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[LCG] Special case the removal of self edges. These don't impact the SCC

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graph in any way because we don't track edges in the SCC graph, just
nodes. This also lets us add a nice assert about the invariant that
we're working on at least a certain number of nodes within the SCC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207305 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chandler Carruth 2014-04-26 03:36:37 +00:00
parent d10a9fb25a
commit 0c8f0bfce2
1 changed files with 6 additions and 0 deletions
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6
lib/Analysis/LazyCallGraph.cpp
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@ -188,6 +188,10 @@ LazyCallGraph::SCC::removeInternalEdge(LazyCallGraph &G, Node &Caller,
SmallVector<SCC *, 1> ResultSCCs;
ResultSCCs.push_back(this);
// Direct recursion doesn't impact the SCC graph at all.
if (&Caller == &Callee)
return ResultSCCs;
// We're going to do a full mini-Tarjan's walk using a local stack here.
int NextDFSNumber;
SmallVector<std::pair<Node *, Node::iterator>, 4> DFSStack;
@ -202,6 +206,8 @@ LazyCallGraph::SCC::removeInternalEdge(LazyCallGraph &G, Node &Caller,
N->LowLink = 0;
G.SCCMap.erase(N);
}
assert(Worklist.size() > 1 && "We have to have at least two nodes to have an "
"edge between them that is within the SCC.");
// The callee can already reach every node in this SCC (by definition). It is
// the only node we know will stay inside this SCC. Everything which