return I != Ranges.end() && I->Low <= R.Low;
}
- /// LowerSwitch Pass - Replace all SwitchInst instructions with chained branch
- /// instructions.
+ /// Replace all SwitchInst instructions with chained branch instructions.
class LowerSwitch : public FunctionPass {
public:
static char ID; // Pass identification, replacement for typeid
typedef std::vector<CaseRange> CaseVector;
typedef std::vector<CaseRange>::iterator CaseItr;
private:
- void processSwitchInst(SwitchInst *SI);
+ void processSwitchInst(SwitchInst *SI, SmallPtrSetImpl<BasicBlock*> &DeleteList);
BasicBlock *switchConvert(CaseItr Begin, CaseItr End,
ConstantInt *LowerBound, ConstantInt *UpperBound,
return CI1->getValue().slt(CI2->getValue());
}
};
-} // namespace
+}
char LowerSwitch::ID = 0;
INITIALIZE_PASS(LowerSwitch, "lowerswitch",
bool LowerSwitch::runOnFunction(Function &F) {
bool Changed = false;
+ SmallPtrSet<BasicBlock*, 8> DeleteList;
for (Function::iterator I = F.begin(), E = F.end(); I != E; ) {
- BasicBlock *Cur = I++; // Advance over block so we don't traverse new blocks
+ BasicBlock *Cur = &*I++; // Advance over block so we don't traverse new blocks
+
+ // If the block is a dead Default block that will be deleted later, don't
+ // waste time processing it.
+ if (DeleteList.count(Cur))
+ continue;
if (SwitchInst *SI = dyn_cast<SwitchInst>(Cur->getTerminator())) {
Changed = true;
- processSwitchInst(SI);
+ processSwitchInst(SI, DeleteList);
}
}
+ for (BasicBlock* BB: DeleteList) {
+ DeleteDeadBlock(BB);
+ }
+
return Changed;
}
-// operator<< - Used for debugging purposes.
-//
+/// Used for debugging purposes.
static raw_ostream& operator<<(raw_ostream &O,
const LowerSwitch::CaseVector &C)
LLVM_ATTRIBUTE_USED;
return O << "]";
}
-// \brief Update the first occurrence of the "switch statement" BB in the PHI
-// node with the "new" BB. The other occurrences will:
-//
-// 1) Be updated by subsequent calls to this function. Switch statements may
-// have more than one outcoming edge into the same BB if they all have the same
-// value. When the switch statement is converted these incoming edges are now
-// coming from multiple BBs.
-// 2) Removed if subsequent incoming values now share the same case, i.e.,
-// multiple outcome edges are condensed into one. This is necessary to keep the
-// number of phi values equal to the number of branches to SuccBB.
+/// \brief Update the first occurrence of the "switch statement" BB in the PHI
+/// node with the "new" BB. The other occurrences will:
+///
+/// 1) Be updated by subsequent calls to this function. Switch statements may
+/// have more than one outcoming edge into the same BB if they all have the same
+/// value. When the switch statement is converted these incoming edges are now
+/// coming from multiple BBs.
+/// 2) Removed if subsequent incoming values now share the same case, i.e.,
+/// multiple outcome edges are condensed into one. This is necessary to keep the
+/// number of phi values equal to the number of branches to SuccBB.
static void fixPhis(BasicBlock *SuccBB, BasicBlock *OrigBB, BasicBlock *NewBB,
unsigned NumMergedCases) {
- for (BasicBlock::iterator I = SuccBB->begin(), IE = SuccBB->getFirstNonPHI();
+ for (BasicBlock::iterator I = SuccBB->begin(),
+ IE = SuccBB->getFirstNonPHI()->getIterator();
I != IE; ++I) {
PHINode *PN = cast<PHINode>(I);
- // Only update the first occurence.
+ // Only update the first occurrence.
unsigned Idx = 0, E = PN->getNumIncomingValues();
unsigned LocalNumMergedCases = NumMergedCases;
for (; Idx != E; ++Idx) {
}
}
- // Remove additional occurences coming from condensed cases and keep the
+ // Remove additional occurrences coming from condensed cases and keep the
// number of incoming values equal to the number of branches to SuccBB.
SmallVector<unsigned, 8> Indices;
for (++Idx; LocalNumMergedCases > 0 && Idx < E; ++Idx)
}
}
-// switchConvert - Convert the switch statement into a binary lookup of
-// the case values. The function recursively builds this tree.
-// LowerBound and UpperBound are used to keep track of the bounds for Val
-// that have already been checked by a block emitted by one of the previous
-// calls to switchConvert in the call stack.
+/// Convert the switch statement into a binary lookup of the case values.
+/// The function recursively builds this tree. LowerBound and UpperBound are
+/// used to keep track of the bounds for Val that have already been checked by
+/// a block emitted by one of the previous calls to switchConvert in the call
+/// stack.
BasicBlock *
LowerSwitch::switchConvert(CaseItr Begin, CaseItr End, ConstantInt *LowerBound,
ConstantInt *UpperBound, Value *Val,
UpperBound, Val, NewNode, OrigBlock,
Default, UnreachableRanges);
- Function::iterator FI = OrigBlock;
- F->getBasicBlockList().insert(++FI, NewNode);
+ F->getBasicBlockList().insert(++OrigBlock->getIterator(), NewNode);
NewNode->getInstList().push_back(Comp);
BranchInst::Create(LBranch, RBranch, Comp, NewNode);
return NewNode;
}
-// newLeafBlock - Create a new leaf block for the binary lookup tree. It
-// checks if the switch's value == the case's value. If not, then it
-// jumps to the default branch. At this point in the tree, the value
-// can't be another valid case value, so the jump to the "default" branch
-// is warranted.
-//
+/// Create a new leaf block for the binary lookup tree. It checks if the
+/// switch's value == the case's value. If not, then it jumps to the default
+/// branch. At this point in the tree, the value can't be another valid case
+/// value, so the jump to the "default" branch is warranted.
BasicBlock* LowerSwitch::newLeafBlock(CaseRange& Leaf, Value* Val,
BasicBlock* OrigBlock,
BasicBlock* Default)
{
Function* F = OrigBlock->getParent();
BasicBlock* NewLeaf = BasicBlock::Create(Val->getContext(), "LeafBlock");
- Function::iterator FI = OrigBlock;
- F->getBasicBlockList().insert(++FI, NewLeaf);
+ F->getBasicBlockList().insert(++OrigBlock->getIterator(), NewLeaf);
// Emit comparison
ICmpInst* Comp = nullptr;
return NewLeaf;
}
-// Clusterify - Transform simple list of Cases into list of CaseRange's
+/// Transform simple list of Cases into list of CaseRange's.
unsigned LowerSwitch::Clusterify(CaseVector& Cases, SwitchInst *SI) {
unsigned numCmps = 0;
std::sort(Cases.begin(), Cases.end(), CaseCmp());
// Merge case into clusters
- if (Cases.size()>=2)
- for (CaseItr I = Cases.begin(), J = std::next(Cases.begin());
- J != Cases.end();) {
+ if (Cases.size() >= 2) {
+ CaseItr I = Cases.begin();
+ for (CaseItr J = std::next(I), E = Cases.end(); J != E; ++J) {
int64_t nextValue = J->Low->getSExtValue();
int64_t currentValue = I->High->getSExtValue();
BasicBlock* nextBB = J->BB;
assert(nextValue > currentValue && "Cases should be strictly ascending");
if ((nextValue == currentValue + 1) && (currentBB == nextBB)) {
I->High = J->High;
- J = Cases.erase(J);
- } else {
- I = J++;
+ // FIXME: Combine branch weights.
+ } else if (++I != J) {
+ *I = *J;
}
}
+ Cases.erase(std::next(I), Cases.end());
+ }
for (CaseItr I=Cases.begin(), E=Cases.end(); I!=E; ++I, ++numCmps) {
if (I->Low != I->High)
return numCmps;
}
-// processSwitchInst - Replace the specified switch instruction with a sequence
-// of chained if-then insts in a balanced binary search.
-//
-void LowerSwitch::processSwitchInst(SwitchInst *SI) {
+/// Replace the specified switch instruction with a sequence of chained if-then
+/// insts in a balanced binary search.
+void LowerSwitch::processSwitchInst(SwitchInst *SI,
+ SmallPtrSetImpl<BasicBlock*> &DeleteList) {
BasicBlock *CurBlock = SI->getParent();
BasicBlock *OrigBlock = CurBlock;
Function *F = CurBlock->getParent();
std::vector<IntRange> UnreachableRanges;
if (isa<UnreachableInst>(Default->getFirstNonPHIOrDbg())) {
- // Make the bounds tightly fitted around the case value range, becase we
+ // Make the bounds tightly fitted around the case value range, because we
// know that the value passed to the switch must be exactly one of the case
// values.
assert(!Cases.empty());
// cases.
assert(MaxPop > 0 && PopSucc);
Default = PopSucc;
- for (CaseItr I = Cases.begin(); I != Cases.end();) {
- if (I->BB == PopSucc)
- I = Cases.erase(I);
- else
- ++I;
- }
+ Cases.erase(std::remove_if(
+ Cases.begin(), Cases.end(),
+ [PopSucc](const CaseRange &R) { return R.BB == PopSucc; }),
+ Cases.end());
// If there are no cases left, just branch.
if (Cases.empty()) {
// Create a new, empty default block so that the new hierarchy of
// if-then statements go to this and the PHI nodes are happy.
BasicBlock *NewDefault = BasicBlock::Create(SI->getContext(), "NewDefault");
- F->getBasicBlockList().insert(Default, NewDefault);
+ F->getBasicBlockList().insert(Default->getIterator(), NewDefault);
BranchInst::Create(Default, NewDefault);
// If there is an entry in any PHI nodes for the default edge, make sure
BasicBlock *OldDefault = SI->getDefaultDest();
CurBlock->getInstList().erase(SI);
- // If the Default block has no more predecessors just remove it.
+ // If the Default block has no more predecessors just add it to DeleteList.
if (pred_begin(OldDefault) == pred_end(OldDefault))
- DeleteDeadBlock(OldDefault);
+ DeleteList.insert(OldDefault);
}
projects / oota-llvm.git / blobdiff