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[LCG] Remove a completely unnecessary loop. It wasn't even doing any

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thing, just mucking up the code. I feel bad that I even wrote this loop.
Very sorry. The diff is huge because of the indent change, but I promise
all this is doing is realizing that the outer two loops were actually
the exact same loops, and we didn't need two of them.

llvm-svn: 207202
This commit is contained in:
Chandler Carruth 2014-04-25 06:45:06 +00:00
parent 6a4aae8f97
commit a937a4a8a9
1 changed files with 56 additions and 62 deletions
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118
lib/Analysis/LazyCallGraph.cpp
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@ -218,79 +218,73 @@ LazyCallGraph::SCC::removeInternalEdge(LazyCallGraph &G, Node &Caller,
"pending nodes from a prior walk.");
}
// We simulate recursion by popping out of all the nested loops and
// continuing.
bool Recurse = false;
do {
Node *N = DFSStack.back().first;
assert(N->DFSNumber != 0 && "We should always assign a DFS number "
"before placing a node onto the stack.");
for (auto I = DFSStack.back().second, E = N->end(); I != E; ++I) {
Node &ChildN = *I;
// If this child isn't currently in this SCC, no need to process it.
// However, we do need to remove this SCC from its SCC's parent set.
SCC &ChildSCC = *G.SCCMap.lookup(&ChildN);
if (&ChildSCC != this) {
ChildSCC.ParentSCCs.erase(this);
continue;
}
// Check if we have reached a node in the new (known connected) set. If
// so, the entire stack is necessarily in that set and we can re-start.
if (NewNodes.count(&ChildN)) {
while (!PendingSCCStack.empty())
NewNodes.insert(PendingSCCStack.pop_back_val());
while (!DFSStack.empty())
NewNodes.insert(DFSStack.pop_back_val().first);
Recurse = true;
break;
}
if (ChildN.DFSNumber == 0) {
// Mark that we should start at this child when next this node is the
// top of the stack. We don't start at the next child to ensure this
// child's lowlink is reflected.
DFSStack.back().second = I;
// Recurse onto this node via a tail call.
ChildN.LowLink = ChildN.DFSNumber = NextDFSNumber++;
Worklist.remove(&ChildN);
DFSStack.push_back(std::make_pair(&ChildN, ChildN.begin()));
Recurse = true;
break;
}
// Track the lowest link of the childen, if any are still in the stack.
// Any child not on the stack will have a LowLink of -1.
assert(ChildN.LowLink != 0 &&
"Low-link must not be zero with a non-zero DFS number.");
if (ChildN.LowLink >= 0 && ChildN.LowLink < N->LowLink)
N->LowLink = ChildN.LowLink;
// We simulate recursion by popping out of the nested loop and continuing.
bool Recurse = false;
for (auto I = DFSStack.back().second, E = N->end(); I != E; ++I) {
Node &ChildN = *I;
// If this child isn't currently in this SCC, no need to process it.
// However, we do need to remove this SCC from its SCC's parent set.
SCC &ChildSCC = *G.SCCMap.lookup(&ChildN);
if (&ChildSCC != this) {
ChildSCC.ParentSCCs.erase(this);
continue;
}
if (Recurse)
break;
// No more children to process, pop it off the core DFS stack.
DFSStack.pop_back();
if (N->LowLink == N->DFSNumber) {
ResultSCCs.push_back(G.formSCC(N, PendingSCCStack));
// Check if we have reached a node in the new (known connected) set. If
// so, the entire stack is necessarily in that set and we can re-start.
if (NewNodes.count(&ChildN)) {
while (!PendingSCCStack.empty())
NewNodes.insert(PendingSCCStack.pop_back_val());
while (!DFSStack.empty())
NewNodes.insert(DFSStack.pop_back_val().first);
Recurse = true;
break;
}
assert(!DFSStack.empty() && "We shouldn't have an empty stack!");
if (ChildN.DFSNumber == 0) {
// Mark that we should start at this child when next this node is the
// top of the stack. We don't start at the next child to ensure this
// child's lowlink is reflected.
DFSStack.back().second = I;
// At this point we know that N cannot ever be an SCC root. Its low-link
// is not its dfs-number, and we've processed all of its children. It is
// just sitting here waiting until some node further down the stack gets
// low-link == dfs-number and pops it off as well. Move it to the pending
// stack which is pulled into the next SCC to be formed.
PendingSCCStack.push_back(N);
} while (!DFSStack.empty());
// Recurse onto this node via a tail call.
ChildN.LowLink = ChildN.DFSNumber = NextDFSNumber++;
Worklist.remove(&ChildN);
DFSStack.push_back(std::make_pair(&ChildN, ChildN.begin()));
Recurse = true;
break;
}
// We reach here when we're going to "recurse".
// Track the lowest link of the childen, if any are still in the stack.
// Any child not on the stack will have a LowLink of -1.
assert(ChildN.LowLink != 0 &&
"Low-link must not be zero with a non-zero DFS number.");
if (ChildN.LowLink >= 0 && ChildN.LowLink < N->LowLink)
N->LowLink = ChildN.LowLink;
}
if (Recurse)
continue;
// No more children to process, pop it off the core DFS stack.
DFSStack.pop_back();
if (N->LowLink == N->DFSNumber) {
ResultSCCs.push_back(G.formSCC(N, PendingSCCStack));
continue;
}
assert(!DFSStack.empty() && "We shouldn't have an empty stack!");
// At this point we know that N cannot ever be an SCC root. Its low-link
// is not its dfs-number, and we've processed all of its children. It is
// just sitting here waiting until some node further down the stack gets
// low-link == dfs-number and pops it off as well. Move it to the pending
// stack which is pulled into the next SCC to be formed.
PendingSCCStack.push_back(N);
}
// Replace this SCC with the NewNodes we collected above.