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(0.33) Move removal of exception edges to before collecting fixable predecessors #152

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Jun 29, 2022
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(0.33) Move removal of exception edges to before collecting fixable predecessors #152

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34 changes: 20 additions & 14 deletions compiler/optimizer/LocalOpts.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3376,7 +3376,6 @@ int32_t TR_EliminateRedundantGotos::process(TR::TreeTop *startTree, TR::TreeTop
firstNonFenceTree = firstNonFenceTree->getNextRealTreeTop();
}


bool containsTreesOtherThanGoto = false;
if (firstNonFenceTree != lastNonFenceTree &&
!emptyBlock)
Expand Down Expand Up @@ -3440,6 +3439,26 @@ int32_t TR_EliminateRedundantGotos::process(TR::TreeTop *startTree, TR::TreeTop
if (destBlock == block)
continue; // No point trying to "update" predecessors

if (!containsTreesOtherThanGoto && !block->getExceptionSuccessors().empty())
{
// Structure repair doesn't deal well with exception successors in this case.
if (!performTransformation(comp(), "%sRemoving exception successor edges for block_%d\n", optDetailString(), block->getNumber()))
continue; // The exception successors remain, so skip this block

TR::CFGEdgeList &excSuccs = block->getExceptionSuccessors();
while (!excSuccs.empty())
{
if (trace())
{
TR::Block *from = excSuccs.front()->getFrom()->asBlock();
TR::Block *to = excSuccs.front()->getTo()->asBlock();
traceMsg(comp(), "Remove exception edge: block_%d (isValid %d) -> block_%d (isValid %d)\n", from->getNumber(), from->isValid(), to->getNumber(), to->isValid());
}

cfg->removeEdge(excSuccs.front());
}
}

TR::CFGEdgeList fixablePreds(comp()->trMemory()->currentStackRegion());
auto preds = block->getPredecessors();
for (auto inEdge = preds.begin(); inEdge != preds.end(); ++inEdge)
Expand Down Expand Up @@ -3527,19 +3546,6 @@ int32_t TR_EliminateRedundantGotos::process(TR::TreeTop *startTree, TR::TreeTop
//destBlock->setEntry(block->getEntry());
//destBlock->setExit(block->getExit());
}
else
{
if (!block->getExceptionSuccessors().empty())
{
// A block with a goto, only a goto and nothing but the goto needs
// no exception successors (removing them is a good idea in general, but
// structure repair below specifically does not like such nasty nasty
// goto blocks)
//
for (auto edge = block->getExceptionSuccessors().begin(); edge != block->getExceptionSuccessors().end();)
cfg->removeEdge(*(edge++));
}
}

if (emptyBlock &&
!performTransformation(comp(), "%sRemoving empty block_%d with BBStart %p\n", optDetailString(), block->getNumber(), block->getEntry()->getNode()))
Expand Down