C++ SmallSetVector::begin方法代码示例

/// setupEntryBlockAndCallSites - Setup the entry block by creating and filling
/// the function context and marking the call sites with the appropriate
/// values. These values are used by the DWARF EH emitter.
bool SjLjEHPrepare::setupEntryBlockAndCallSites(Function &F) {
  SmallVector<ReturnInst *, 16> Returns;
  SmallVector<InvokeInst *, 16> Invokes;
  SmallSetVector<LandingPadInst *, 16> LPads;

  // Look through the terminators of the basic blocks to find invokes.
  for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
    if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
      if (Function *Callee = II->getCalledFunction())
        if (Callee->isIntrinsic() &&
            Callee->getIntrinsicID() == Intrinsic::donothing) {
          // Remove the NOP invoke.
          BranchInst::Create(II->getNormalDest(), II);
          II->eraseFromParent();
          continue;
        }

      Invokes.push_back(II);
      LPads.insert(II->getUnwindDest()->getLandingPadInst());
    } else if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) {
      Returns.push_back(RI);
    }

  if (Invokes.empty())
    return false;

  NumInvokes += Invokes.size();

  lowerIncomingArguments(F);
  lowerAcrossUnwindEdges(F, Invokes);

  Value *FuncCtx =
      setupFunctionContext(F, makeArrayRef(LPads.begin(), LPads.end()));
  BasicBlock *EntryBB = &F.front();
  IRBuilder<> Builder(EntryBB->getTerminator());

  // Get a reference to the jump buffer.
  Value *JBufPtr =
      Builder.CreateConstGEP2_32(FunctionContextTy, FuncCtx, 0, 5, "jbuf_gep");

  // Save the frame pointer.
  Value *FramePtr = Builder.CreateConstGEP2_32(doubleUnderJBufTy, JBufPtr, 0, 0,
                                               "jbuf_fp_gep");

  Value *Val = Builder.CreateCall(FrameAddrFn, Builder.getInt32(0), "fp");
  Builder.CreateStore(Val, FramePtr, /*isVolatile=*/true);

  // Save the stack pointer.
  Value *StackPtr = Builder.CreateConstGEP2_32(doubleUnderJBufTy, JBufPtr, 0, 2,
                                               "jbuf_sp_gep");

  Val = Builder.CreateCall(StackAddrFn, {}, "sp");
  Builder.CreateStore(Val, StackPtr, /*isVolatile=*/true);

  // Call the setup_dispatch instrinsic. It fills in the rest of the jmpbuf.
  Builder.CreateCall(BuiltinSetupDispatchFn, {});

  // Store a pointer to the function context so that the back-end will know
  // where to look for it.
  Value *FuncCtxArg = Builder.CreateBitCast(FuncCtx, Builder.getInt8PtrTy());
  Builder.CreateCall(FuncCtxFn, FuncCtxArg);

  // At this point, we are all set up, update the invoke instructions to mark
  // their call_site values.
  for (unsigned I = 0, E = Invokes.size(); I != E; ++I) {
    insertCallSiteStore(Invokes[I], I + 1);

    ConstantInt *CallSiteNum =
        ConstantInt::get(Type::getInt32Ty(F.getContext()), I + 1);

    // Record the call site value for the back end so it stays associated with
    // the invoke.
    CallInst::Create(CallSiteFn, CallSiteNum, "", Invokes[I]);
  }

  // Mark call instructions that aren't nounwind as no-action (call_site ==
  // -1). Skip the entry block, as prior to then, no function context has been
  // created for this function and any unexpected exceptions thrown will go
  // directly to the caller's context, which is what we want anyway, so no need
  // to do anything here.
  for (Function::iterator BB = F.begin(), E = F.end(); ++BB != E;)
    for (BasicBlock::iterator I = BB->begin(), end = BB->end(); I != end; ++I)
      if (CallInst *CI = dyn_cast<CallInst>(I)) {
        if (!CI->doesNotThrow())
          insertCallSiteStore(CI, -1);
      } else if (ResumeInst *RI = dyn_cast<ResumeInst>(I)) {
        insertCallSiteStore(RI, -1);
      }

  // Register the function context and make sure it's known to not throw
  CallInst *Register =
      CallInst::Create(RegisterFn, FuncCtx, "", EntryBB->getTerminator());
  Register->setDoesNotThrow();

  // Following any allocas not in the entry block, update the saved SP in the
  // jmpbuf to the new value.
  for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
//.........这里部分代码省略.........

/// UpdateSuccessorsPHIs - After FromBB is tail duplicated into its predecessor
/// blocks, the successors have gained new predecessors. Update the PHI
/// instructions in them accordingly.
void
TailDuplicatePass::UpdateSuccessorsPHIs(MachineBasicBlock *FromBB, bool isDead,
                                  SmallVector<MachineBasicBlock*, 8> &TDBBs,
                                  SmallSetVector<MachineBasicBlock*,8> &Succs) {
  for (SmallSetVector<MachineBasicBlock*, 8>::iterator SI = Succs.begin(),
         SE = Succs.end(); SI != SE; ++SI) {
    MachineBasicBlock *SuccBB = *SI;
    for (MachineBasicBlock::iterator II = SuccBB->begin(), EE = SuccBB->end();
         II != EE; ++II) {
      if (!II->isPHI())
        break;
      unsigned Idx = 0;
      for (unsigned i = 1, e = II->getNumOperands(); i != e; i += 2) {
        MachineOperand &MO = II->getOperand(i+1);
        if (MO.getMBB() == FromBB) {
          Idx = i;
          break;
        }
      }

      assert(Idx != 0);
      MachineOperand &MO0 = II->getOperand(Idx);
      unsigned Reg = MO0.getReg();
      if (isDead) {
        // Folded into the previous BB.
        // There could be duplicate phi source entries. FIXME: Should sdisel
        // or earlier pass fixed this?
        for (unsigned i = II->getNumOperands()-2; i != Idx; i -= 2) {
          MachineOperand &MO = II->getOperand(i+1);
          if (MO.getMBB() == FromBB) {
            II->RemoveOperand(i+1);
            II->RemoveOperand(i);
          }
        }
      } else
        Idx = 0;

      // If Idx is set, the operands at Idx and Idx+1 must be removed.
      // We reuse the location to avoid expensive RemoveOperand calls.

      DenseMap<unsigned,AvailableValsTy>::iterator LI=SSAUpdateVals.find(Reg);
      if (LI != SSAUpdateVals.end()) {
        // This register is defined in the tail block.
        for (unsigned j = 0, ee = LI->second.size(); j != ee; ++j) {
          MachineBasicBlock *SrcBB = LI->second[j].first;
          // If we didn't duplicate a bb into a particular predecessor, we
          // might still have added an entry to SSAUpdateVals to correcly
          // recompute SSA. If that case, avoid adding a dummy extra argument
          // this PHI.
          if (!SrcBB->isSuccessor(SuccBB))
            continue;

          unsigned SrcReg = LI->second[j].second;
          if (Idx != 0) {
            II->getOperand(Idx).setReg(SrcReg);
            II->getOperand(Idx+1).setMBB(SrcBB);
            Idx = 0;
          } else {
            II->addOperand(MachineOperand::CreateReg(SrcReg, false));
            II->addOperand(MachineOperand::CreateMBB(SrcBB));
          }
        }
      } else {
        // Live in tail block, must also be live in predecessors.
        for (unsigned j = 0, ee = TDBBs.size(); j != ee; ++j) {
          MachineBasicBlock *SrcBB = TDBBs[j];
          if (Idx != 0) {
            II->getOperand(Idx).setReg(Reg);
            II->getOperand(Idx+1).setMBB(SrcBB);
            Idx = 0;
          } else {
            II->addOperand(MachineOperand::CreateReg(Reg, false));
            II->addOperand(MachineOperand::CreateMBB(SrcBB));
          }
        }
      }
      if (Idx != 0) {
        II->RemoveOperand(Idx+1);
        II->RemoveOperand(Idx);
      }
    }
  }
}

bool MachineCopyPropagation::CopyPropagateBlock(MachineBasicBlock &MBB) {
  SmallSetVector<MachineInstr*, 8> MaybeDeadCopies;  // Candidates for deletion
  DenseMap<unsigned, MachineInstr*> AvailCopyMap;    // Def -> available copies map
  DenseMap<unsigned, MachineInstr*> CopyMap;         // Def -> copies map
  SourceMap SrcMap; // Src -> Def map

  bool Changed = false;
  for (MachineBasicBlock::iterator I = MBB.begin(), E = MBB.end(); I != E; ) {
    MachineInstr *MI = &*I;
    ++I;

    if (MI->isCopy()) {
      unsigned Def = MI->getOperand(0).getReg();
      unsigned Src = MI->getOperand(1).getReg();

      if (TargetRegisterInfo::isVirtualRegister(Def) ||
          TargetRegisterInfo::isVirtualRegister(Src))
        report_fatal_error("MachineCopyPropagation should be run after"
                           " register allocation!");

      DenseMap<unsigned, MachineInstr*>::iterator CI = AvailCopyMap.find(Src);
      if (CI != AvailCopyMap.end()) {
        MachineInstr *CopyMI = CI->second;
        if (!MRI->isReserved(Def) &&
            (!MRI->isReserved(Src) || NoInterveningSideEffect(CopyMI, MI)) &&
            isNopCopy(CopyMI, Def, Src, TRI)) {
          // The two copies cancel out and the source of the first copy
          // hasn't been overridden, eliminate the second one. e.g.
          //  %ECX<def> = COPY %EAX<kill>
          //  ... nothing clobbered EAX.
          //  %EAX<def> = COPY %ECX
          // =>
          //  %ECX<def> = COPY %EAX
          //
          // Also avoid eliminating a copy from reserved registers unless the
          // definition is proven not clobbered. e.g.
          // %RSP<def> = COPY %RAX
          // CALL
          // %RAX<def> = COPY %RSP

          // Clear any kills of Def between CopyMI and MI. This extends the
          // live range.
          for (MachineBasicBlock::iterator I = CopyMI, E = MI; I != E; ++I)
            I->clearRegisterKills(Def, TRI);

          removeCopy(MI);
          Changed = true;
          ++NumDeletes;
          continue;
        }
      }

      // If Src is defined by a previous copy, it cannot be eliminated.
      for (MCRegAliasIterator AI(Src, TRI, true); AI.isValid(); ++AI) {
        CI = CopyMap.find(*AI);
        if (CI != CopyMap.end())
          MaybeDeadCopies.remove(CI->second);
      }

      // Copy is now a candidate for deletion.
      MaybeDeadCopies.insert(MI);

      // If 'Src' is previously source of another copy, then this earlier copy's
      // source is no longer available. e.g.
      // %xmm9<def> = copy %xmm2
      // ...
      // %xmm2<def> = copy %xmm0
      // ...
      // %xmm2<def> = copy %xmm9
      SourceNoLongerAvailable(Def, SrcMap, AvailCopyMap);

      // Remember Def is defined by the copy.
      // ... Make sure to clear the def maps of aliases first.
      for (MCRegAliasIterator AI(Def, TRI, false); AI.isValid(); ++AI) {
        CopyMap.erase(*AI);
        AvailCopyMap.erase(*AI);
      }
      CopyMap[Def] = MI;
      AvailCopyMap[Def] = MI;
      for (MCSubRegIterator SR(Def, TRI); SR.isValid(); ++SR) {
        CopyMap[*SR] = MI;
        AvailCopyMap[*SR] = MI;
      }

      // Remember source that's copied to Def. Once it's clobbered, then
      // it's no longer available for copy propagation.
      if (std::find(SrcMap[Src].begin(), SrcMap[Src].end(), Def) ==
          SrcMap[Src].end()) {
        SrcMap[Src].push_back(Def);
      }

      continue;
    }

    // Not a copy.
    SmallVector<unsigned, 2> Defs;
    int RegMaskOpNum = -1;
    for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
      MachineOperand &MO = MI->getOperand(i);
      if (MO.isRegMask())
//.........这里部分代码省略.........

//.........这里部分代码省略.........
      continue;
    }

    // If there is no existing flag with this ID, just add it.
    if (!DstOp) {
      Flags[ID] = std::make_pair(SrcOp, DstModFlags->getNumOperands());
      DstModFlags->addOperand(SrcOp);
      continue;
    }

    // Otherwise, perform a merge.
    ConstantInt *DstBehavior =
        mdconst::extract<ConstantInt>(DstOp->getOperand(0));
    unsigned DstBehaviorValue = DstBehavior->getZExtValue();

    // If either flag has override behavior, handle it first.
    if (DstBehaviorValue == Module::Override) {
      // Diagnose inconsistent flags which both have override behavior.
      if (SrcBehaviorValue == Module::Override &&
          SrcOp->getOperand(2) != DstOp->getOperand(2))
        return stringErr("linking module flags '" + ID->getString() +
                         "': IDs have conflicting override values");
      continue;
    } else if (SrcBehaviorValue == Module::Override) {
      // Update the destination flag to that of the source.
      DstModFlags->setOperand(DstIndex, SrcOp);
      Flags[ID].first = SrcOp;
      continue;
    }

    // Diagnose inconsistent merge behavior types.
    if (SrcBehaviorValue != DstBehaviorValue)
      return stringErr("linking module flags '" + ID->getString() +
                       "': IDs have conflicting behaviors");

    auto replaceDstValue = [&](MDNode *New) {
      Metadata *FlagOps[] = {DstOp->getOperand(0), ID, New};
      MDNode *Flag = MDNode::get(DstM.getContext(), FlagOps);
      DstModFlags->setOperand(DstIndex, Flag);
      Flags[ID].first = Flag;
    };

    // Perform the merge for standard behavior types.
    switch (SrcBehaviorValue) {
    case Module::Require:
    case Module::Override:
      llvm_unreachable("not possible");
    case Module::Error: {
      // Emit an error if the values differ.
      if (SrcOp->getOperand(2) != DstOp->getOperand(2))
        return stringErr("linking module flags '" + ID->getString() +
                         "': IDs have conflicting values");
      continue;
    }
    case Module::Warning: {
      // Emit a warning if the values differ.
      if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
        emitWarning("linking module flags '" + ID->getString() +
                    "': IDs have conflicting values");
      }
      continue;
    }
    case Module::Append: {
      MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
      MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
      SmallVector<Metadata *, 8> MDs;
      MDs.reserve(DstValue->getNumOperands() + SrcValue->getNumOperands());
      MDs.append(DstValue->op_begin(), DstValue->op_end());
      MDs.append(SrcValue->op_begin(), SrcValue->op_end());

      replaceDstValue(MDNode::get(DstM.getContext(), MDs));
      break;
    }
    case Module::AppendUnique: {
      SmallSetVector<Metadata *, 16> Elts;
      MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
      MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
      Elts.insert(DstValue->op_begin(), DstValue->op_end());
      Elts.insert(SrcValue->op_begin(), SrcValue->op_end());

      replaceDstValue(MDNode::get(DstM.getContext(),
                                  makeArrayRef(Elts.begin(), Elts.end())));
      break;
    }
    }
  }

  // Check all of the requirements.
  for (unsigned I = 0, E = Requirements.size(); I != E; ++I) {
    MDNode *Requirement = Requirements[I];
    MDString *Flag = cast<MDString>(Requirement->getOperand(0));
    Metadata *ReqValue = Requirement->getOperand(1);

    MDNode *Op = Flags[Flag].first;
    if (!Op || Op->getOperand(2) != ReqValue)
      return stringErr("linking module flags '" + Flag->getString() +
                       "': does not have the required value");
  }
  return Error::success();
}

bool AArch64RedundantCopyElimination::optimizeCopy(MachineBasicBlock *MBB) {
  // Check if the current basic block has a single predecessor.
  if (MBB->pred_size() != 1)
    return false;

  MachineBasicBlock *PredMBB = *MBB->pred_begin();
  MachineBasicBlock::iterator CompBr = PredMBB->getLastNonDebugInstr();
  if (CompBr == PredMBB->end() || PredMBB->succ_size() != 2)
    return false;

  ++CompBr;
  do {
    --CompBr;
    if (guaranteesZeroRegInBlock(*CompBr, MBB))
      break;
  } while (CompBr != PredMBB->begin() && CompBr->isTerminator());

  // We've not found a CBZ/CBNZ, time to bail out.
  if (!guaranteesZeroRegInBlock(*CompBr, MBB))
    return false;

  unsigned TargetReg = CompBr->getOperand(0).getReg();
  if (!TargetReg)
    return false;
  assert(TargetRegisterInfo::isPhysicalRegister(TargetReg) &&
         "Expect physical register");

  // Remember all registers aliasing with TargetReg.
  SmallSetVector<unsigned, 8> TargetRegs;
  for (MCRegAliasIterator AI(TargetReg, TRI, true); AI.isValid(); ++AI)
    TargetRegs.insert(*AI);

  bool Changed = false;
  MachineBasicBlock::iterator LastChange = MBB->begin();
  unsigned SmallestDef = TargetReg;
  // Remove redundant Copy instructions unless TargetReg is modified.
  for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end(); I != E;) {
    MachineInstr *MI = &*I;
    ++I;
    if (MI->isCopy() && MI->getOperand(0).isReg() &&
        MI->getOperand(1).isReg()) {

      unsigned DefReg = MI->getOperand(0).getReg();
      unsigned SrcReg = MI->getOperand(1).getReg();

      if ((SrcReg == AArch64::XZR || SrcReg == AArch64::WZR) &&
          !MRI->isReserved(DefReg) &&
          (TargetReg == DefReg || TRI->isSuperRegister(DefReg, TargetReg))) {
        DEBUG(dbgs() << "Remove redundant Copy : ");
        DEBUG((MI)->print(dbgs()));

        MI->eraseFromParent();
        Changed = true;
        LastChange = I;
        NumCopiesRemoved++;
        SmallestDef =
            TRI->isSubRegister(SmallestDef, DefReg) ? DefReg : SmallestDef;
        continue;
      }
    }

    if (MI->modifiesRegister(TargetReg, TRI))
      break;
  }

  if (!Changed)
    return false;

  // Otherwise, we have to fixup the use-def chain, starting with the
  // CBZ/CBNZ. Conservatively mark as much as we can live.
  CompBr->clearRegisterKills(SmallestDef, TRI);

  if (std::none_of(TargetRegs.begin(), TargetRegs.end(),
                   [&](unsigned Reg) { return MBB->isLiveIn(Reg); }))
    MBB->addLiveIn(TargetReg);

  // Clear any kills of TargetReg between CompBr and the last removed COPY.
  for (MachineInstr &MMI :
       make_range(MBB->begin()->getIterator(), LastChange->getIterator()))
    MMI.clearRegisterKills(SmallestDef, TRI);

  return true;
}

/// linkModuleFlagsMetadata - Merge the linker flags in Src into the Dest
/// module.
bool ModuleLinker::linkModuleFlagsMetadata() {
  const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
  if (!SrcModFlags) return false;

  NamedMDNode *DstModFlags = DstM->getOrInsertModuleFlagsMetadata();

  // If the destination module doesn't have module flags yet, then just copy
  // over the source module's flags.
  if (DstModFlags->getNumOperands() == 0) {
    for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I)
      DstModFlags->addOperand(SrcModFlags->getOperand(I));

    return false;
  }

  bool HasErr = false;

  // Otherwise, we have to merge them based on their behaviors. First,
  // categorize all of the nodes in the modules' module flags. If an error or
  // warning occurs, then emit the appropriate message(s).
  DenseMap<MDString*, MDNode*> ErrorNode;
  DenseMap<MDString*, MDNode*> WarningNode;
  DenseMap<MDString*, MDNode*> OverrideNode;
  DenseMap<MDString*, SmallSetVector<MDNode*, 8> > RequireNodes;
  SmallSetVector<MDString*, 16> SeenIDs;

  HasErr |= categorizeModuleFlagNodes(SrcModFlags, ErrorNode, WarningNode,
                                      OverrideNode, RequireNodes, SeenIDs);
  HasErr |= categorizeModuleFlagNodes(DstModFlags, ErrorNode, WarningNode,
                                      OverrideNode, RequireNodes, SeenIDs);

  // Check that there isn't both an error and warning node for a flag.
  for (SmallSetVector<MDString*, 16>::iterator
         I = SeenIDs.begin(), E = SeenIDs.end(); I != E; ++I) {
    MDString *ID = *I;
    if (ErrorNode[ID] && WarningNode[ID])
      HasErr = emitError("linking module flags '" + ID->getString() +
                         "': IDs have conflicting behaviors");
  }

  // Early exit if we had an error.
  if (HasErr) return true;

  // Get the destination's module flags ready for new operands.
  DstModFlags->dropAllReferences();

  // Add all of the module flags to the destination module.
  DenseMap<MDString*, SmallVector<MDNode*, 4> > AddedNodes;
  for (SmallSetVector<MDString*, 16>::iterator
         I = SeenIDs.begin(), E = SeenIDs.end(); I != E; ++I) {
    MDString *ID = *I;
    if (OverrideNode[ID]) {
      DstModFlags->addOperand(OverrideNode[ID]);
      AddedNodes[ID].push_back(OverrideNode[ID]);
    } else if (ErrorNode[ID]) {
      DstModFlags->addOperand(ErrorNode[ID]);
      AddedNodes[ID].push_back(ErrorNode[ID]);
    } else if (WarningNode[ID]) {
      DstModFlags->addOperand(WarningNode[ID]);
      AddedNodes[ID].push_back(WarningNode[ID]);
    }

    for (SmallSetVector<MDNode*, 8>::iterator
           II = RequireNodes[ID].begin(), IE = RequireNodes[ID].end();
         II != IE; ++II)
      DstModFlags->addOperand(*II);
  }

  // Now check that all of the requirements have been satisfied.
  for (SmallSetVector<MDString*, 16>::iterator
         I = SeenIDs.begin(), E = SeenIDs.end(); I != E; ++I) {
    MDString *ID = *I;
    SmallSetVector<MDNode*, 8> &Set = RequireNodes[ID];

    for (SmallSetVector<MDNode*, 8>::iterator
           II = Set.begin(), IE = Set.end(); II != IE; ++II) {
      MDNode *Node = *II;
      assert(isa<MDNode>(Node->getOperand(2)) &&
             "Module flag's third operand must be an MDNode!");
      MDNode *Val = cast<MDNode>(Node->getOperand(2));

      MDString *ReqID = cast<MDString>(Val->getOperand(0));
      Value *ReqVal = Val->getOperand(1);

      bool HasValue = false;
      for (SmallVectorImpl<MDNode*>::iterator
             RI = AddedNodes[ReqID].begin(), RE = AddedNodes[ReqID].end();
           RI != RE; ++RI) {
        MDNode *ReqNode = *RI;
        if (ReqNode->getOperand(2) == ReqVal) {
          HasValue = true;
          break;
        }
      }

      if (!HasValue)
        HasErr = emitError("linking module flags '" + ReqID->getString() +
                           "': does not have the required value");
//.........这里部分代码省略.........