X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=blobdiff_plain;f=include%2Fllvm%2FCodeGen%2FMachineBasicBlock.h;h=619894c077ce669c50d0b19808603c687ec016ba;hp=aacc31455eab793f5f2235d1ee5179fd6e8345d1;hb=cf0db29df20d9c665da7e82bb261bdd7cf7f1b2b;hpb=3380d5c4aaafc3d78d32f583d685d64a67ae5224 diff --git a/include/llvm/CodeGen/MachineBasicBlock.h b/include/llvm/CodeGen/MachineBasicBlock.h index aacc31455ea..619894c077c 100644 --- a/include/llvm/CodeGen/MachineBasicBlock.h +++ b/include/llvm/CodeGen/MachineBasicBlock.h @@ -14,18 +14,26 @@ #ifndef LLVM_CODEGEN_MACHINEBASICBLOCK_H #define LLVM_CODEGEN_MACHINEBASICBLOCK_H -#include "llvm/CodeGen/MachineInstr.h" #include "llvm/ADT/GraphTraits.h" +#include "llvm/CodeGen/MachineInstr.h" +#include "llvm/Support/DataTypes.h" +#include namespace llvm { +class Pass; class BasicBlock; class MachineFunction; +class MCSymbol; +class SlotIndexes; +class StringRef; +class raw_ostream; +class MachineBranchProbabilityInfo; template <> struct ilist_traits : public ilist_default_traits { private: - mutable ilist_node Sentinel; + mutable ilist_half_node Sentinel; // this is only set by the MachineBasicBlock owning the LiveList friend class MachineBasicBlock; @@ -57,24 +65,40 @@ class MachineBasicBlock : public ilist_node { const BasicBlock *BB; int Number; MachineFunction *xParent; - + /// Predecessors/Successors - Keep track of the predecessor / successor /// basicblocks. std::vector Predecessors; std::vector Successors; + /// Weights - Keep track of the weights to the successors. This vector + /// has the same order as Successors, or it is empty if we don't use it + /// (disable optimization). + std::vector Weights; + typedef std::vector::iterator weight_iterator; + typedef std::vector::const_iterator const_weight_iterator; + /// LiveIns - Keep track of the physical registers that are livein of /// the basicblock. std::vector LiveIns; /// Alignment - Alignment of the basic block. Zero if the basic block does /// not need to be aligned. + /// The alignment is specified as log2(bytes). unsigned Alignment; - + /// IsLandingPad - Indicate that this basic block is entered via an /// exception handler. bool IsLandingPad; + /// AddressTaken - Indicate that this basic block is potentially the + /// target of an indirect branch. + bool AddressTaken; + + /// \brief since getSymbol is a relatively heavy-weight operation, the symbol + /// is only computed once and is cached. + mutable MCSymbol *CachedMCSymbol; + // Intrusive list support MachineBasicBlock() {} @@ -87,36 +111,148 @@ class MachineBasicBlock : public ilist_node { public: /// getBasicBlock - Return the LLVM basic block that this instance - /// corresponded to originally. + /// corresponded to originally. Note that this may be NULL if this instance + /// does not correspond directly to an LLVM basic block. /// const BasicBlock *getBasicBlock() const { return BB; } + /// getName - Return the name of the corresponding LLVM basic block, or + /// "(null)". + StringRef getName() const; + + /// getFullName - Return a formatted string to identify this block and its + /// parent function. + std::string getFullName() const; + + /// hasAddressTaken - Test whether this block is potentially the target + /// of an indirect branch. + bool hasAddressTaken() const { return AddressTaken; } + + /// setHasAddressTaken - Set this block to reflect that it potentially + /// is the target of an indirect branch. + void setHasAddressTaken() { AddressTaken = true; } + /// getParent - Return the MachineFunction containing this basic block. /// const MachineFunction *getParent() const { return xParent; } MachineFunction *getParent() { return xParent; } - typedef Instructions::iterator iterator; - typedef Instructions::const_iterator const_iterator; - typedef std::reverse_iterator const_reverse_iterator; - typedef std::reverse_iterator reverse_iterator; + + /// bundle_iterator - MachineBasicBlock iterator that automatically skips over + /// MIs that are inside bundles (i.e. walk top level MIs only). + template + class bundle_iterator + : public std::iterator { + IterTy MII; + + public: + bundle_iterator(IterTy mii) : MII(mii) {} + + bundle_iterator(Ty &mi) : MII(mi) { + assert(!mi.isBundledWithPred() && + "It's not legal to initialize bundle_iterator with a bundled MI"); + } + bundle_iterator(Ty *mi) : MII(mi) { + assert((!mi || !mi->isBundledWithPred()) && + "It's not legal to initialize bundle_iterator with a bundled MI"); + } + // Template allows conversion from const to nonconst. + template + bundle_iterator(const bundle_iterator &I) + : MII(I.getInstrIterator()) {} + bundle_iterator() : MII(nullptr) {} + + Ty &operator*() const { return *MII; } + Ty *operator->() const { return &operator*(); } + + operator Ty*() const { return MII; } + + bool operator==(const bundle_iterator &x) const { + return MII == x.MII; + } + bool operator!=(const bundle_iterator &x) const { + return !operator==(x); + } + + // Increment and decrement operators... + bundle_iterator &operator--() { // predecrement - Back up + do --MII; + while (MII->isBundledWithPred()); + return *this; + } + bundle_iterator &operator++() { // preincrement - Advance + while (MII->isBundledWithSucc()) + ++MII; + ++MII; + return *this; + } + bundle_iterator operator--(int) { // postdecrement operators... + bundle_iterator tmp = *this; + --*this; + return tmp; + } + bundle_iterator operator++(int) { // postincrement operators... + bundle_iterator tmp = *this; + ++*this; + return tmp; + } + + IterTy getInstrIterator() const { + return MII; + } + }; + + typedef Instructions::iterator instr_iterator; + typedef Instructions::const_iterator const_instr_iterator; + typedef std::reverse_iterator reverse_instr_iterator; + typedef + std::reverse_iterator const_reverse_instr_iterator; + + typedef + bundle_iterator iterator; + typedef + bundle_iterator const_iterator; + typedef std::reverse_iterator const_reverse_iterator; + typedef std::reverse_iterator reverse_iterator; + unsigned size() const { return (unsigned)Insts.size(); } bool empty() const { return Insts.empty(); } - MachineInstr& front() { return Insts.front(); } - MachineInstr& back() { return Insts.back(); } - const MachineInstr& front() const { return Insts.front(); } - const MachineInstr& back() const { return Insts.back(); } - - iterator begin() { return Insts.begin(); } - const_iterator begin() const { return Insts.begin(); } - iterator end() { return Insts.end(); } - const_iterator end() const { return Insts.end(); } - reverse_iterator rbegin() { return Insts.rbegin(); } - const_reverse_iterator rbegin() const { return Insts.rbegin(); } - reverse_iterator rend () { return Insts.rend(); } - const_reverse_iterator rend () const { return Insts.rend(); } + MachineInstr &instr_front() { return Insts.front(); } + MachineInstr &instr_back() { return Insts.back(); } + const MachineInstr &instr_front() const { return Insts.front(); } + const MachineInstr &instr_back() const { return Insts.back(); } + + MachineInstr &front() { return Insts.front(); } + MachineInstr &back() { return *--end(); } + const MachineInstr &front() const { return Insts.front(); } + const MachineInstr &back() const { return *--end(); } + + instr_iterator instr_begin() { return Insts.begin(); } + const_instr_iterator instr_begin() const { return Insts.begin(); } + instr_iterator instr_end() { return Insts.end(); } + const_instr_iterator instr_end() const { return Insts.end(); } + reverse_instr_iterator instr_rbegin() { return Insts.rbegin(); } + const_reverse_instr_iterator instr_rbegin() const { return Insts.rbegin(); } + reverse_instr_iterator instr_rend () { return Insts.rend(); } + const_reverse_instr_iterator instr_rend () const { return Insts.rend(); } + + iterator begin() { return instr_begin(); } + const_iterator begin() const { return instr_begin(); } + iterator end () { return instr_end(); } + const_iterator end () const { return instr_end(); } + reverse_iterator rbegin() { return instr_rbegin(); } + const_reverse_iterator rbegin() const { return instr_rbegin(); } + reverse_iterator rend () { return instr_rend(); } + const_reverse_iterator rend () const { return instr_rend(); } + + inline iterator_range terminators() { + return iterator_range(getFirstTerminator(), end()); + } + inline iterator_range terminators() const { + return iterator_range(getFirstTerminator(), end()); + } // Machine-CFG iterators typedef std::vector::iterator pred_iterator; @@ -131,7 +267,6 @@ public: succ_reverse_iterator; typedef std::vector::const_reverse_iterator const_succ_reverse_iterator; - pred_iterator pred_begin() { return Predecessors.begin(); } const_pred_iterator pred_begin() const { return Predecessors.begin(); } pred_iterator pred_end() { return Predecessors.end(); } @@ -165,11 +300,38 @@ public: } bool succ_empty() const { return Successors.empty(); } + inline iterator_range predecessors() { + return iterator_range(pred_begin(), pred_end()); + } + inline iterator_range predecessors() const { + return iterator_range(pred_begin(), pred_end()); + } + inline iterator_range successors() { + return iterator_range(succ_begin(), succ_end()); + } + inline iterator_range successors() const { + return iterator_range(succ_begin(), succ_end()); + } + // LiveIn management methods. - /// addLiveIn - Add the specified register as a live in. Note that it - /// is an error to add the same register to the same set more than once. - void addLiveIn(unsigned Reg) { LiveIns.push_back(Reg); } + /// Adds the specified register as a live in. Note that it is an error to add + /// the same register to the same set more than once unless the intention is + /// to call sortUniqueLiveIns after all registers are added. + void addLiveIn(unsigned Reg) { LiveIns.push_back(Reg); } + + /// Sorts and uniques the LiveIns vector. It can be significantly faster to do + /// this than repeatedly calling isLiveIn before calling addLiveIn for every + /// LiveIn insertion. + void sortUniqueLiveIns() { + std::sort(LiveIns.begin(), LiveIns.end()); + LiveIns.erase(std::unique(LiveIns.begin(), LiveIns.end()), LiveIns.end()); + } + + /// Add PhysReg as live in to this block, and ensure that there is a copy of + /// PhysReg to a virtual register of class RC. Return the virtual register + /// that is a copy of the live in PhysReg. + unsigned addLiveIn(unsigned PhysReg, const TargetRegisterClass *RC); /// removeLiveIn - Remove the specified register from the live in set. /// @@ -181,19 +343,18 @@ public: // Iteration support for live in sets. These sets are kept in sorted // order by their register number. - typedef std::vector::iterator livein_iterator; - typedef std::vector::const_iterator const_livein_iterator; - livein_iterator livein_begin() { return LiveIns.begin(); } - const_livein_iterator livein_begin() const { return LiveIns.begin(); } - livein_iterator livein_end() { return LiveIns.end(); } - const_livein_iterator livein_end() const { return LiveIns.end(); } + typedef std::vector::const_iterator livein_iterator; + livein_iterator livein_begin() const { return LiveIns.begin(); } + livein_iterator livein_end() const { return LiveIns.end(); } bool livein_empty() const { return LiveIns.empty(); } /// getAlignment - Return alignment of the basic block. + /// The alignment is specified as log2(bytes). /// unsigned getAlignment() const { return Alignment; } /// setAlignment - Set alignment of the basic block. + /// The alignment is specified as log2(bytes). /// void setAlignment(unsigned Align) { Alignment = Align; } @@ -203,22 +364,39 @@ public: /// setIsLandingPad - Indicates the block is a landing pad. That is /// this basic block is entered via an exception handler. - void setIsLandingPad() { IsLandingPad = true; } + void setIsLandingPad(bool V = true) { IsLandingPad = V; } + + /// getLandingPadSuccessor - If this block has a successor that is a landing + /// pad, return it. Otherwise return NULL. + const MachineBasicBlock *getLandingPadSuccessor() const; // Code Layout methods. - + /// moveBefore/moveAfter - move 'this' block before or after the specified /// block. This only moves the block, it does not modify the CFG or adjust /// potential fall-throughs at the end of the block. void moveBefore(MachineBasicBlock *NewAfter); void moveAfter(MachineBasicBlock *NewBefore); - + + /// updateTerminator - Update the terminator instructions in block to account + /// for changes to the layout. If the block previously used a fallthrough, + /// it may now need a branch, and if it previously used branching it may now + /// be able to use a fallthrough. + void updateTerminator(); + // Machine-CFG mutators - + /// addSuccessor - Add succ as a successor of this MachineBasicBlock. - /// The Predecessors list of succ is automatically updated. + /// The Predecessors list of succ is automatically updated. WEIGHT + /// parameter is stored in Weights list and it may be used by + /// MachineBranchProbabilityInfo analysis to calculate branch probability. /// - void addSuccessor(MachineBasicBlock *succ); + /// Note that duplicate Machine CFG edges are not allowed. + /// + void addSuccessor(MachineBasicBlock *succ, uint32_t weight = 0); + + /// Set successor weight of a given iterator. + void setSuccWeight(succ_iterator I, uint32_t weight); /// removeSuccessor - Remove successor from the successors list of this /// MachineBasicBlock. The Predecessors list of succ is automatically updated. @@ -230,12 +408,26 @@ public: /// updated. Return the iterator to the element after the one removed. /// succ_iterator removeSuccessor(succ_iterator I); - + + /// replaceSuccessor - Replace successor OLD with NEW and update weight info. + /// + void replaceSuccessor(MachineBasicBlock *Old, MachineBasicBlock *New); + + /// transferSuccessors - Transfers all the successors from MBB to this /// machine basic block (i.e., copies all the successors fromMBB and - /// remove all the successors fromBB). + /// remove all the successors from fromMBB). void transferSuccessors(MachineBasicBlock *fromMBB); - + + /// transferSuccessorsAndUpdatePHIs - Transfers all the successors, as + /// in transferSuccessors, and update PHI operands in the successor blocks + /// which refer to fromMBB to refer to this. + void transferSuccessorsAndUpdatePHIs(MachineBasicBlock *fromMBB); + + /// isPredecessor - Return true if the specified MBB is a predecessor of this + /// block. + bool isPredecessor(const MachineBasicBlock *MBB) const; + /// isSuccessor - Return true if the specified MBB is a successor of this /// block. bool isSuccessor(const MachineBasicBlock *MBB) const; @@ -247,48 +439,165 @@ public: /// ends with an unconditional branch to some other block. bool isLayoutSuccessor(const MachineBasicBlock *MBB) const; + /// canFallThrough - Return true if the block can implicitly transfer + /// control to the block after it by falling off the end of it. This should + /// return false if it can reach the block after it, but it uses an explicit + /// branch to do so (e.g., a table jump). True is a conservative answer. + bool canFallThrough(); + + /// Returns a pointer to the first instruction in this block that is not a + /// PHINode instruction. When adding instructions to the beginning of the + /// basic block, they should be added before the returned value, not before + /// the first instruction, which might be PHI. + /// Returns end() is there's no non-PHI instruction. + iterator getFirstNonPHI(); + + /// SkipPHIsAndLabels - Return the first instruction in MBB after I that is + /// not a PHI or a label. This is the correct point to insert copies at the + /// beginning of a basic block. + iterator SkipPHIsAndLabels(iterator I); + /// getFirstTerminator - returns an iterator to the first terminator /// instruction of this basic block. If a terminator does not exist, /// it returns end() iterator getFirstTerminator(); + const_iterator getFirstTerminator() const; + + /// getFirstInstrTerminator - Same getFirstTerminator but it ignores bundles + /// and return an instr_iterator instead. + instr_iterator getFirstInstrTerminator(); + + /// getLastNonDebugInstr - returns an iterator to the last non-debug + /// instruction in the basic block, or end() + iterator getLastNonDebugInstr(); + const_iterator getLastNonDebugInstr() const; - /// isOnlyReachableViaFallthough - Return true if this basic block has - /// exactly one predecessor and the control transfer mechanism between - /// the predecessor and this block is a fall-through. - bool isOnlyReachableByFallthrough() const; + /// SplitCriticalEdge - Split the critical edge from this block to the + /// given successor block, and return the newly created block, or null + /// if splitting is not possible. + /// + /// This function updates LiveVariables, MachineDominatorTree, and + /// MachineLoopInfo, as applicable. + MachineBasicBlock *SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P); void pop_front() { Insts.pop_front(); } void pop_back() { Insts.pop_back(); } void push_back(MachineInstr *MI) { Insts.push_back(MI); } + + /// Insert MI into the instruction list before I, possibly inside a bundle. + /// + /// If the insertion point is inside a bundle, MI will be added to the bundle, + /// otherwise MI will not be added to any bundle. That means this function + /// alone can't be used to prepend or append instructions to bundles. See + /// MIBundleBuilder::insert() for a more reliable way of doing that. + instr_iterator insert(instr_iterator I, MachineInstr *M); + + /// Insert a range of instructions into the instruction list before I. template - void insert(iterator I, IT S, IT E) { Insts.insert(I, S, E); } - iterator insert(iterator I, MachineInstr *M) { return Insts.insert(I, M); } + void insert(iterator I, IT S, IT E) { + assert((I == end() || I->getParent() == this) && + "iterator points outside of basic block"); + Insts.insert(I.getInstrIterator(), S, E); + } - // erase - Remove the specified element or range from the instruction list. - // These functions delete any instructions removed. - // - iterator erase(iterator I) { return Insts.erase(I); } - iterator erase(iterator I, iterator E) { return Insts.erase(I, E); } - MachineInstr *remove(MachineInstr *I) { return Insts.remove(I); } - void clear() { Insts.clear(); } + /// Insert MI into the instruction list before I. + iterator insert(iterator I, MachineInstr *MI) { + assert((I == end() || I->getParent() == this) && + "iterator points outside of basic block"); + assert(!MI->isBundledWithPred() && !MI->isBundledWithSucc() && + "Cannot insert instruction with bundle flags"); + return Insts.insert(I.getInstrIterator(), MI); + } - /// splice - Take an instruction from MBB 'Other' at the position From, - /// and insert it into this MBB right before 'where'. - void splice(iterator where, MachineBasicBlock *Other, iterator From) { - Insts.splice(where, Other->Insts, From); + /// Insert MI into the instruction list after I. + iterator insertAfter(iterator I, MachineInstr *MI) { + assert((I == end() || I->getParent() == this) && + "iterator points outside of basic block"); + assert(!MI->isBundledWithPred() && !MI->isBundledWithSucc() && + "Cannot insert instruction with bundle flags"); + return Insts.insertAfter(I.getInstrIterator(), MI); } - /// splice - Take a block of instructions from MBB 'Other' in the range [From, - /// To), and insert them into this MBB right before 'where'. - void splice(iterator where, MachineBasicBlock *Other, iterator From, - iterator To) { - Insts.splice(where, Other->Insts, From, To); + /// Remove an instruction from the instruction list and delete it. + /// + /// If the instruction is part of a bundle, the other instructions in the + /// bundle will still be bundled after removing the single instruction. + instr_iterator erase(instr_iterator I); + + /// Remove an instruction from the instruction list and delete it. + /// + /// If the instruction is part of a bundle, the other instructions in the + /// bundle will still be bundled after removing the single instruction. + instr_iterator erase_instr(MachineInstr *I) { + return erase(instr_iterator(I)); + } + + /// Remove a range of instructions from the instruction list and delete them. + iterator erase(iterator I, iterator E) { + return Insts.erase(I.getInstrIterator(), E.getInstrIterator()); + } + + /// Remove an instruction or bundle from the instruction list and delete it. + /// + /// If I points to a bundle of instructions, they are all erased. + iterator erase(iterator I) { + return erase(I, std::next(I)); + } + + /// Remove an instruction from the instruction list and delete it. + /// + /// If I is the head of a bundle of instructions, the whole bundle will be + /// erased. + iterator erase(MachineInstr *I) { + return erase(iterator(I)); + } + + /// Remove the unbundled instruction from the instruction list without + /// deleting it. + /// + /// This function can not be used to remove bundled instructions, use + /// remove_instr to remove individual instructions from a bundle. + MachineInstr *remove(MachineInstr *I) { + assert(!I->isBundled() && "Cannot remove bundled instructions"); + return Insts.remove(I); + } + + /// Remove the possibly bundled instruction from the instruction list + /// without deleting it. + /// + /// If the instruction is part of a bundle, the other instructions in the + /// bundle will still be bundled after removing the single instruction. + MachineInstr *remove_instr(MachineInstr *I); + + void clear() { + Insts.clear(); + } + + /// Take an instruction from MBB 'Other' at the position From, and insert it + /// into this MBB right before 'Where'. + /// + /// If From points to a bundle of instructions, the whole bundle is moved. + void splice(iterator Where, MachineBasicBlock *Other, iterator From) { + // The range splice() doesn't allow noop moves, but this one does. + if (Where != From) + splice(Where, Other, From, std::next(From)); + } + + /// Take a block of instructions from MBB 'Other' in the range [From, To), + /// and insert them into this MBB right before 'Where'. + /// + /// The instruction at 'Where' must not be included in the range of + /// instructions to move. + void splice(iterator Where, MachineBasicBlock *Other, + iterator From, iterator To) { + Insts.splice(Where.getInstrIterator(), Other->Insts, + From.getInstrIterator(), To.getInstrIterator()); } /// removeFromParent - This method unlinks 'this' from the containing /// function, and returns it, but does not delete it. MachineBasicBlock *removeFromParent(); - + /// eraseFromParent - This method unlinks 'this' from the containing /// function and deletes it. void eraseFromParent(); @@ -307,10 +616,42 @@ public: MachineBasicBlock *DestB, bool isCond); + /// findDebugLoc - find the next valid DebugLoc starting at MBBI, skipping + /// any DBG_VALUE instructions. Return UnknownLoc if there is none. + DebugLoc findDebugLoc(instr_iterator MBBI); + DebugLoc findDebugLoc(iterator MBBI) { + return findDebugLoc(MBBI.getInstrIterator()); + } + + /// Possible outcome of a register liveness query to computeRegisterLiveness() + enum LivenessQueryResult { + LQR_Live, ///< Register is known to be live. + LQR_OverlappingLive, ///< Register itself is not live, but some overlapping + ///< register is. + LQR_Dead, ///< Register is known to be dead. + LQR_Unknown ///< Register liveness not decidable from local + ///< neighborhood. + }; + + /// Return whether (physical) register \p Reg has been ined and not + /// ed as of just before \p Before. + /// + /// Search is localised to a neighborhood of \p Neighborhood instructions + /// before (searching for defs or kills) and \p Neighborhood instructions + /// after (searching just for defs) \p Before. + /// + /// \p Reg must be a physical register. + LivenessQueryResult computeRegisterLiveness(const TargetRegisterInfo *TRI, + unsigned Reg, + const_iterator Before, + unsigned Neighborhood=10) const; + // Debugging methods. void dump() const; - void print(std::ostream &OS) const; - void print(std::ostream *OS) const { if (OS) print(*OS); } + void print(raw_ostream &OS, SlotIndexes* = nullptr) const; + + // Printing method used by LoopInfo. + void printAsOperand(raw_ostream &OS, bool PrintType = true) const; /// getNumber - MachineBasicBlocks are uniquely numbered at the function /// level, unless they're not in a MachineFunction yet, in which case this @@ -319,7 +660,26 @@ public: int getNumber() const { return Number; } void setNumber(int N) { Number = N; } -private: // Methods used to maintain doubly linked list of blocks... + /// getSymbol - Return the MCSymbol for this basic block. + /// + MCSymbol *getSymbol() const; + + +private: + /// getWeightIterator - Return weight iterator corresponding to the I + /// successor iterator. + weight_iterator getWeightIterator(succ_iterator I); + const_weight_iterator getWeightIterator(const_succ_iterator I) const; + + friend class MachineBranchProbabilityInfo; + + /// getSuccWeight - Return weight of the edge from this block to MBB. This + /// method should NOT be called directly, but by using getEdgeWeight method + /// from MachineBranchProbabilityInfo class. + uint32_t getSuccWeight(const_succ_iterator Succ) const; + + + // Methods used to maintain doubly linked list of blocks... friend struct ilist_traits; // Machine-CFG mutators @@ -338,7 +698,15 @@ private: // Methods used to maintain doubly linked list of blocks... void removePredecessor(MachineBasicBlock *pred); }; -std::ostream& operator<<(std::ostream &OS, const MachineBasicBlock &MBB); +raw_ostream& operator<<(raw_ostream &OS, const MachineBasicBlock &MBB); + +// This is useful when building IndexedMaps keyed on basic block pointers. +struct MBB2NumberFunctor : + public std::unary_function { + unsigned operator()(const MachineBasicBlock *MBB) const { + return MBB->getNumber(); + } +}; //===--------------------------------------------------------------------===// // GraphTraits specializations for machine basic block graphs (machine-CFGs) @@ -408,6 +776,31 @@ template <> struct GraphTraits > { } }; -} // End llvm namespace + + +/// MachineInstrSpan provides an interface to get an iteration range +/// containing the instruction it was initialized with, along with all +/// those instructions inserted prior to or following that instruction +/// at some point after the MachineInstrSpan is constructed. +class MachineInstrSpan { + MachineBasicBlock &MBB; + MachineBasicBlock::iterator I, B, E; +public: + MachineInstrSpan(MachineBasicBlock::iterator I) + : MBB(*I->getParent()), + I(I), + B(I == MBB.begin() ? MBB.end() : std::prev(I)), + E(std::next(I)) {} + + MachineBasicBlock::iterator begin() { + return B == MBB.end() ? MBB.begin() : std::next(B); + } + MachineBasicBlock::iterator end() { return E; } + bool empty() { return begin() == end(); } + + MachineBasicBlock::iterator getInitial() { return I; } +}; + +} // namespace llvm #endif