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Remove globals on the bottom up pass which do not contain any information

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@5451 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2003-01-31 23:57:36 +00:00
parent 11d71edd0d
commit 100f87252d
1 changed files with 22 additions and 3 deletions
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25
lib/Analysis/DataStructure/DataStructure.cpp
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@ -1005,6 +1005,24 @@ static bool CallSiteUsesAliveArgs(DSCallSite &CS, std::set<DSNode*> &Alive,
return false;
}
// GlobalIsAlivenessRoot - Return true if the specified global node is
// intrinsically alive in the context of the current graph (ie, it is a root of
// aliveness). For TD graphs, no globals are. For the BU graphs all are unless
// they are trivial globals...
//
static bool GlobalIsAlivenessRoot(DSNode *N, unsigned Flags) {
if (Flags & DSGraph::RemoveUnreachableGlobals)
return false; // If we are to remove all globals, go for it.
// Ok, we are keeping globals... hrm, we can still delete it if it has no
// links, and no mod/ref or other info... If it is not modified, it can't
// have links...
//
if ((N->NodeType & ~(DSNode::Composition | DSNode::Array)) == 0)
return false;
return true;
}
// removeDeadNodes - Use a more powerful reachability analysis to eliminate
// subgraphs that are unreachable. This often occurs because the data
// structure doesn't "escape" into it's caller, and thus should be eliminated
@ -1024,8 +1042,8 @@ void DSGraph::removeDeadNodes(unsigned Flags) {
// Mark all nodes reachable by (non-global) scalar nodes as alive...
for (std::map<Value*, DSNodeHandle>::iterator I = ScalarMap.begin(),
E = ScalarMap.end(); I != E; ++I)
if (!(Flags & DSGraph::RemoveUnreachableGlobals) ||
!isa<GlobalValue>(I->first)) // Don't mark globals!
if (!isa<GlobalValue>(I->first) ||
GlobalIsAlivenessRoot(I->second.getNode(), Flags))
I->second.getNode()->markReachableNodes(Alive);
else // Keep track of global nodes
GlobalNodes.push_back(std::make_pair(I->first, I->second.getNode()));
@ -1042,7 +1060,8 @@ void DSGraph::removeDeadNodes(unsigned Flags) {
std::vector<bool> FCallsAlive(FunctionCalls.size());
for (unsigned i = 0, e = FunctionCalls.size(); i != e; ++i)
if (CallSiteUsesAliveArgs(FunctionCalls[i], Alive, Visited)) {
if (!(Flags & DSGraph::RemoveUnreachableGlobals) ||
CallSiteUsesAliveArgs(FunctionCalls[i], Alive, Visited)) {
FunctionCalls[i].markReachableNodes(Alive);
FCallsAlive[i] = true;
}