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[LCG] Now that the loop structure of the core SCC finding routine is

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factored into a more reasonable form, replace the tail call with
a simple outer-loop continuation. It's sad that C++ makes this so
awkward to write, but it seems more direct and clear than the tail call
at this point.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207201 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chandler Carruth 2014-04-25 06:38:58 +00:00
parent 64b5470866
commit fe0f0187be
1 changed files with 8 additions and 1 deletions
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9
lib/Analysis/LazyCallGraph.cpp
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@ -449,6 +449,7 @@ LazyCallGraph::SCC *LazyCallGraph::getNextSCCInPostOrder() {
assert(N->DFSNumber != 0 && "We should always assign a DFS number "
"before placing a node onto the stack.");
bool Recurse = false; // Used to simulate recursing onto a child.
for (auto I = DFSStack.back().second, E = N->end(); I != E; ++I) {
Node &ChildN = *I;
if (ChildN.DFSNumber == 0) {
@ -463,7 +464,8 @@ LazyCallGraph::SCC *LazyCallGraph::getNextSCCInPostOrder() {
ChildN.LowLink = ChildN.DFSNumber = NextDFSNumber++;
SCCEntryNodes.remove(&ChildN.getFunction());
DFSStack.push_back(std::make_pair(&ChildN, ChildN.begin()));
return LazyCallGraph::getNextSCCInPostOrder();
Recurse = true;
break;
}
// Track the lowest link of the childen, if any are still in the stack.
@ -472,6 +474,11 @@ LazyCallGraph::SCC *LazyCallGraph::getNextSCCInPostOrder() {
if (ChildN.LowLink >= 0 && ChildN.LowLink < N->LowLink)
N->LowLink = ChildN.LowLink;
}
if (Recurse)
// Continue the outer loop when we exit the inner loop in order to
// recurse onto a child.
continue;
// No more children to process here, pop the node off the stack.
DFSStack.pop_back();