/// function, updating the CFG.
void BranchFolder::RemoveDeadBlock(MachineBasicBlock *MBB) {
assert(MBB->pred_empty() && "MBB must be dead!");
- DEBUG(errs() << "\nRemoving MBB: " << *MBB);
+ DEBUG(dbgs() << "\nRemoving MBB: " << *MBB);
MachineFunction *MF = MBB->getParent();
// drop all successors.
// See if any jump tables have become mergable or dead as the code generator
// did its thing.
MachineJumpTableInfo *JTI = MF.getJumpTableInfo();
+ if (JTI == 0) {
+ delete RS;
+ return MadeChange;
+ }
+
const std::vector<MachineJumpTableEntry> &JTs = JTI->getJumpTables();
- if (!JTs.empty()) {
- // Figure out how these jump tables should be merged.
- std::vector<unsigned> JTMapping;
- JTMapping.reserve(JTs.size());
-
- // We always keep the 0th jump table.
- JTMapping.push_back(0);
-
- // Scan the jump tables, seeing if there are any duplicates. Note that this
- // is N^2, which should be fixed someday.
- for (unsigned i = 1, e = JTs.size(); i != e; ++i) {
- if (JTs[i].MBBs.empty())
- JTMapping.push_back(i);
- else
- JTMapping.push_back(JTI->getJumpTableIndex(JTs[i].MBBs));
- }
-
- // If a jump table was merge with another one, walk the function rewriting
- // references to jump tables to reference the new JT ID's. Keep track of
- // whether we see a jump table idx, if not, we can delete the JT.
- BitVector JTIsLive(JTs.size());
- for (MachineFunction::iterator BB = MF.begin(), E = MF.end();
- BB != E; ++BB) {
- for (MachineBasicBlock::iterator I = BB->begin(), E = BB->end();
- I != E; ++I)
- for (unsigned op = 0, e = I->getNumOperands(); op != e; ++op) {
- MachineOperand &Op = I->getOperand(op);
- if (!Op.isJTI()) continue;
- unsigned NewIdx = JTMapping[Op.getIndex()];
- Op.setIndex(NewIdx);
-
- // Remember that this JT is live.
- JTIsLive.set(NewIdx);
- }
- }
+ // Figure out how these jump tables should be merged.
+ std::vector<unsigned> JTMapping;
+ JTMapping.reserve(JTs.size());
+
+ // We always keep the 0th jump table.
+ JTMapping.push_back(0);
+
+ // Scan the jump tables, seeing if there are any duplicates. Note that this
+ // is N^2, which should be fixed someday.
+ for (unsigned i = 1, e = JTs.size(); i != e; ++i) {
+ if (JTs[i].MBBs.empty())
+ JTMapping.push_back(i);
+ else
+ JTMapping.push_back(JTI->getJumpTableIndex(JTs[i].MBBs));
+ }
- // Finally, remove dead jump tables. This happens either because the
- // indirect jump was unreachable (and thus deleted) or because the jump
- // table was merged with some other one.
- for (unsigned i = 0, e = JTIsLive.size(); i != e; ++i)
- if (!JTIsLive.test(i)) {
- JTI->RemoveJumpTable(i);
- MadeChange = true;
+ // If a jump table was merge with another one, walk the function rewriting
+ // references to jump tables to reference the new JT ID's. Keep track of
+ // whether we see a jump table idx, if not, we can delete the JT.
+ BitVector JTIsLive(JTs.size());
+ for (MachineFunction::iterator BB = MF.begin(), E = MF.end();
+ BB != E; ++BB) {
+ for (MachineBasicBlock::iterator I = BB->begin(), E = BB->end();
+ I != E; ++I)
+ for (unsigned op = 0, e = I->getNumOperands(); op != e; ++op) {
+ MachineOperand &Op = I->getOperand(op);
+ if (!Op.isJTI()) continue;
+ unsigned NewIdx = JTMapping[Op.getIndex()];
+ Op.setIndex(NewIdx);
+
+ // Remember that this JT is live.
+ JTIsLive.set(NewIdx);
}
}
+ // Finally, remove dead jump tables. This happens either because the
+ // indirect jump was unreachable (and thus deleted) or because the jump
+ // table was merged with some other one.
+ for (unsigned i = 0, e = JTIsLive.size(); i != e; ++i)
+ if (!JTIsLive.test(i)) {
+ JTI->RemoveJumpTable(i);
+ MadeChange = true;
+ }
+
delete RS;
return MadeChange;
}
SameTails[commonTailIndex].getTailStartPos();
MachineBasicBlock *MBB = SameTails[commonTailIndex].getBlock();
- DEBUG(errs() << "\nSplitting BB#" << MBB->getNumber() << ", size "
+ DEBUG(dbgs() << "\nSplitting BB#" << MBB->getNumber() << ", size "
<< maxCommonTailLength);
MachineBasicBlock *newMBB = SplitMBBAt(*MBB, BBI);
// this many instructions in common.
unsigned minCommonTailLength = TailMergeSize;
- DEBUG(errs() << "\nTryTailMergeBlocks: ";
+ DEBUG(dbgs() << "\nTryTailMergeBlocks: ";
for (unsigned i = 0, e = MergePotentials.size(); i != e; ++i)
- errs() << "BB#" << MergePotentials[i].getBlock()->getNumber()
+ dbgs() << "BB#" << MergePotentials[i].getBlock()->getNumber()
<< (i == e-1 ? "" : ", ");
- errs() << "\n";
+ dbgs() << "\n";
if (SuccBB) {
- errs() << " with successor BB#" << SuccBB->getNumber() << '\n';
+ dbgs() << " with successor BB#" << SuccBB->getNumber() << '\n';
if (PredBB)
- errs() << " which has fall-through from BB#"
+ dbgs() << " which has fall-through from BB#"
<< PredBB->getNumber() << "\n";
}
- errs() << "Looking for common tails of at least "
+ dbgs() << "Looking for common tails of at least "
<< minCommonTailLength << " instruction"
<< (minCommonTailLength == 1 ? "" : "s") << '\n';
);
MachineBasicBlock *MBB = SameTails[commonTailIndex].getBlock();
// MBB is common tail. Adjust all other BB's to jump to this one.
// Traversal must be forwards so erases work.
- DEBUG(errs() << "\nUsing common tail in BB#" << MBB->getNumber()
+ DEBUG(dbgs() << "\nUsing common tail in BB#" << MBB->getNumber()
<< " for ");
for (unsigned int i=0, e = SameTails.size(); i != e; ++i) {
if (commonTailIndex == i)
continue;
- DEBUG(errs() << "BB#" << SameTails[i].getBlock()->getNumber()
+ DEBUG(dbgs() << "BB#" << SameTails[i].getBlock()->getNumber()
<< (i == e-1 ? "" : ", "));
// Hack the end off BB i, making it jump to BB commonTailIndex instead.
ReplaceTailWithBranchTo(SameTails[i].getTailStartPos(), MBB);
// BB i is no longer a predecessor of SuccBB; remove it from the worklist.
MergePotentials.erase(SameTails[i].getMPIter());
}
- DEBUG(errs() << "\n");
+ DEBUG(dbgs() << "\n");
// We leave commonTailIndex in the worklist in case there are other blocks
// that match it with a smaller number of instructions.
MadeChange = true;
}
// If MBB was the target of a jump table, update jump tables to go to the
// fallthrough instead.
- MF.getJumpTableInfo()->ReplaceMBBInJumpTables(MBB, FallThrough);
+ if (MachineJumpTableInfo *MJTI = MF.getJumpTableInfo())
+ MJTI->ReplaceMBBInJumpTables(MBB, FallThrough);
MadeChange = true;
}
return MadeChange;
if (PriorCond.empty() && !PriorTBB && MBB->pred_size() == 1 &&
PrevBB.succ_size() == 1 &&
!MBB->hasAddressTaken()) {
- DEBUG(errs() << "\nMerging into block: " << PrevBB
+ DEBUG(dbgs() << "\nMerging into block: " << PrevBB
<< "From MBB: " << *MBB);
PrevBB.splice(PrevBB.end(), MBB, MBB->begin(), MBB->end());
PrevBB.removeSuccessor(PrevBB.succ_begin());;
// Reverse the branch so we will fall through on the previous true cond.
SmallVector<MachineOperand, 4> NewPriorCond(PriorCond);
if (!TII->ReverseBranchCondition(NewPriorCond)) {
- DEBUG(errs() << "\nMoving MBB: " << *MBB
+ DEBUG(dbgs() << "\nMoving MBB: " << *MBB
<< "To make fallthrough to: " << *PriorTBB << "\n");
TII->RemoveBranch(PrevBB);
}
// Change any jumptables to go to the new MBB.
- MF.getJumpTableInfo()->ReplaceMBBInJumpTables(MBB, CurTBB);
+ if (MachineJumpTableInfo *MJTI = MF.getJumpTableInfo())
+ MJTI->ReplaceMBBInJumpTables(MBB, CurTBB);
if (DidChange) {
++NumBranchOpts;
MadeChange = true;
// Analyze the branch at the end of the pred.
MachineBasicBlock *PredBB = *PI;
MachineFunction::iterator PredFallthrough = PredBB; ++PredFallthrough;
- MachineBasicBlock *PredTBB, *PredFBB;
+ MachineBasicBlock *PredTBB = 0, *PredFBB = 0;
SmallVector<MachineOperand, 4> PredCond;
if (PredBB != MBB && !PredBB->canFallThrough() &&
!TII->AnalyzeBranch(*PredBB, PredTBB, PredFBB, PredCond, true)
// Okay, there is no really great place to put this block. If, however,
// the block before this one would be a fall-through if this block were
// removed, move this block to the end of the function.
- MachineBasicBlock *PrevTBB, *PrevFBB;
+ MachineBasicBlock *PrevTBB = 0, *PrevFBB = 0;
SmallVector<MachineOperand, 4> PrevCond;
if (FallThrough != MF.end() &&
!TII->AnalyzeBranch(PrevBB, PrevTBB, PrevFBB, PrevCond, true) &&
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