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Fixed minor bug in SafeToHoist and made some changes suggested by Chris.

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llvm-svn: 7614
This commit is contained in:
Tanya Lattner 2003-08-05 20:39:02 +00:00
parent 9d218f68d1
commit 6fbe85279f
1 changed files with 10 additions and 19 deletions
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29
lib/Transforms/Scalar/LICM.cpp
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@ -67,7 +67,7 @@ namespace {
BasicBlock *Preheader; // The preheader block of the current loop...
Loop *CurLoop; // The current loop we are working on...
AliasSetTracker *CurAST; // AliasSet information for the current loop...
DominatorTree *CurDT; // Dominator Tree for the current Loop...
DominatorTree *DT; // Dominator Tree for the current Loop...
/// visitLoop - Hoist expressions out of the specified loop...
///
@ -173,6 +173,7 @@ bool LICM::runOnFunction(Function &) {
// Get our Loop and Alias Analysis information...
LI = &getAnalysis<LoopInfo>();
AA = &getAnalysis<AliasAnalysis>();
DT = &getAnalysis<DominatorTree>();
// Hoist expressions out of all of the top-level loops.
const std::vector<Loop*> &TopLevelLoops = LI->getTopLevelLoops();
@ -223,9 +224,7 @@ void LICM::visitLoop(Loop *L, AliasSetTracker &AST) {
// that we are guaranteed to see definitions before we see uses. This allows
// us to perform the LICM transformation in one pass, without iteration.
//
CurDT = &getAnalysis<DominatorTree>();
HoistRegion(CurDT->getNode(L->getHeader()));
HoistRegion(DT->getNode(L->getHeader()));
// Now that all loop invariants have been removed from the loop, promote any
// memory references to scalars that we can...
@ -290,36 +289,28 @@ bool LICM::SafeToHoist(Instruction &Inst) {
BasicBlock *InstBB = Inst.getParent();
//Get the Dominator Tree Node for the instruction's basic block/
DominatorTree::Node *InstDTNode = CurDT->getNode(InstBB);
DominatorTree::Node *InstDTNode = DT->getNode(InstBB);
//Get the exit blocks for the current loop.
const std::vector<BasicBlock* > ExitBlocks = CurLoop->getExitBlocks();
const std::vector<BasicBlock* > &ExitBlocks = CurLoop->getExitBlocks();
//For each exit block, get the DT node and walk up the DT until
//the instruction's basic block is found or we exit the loop.
for(unsigned i=0; i < ExitBlocks.size(); ++i) {
DominatorTree::Node *IDom = CurDT->getNode(ExitBlocks[i]);
DominatorTree::Node *IDom = DT->getNode(ExitBlocks[i]);
//Using boolean variable because exit nodes are not "contained"
//in the loop, so can not use that as the while test condition
//for first pass.
bool inLoop = true;
while(inLoop) {
//compare Instruction DT node to Current DT Node
if(IDom == InstDTNode)
return true;
while(IDom != InstDTNode) {
//Get next Immediate Dominator.
IDom = IDom->getIDom();
//See if we exited the loop.
inLoop = CurLoop->contains(IDom->getNode());
if(!CurLoop->contains(IDom->getNode()))
return false;
}
return false;
}
}
return true;
}