E && NumNodesExplored < 1024; ++I, ++NumNodesExplored)
if (I.getOperandNo() == 0) if (I.getOperandNo() == 0)
if (StoreSDNode *OtherST = dyn_cast<StoreSDNode>(*I)) { if (StoreSDNode *OtherST = dyn_cast<StoreSDNode>(*I)) {
BaseIndexOffset Ptr; BaseIndexOffset Ptr;