mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2025-01-14 16:33:28 +00:00
Whitespace cleanups.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86855 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman
parent
a127edceae
commit
4e3f125e18
@ -40,18 +40,18 @@ using namespace llvm;
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STATISTIC(NumDeadBlocks, "Number of dead blocks removed");
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STATISTIC(NumBranchOpts, "Number of branches optimized");
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STATISTIC(NumTailMerge , "Number of block tails merged");
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static cl::opt<cl::boolOrDefault> FlagEnableTailMerge("enable-tail-merge",
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static cl::opt<cl::boolOrDefault> FlagEnableTailMerge("enable-tail-merge",
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cl::init(cl::BOU_UNSET), cl::Hidden);
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// Throttle for huge numbers of predecessors (compile speed problems)
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static cl::opt<unsigned>
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TailMergeThreshold("tail-merge-threshold",
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TailMergeThreshold("tail-merge-threshold",
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cl::desc("Max number of predecessors to consider tail merging"),
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cl::init(150), cl::Hidden);
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char BranchFolderPass::ID = 0;
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FunctionPass *llvm::createBranchFoldingPass(bool DefaultEnableTailMerge) {
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FunctionPass *llvm::createBranchFoldingPass(bool DefaultEnableTailMerge) {
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return new BranchFolderPass(DefaultEnableTailMerge);
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}
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@ -63,7 +63,6 @@ bool BranchFolderPass::runOnMachineFunction(MachineFunction &MF) {
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}
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BranchFolder::BranchFolder(bool defaultEnableTailMerge) {
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switch (FlagEnableTailMerge) {
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case cl::BOU_UNSET: EnableTailMerge = defaultEnableTailMerge; break;
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@ -77,12 +76,12 @@ BranchFolder::BranchFolder(bool defaultEnableTailMerge) {
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void BranchFolder::RemoveDeadBlock(MachineBasicBlock *MBB) {
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assert(MBB->pred_empty() && "MBB must be dead!");
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DEBUG(errs() << "\nRemoving MBB: " << *MBB);
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MachineFunction *MF = MBB->getParent();
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// drop all successors.
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while (!MBB->succ_empty())
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MBB->removeSuccessor(MBB->succ_end()-1);
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// If there are any labels in the basic block, unregister them from
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// MachineModuleInfo.
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if (MMI && !MBB->empty()) {
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@ -93,7 +92,7 @@ void BranchFolder::RemoveDeadBlock(MachineBasicBlock *MBB) {
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MMI->InvalidateLabel(I->getOperand(0).getImm());
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}
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}
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// Remove the block.
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MF->erase(MBB);
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}
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@ -190,7 +189,7 @@ bool BranchFolder::OptimizeFunction(MachineFunction &MF,
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// Figure out how these jump tables should be merged.
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std::vector<unsigned> JTMapping;
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JTMapping.reserve(JTs.size());
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// We always keep the 0th jump table.
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JTMapping.push_back(0);
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@ -202,7 +201,7 @@ bool BranchFolder::OptimizeFunction(MachineFunction &MF,
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else
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JTMapping.push_back(JTI->getJumpTableIndex(JTs[i].MBBs));
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}
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// If a jump table was merge with another one, walk the function rewriting
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// references to jump tables to reference the new JT ID's. Keep track of
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// whether we see a jump table idx, if not, we can delete the JT.
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@ -221,7 +220,7 @@ bool BranchFolder::OptimizeFunction(MachineFunction &MF,
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JTIsLive.set(NewIdx);
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}
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}
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// Finally, remove dead jump tables. This happens either because the
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// indirect jump was unreachable (and thus deleted) or because the jump
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// table was merged with some other one.
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@ -245,7 +244,7 @@ static unsigned HashMachineInstr(const MachineInstr *MI) {
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unsigned Hash = MI->getOpcode();
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for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
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const MachineOperand &Op = MI->getOperand(i);
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// Merge in bits from the operand if easy.
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unsigned OperandHash = 0;
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switch (Op.getType()) {
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@ -267,31 +266,30 @@ static unsigned HashMachineInstr(const MachineInstr *MI) {
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break;
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default: break;
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}
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Hash += ((OperandHash << 3) | Op.getType()) << (i&31);
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}
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return Hash;
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}
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/// HashEndOfMBB - Hash the last few instructions in the MBB. For blocks
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/// with no successors, we hash two instructions, because cross-jumping
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/// only saves code when at least two instructions are removed (since a
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/// with no successors, we hash two instructions, because cross-jumping
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/// only saves code when at least two instructions are removed (since a
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/// branch must be inserted). For blocks with a successor, one of the
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/// two blocks to be tail-merged will end with a branch already, so
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/// it gains to cross-jump even for one instruction.
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static unsigned HashEndOfMBB(const MachineBasicBlock *MBB,
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unsigned minCommonTailLength) {
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MachineBasicBlock::const_iterator I = MBB->end();
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if (I == MBB->begin())
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return 0; // Empty MBB.
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--I;
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unsigned Hash = HashMachineInstr(I);
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if (I == MBB->begin() || minCommonTailLength == 1)
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return Hash; // Single instr MBB.
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--I;
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// Hash in the second-to-last instruction.
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Hash ^= HashMachineInstr(I) << 2;
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@ -307,11 +305,11 @@ static unsigned ComputeCommonTailLength(MachineBasicBlock *MBB1,
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MachineBasicBlock::iterator &I2) {
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I1 = MBB1->end();
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I2 = MBB2->end();
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unsigned TailLen = 0;
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while (I1 != MBB1->begin() && I2 != MBB2->begin()) {
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--I1; --I2;
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if (!I1->isIdenticalTo(I2) ||
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if (!I1->isIdenticalTo(I2) ||
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// FIXME: This check is dubious. It's used to get around a problem where
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// people incorrectly expect inline asm directives to remain in the same
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// relative order. This is untenable because normal compiler
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@ -332,11 +330,11 @@ static unsigned ComputeCommonTailLength(MachineBasicBlock *MBB1,
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void BranchFolder::ReplaceTailWithBranchTo(MachineBasicBlock::iterator OldInst,
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MachineBasicBlock *NewDest) {
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MachineBasicBlock *OldBB = OldInst->getParent();
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// Remove all the old successors of OldBB from the CFG.
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while (!OldBB->succ_empty())
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OldBB->removeSuccessor(OldBB->succ_begin());
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// Remove all the dead instructions from the end of OldBB.
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OldBB->erase(OldInst, OldBB->end());
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@ -361,10 +359,10 @@ MachineBasicBlock *BranchFolder::SplitMBBAt(MachineBasicBlock &CurMBB,
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// Move all the successors of this block to the specified block.
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NewMBB->transferSuccessors(&CurMBB);
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// Add an edge from CurMBB to NewMBB for the fall-through.
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CurMBB.addSuccessor(NewMBB);
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// Splice the code over.
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NewMBB->splice(NewMBB->end(), &CurMBB, BBI1, CurMBB.end());
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@ -404,7 +402,6 @@ static unsigned EstimateRuntime(MachineBasicBlock::iterator I,
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// branches temporarily for tail merging). In the case where CurMBB ends
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// with a conditional branch to the next block, optimize by reversing the
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// test and conditionally branching to SuccMBB instead.
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static void FixTail(MachineBasicBlock* CurMBB, MachineBasicBlock *SuccBB,
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const TargetInstrInfo *TII) {
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MachineFunction *MF = CurMBB->getParent();
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@ -476,26 +473,26 @@ static bool ProfitableToMerge(MachineBasicBlock *MBB1,
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}
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/// ComputeSameTails - Look through all the blocks in MergePotentials that have
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/// hash CurHash (guaranteed to match the last element). Build the vector
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/// hash CurHash (guaranteed to match the last element). Build the vector
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/// SameTails of all those that have the (same) largest number of instructions
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/// in common of any pair of these blocks. SameTails entries contain an
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/// iterator into MergePotentials (from which the MachineBasicBlock can be
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/// found) and a MachineBasicBlock::iterator into that MBB indicating the
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/// iterator into MergePotentials (from which the MachineBasicBlock can be
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/// found) and a MachineBasicBlock::iterator into that MBB indicating the
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/// instruction where the matching code sequence begins.
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/// Order of elements in SameTails is the reverse of the order in which
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/// those blocks appear in MergePotentials (where they are not necessarily
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/// consecutive).
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unsigned BranchFolder::ComputeSameTails(unsigned CurHash,
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unsigned BranchFolder::ComputeSameTails(unsigned CurHash,
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unsigned minCommonTailLength) {
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unsigned maxCommonTailLength = 0U;
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SameTails.clear();
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MachineBasicBlock::iterator TrialBBI1, TrialBBI2;
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MPIterator HighestMPIter = prior(MergePotentials.end());
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for (MPIterator CurMPIter = prior(MergePotentials.end()),
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B = MergePotentials.begin();
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CurMPIter!=B && CurMPIter->first==CurHash;
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B = MergePotentials.begin();
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CurMPIter!=B && CurMPIter->first == CurHash;
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--CurMPIter) {
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for (MPIterator I = prior(CurMPIter); I->first==CurHash ; --I) {
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for (MPIterator I = prior(CurMPIter); I->first == CurHash ; --I) {
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unsigned CommonTailLen;
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if (ProfitableToMerge(CurMPIter->second, I->second, minCommonTailLength,
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CommonTailLen, TrialBBI1, TrialBBI2)) {
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@ -509,7 +506,7 @@ unsigned BranchFolder::ComputeSameTails(unsigned CurHash,
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CommonTailLen == maxCommonTailLength)
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SameTails.push_back(std::make_pair(I, TrialBBI2));
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}
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if (I==B)
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if (I == B)
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break;
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}
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}
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@ -518,18 +515,18 @@ unsigned BranchFolder::ComputeSameTails(unsigned CurHash,
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/// RemoveBlocksWithHash - Remove all blocks with hash CurHash from
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/// MergePotentials, restoring branches at ends of blocks as appropriate.
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void BranchFolder::RemoveBlocksWithHash(unsigned CurHash,
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void BranchFolder::RemoveBlocksWithHash(unsigned CurHash,
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MachineBasicBlock* SuccBB,
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MachineBasicBlock* PredBB) {
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MPIterator CurMPIter, B;
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for (CurMPIter = prior(MergePotentials.end()), B = MergePotentials.begin();
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CurMPIter->first==CurHash;
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for (CurMPIter = prior(MergePotentials.end()), B = MergePotentials.begin();
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CurMPIter->first == CurHash;
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--CurMPIter) {
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// Put the unconditional branch back, if we need one.
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MachineBasicBlock *CurMBB = CurMPIter->second;
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if (SuccBB && CurMBB != PredBB)
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FixTail(CurMBB, SuccBB, TII);
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if (CurMPIter==B)
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if (CurMPIter == B)
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break;
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}
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if (CurMPIter->first!=CurHash)
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@ -545,15 +542,15 @@ unsigned BranchFolder::CreateCommonTailOnlyBlock(MachineBasicBlock *&PredBB,
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unsigned TimeEstimate = ~0U;
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for (i=0, commonTailIndex=0; i<SameTails.size(); i++) {
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// Use PredBB if possible; that doesn't require a new branch.
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if (SameTails[i].first->second==PredBB) {
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if (SameTails[i].first->second == PredBB) {
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commonTailIndex = i;
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break;
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}
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// Otherwise, make a (fairly bogus) choice based on estimate of
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// how long it will take the various blocks to execute.
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unsigned t = EstimateRuntime(SameTails[i].first->second->begin(),
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unsigned t = EstimateRuntime(SameTails[i].first->second->begin(),
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SameTails[i].second);
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if (t<=TimeEstimate) {
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if (t <= TimeEstimate) {
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TimeEstimate = t;
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commonTailIndex = i;
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}
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@ -568,8 +565,9 @@ unsigned BranchFolder::CreateCommonTailOnlyBlock(MachineBasicBlock *&PredBB,
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MachineBasicBlock *newMBB = SplitMBBAt(*MBB, BBI);
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SameTails[commonTailIndex].first->second = newMBB;
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SameTails[commonTailIndex].second = newMBB->begin();
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// If we split PredBB, newMBB is the new predecessor.
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if (PredBB==MBB)
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if (PredBB == MBB)
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PredBB = newMBB;
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return commonTailIndex;
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@ -579,7 +577,7 @@ unsigned BranchFolder::CreateCommonTailOnlyBlock(MachineBasicBlock *&PredBB,
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// successor, or all have no successor) can be tail-merged. If there is a
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// successor, any blocks in MergePotentials that are not tail-merged and
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// are not immediately before Succ must have an unconditional branch to
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// Succ added (but the predecessor/successor lists need no adjustment).
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// Succ added (but the predecessor/successor lists need no adjustment).
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// The lone predecessor of Succ that falls through into Succ,
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// if any, is given in PredBB.
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@ -591,7 +589,7 @@ bool BranchFolder::TryMergeBlocks(MachineBasicBlock *SuccBB,
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// will add a jump.
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// FIXME: Ask the target to provide the threshold?
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unsigned minCommonTailLength = (SuccBB ? 1 : 2) + 1;
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DEBUG(errs() << "\nTryMergeBlocks " << MergePotentials.size() << '\n');
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// Sort by hash value so that blocks with identical end sequences sort
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@ -601,13 +599,13 @@ bool BranchFolder::TryMergeBlocks(MachineBasicBlock *SuccBB,
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// Walk through equivalence sets looking for actual exact matches.
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while (MergePotentials.size() > 1) {
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unsigned CurHash = MergePotentials.back().first;
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// Build SameTails, identifying the set of blocks with this hash code
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// and with the maximum number of instructions in common.
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unsigned maxCommonTailLength = ComputeSameTails(CurHash,
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unsigned maxCommonTailLength = ComputeSameTails(CurHash,
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minCommonTailLength);
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// If we didn't find any pair that has at least minCommonTailLength
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// If we didn't find any pair that has at least minCommonTailLength
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// instructions in common, remove all blocks with this hash code and retry.
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if (SameTails.empty()) {
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RemoveBlocksWithHash(CurHash, SuccBB, PredBB);
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@ -625,12 +623,12 @@ bool BranchFolder::TryMergeBlocks(MachineBasicBlock *SuccBB,
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MachineBasicBlock *MBB = SameTails[i].first->second;
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if (MBB->begin() == SameTails[i].second && MBB != EntryBB) {
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commonTailIndex = i;
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if (MBB==PredBB)
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if (MBB == PredBB)
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break;
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}
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}
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if (commonTailIndex==SameTails.size()) {
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if (commonTailIndex == SameTails.size()) {
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// None of the blocks consist entirely of the common tail.
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// Split a block so that one does.
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commonTailIndex = CreateCommonTailOnlyBlock(PredBB, maxCommonTailLength);
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@ -641,7 +639,7 @@ bool BranchFolder::TryMergeBlocks(MachineBasicBlock *SuccBB,
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// Traversal must be forwards so erases work.
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DEBUG(errs() << "\nUsing common tail BB#" << MBB->getNumber() << " for ");
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for (unsigned int i=0; i<SameTails.size(); ++i) {
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if (commonTailIndex==i)
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if (commonTailIndex == i)
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continue;
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DEBUG(errs() << "BB#" << SameTails[i].first->second->getNumber() << ", ");
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// Hack the end off BB i, making it jump to BB commonTailIndex instead.
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@ -660,7 +658,7 @@ bool BranchFolder::TryMergeBlocks(MachineBasicBlock *SuccBB,
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bool BranchFolder::TailMergeBlocks(MachineFunction &MF) {
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if (!EnableTailMerge) return false;
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bool MadeChange = false;
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// First find blocks with no successors.
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@ -669,6 +667,7 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) {
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if (I->succ_empty())
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MergePotentials.push_back(std::make_pair(HashEndOfMBB(I, 2U), I));
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}
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// See if we can do any tail merging on those.
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if (MergePotentials.size() < TailMergeThreshold &&
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MergePotentials.size() >= 2)
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@ -679,7 +678,7 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) {
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// (1) temporarily removing any unconditional branch from the predecessor
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// to IBB, and
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// (2) alter conditional branches so they branch to the other block
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// not IBB; this may require adding back an unconditional branch to IBB
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// not IBB; this may require adding back an unconditional branch to IBB
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// later, where there wasn't one coming in. E.g.
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// Bcc IBB
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// fallthrough to QBB
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@ -699,12 +698,12 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) {
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MachineBasicBlock *IBB = I;
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MachineBasicBlock *PredBB = prior(I);
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MergePotentials.clear();
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for (MachineBasicBlock::pred_iterator P = I->pred_begin(),
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for (MachineBasicBlock::pred_iterator P = I->pred_begin(),
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E2 = I->pred_end();
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P != E2; ++P) {
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MachineBasicBlock* PBB = *P;
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// Skip blocks that loop to themselves, can't tail merge these.
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if (PBB==IBB)
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if (PBB == IBB)
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continue;
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// Visit each predecessor only once.
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if (!UniquePreds.insert(PBB))
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@ -715,7 +714,7 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) {
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// Failing case: IBB is the target of a cbr, and
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// we cannot reverse the branch.
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SmallVector<MachineOperand, 4> NewCond(Cond);
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if (!Cond.empty() && TBB==IBB) {
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if (!Cond.empty() && TBB == IBB) {
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if (TII->ReverseBranchCondition(NewCond))
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continue;
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// This is the QBB case described above
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@ -730,7 +729,7 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) {
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MachineBasicBlock* PredNextBB = NULL;
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if (IP!=MF.end())
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PredNextBB = IP;
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if (TBB==NULL) {
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if (TBB == NULL) {
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if (IBB!=PredNextBB) // fallthrough
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continue;
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} else if (FBB) {
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@ -749,7 +748,7 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) {
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TII->RemoveBranch(*PBB);
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if (!Cond.empty())
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// reinsert conditional branch only, for now
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TII->InsertBranch(*PBB, (TBB==IBB) ? FBB : TBB, 0, NewCond);
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TII->InsertBranch(*PBB, (TBB == IBB) ? FBB : TBB, 0, NewCond);
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}
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MergePotentials.push_back(std::make_pair(HashEndOfMBB(PBB, 1U), *P));
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}
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@ -759,7 +758,7 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) {
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// Reinsert an unconditional branch if needed.
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// The 1 below can occur as a result of removing blocks in TryMergeBlocks.
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PredBB = prior(I); // this may have been changed in TryMergeBlocks
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if (MergePotentials.size()==1 &&
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if (MergePotentials.size() == 1 &&
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MergePotentials.begin()->second != PredBB)
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FixTail(MergePotentials.begin()->second, I, TII);
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||||
}
|
||||
@ -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<MachineOperand> &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<MachineOperand, 4> 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<MachineOperand, 4> 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.
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user