From 4e3f125e184f96ae72f2c44d16cafe0d44158283 Mon Sep 17 00:00:00 2001 From: Dan Gohman Date: Wed, 11 Nov 2009 18:38:14 +0000 Subject: [PATCH] Whitespace cleanups. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86855 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/BranchFolding.cpp | 185 +++++++++++++++++----------------- 1 file changed, 92 insertions(+), 93 deletions(-) diff --git a/lib/CodeGen/BranchFolding.cpp b/lib/CodeGen/BranchFolding.cpp index c3b2b80787e..a91fc1ecf5a 100644 --- a/lib/CodeGen/BranchFolding.cpp +++ b/lib/CodeGen/BranchFolding.cpp @@ -40,18 +40,18 @@ using namespace llvm; STATISTIC(NumDeadBlocks, "Number of dead blocks removed"); STATISTIC(NumBranchOpts, "Number of branches optimized"); STATISTIC(NumTailMerge , "Number of block tails merged"); -static cl::opt FlagEnableTailMerge("enable-tail-merge", +static cl::opt FlagEnableTailMerge("enable-tail-merge", cl::init(cl::BOU_UNSET), cl::Hidden); // Throttle for huge numbers of predecessors (compile speed problems) static cl::opt -TailMergeThreshold("tail-merge-threshold", +TailMergeThreshold("tail-merge-threshold", cl::desc("Max number of predecessors to consider tail merging"), cl::init(150), cl::Hidden); char BranchFolderPass::ID = 0; -FunctionPass *llvm::createBranchFoldingPass(bool DefaultEnableTailMerge) { +FunctionPass *llvm::createBranchFoldingPass(bool DefaultEnableTailMerge) { return new BranchFolderPass(DefaultEnableTailMerge); } @@ -63,7 +63,6 @@ bool BranchFolderPass::runOnMachineFunction(MachineFunction &MF) { } - BranchFolder::BranchFolder(bool defaultEnableTailMerge) { switch (FlagEnableTailMerge) { case cl::BOU_UNSET: EnableTailMerge = defaultEnableTailMerge; break; @@ -77,12 +76,12 @@ BranchFolder::BranchFolder(bool defaultEnableTailMerge) { void BranchFolder::RemoveDeadBlock(MachineBasicBlock *MBB) { assert(MBB->pred_empty() && "MBB must be dead!"); DEBUG(errs() << "\nRemoving MBB: " << *MBB); - + MachineFunction *MF = MBB->getParent(); // drop all successors. while (!MBB->succ_empty()) MBB->removeSuccessor(MBB->succ_end()-1); - + // If there are any labels in the basic block, unregister them from // MachineModuleInfo. if (MMI && !MBB->empty()) { @@ -93,7 +92,7 @@ void BranchFolder::RemoveDeadBlock(MachineBasicBlock *MBB) { MMI->InvalidateLabel(I->getOperand(0).getImm()); } } - + // Remove the block. MF->erase(MBB); } @@ -190,7 +189,7 @@ bool BranchFolder::OptimizeFunction(MachineFunction &MF, // Figure out how these jump tables should be merged. std::vector JTMapping; JTMapping.reserve(JTs.size()); - + // We always keep the 0th jump table. JTMapping.push_back(0); @@ -202,7 +201,7 @@ bool BranchFolder::OptimizeFunction(MachineFunction &MF, 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. @@ -221,7 +220,7 @@ bool BranchFolder::OptimizeFunction(MachineFunction &MF, 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. @@ -245,7 +244,7 @@ static unsigned HashMachineInstr(const MachineInstr *MI) { unsigned Hash = MI->getOpcode(); for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { const MachineOperand &Op = MI->getOperand(i); - + // Merge in bits from the operand if easy. unsigned OperandHash = 0; switch (Op.getType()) { @@ -267,31 +266,30 @@ static unsigned HashMachineInstr(const MachineInstr *MI) { break; default: break; } - + Hash += ((OperandHash << 3) | Op.getType()) << (i&31); } return Hash; } /// HashEndOfMBB - Hash the last few instructions in the MBB. For blocks -/// with no successors, we hash two instructions, because cross-jumping -/// only saves code when at least two instructions are removed (since a +/// with no successors, we hash two instructions, because cross-jumping +/// only saves code when at least two instructions are removed (since a /// branch must be inserted). For blocks with a successor, one of the /// two blocks to be tail-merged will end with a branch already, so /// it gains to cross-jump even for one instruction. - static unsigned HashEndOfMBB(const MachineBasicBlock *MBB, unsigned minCommonTailLength) { MachineBasicBlock::const_iterator I = MBB->end(); if (I == MBB->begin()) return 0; // Empty MBB. - + --I; unsigned Hash = HashMachineInstr(I); - + if (I == MBB->begin() || minCommonTailLength == 1) return Hash; // Single instr MBB. - + --I; // Hash in the second-to-last instruction. Hash ^= HashMachineInstr(I) << 2; @@ -307,11 +305,11 @@ static unsigned ComputeCommonTailLength(MachineBasicBlock *MBB1, MachineBasicBlock::iterator &I2) { I1 = MBB1->end(); I2 = MBB2->end(); - + unsigned TailLen = 0; while (I1 != MBB1->begin() && I2 != MBB2->begin()) { --I1; --I2; - if (!I1->isIdenticalTo(I2) || + if (!I1->isIdenticalTo(I2) || // FIXME: This check is dubious. It's used to get around a problem where // people incorrectly expect inline asm directives to remain in the same // relative order. This is untenable because normal compiler @@ -332,11 +330,11 @@ static unsigned ComputeCommonTailLength(MachineBasicBlock *MBB1, void BranchFolder::ReplaceTailWithBranchTo(MachineBasicBlock::iterator OldInst, MachineBasicBlock *NewDest) { MachineBasicBlock *OldBB = OldInst->getParent(); - + // Remove all the old successors of OldBB from the CFG. while (!OldBB->succ_empty()) OldBB->removeSuccessor(OldBB->succ_begin()); - + // Remove all the dead instructions from the end of OldBB. OldBB->erase(OldInst, OldBB->end()); @@ -361,10 +359,10 @@ MachineBasicBlock *BranchFolder::SplitMBBAt(MachineBasicBlock &CurMBB, // Move all the successors of this block to the specified block. NewMBB->transferSuccessors(&CurMBB); - + // Add an edge from CurMBB to NewMBB for the fall-through. CurMBB.addSuccessor(NewMBB); - + // Splice the code over. NewMBB->splice(NewMBB->end(), &CurMBB, BBI1, CurMBB.end()); @@ -404,7 +402,6 @@ static unsigned EstimateRuntime(MachineBasicBlock::iterator I, // branches temporarily for tail merging). In the case where CurMBB ends // with a conditional branch to the next block, optimize by reversing the // test and conditionally branching to SuccMBB instead. - static void FixTail(MachineBasicBlock* CurMBB, MachineBasicBlock *SuccBB, const TargetInstrInfo *TII) { MachineFunction *MF = CurMBB->getParent(); @@ -476,26 +473,26 @@ static bool ProfitableToMerge(MachineBasicBlock *MBB1, } /// ComputeSameTails - Look through all the blocks in MergePotentials that have -/// hash CurHash (guaranteed to match the last element). Build the vector +/// hash CurHash (guaranteed to match the last element). Build the vector /// SameTails of all those that have the (same) largest number of instructions /// in common of any pair of these blocks. SameTails entries contain an -/// iterator into MergePotentials (from which the MachineBasicBlock can be -/// found) and a MachineBasicBlock::iterator into that MBB indicating the +/// iterator into MergePotentials (from which the MachineBasicBlock can be +/// found) and a MachineBasicBlock::iterator into that MBB indicating the /// instruction where the matching code sequence begins. /// Order of elements in SameTails is the reverse of the order in which /// those blocks appear in MergePotentials (where they are not necessarily /// consecutive). -unsigned BranchFolder::ComputeSameTails(unsigned CurHash, +unsigned BranchFolder::ComputeSameTails(unsigned CurHash, unsigned minCommonTailLength) { unsigned maxCommonTailLength = 0U; SameTails.clear(); MachineBasicBlock::iterator TrialBBI1, TrialBBI2; MPIterator HighestMPIter = prior(MergePotentials.end()); for (MPIterator CurMPIter = prior(MergePotentials.end()), - B = MergePotentials.begin(); - CurMPIter!=B && CurMPIter->first==CurHash; + B = MergePotentials.begin(); + CurMPIter!=B && CurMPIter->first == CurHash; --CurMPIter) { - for (MPIterator I = prior(CurMPIter); I->first==CurHash ; --I) { + for (MPIterator I = prior(CurMPIter); I->first == CurHash ; --I) { unsigned CommonTailLen; if (ProfitableToMerge(CurMPIter->second, I->second, minCommonTailLength, CommonTailLen, TrialBBI1, TrialBBI2)) { @@ -509,7 +506,7 @@ unsigned BranchFolder::ComputeSameTails(unsigned CurHash, CommonTailLen == maxCommonTailLength) SameTails.push_back(std::make_pair(I, TrialBBI2)); } - if (I==B) + if (I == B) break; } } @@ -518,18 +515,18 @@ unsigned BranchFolder::ComputeSameTails(unsigned CurHash, /// RemoveBlocksWithHash - Remove all blocks with hash CurHash from /// MergePotentials, restoring branches at ends of blocks as appropriate. -void BranchFolder::RemoveBlocksWithHash(unsigned CurHash, +void BranchFolder::RemoveBlocksWithHash(unsigned CurHash, MachineBasicBlock* SuccBB, MachineBasicBlock* PredBB) { MPIterator CurMPIter, B; - for (CurMPIter = prior(MergePotentials.end()), B = MergePotentials.begin(); - CurMPIter->first==CurHash; + for (CurMPIter = prior(MergePotentials.end()), B = MergePotentials.begin(); + CurMPIter->first == CurHash; --CurMPIter) { // Put the unconditional branch back, if we need one. MachineBasicBlock *CurMBB = CurMPIter->second; if (SuccBB && CurMBB != PredBB) FixTail(CurMBB, SuccBB, TII); - if (CurMPIter==B) + if (CurMPIter == B) break; } if (CurMPIter->first!=CurHash) @@ -545,15 +542,15 @@ unsigned BranchFolder::CreateCommonTailOnlyBlock(MachineBasicBlock *&PredBB, unsigned TimeEstimate = ~0U; for (i=0, commonTailIndex=0; isecond==PredBB) { + if (SameTails[i].first->second == PredBB) { commonTailIndex = i; break; } // Otherwise, make a (fairly bogus) choice based on estimate of // how long it will take the various blocks to execute. - unsigned t = EstimateRuntime(SameTails[i].first->second->begin(), + unsigned t = EstimateRuntime(SameTails[i].first->second->begin(), SameTails[i].second); - if (t<=TimeEstimate) { + if (t <= TimeEstimate) { TimeEstimate = t; commonTailIndex = i; } @@ -568,8 +565,9 @@ unsigned BranchFolder::CreateCommonTailOnlyBlock(MachineBasicBlock *&PredBB, MachineBasicBlock *newMBB = SplitMBBAt(*MBB, BBI); SameTails[commonTailIndex].first->second = newMBB; SameTails[commonTailIndex].second = newMBB->begin(); + // If we split PredBB, newMBB is the new predecessor. - if (PredBB==MBB) + if (PredBB == MBB) PredBB = newMBB; return commonTailIndex; @@ -579,7 +577,7 @@ unsigned BranchFolder::CreateCommonTailOnlyBlock(MachineBasicBlock *&PredBB, // successor, or all have no successor) can be tail-merged. If there is a // successor, any blocks in MergePotentials that are not tail-merged and // are not immediately before Succ must have an unconditional branch to -// Succ added (but the predecessor/successor lists need no adjustment). +// Succ added (but the predecessor/successor lists need no adjustment). // The lone predecessor of Succ that falls through into Succ, // if any, is given in PredBB. @@ -591,7 +589,7 @@ bool BranchFolder::TryMergeBlocks(MachineBasicBlock *SuccBB, // will add a jump. // FIXME: Ask the target to provide the threshold? unsigned minCommonTailLength = (SuccBB ? 1 : 2) + 1; - + DEBUG(errs() << "\nTryMergeBlocks " << MergePotentials.size() << '\n'); // Sort by hash value so that blocks with identical end sequences sort @@ -601,13 +599,13 @@ bool BranchFolder::TryMergeBlocks(MachineBasicBlock *SuccBB, // Walk through equivalence sets looking for actual exact matches. while (MergePotentials.size() > 1) { unsigned CurHash = MergePotentials.back().first; - + // Build SameTails, identifying the set of blocks with this hash code // and with the maximum number of instructions in common. - unsigned maxCommonTailLength = ComputeSameTails(CurHash, + unsigned maxCommonTailLength = ComputeSameTails(CurHash, minCommonTailLength); - // If we didn't find any pair that has at least minCommonTailLength + // If we didn't find any pair that has at least minCommonTailLength // instructions in common, remove all blocks with this hash code and retry. if (SameTails.empty()) { RemoveBlocksWithHash(CurHash, SuccBB, PredBB); @@ -625,12 +623,12 @@ bool BranchFolder::TryMergeBlocks(MachineBasicBlock *SuccBB, MachineBasicBlock *MBB = SameTails[i].first->second; if (MBB->begin() == SameTails[i].second && MBB != EntryBB) { commonTailIndex = i; - if (MBB==PredBB) + if (MBB == PredBB) break; } } - if (commonTailIndex==SameTails.size()) { + if (commonTailIndex == SameTails.size()) { // None of the blocks consist entirely of the common tail. // Split a block so that one does. commonTailIndex = CreateCommonTailOnlyBlock(PredBB, maxCommonTailLength); @@ -641,7 +639,7 @@ bool BranchFolder::TryMergeBlocks(MachineBasicBlock *SuccBB, // Traversal must be forwards so erases work. DEBUG(errs() << "\nUsing common tail BB#" << MBB->getNumber() << " for "); for (unsigned int i=0; isecond->getNumber() << ", "); // Hack the end off BB i, making it jump to BB commonTailIndex instead. @@ -660,7 +658,7 @@ bool BranchFolder::TryMergeBlocks(MachineBasicBlock *SuccBB, bool BranchFolder::TailMergeBlocks(MachineFunction &MF) { if (!EnableTailMerge) return false; - + bool MadeChange = false; // First find blocks with no successors. @@ -669,6 +667,7 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) { if (I->succ_empty()) MergePotentials.push_back(std::make_pair(HashEndOfMBB(I, 2U), I)); } + // See if we can do any tail merging on those. if (MergePotentials.size() < TailMergeThreshold && MergePotentials.size() >= 2) @@ -679,7 +678,7 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) { // (1) temporarily removing any unconditional branch from the predecessor // to IBB, and // (2) alter conditional branches so they branch to the other block - // not IBB; this may require adding back an unconditional branch to IBB + // not IBB; this may require adding back an unconditional branch to IBB // later, where there wasn't one coming in. E.g. // Bcc IBB // fallthrough to QBB @@ -699,12 +698,12 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) { MachineBasicBlock *IBB = I; MachineBasicBlock *PredBB = prior(I); MergePotentials.clear(); - for (MachineBasicBlock::pred_iterator P = I->pred_begin(), + for (MachineBasicBlock::pred_iterator P = I->pred_begin(), E2 = I->pred_end(); P != E2; ++P) { MachineBasicBlock* PBB = *P; // Skip blocks that loop to themselves, can't tail merge these. - if (PBB==IBB) + if (PBB == IBB) continue; // Visit each predecessor only once. if (!UniquePreds.insert(PBB)) @@ -715,7 +714,7 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) { // Failing case: IBB is the target of a cbr, and // we cannot reverse the branch. SmallVector NewCond(Cond); - if (!Cond.empty() && TBB==IBB) { + if (!Cond.empty() && TBB == IBB) { if (TII->ReverseBranchCondition(NewCond)) continue; // This is the QBB case described above @@ -730,7 +729,7 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) { MachineBasicBlock* PredNextBB = NULL; if (IP!=MF.end()) PredNextBB = IP; - if (TBB==NULL) { + if (TBB == NULL) { if (IBB!=PredNextBB) // fallthrough continue; } else if (FBB) { @@ -749,7 +748,7 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) { TII->RemoveBranch(*PBB); if (!Cond.empty()) // reinsert conditional branch only, for now - TII->InsertBranch(*PBB, (TBB==IBB) ? FBB : TBB, 0, NewCond); + TII->InsertBranch(*PBB, (TBB == IBB) ? FBB : TBB, 0, NewCond); } MergePotentials.push_back(std::make_pair(HashEndOfMBB(PBB, 1U), *P)); } @@ -759,7 +758,7 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) { // Reinsert an unconditional branch if needed. // The 1 below can occur as a result of removing blocks in TryMergeBlocks. PredBB = prior(I); // this may have been changed in TryMergeBlocks - if (MergePotentials.size()==1 && + if (MergePotentials.size() == 1 && MergePotentials.begin()->second != PredBB) FixTail(MergePotentials.begin()->second, I, TII); } @@ -773,14 +772,14 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) { bool BranchFolder::OptimizeBranches(MachineFunction &MF) { bool MadeChange = false; - + // Make sure blocks are numbered in order MF.RenumberBlocks(); for (MachineFunction::iterator I = ++MF.begin(), E = MF.end(); I != E; ) { MachineBasicBlock *MBB = I++; MadeChange |= OptimizeBlock(MBB); - + // If it is dead, remove it. if (MBB->pred_empty()) { RemoveDeadBlock(MBB); @@ -801,7 +800,7 @@ bool BranchFolder::OptimizeBranches(MachineFunction &MF) { /// bool BranchFolder::CanFallThrough(MachineBasicBlock *CurBB, bool BranchUnAnalyzable, - MachineBasicBlock *TBB, + MachineBasicBlock *TBB, MachineBasicBlock *FBB, const SmallVectorImpl &Cond) { MachineFunction::iterator Fallthrough = CurBB; @@ -809,14 +808,14 @@ bool BranchFolder::CanFallThrough(MachineBasicBlock *CurBB, // If FallthroughBlock is off the end of the function, it can't fall through. if (Fallthrough == CurBB->getParent()->end()) return false; - + // If FallthroughBlock isn't a successor of CurBB, no fallthrough is possible. if (!CurBB->isSuccessor(Fallthrough)) return false; - + // If we couldn't analyze the branch, assume it could fall through. if (BranchUnAnalyzable) return true; - + // If there is no branch, control always falls through. if (TBB == 0) return true; @@ -825,11 +824,11 @@ bool BranchFolder::CanFallThrough(MachineBasicBlock *CurBB, if (MachineFunction::iterator(TBB) == Fallthrough || MachineFunction::iterator(FBB) == Fallthrough) return true; - - // If it's an unconditional branch to some block not the fall through, it + + // If it's an unconditional branch to some block not the fall through, it // doesn't fall through. if (Cond.empty()) return false; - + // Otherwise, if it is conditional and has no explicit false block, it falls // through. return FBB == 0; @@ -853,14 +852,14 @@ bool BranchFolder::CanFallThrough(MachineBasicBlock *CurBB) { /// fall-through to MBB1 than to fall through into MBB2. This has to return /// a strict ordering, returning true for both (MBB1,MBB2) and (MBB2,MBB1) will /// result in infinite loops. -static bool IsBetterFallthrough(MachineBasicBlock *MBB1, +static bool IsBetterFallthrough(MachineBasicBlock *MBB1, MachineBasicBlock *MBB2) { // Right now, we use a simple heuristic. If MBB2 ends with a call, and // MBB1 doesn't, we prefer to fall through into MBB1. This allows us to // optimize branches that branch to either a return block or an assert block // into a fallthrough to the return. if (MBB1->empty() || MBB2->empty()) return false; - + // If there is a clear successor ordering we make sure that one block // will fall through to the next if (MBB1->isSuccessor(MBB2)) return true; @@ -879,7 +878,7 @@ bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) { MachineFunction::iterator FallThrough = MBB; ++FallThrough; - + // If this block is empty, make everyone use its fall-through, not the block // explicitly. Landing pads should not do this since the landing-pad table // points to this block. Blocks with their addresses taken shouldn't be @@ -887,7 +886,7 @@ bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) { if (MBB->empty() && !MBB->isLandingPad() && !MBB->hasAddressTaken()) { // Dead block? Leave for cleanup later. if (MBB->pred_empty()) return MadeChange; - + if (FallThrough == MF.end()) { // TODO: Simplify preds to not branch here if possible! } else { @@ -917,20 +916,20 @@ bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) { // If the CFG for the prior block has extra edges, remove them. MadeChange |= PrevBB.CorrectExtraCFGEdges(PriorTBB, PriorFBB, !PriorCond.empty()); - + // If the previous branch is conditional and both conditions go to the same // destination, remove the branch, replacing it with an unconditional one or // a fall-through. if (PriorTBB && PriorTBB == PriorFBB) { TII->RemoveBranch(PrevBB); - PriorCond.clear(); + PriorCond.clear(); if (PriorTBB != MBB) TII->InsertBranch(PrevBB, PriorTBB, 0, PriorCond); MadeChange = true; ++NumBranchOpts; return OptimizeBlock(MBB); } - + // If the previous branch *only* branches to *this* block (conditional or // not) remove the branch. if (PriorTBB == MBB && PriorFBB == 0) { @@ -939,7 +938,7 @@ bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) { ++NumBranchOpts; return OptimizeBlock(MBB); } - + // If the prior block branches somewhere else on the condition and here if // the condition is false, remove the uncond second branch. if (PriorFBB == MBB) { @@ -949,7 +948,7 @@ bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) { ++NumBranchOpts; return OptimizeBlock(MBB); } - + // If the prior block branches here on true and somewhere else on false, and // if the branch condition is reversible, reverse the branch to create a // fall-through. @@ -963,7 +962,7 @@ bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) { return OptimizeBlock(MBB); } } - + // If this block has no successors (e.g. it is a return block or ends with // a call to a no-return function like abort or __cxa_throw) and if the pred // falls through into this block, and if it would otherwise fall through @@ -976,7 +975,7 @@ bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) { MachineFunction::iterator(PriorTBB) == FallThrough && !CanFallThrough(MBB)) { bool DoTransform = true; - + // We have to be careful that the succs of PredBB aren't both no-successor // blocks. If neither have successors and if PredBB is the second from // last block in the function, we'd just keep swapping the two blocks for @@ -1000,15 +999,15 @@ bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) { if (DoTransform && !MBB->succ_empty() && (!CanFallThrough(PriorTBB) || PriorTBB->empty())) DoTransform = false; - - + + if (DoTransform) { // Reverse the branch so we will fall through on the previous true cond. SmallVector NewPriorCond(PriorCond); if (!TII->ReverseBranchCondition(NewPriorCond)) { DEBUG(errs() << "\nMoving MBB: " << *MBB << "To make fallthrough to: " << *PriorTBB << "\n"); - + TII->RemoveBranch(PrevBB); TII->InsertBranch(PrevBB, MBB, 0, NewPriorCond); @@ -1021,7 +1020,7 @@ bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) { } } } - + // Analyze the branch in the current block. MachineBasicBlock *CurTBB = 0, *CurFBB = 0; SmallVector CurCond; @@ -1030,7 +1029,7 @@ bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) { // If the CFG for the prior block has extra edges, remove them. MadeChange |= MBB->CorrectExtraCFGEdges(CurTBB, CurFBB, !CurCond.empty()); - // If this is a two-way branch, and the FBB branches to this block, reverse + // If this is a two-way branch, and the FBB branches to this block, reverse // the condition so the single-basic-block loop is faster. Instead of: // Loop: xxx; jcc Out; jmp Loop // we want: @@ -1045,11 +1044,11 @@ bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) { return OptimizeBlock(MBB); } } - - + + // If this branch is the only thing in its block, see if we can forward // other blocks across it. - if (CurTBB && CurCond.empty() && CurFBB == 0 && + if (CurTBB && CurCond.empty() && CurFBB == 0 && MBB->begin()->getDesc().isBranch() && CurTBB != MBB && !MBB->hasAddressTaken()) { // This block may contain just an unconditional branch. Because there can @@ -1068,7 +1067,7 @@ bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) { !PrevBB.isSuccessor(MBB)) { // If the prior block falls through into us, turn it into an // explicit branch to us to make updates simpler. - if (!PredHasNoFallThrough && PrevBB.isSuccessor(MBB) && + if (!PredHasNoFallThrough && PrevBB.isSuccessor(MBB) && PriorTBB != MBB && PriorFBB != MBB) { if (PriorTBB == 0) { assert(PriorCond.empty() && PriorFBB == 0 && @@ -1104,7 +1103,7 @@ bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) { NewCurFBB, NewCurCond, true); if (!NewCurUnAnalyzable && NewCurTBB && NewCurTBB == NewCurFBB) { TII->RemoveBranch(*PMBB); - NewCurCond.clear(); + NewCurCond.clear(); TII->InsertBranch(*PMBB, NewCurTBB, 0, NewCurCond); MadeChange = true; ++NumBranchOpts; @@ -1122,7 +1121,7 @@ bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) { } } } - + // Add the branch back if the block is more than just an uncond branch. TII->InsertBranch(*MBB, CurTBB, 0, CurCond); } @@ -1135,7 +1134,7 @@ bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) { PriorTBB, PriorFBB, PriorCond)) { // Now we know that there was no fall-through into this block, check to // see if it has a fall-through into its successor. - bool CurFallsThru = CanFallThrough(MBB, CurUnAnalyzable, CurTBB, CurFBB, + bool CurFallsThru = CanFallThrough(MBB, CurUnAnalyzable, CurTBB, CurFBB, CurCond); if (!MBB->isLandingPad()) { @@ -1151,7 +1150,7 @@ bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) { && (!CurFallsThru || MBB->getNumber() >= PredBB->getNumber())) { // If the current block doesn't fall through, just move it. // If the current block can fall through and does not end with a - // conditional branch, we need to append an unconditional jump to + // conditional branch, we need to append an unconditional jump to // the (current) next block. To avoid a possible compile-time // infinite loop, move blocks only backward in this case. // Also, if there are already 2 branches here, we cannot add a third; @@ -1170,7 +1169,7 @@ bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) { } } } - + if (!CurFallsThru) { // Check all successors to see if we can move this block before it. for (MachineBasicBlock::succ_iterator SI = MBB->succ_begin(), @@ -1178,7 +1177,7 @@ bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) { // Analyze the branch at the end of the block before the succ. MachineBasicBlock *SuccBB = *SI; MachineFunction::iterator SuccPrev = SuccBB; --SuccPrev; - + // If this block doesn't already fall-through to that successor, and if // the succ doesn't already have a block that can fall through into it, // and if the successor isn't an EH destination, we can arrange for the @@ -1190,7 +1189,7 @@ bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) { return OptimizeBlock(MBB); } } - + // 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. -- 2.34.1