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The hasConstantReferences predicate always returns false.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@11301 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
2004-02-11 01:17:07 +00:00
parent cf2e9f72e4
commit 2355f948c5
1 changed files with 50 additions and 53 deletions
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103
lib/Transforms/Utils/SimplifyCFG.cpp
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@@ -105,9 +105,9 @@ bool llvm::SimplifyCFG(BasicBlock *BB) {
assert(BB->getTerminator() && "Degenerate basic block encountered!"); assert(BB->getTerminator() && "Degenerate basic block encountered!");
assert(&BB->getParent()->front() != BB && "Can't Simplify entry block!"); assert(&BB->getParent()->front() != BB && "Can't Simplify entry block!");
// Check to see if the first instruction in this block is just an // Check to see if the first instruction in this block is just an unwind. If
// 'llvm.unwind'. If so, replace any invoke instructions which use this as an // so, replace any invoke instructions which use this as an exception
// exception destination with call instructions. // destination with call instructions.
// //
if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator()))
if (BB->begin() == BasicBlock::iterator(UI)) { // Empty block? if (BB->begin() == BasicBlock::iterator(UI)) { // Empty block?
@@ -136,8 +136,7 @@ bool llvm::SimplifyCFG(BasicBlock *BB) {
} }
// Remove basic blocks that have no predecessors... which are unreachable. // Remove basic blocks that have no predecessors... which are unreachable.
if (pred_begin(BB) == pred_end(BB) && if (pred_begin(BB) == pred_end(BB)) {
!BB->hasConstantReferences()) {
//cerr << "Removing BB: \n" << BB; //cerr << "Removing BB: \n" << BB;
// Loop through all of our successors and make sure they know that one // Loop through all of our successors and make sure they know that one
@@ -237,64 +236,62 @@ bool llvm::SimplifyCFG(BasicBlock *BB) {
// pred, and if there is only one distinct successor of the predecessor, and // pred, and if there is only one distinct successor of the predecessor, and
// if there are no PHI nodes. // if there are no PHI nodes.
// //
if (!BB->hasConstantReferences()) { pred_iterator PI(pred_begin(BB)), PE(pred_end(BB));
pred_iterator PI(pred_begin(BB)), PE(pred_end(BB)); BasicBlock *OnlyPred = *PI++;
BasicBlock *OnlyPred = *PI++; for (; PI != PE; ++PI) // Search all predecessors, see if they are all same
for (; PI != PE; ++PI) // Search all predecessors, see if they are all same if (*PI != OnlyPred) {
if (*PI != OnlyPred) { OnlyPred = 0; // There are multiple different predecessors...
OnlyPred = 0; // There are multiple different predecessors... break;
}
BasicBlock *OnlySucc = 0;
if (OnlyPred && OnlyPred != BB && // Don't break self loops
OnlyPred->getTerminator()->getOpcode() != Instruction::Invoke) {
// Check to see if there is only one distinct successor...
succ_iterator SI(succ_begin(OnlyPred)), SE(succ_end(OnlyPred));
OnlySucc = BB;
for (; SI != SE; ++SI)
if (*SI != OnlySucc) {
OnlySucc = 0; // There are multiple distinct successors!
break; break;
} }
}
BasicBlock *OnlySucc = 0;
if (OnlyPred && OnlyPred != BB && // Don't break self loops if (OnlySucc) {
OnlyPred->getTerminator()->getOpcode() != Instruction::Invoke) { //cerr << "Merging: " << BB << "into: " << OnlyPred;
// Check to see if there is only one distinct successor... TerminatorInst *Term = OnlyPred->getTerminator();
succ_iterator SI(succ_begin(OnlyPred)), SE(succ_end(OnlyPred));
OnlySucc = BB; // Resolve any PHI nodes at the start of the block. They are all
for (; SI != SE; ++SI) // guaranteed to have exactly one entry if they exist, unless there are
if (*SI != OnlySucc) { // multiple duplicate (but guaranteed to be equal) entries for the
OnlySucc = 0; // There are multiple distinct successors! // incoming edges. This occurs when there are multiple edges from
break; // OnlyPred to OnlySucc.
} //
while (PHINode *PN = dyn_cast<PHINode>(&BB->front())) {
PN->replaceAllUsesWith(PN->getIncomingValue(0));
BB->getInstList().pop_front(); // Delete the phi node...
} }
if (OnlySucc) { // Delete the unconditional branch from the predecessor...
//cerr << "Merging: " << BB << "into: " << OnlyPred; OnlyPred->getInstList().pop_back();
TerminatorInst *Term = OnlyPred->getTerminator();
// Resolve any PHI nodes at the start of the block. They are all
// guaranteed to have exactly one entry if they exist, unless there are
// multiple duplicate (but guaranteed to be equal) entries for the
// incoming edges. This occurs when there are multiple edges from
// OnlyPred to OnlySucc.
//
while (PHINode *PN = dyn_cast<PHINode>(&BB->front())) {
PN->replaceAllUsesWith(PN->getIncomingValue(0));
BB->getInstList().pop_front(); // Delete the phi node...
}
// Delete the unconditional branch from the predecessor...
OnlyPred->getInstList().pop_back();
// Move all definitions in the successor to the predecessor... // Move all definitions in the successor to the predecessor...
OnlyPred->getInstList().splice(OnlyPred->end(), BB->getInstList()); OnlyPred->getInstList().splice(OnlyPred->end(), BB->getInstList());
// Make all PHI nodes that referred to BB now refer to Pred as their // Make all PHI nodes that referred to BB now refer to Pred as their
// source... // source...
BB->replaceAllUsesWith(OnlyPred); BB->replaceAllUsesWith(OnlyPred);
std::string OldName = BB->getName(); std::string OldName = BB->getName();
// Erase basic block from the function... // Erase basic block from the function...
M->getBasicBlockList().erase(BB); M->getBasicBlockList().erase(BB);
// Inherit predecessors name if it exists... // Inherit predecessors name if it exists...
if (!OldName.empty() && !OnlyPred->hasName()) if (!OldName.empty() && !OnlyPred->hasName())
OnlyPred->setName(OldName); OnlyPred->setName(OldName);
return true; return true;
}
} }
return Changed; return Changed;