/// IfcvtToken - Record information about pending if-conversions to attemp:
/// BBI - Corresponding BBInfo.
/// Kind - Type of block. See IfcvtKind.
- /// NeedSubsumsion - True if the to be predicated BB has already been
+ /// NeedSubsumption - True if the to-be-predicated BB has already been
/// predicated.
/// NumDups - Number of instructions that would be duplicated due
/// to this if-conversion. (For diamonds, the number of
struct IfcvtToken {
BBInfo &BBI;
IfcvtKind Kind;
- bool NeedSubsumsion;
+ bool NeedSubsumption;
unsigned NumDups;
unsigned NumDups2;
IfcvtToken(BBInfo &b, IfcvtKind k, bool s, unsigned d, unsigned d2 = 0)
- : BBI(b), Kind(k), NeedSubsumsion(s), NumDups(d), NumDups2(d2) {}
+ : BBI(b), Kind(k), NeedSubsumption(s), NumDups(d), NumDups2(d2) {}
};
/// Roots - Basic blocks that do not have successors. These are the starting
const TargetLowering *TLI;
const TargetInstrInfo *TII;
bool MadeChange;
+ int FnNum;
public:
static char ID;
- IfConverter() : MachineFunctionPass(&ID) {}
+ IfConverter() : MachineFunctionPass(&ID), FnNum(-1) {}
virtual bool runOnMachineFunction(MachineFunction &MF);
virtual const char *getPassName() const { return "If Converter"; }
if (Incr1 > Incr2)
return true;
else if (Incr1 == Incr2) {
- // Favors subsumsion.
- if (C1->NeedSubsumsion == false && C2->NeedSubsumsion == true)
+ // Favors subsumption.
+ if (C1->NeedSubsumption == false && C2->NeedSubsumption == true)
return true;
- else if (C1->NeedSubsumsion == C2->NeedSubsumsion) {
+ else if (C1->NeedSubsumption == C2->NeedSubsumption) {
// Favors diamond over triangle, etc.
if ((unsigned)C1->Kind < (unsigned)C2->Kind)
return true;
TII = MF.getTarget().getInstrInfo();
if (!TII) return false;
- static int FnNum = -1;
DOUT << "\nIfcvt: function (" << ++FnNum << ") \'"
<< MF.getFunction()->getName() << "\'";
unsigned NumIfCvts = NumSimple + NumSimpleFalse + NumTriangle +
NumTriangleRev + NumTriangleFalse + NumTriangleFRev + NumDiamonds;
while (IfCvtLimit == -1 || (int)NumIfCvts < IfCvtLimit) {
- // Do an intial analysis for each basic block and finding all the potential
- // candidates to perform if-convesion.
+ // Do an initial analysis for each basic block and find all the potential
+ // candidates to perform if-conversion.
bool Change = AnalyzeBlocks(MF, Tokens);
while (!Tokens.empty()) {
IfcvtToken *Token = Tokens.back();
}
/// ReverseBranchCondition - Reverse the condition of the end of the block
-/// branchs. Swap block's 'true' and 'false' successors.
+/// branch. Swap block's 'true' and 'false' successors.
bool IfConverter::ReverseBranchCondition(BBInfo &BBI) {
if (!TII->ReverseBranchCondition(BBI.BrCond)) {
TII->RemoveBranch(*BBI.BB);
unsigned Size = TrueBBI.NonPredSize;
if (TrueBBI.IsBrAnalyzable) {
if (TrueBBI.TrueBB && TrueBBI.BrCond.empty())
- // End with an unconditional branch. It will be removed.
+ // Ends with an unconditional branch. It will be removed.
--Size;
else {
MachineBasicBlock *FExit = FalseBranch
// fallthrough.
if (!BBI.FalseBB)
BBI.FalseBB = findFalseBlock(BBI.BB, BBI.TrueBB);
- assert(BBI.FalseBB && "Expected to find the fallthrough block!");
+ if (!BBI.FalseBB) {
+ // Malformed bcc? True and false blocks are the same?
+ BBI.IsUnpredicable = true;
+ return;
+ }
}
// Then scan all the instructions.
BBI.NonPredSize = 0;
BBI.ClobbersPred = false;
- bool SeenCondBr = false;
for (MachineBasicBlock::iterator I = BBI.BB->begin(), E = BBI.BB->end();
I != E; ++I) {
const TargetInstrDesc &TID = I->getDesc();
BBI.IsUnpredicable = true;
return;
}
-
}
if (BBI.ClobbersPred && !isPredicated) {
// Predicate modification instruction should end the block (except for
// already predicated instructions and end of block branches).
if (isCondBr) {
- SeenCondBr = true;
-
- // Conditional branches is not predicable. But it may be eliminated.
+ // A conditional branch is not predicable, but it may be eliminated.
continue;
}
if (!isTriangle)
return false;
- // Test predicate subsumsion.
+ // Test predicate subsumption.
SmallVector<MachineOperand, 4> RevPred(Pred.begin(), Pred.end());
SmallVector<MachineOperand, 4> Cond(BBI.BrCond.begin(), BBI.BrCond.end());
if (RevBranch) {
ScanInstructions(BBI);
- // Unanalyable or ends with fallthrough or unconditional branch.
+ // Unanalyzable or ends with fallthrough or unconditional branch.
if (!BBI.IsBrAnalyzable || BBI.BrCond.empty()) {
BBI.IsBeingAnalyzed = false;
BBI.IsAnalyzed = true;
return BBI;
}
+ // Do not ifcvt if true and false fallthrough blocks are the same.
+ if (!BBI.FalseBB) {
+ BBI.IsBeingAnalyzed = false;
+ BBI.IsAnalyzed = true;
+ return BBI;
+ }
+
BBInfo &TrueBBI = AnalyzeBlock(BBI.TrueBB, Tokens);
BBInfo &FalseBBI = AnalyzeBlock(BBI.FalseBB, Tokens);
if (CvtBBI->BB->pred_size() > 1) {
BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
- // Copy instructions in the true block, predicate them add them to
+ // Copy instructions in the true block, predicate them, and add them to
// the entry block.
CopyAndPredicateBlock(BBI, *CvtBBI, Cond);
} else {
bool DupBB = CvtBBI->BB->pred_size() > 1;
if (DupBB) {
BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
- // Copy instructions in the true block, predicate them add them to
+ // Copy instructions in the true block, predicate them, and add them to
// the entry block.
CopyAndPredicateBlock(BBI, *CvtBBI, Cond, true);
} else {
// Predicate the 'true' block after removing its branch.
CvtBBI->NonPredSize -= TII->RemoveBranch(*CvtBBI->BB);
PredicateBlock(*CvtBBI, CvtBBI->BB->end(), Cond);
- }
- if (!DupBB) {
// Now merge the entry of the triangle with the true block.
BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
MergeBlocks(BBI, *CvtBBI);
}
// Merge in the 'false' block if the 'false' block has no other
- // predecessors. Otherwise, add a unconditional branch from to 'false'.
+ // predecessors. Otherwise, add an unconditional branch to 'false'.
bool FalseBBDead = false;
bool IterIfcvt = true;
bool isFallThrough = canFallThroughTo(BBI.BB, NextBBI->BB);
BBInfo &TrueBBI = BBAnalysis[BBI.TrueBB->getNumber()];
BBInfo &FalseBBI = BBAnalysis[BBI.FalseBB->getNumber()];
MachineBasicBlock *TailBB = TrueBBI.TrueBB;
- // True block must fall through or ended with unanalyzable terminator.
+ // True block must fall through or end with an unanalyzable terminator.
if (!TailBB) {
if (blockAlwaysFallThrough(TrueBBI))
TailBB = FalseBBI.TrueBB;
MergeBlocks(BBI, *BBI1);
MergeBlocks(BBI, *BBI2);
- // If the if-converted block fallthrough or unconditionally branch into the
- // tail block, and the tail block does not have other predecessors, then
+ // If the if-converted block falls through or unconditionally branches into
+ // the tail block, and the tail block does not have other predecessors, then
// fold the tail block in as well. Otherwise, unless it falls through to the
// tail, add a unconditional branch to it.
if (TailBB) {
// Fallthrough edge can't be transferred.
if (Succ == FallThrough)
continue;
- if (!ToBBI.BB->isSuccessor(Succ))
- ToBBI.BB->addSuccessor(Succ);
+ ToBBI.BB->addSuccessor(Succ);
}
std::copy(FromBBI.Predicate.begin(), FromBBI.Predicate.end(),
if (Succ == FallThrough)
continue;
FromBBI.BB->removeSuccessor(Succ);
- if (!ToBBI.BB->isSuccessor(Succ))
- ToBBI.BB->addSuccessor(Succ);
+ ToBBI.BB->addSuccessor(Succ);
}
- // Now FromBBI always fall through to the next block!
+ // Now FromBBI always falls through to the next block!
if (NBB && !FromBBI.BB->isSuccessor(NBB))
FromBBI.BB->addSuccessor(NBB);
projects / oota-llvm.git / blobdiff