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* Changes to make NodeType be private to DSNode.

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* Add new MultiObject flag to DSNode which keeps track of whether or not
  multiple objects have been merged into the node, allowing must-alias info
  to be tracked.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@6794 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
2003-06-19 21:15:11 +00:00
parent 160cf48671
commit bd92b73be7
5 changed files with 107 additions and 76 deletions
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45
lib/Analysis/DataStructure/DataStructureAA.cpp
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@ -68,15 +68,12 @@ static const Function *getValueFunction(const Value *V) {
// alias - This is the only method here that does anything interesting...
AliasAnalysis::AliasResult DSAA::alias(const Value *V1, unsigned V1Size,
const Value *V2, unsigned V2Size) {
// FIXME: This should handle the Size argument as well!
if (V1 == V2) return MustAlias;
const Function *F1 = getValueFunction(V1);
const Function *F2 = getValueFunction(V2);
assert((!F1 || !F2 || F1 == F2) && "Alias query for 2 different functions?");
// FIXME: This can return must alias if querying a DSNode for a global value
// where the node has only the G composition bit set, and only one entry in
// the globals list...
if (F2) F1 = F2;
if (F1) {
// Get the graph for a function...
@ -88,17 +85,33 @@ AliasAnalysis::AliasResult DSAA::alias(const Value *V1, unsigned V1Size,
hash_map<Value*, DSNodeHandle>::iterator J = GSM.find((Value*)V2);
if (J != GSM.end()) {
assert(J->second.getNode() && "Scalar map points to null node?");
if (I->second.getNode() != J->second.getNode()) {
// Return noalias if one of the nodes is complete...
if ((~I->second.getNode()->NodeType | ~J->second.getNode()->NodeType)
& DSNode::Incomplete)
return NoAlias;
// both are incomplete, they may alias...
} else {
// Both point to the same node, see if they point to different
// offsets... FIXME: This needs to know the size of the alias query
if (I->second.getOffset() != J->second.getOffset())
return NoAlias;
DSNode *N1 = I->second.getNode(), *N2 = J->second.getNode();
unsigned O1 = I->second.getOffset(), O2 = J->second.getOffset();
// We can only make a judgement of one of the nodes is complete...
if (!N1->isIncomplete() || !N2->isIncomplete()) {
if (N1 != N2)
return NoAlias; // Completely different nodes.
// Both point to the same node and same offset, and there is only one
// physical memory object represented in the node, return must alias.
if (O1 == O2 && !N1->isMultiObject())
return MustAlias; // Exactly the same object & offset
// See if they point to different offsets... if so, we may be able to
// determine that they do not alias...
if (O1 != O2) {
if (O2 < O1) { // Ensure that O1 <= O2
std::swap(V1, V2);
std::swap(O1, O2);
std::swap(V1Size, V2Size);
}
// FIXME: This is not correct because we do not handle array
// indexing correctly with this check!
//if (O1+V1Size <= O2) return NoAlias;
}
}
}
}