third_party/LLVM/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h - SwiftShader - Git at Google

 //===-- SelectionDAGBuilder.h - Selection-DAG building --------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This implements routines for translating from LLVM IR into SelectionDAG IR.
 //
 //===----------------------------------------------------------------------===//

 #ifndef SELECTIONDAGBUILDER_H
 #define SELECTIONDAGBUILDER_H

 #include "llvm/Constants.h"
 #include "llvm/CodeGen/SelectionDAG.h"
 #include "llvm/ADT/APInt.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/CodeGen/SelectionDAGNodes.h"
 #include "llvm/CodeGen/ValueTypes.h"
 #include "llvm/Support/CallSite.h"
 #include "llvm/Support/ErrorHandling.h"
 #include <vector>

 namespace llvm {

 class AliasAnalysis;
 class AllocaInst;
 class BasicBlock;
 class BitCastInst;
 class BranchInst;
 class CallInst;
 class DbgValueInst;
 class ExtractElementInst;
 class ExtractValueInst;
 class FCmpInst;
 class FPExtInst;
 class FPToSIInst;
 class FPToUIInst;
 class FPTruncInst;
 class Function;
 class FunctionLoweringInfo;
 class GetElementPtrInst;
 class GCFunctionInfo;
 class ICmpInst;
 class IntToPtrInst;
 class IndirectBrInst;
 class InvokeInst;
 class InsertElementInst;
 class InsertValueInst;
 class Instruction;
 class LoadInst;
 class MachineBasicBlock;
 class MachineInstr;
 class MachineRegisterInfo;
 class MDNode;
 class PHINode;
 class PtrToIntInst;
 class ReturnInst;
 class SDDbgValue;
 class SExtInst;
 class SelectInst;
 class ShuffleVectorInst;
 class SIToFPInst;
 class StoreInst;
 class SwitchInst;
 class TargetData;
 class TargetLowering;
 class TruncInst;
 class UIToFPInst;
 class UnreachableInst;
 class UnwindInst;
 class VAArgInst;
 class ZExtInst;

 //===----------------------------------------------------------------------===//
 /// SelectionDAGBuilder - This is the common target-independent lowering
 /// implementation that is parameterized by a TargetLowering object.
 ///
 class SelectionDAGBuilder {
   /// CurDebugLoc - current file + line number.  Changes as we build the DAG.
   DebugLoc CurDebugLoc;

   DenseMap<const Value*, SDValue> NodeMap;

   /// UnusedArgNodeMap - Maps argument value for unused arguments. This is used
   /// to preserve debug information for incoming arguments.
   DenseMap<const Value*, SDValue> UnusedArgNodeMap;

   /// DanglingDebugInfo - Helper type for DanglingDebugInfoMap.
   class DanglingDebugInfo {
     const DbgValueInst* DI;
     DebugLoc dl;
     unsigned SDNodeOrder;
   public:
     DanglingDebugInfo() : DI(0), dl(DebugLoc()), SDNodeOrder(0) { }
     DanglingDebugInfo(const DbgValueInst *di, DebugLoc DL, unsigned SDNO) :
       DI(di), dl(DL), SDNodeOrder(SDNO) { }
     const DbgValueInst* getDI() { return DI; }
     DebugLoc getdl() { return dl; }
     unsigned getSDNodeOrder() { return SDNodeOrder; }
   };

   /// DanglingDebugInfoMap - Keeps track of dbg_values for which we have not
   /// yet seen the referent.  We defer handling these until we do see it.
   DenseMap<const Value*, DanglingDebugInfo> DanglingDebugInfoMap;

 public:
   /// PendingLoads - Loads are not emitted to the program immediately.  We bunch
   /// them up and then emit token factor nodes when possible.  This allows us to
   /// get simple disambiguation between loads without worrying about alias
   /// analysis.
   SmallVector<SDValue, 8> PendingLoads;
 private:

   /// PendingExports - CopyToReg nodes that copy values to virtual registers
   /// for export to other blocks need to be emitted before any terminator
   /// instruction, but they have no other ordering requirements. We bunch them
   /// up and the emit a single tokenfactor for them just before terminator
   /// instructions.
   SmallVector<SDValue, 8> PendingExports;

   /// SDNodeOrder - A unique monotonically increasing number used to order the
   /// SDNodes we create.
   unsigned SDNodeOrder;

   /// Case - A struct to record the Value for a switch case, and the
   /// case's target basic block.
   struct Case {
     Constant* Low;
     Constant* High;
     MachineBasicBlock* BB;
     uint32_t ExtraWeight;

     Case() : Low(0), High(0), BB(0), ExtraWeight(0) { }
     Case(Constant* low, Constant* high, MachineBasicBlock* bb,
          uint32_t extraweight) : Low(low), High(high), BB(bb),
          ExtraWeight(extraweight) { }

     APInt size() const {
       const APInt &rHigh = cast<ConstantInt>(High)->getValue();
       const APInt &rLow  = cast<ConstantInt>(Low)->getValue();
       return (rHigh - rLow + 1ULL);
     }
   };

   struct CaseBits {
     uint64_t Mask;
     MachineBasicBlock* BB;
     unsigned Bits;

     CaseBits(uint64_t mask, MachineBasicBlock* bb, unsigned bits):
       Mask(mask), BB(bb), Bits(bits) { }
   };

   typedef std::vector<Case>           CaseVector;
   typedef std::vector<CaseBits>       CaseBitsVector;
   typedef CaseVector::iterator        CaseItr;
   typedef std::pair<CaseItr, CaseItr> CaseRange;

   /// CaseRec - A struct with ctor used in lowering switches to a binary tree
   /// of conditional branches.
   struct CaseRec {
     CaseRec(MachineBasicBlock *bb, const Constant *lt, const Constant *ge,
             CaseRange r) :
     CaseBB(bb), LT(lt), GE(ge), Range(r) {}

     /// CaseBB - The MBB in which to emit the compare and branch
     MachineBasicBlock *CaseBB;
     /// LT, GE - If nonzero, we know the current case value must be less-than or
     /// greater-than-or-equal-to these Constants.
     const Constant *LT;
     const Constant *GE;
     /// Range - A pair of iterators representing the range of case values to be
     /// processed at this point in the binary search tree.
     CaseRange Range;
   };

   typedef std::vector<CaseRec> CaseRecVector;

   /// The comparison function for sorting the switch case values in the vector.
   /// WARNING: Case ranges should be disjoint!
   struct CaseCmp {
     bool operator()(const Case &C1, const Case &C2) {
       assert(isa<ConstantInt>(C1.Low) && isa<ConstantInt>(C2.High));
       const ConstantInt* CI1 = cast<const ConstantInt>(C1.Low);
       const ConstantInt* CI2 = cast<const ConstantInt>(C2.High);
       return CI1->getValue().slt(CI2->getValue());
     }
   };

   struct CaseBitsCmp {
     bool operator()(const CaseBits &C1, const CaseBits &C2) {
       return C1.Bits > C2.Bits;
     }
   };

   size_t Clusterify(CaseVector &Cases, const SwitchInst &SI);

   /// CaseBlock - This structure is used to communicate between
   /// SelectionDAGBuilder and SDISel for the code generation of additional basic
   /// blocks needed by multi-case switch statements.
   struct CaseBlock {
     CaseBlock(ISD::CondCode cc, const Value *cmplhs, const Value *cmprhs,
               const Value *cmpmiddle,
               MachineBasicBlock *truebb, MachineBasicBlock *falsebb,
               MachineBasicBlock *me,
               uint32_t trueweight = 0, uint32_t falseweight = 0)
       : CC(cc), CmpLHS(cmplhs), CmpMHS(cmpmiddle), CmpRHS(cmprhs),
         TrueBB(truebb), FalseBB(falsebb), ThisBB(me),
         TrueWeight(trueweight), FalseWeight(falseweight) { }

     // CC - the condition code to use for the case block's setcc node
     ISD::CondCode CC;

     // CmpLHS/CmpRHS/CmpMHS - The LHS/MHS/RHS of the comparison to emit.
     // Emit by default LHS op RHS. MHS is used for range comparisons:
     // If MHS is not null: (LHS <= MHS) and (MHS <= RHS).
     const Value *CmpLHS, *CmpMHS, *CmpRHS;

     // TrueBB/FalseBB - the block to branch to if the setcc is true/false.
     MachineBasicBlock *TrueBB, *FalseBB;

     // ThisBB - the block into which to emit the code for the setcc and branches
     MachineBasicBlock *ThisBB;

     // TrueWeight/FalseWeight - branch weights.
     uint32_t TrueWeight, FalseWeight;
   };

   struct JumpTable {
     JumpTable(unsigned R, unsigned J, MachineBasicBlock *M,
               MachineBasicBlock *D): Reg(R), JTI(J), MBB(M), Default(D) {}

     /// Reg - the virtual register containing the index of the jump table entry
     //. to jump to.
     unsigned Reg;
     /// JTI - the JumpTableIndex for this jump table in the function.
     unsigned JTI;
     /// MBB - the MBB into which to emit the code for the indirect jump.
     MachineBasicBlock *MBB;
     /// Default - the MBB of the default bb, which is a successor of the range
     /// check MBB.  This is when updating PHI nodes in successors.
     MachineBasicBlock *Default;
   };
   struct JumpTableHeader {
     JumpTableHeader(APInt F, APInt L, const Value *SV, MachineBasicBlock *H,
                     bool E = false):
       First(F), Last(L), SValue(SV), HeaderBB(H), Emitted(E) {}
     APInt First;
     APInt Last;
     const Value *SValue;
     MachineBasicBlock *HeaderBB;
     bool Emitted;
   };
   typedef std::pair<JumpTableHeader, JumpTable> JumpTableBlock;

   struct BitTestCase {
     BitTestCase(uint64_t M, MachineBasicBlock* T, MachineBasicBlock* Tr):
       Mask(M), ThisBB(T), TargetBB(Tr) { }
     uint64_t Mask;
     MachineBasicBlock *ThisBB;
     MachineBasicBlock *TargetBB;
   };

   typedef SmallVector<BitTestCase, 3> BitTestInfo;

   struct BitTestBlock {
     BitTestBlock(APInt F, APInt R, const Value* SV,
                  unsigned Rg, EVT RgVT, bool E,
                  MachineBasicBlock* P, MachineBasicBlock* D,
                  const BitTestInfo& C):
       First(F), Range(R), SValue(SV), Reg(Rg), RegVT(RgVT), Emitted(E),
       Parent(P), Default(D), Cases(C) { }
     APInt First;
     APInt Range;
     const Value *SValue;
     unsigned Reg;
     EVT RegVT;
     bool Emitted;
     MachineBasicBlock *Parent;
     MachineBasicBlock *Default;
     BitTestInfo Cases;
   };

 public:
   // TLI - This is information that describes the available target features we
   // need for lowering.  This indicates when operations are unavailable,
   // implemented with a libcall, etc.
   const TargetMachine &TM;
   const TargetLowering &TLI;
   SelectionDAG &DAG;
   const TargetData *TD;
   AliasAnalysis *AA;

   /// SwitchCases - Vector of CaseBlock structures used to communicate
   /// SwitchInst code generation information.
   std::vector<CaseBlock> SwitchCases;
   /// JTCases - Vector of JumpTable structures used to communicate
   /// SwitchInst code generation information.
   std::vector<JumpTableBlock> JTCases;
   /// BitTestCases - Vector of BitTestBlock structures used to communicate
   /// SwitchInst code generation information.
   std::vector<BitTestBlock> BitTestCases;

   // Emit PHI-node-operand constants only once even if used by multiple
   // PHI nodes.
   DenseMap<const Constant *, unsigned> ConstantsOut;

   /// FuncInfo - Information about the function as a whole.
   ///
   FunctionLoweringInfo &FuncInfo;

   /// OptLevel - What optimization level we're generating code for.
   ///
   CodeGenOpt::Level OptLevel;

   /// GFI - Garbage collection metadata for the function.
   GCFunctionInfo *GFI;

   /// LPadToCallSiteMap - Map a landing pad to the call site indexes.
   DenseMap<MachineBasicBlock*, SmallVector<unsigned, 4> > LPadToCallSiteMap;

   /// HasTailCall - This is set to true if a call in the current
   /// block has been translated as a tail call. In this case,
   /// no subsequent DAG nodes should be created.
   ///
   bool HasTailCall;

   LLVMContext *Context;

   SelectionDAGBuilder(SelectionDAG &dag, FunctionLoweringInfo &funcinfo,
                       CodeGenOpt::Level ol)
     : SDNodeOrder(0), TM(dag.getTarget()), TLI(dag.getTargetLoweringInfo()),
       DAG(dag), FuncInfo(funcinfo), OptLevel(ol),
       HasTailCall(false), Context(dag.getContext()) {
   }

   void init(GCFunctionInfo *gfi, AliasAnalysis &aa);

   /// clear - Clear out the current SelectionDAG and the associated
   /// state and prepare this SelectionDAGBuilder object to be used
   /// for a new block. This doesn't clear out information about
   /// additional blocks that are needed to complete switch lowering
   /// or PHI node updating; that information is cleared out as it is
   /// consumed.
   void clear();

   /// clearDanglingDebugInfo - Clear the dangling debug information
   /// map. This function is seperated from the clear so that debug
   /// information that is dangling in a basic block can be properly
   /// resolved in a different basic block. This allows the
   /// SelectionDAG to resolve dangling debug information attached
   /// to PHI nodes.
   void clearDanglingDebugInfo();

   /// getRoot - Return the current virtual root of the Selection DAG,
   /// flushing any PendingLoad items. This must be done before emitting
   /// a store or any other node that may need to be ordered after any
   /// prior load instructions.
   ///
   SDValue getRoot();

   /// getControlRoot - Similar to getRoot, but instead of flushing all the
   /// PendingLoad items, flush all the PendingExports items. It is necessary
   /// to do this before emitting a terminator instruction.
   ///
   SDValue getControlRoot();

   DebugLoc getCurDebugLoc() const { return CurDebugLoc; }

   unsigned getSDNodeOrder() const { return SDNodeOrder; }

   void CopyValueToVirtualRegister(const Value *V, unsigned Reg);

   /// AssignOrderingToNode - Assign an ordering to the node. The order is gotten
   /// from how the code appeared in the source. The ordering is used by the
   /// scheduler to effectively turn off scheduling.
   void AssignOrderingToNode(const SDNode *Node);

   void visit(const Instruction &I);

   void visit(unsigned Opcode, const User &I);

   // resolveDanglingDebugInfo - if we saw an earlier dbg_value referring to V,
   // generate the debug data structures now that we've seen its definition.
   void resolveDanglingDebugInfo(const Value *V, SDValue Val);
   SDValue getValue(const Value *V);
   SDValue getNonRegisterValue(const Value *V);
   SDValue getValueImpl(const Value *V);

   void setValue(const Value *V, SDValue NewN) {
     SDValue &N = NodeMap[V];
     assert(N.getNode() == 0 && "Already set a value for this node!");
     N = NewN;
   }

   void setUnusedArgValue(const Value *V, SDValue NewN) {
     SDValue &N = UnusedArgNodeMap[V];
     assert(N.getNode() == 0 && "Already set a value for this node!");
     N = NewN;
   }

   void FindMergedConditions(const Value *Cond, MachineBasicBlock *TBB,
                             MachineBasicBlock *FBB, MachineBasicBlock *CurBB,
                             MachineBasicBlock *SwitchBB, unsigned Opc);
   void EmitBranchForMergedCondition(const Value *Cond, MachineBasicBlock *TBB,
                                     MachineBasicBlock *FBB,
                                     MachineBasicBlock *CurBB,
                                     MachineBasicBlock *SwitchBB);
   bool ShouldEmitAsBranches(const std::vector<CaseBlock> &Cases);
   bool isExportableFromCurrentBlock(const Value *V, const BasicBlock *FromBB);
   void CopyToExportRegsIfNeeded(const Value *V);
   void ExportFromCurrentBlock(const Value *V);
   void LowerCallTo(ImmutableCallSite CS, SDValue Callee, bool IsTailCall,
                    MachineBasicBlock *LandingPad = NULL);

   /// UpdateSplitBlock - When an MBB was split during scheduling, update the
   /// references that ned to refer to the last resulting block.
   void UpdateSplitBlock(MachineBasicBlock *First, MachineBasicBlock *Last);

 private:
   // Terminator instructions.
   void visitRet(const ReturnInst &I);
   void visitBr(const BranchInst &I);
   void visitSwitch(const SwitchInst &I);
   void visitIndirectBr(const IndirectBrInst &I);
   void visitUnreachable(const UnreachableInst &I) { /* noop */ }

   // Helpers for visitSwitch
   bool handleSmallSwitchRange(CaseRec& CR,
                               CaseRecVector& WorkList,
                               const Value* SV,
                               MachineBasicBlock* Default,
                               MachineBasicBlock *SwitchBB);
   bool handleJTSwitchCase(CaseRec& CR,
                           CaseRecVector& WorkList,
                           const Value* SV,
                           MachineBasicBlock* Default,
                           MachineBasicBlock *SwitchBB);
   bool handleBTSplitSwitchCase(CaseRec& CR,
                                CaseRecVector& WorkList,
                                const Value* SV,
                                MachineBasicBlock* Default,
                                MachineBasicBlock *SwitchBB);
   bool handleBitTestsSwitchCase(CaseRec& CR,
                                 CaseRecVector& WorkList,
                                 const Value* SV,
                                 MachineBasicBlock* Default,
                                 MachineBasicBlock *SwitchBB);

   uint32_t getEdgeWeight(MachineBasicBlock *Src, MachineBasicBlock *Dst);
   void addSuccessorWithWeight(MachineBasicBlock *Src, MachineBasicBlock *Dst,
                               uint32_t Weight = 0);
 public:
   void visitSwitchCase(CaseBlock &CB,
                        MachineBasicBlock *SwitchBB);
   void visitBitTestHeader(BitTestBlock &B, MachineBasicBlock *SwitchBB);
   void visitBitTestCase(BitTestBlock &BB,
                         MachineBasicBlock* NextMBB,
                         unsigned Reg,
                         BitTestCase &B,
                         MachineBasicBlock *SwitchBB);
   void visitJumpTable(JumpTable &JT);
   void visitJumpTableHeader(JumpTable &JT, JumpTableHeader &JTH,
                             MachineBasicBlock *SwitchBB);

 private:
   // These all get lowered before this pass.
   void visitInvoke(const InvokeInst &I);
   void visitResume(const ResumeInst &I);
   void visitUnwind(const UnwindInst &I);

   void visitBinary(const User &I, unsigned OpCode);
   void visitShift(const User &I, unsigned Opcode);
   void visitAdd(const User &I)  { visitBinary(I, ISD::ADD); }
   void visitFAdd(const User &I) { visitBinary(I, ISD::FADD); }
   void visitSub(const User &I)  { visitBinary(I, ISD::SUB); }
   void visitFSub(const User &I);
   void visitMul(const User &I)  { visitBinary(I, ISD::MUL); }
   void visitFMul(const User &I) { visitBinary(I, ISD::FMUL); }
   void visitURem(const User &I) { visitBinary(I, ISD::UREM); }
   void visitSRem(const User &I) { visitBinary(I, ISD::SREM); }
   void visitFRem(const User &I) { visitBinary(I, ISD::FREM); }
   void visitUDiv(const User &I) { visitBinary(I, ISD::UDIV); }
   void visitSDiv(const User &I);
   void visitFDiv(const User &I) { visitBinary(I, ISD::FDIV); }
   void visitAnd (const User &I) { visitBinary(I, ISD::AND); }
   void visitOr  (const User &I) { visitBinary(I, ISD::OR); }
   void visitXor (const User &I) { visitBinary(I, ISD::XOR); }
   void visitShl (const User &I) { visitShift(I, ISD::SHL); }
   void visitLShr(const User &I) { visitShift(I, ISD::SRL); }
   void visitAShr(const User &I) { visitShift(I, ISD::SRA); }
   void visitICmp(const User &I);
   void visitFCmp(const User &I);
   // Visit the conversion instructions
   void visitTrunc(const User &I);
   void visitZExt(const User &I);
   void visitSExt(const User &I);
   void visitFPTrunc(const User &I);
   void visitFPExt(const User &I);
   void visitFPToUI(const User &I);
   void visitFPToSI(const User &I);
   void visitUIToFP(const User &I);
   void visitSIToFP(const User &I);
   void visitPtrToInt(const User &I);
   void visitIntToPtr(const User &I);
   void visitBitCast(const User &I);

   void visitExtractElement(const User &I);
   void visitInsertElement(const User &I);
   void visitShuffleVector(const User &I);

   void visitExtractValue(const ExtractValueInst &I);
   void visitInsertValue(const InsertValueInst &I);
   void visitLandingPad(const LandingPadInst &I);

   void visitGetElementPtr(const User &I);
   void visitSelect(const User &I);

   void visitAlloca(const AllocaInst &I);
   void visitLoad(const LoadInst &I);
   void visitStore(const StoreInst &I);
   void visitAtomicCmpXchg(const AtomicCmpXchgInst &I);
   void visitAtomicRMW(const AtomicRMWInst &I);
   void visitFence(const FenceInst &I);
   void visitPHI(const PHINode &I);
   void visitCall(const CallInst &I);
   bool visitMemCmpCall(const CallInst &I);
   void visitAtomicLoad(const LoadInst &I);
   void visitAtomicStore(const StoreInst &I);

   void visitInlineAsm(ImmutableCallSite CS);
   const char *visitIntrinsicCall(const CallInst &I, unsigned Intrinsic);
   void visitTargetIntrinsic(const CallInst &I, unsigned Intrinsic);

   void visitPow(const CallInst &I);
   void visitExp2(const CallInst &I);
   void visitExp(const CallInst &I);
   void visitLog(const CallInst &I);
   void visitLog2(const CallInst &I);
   void visitLog10(const CallInst &I);

   void visitVAStart(const CallInst &I);
   void visitVAArg(const VAArgInst &I);
   void visitVAEnd(const CallInst &I);
   void visitVACopy(const CallInst &I);

   void visitUserOp1(const Instruction &I) {
     llvm_unreachable("UserOp1 should not exist at instruction selection time!");
   }
   void visitUserOp2(const Instruction &I) {
     llvm_unreachable("UserOp2 should not exist at instruction selection time!");
   }

   const char *implVisitAluOverflow(const CallInst &I, ISD::NodeType Op);

   void HandlePHINodesInSuccessorBlocks(const BasicBlock *LLVMBB);

   /// EmitFuncArgumentDbgValue - If V is an function argument then create
   /// corresponding DBG_VALUE machine instruction for it now. At the end of
   /// instruction selection, they will be inserted to the entry BB.
   bool EmitFuncArgumentDbgValue(const Value *V, MDNode *Variable,
                                 int64_t Offset, const SDValue &N);
 };

 } // end namespace llvm

 #endif
	//===-- SelectionDAGBuilder.h - Selection-DAG building --------------------===//
	//
	// The LLVM Compiler Infrastructure
	//
	// This file is distributed under the University of Illinois Open Source
	// License. See LICENSE.TXT for details.
	//
	//===----------------------------------------------------------------------===//
	//
	// This implements routines for translating from LLVM IR into SelectionDAG IR.
	//
	//===----------------------------------------------------------------------===//

	#ifndef SELECTIONDAGBUILDER_H
	#define SELECTIONDAGBUILDER_H

	#include "llvm/Constants.h"
	#include "llvm/CodeGen/SelectionDAG.h"
	#include "llvm/ADT/APInt.h"
	#include "llvm/ADT/DenseMap.h"
	#include "llvm/CodeGen/SelectionDAGNodes.h"
	#include "llvm/CodeGen/ValueTypes.h"
	#include "llvm/Support/CallSite.h"
	#include "llvm/Support/ErrorHandling.h"
	#include <vector>

	namespace llvm {

	class AliasAnalysis;
	class AllocaInst;
	class BasicBlock;
	class BitCastInst;
	class BranchInst;
	class CallInst;
	class DbgValueInst;
	class ExtractElementInst;
	class ExtractValueInst;
	class FCmpInst;
	class FPExtInst;
	class FPToSIInst;
	class FPToUIInst;
	class FPTruncInst;
	class Function;
	class FunctionLoweringInfo;
	class GetElementPtrInst;
	class GCFunctionInfo;
	class ICmpInst;
	class IntToPtrInst;
	class IndirectBrInst;
	class InvokeInst;
	class InsertElementInst;
	class InsertValueInst;
	class Instruction;
	class LoadInst;
	class MachineBasicBlock;
	class MachineInstr;
	class MachineRegisterInfo;
	class MDNode;
	class PHINode;
	class PtrToIntInst;
	class ReturnInst;
	class SDDbgValue;
	class SExtInst;
	class SelectInst;
	class ShuffleVectorInst;
	class SIToFPInst;
	class StoreInst;
	class SwitchInst;
	class TargetData;
	class TargetLowering;
	class TruncInst;
	class UIToFPInst;
	class UnreachableInst;
	class UnwindInst;
	class VAArgInst;
	class ZExtInst;

	//===----------------------------------------------------------------------===//
	/// SelectionDAGBuilder - This is the common target-independent lowering
	/// implementation that is parameterized by a TargetLowering object.
	///
	class SelectionDAGBuilder {
	/// CurDebugLoc - current file + line number. Changes as we build the DAG.
	DebugLoc CurDebugLoc;

	DenseMap<const Value*, SDValue> NodeMap;

	/// UnusedArgNodeMap - Maps argument value for unused arguments. This is used
	/// to preserve debug information for incoming arguments.
	DenseMap<const Value*, SDValue> UnusedArgNodeMap;

	/// DanglingDebugInfo - Helper type for DanglingDebugInfoMap.
	class DanglingDebugInfo {
	const DbgValueInst* DI;
	DebugLoc dl;
	unsigned SDNodeOrder;
	public:
	DanglingDebugInfo() : DI(0), dl(DebugLoc()), SDNodeOrder(0) { }
	DanglingDebugInfo(const DbgValueInst *di, DebugLoc DL, unsigned SDNO) :
	DI(di), dl(DL), SDNodeOrder(SDNO) { }
	const DbgValueInst* getDI() { return DI; }
	DebugLoc getdl() { return dl; }
	unsigned getSDNodeOrder() { return SDNodeOrder; }
	};

	/// DanglingDebugInfoMap - Keeps track of dbg_values for which we have not
	/// yet seen the referent. We defer handling these until we do see it.
	DenseMap<const Value*, DanglingDebugInfo> DanglingDebugInfoMap;

	public:
	/// PendingLoads - Loads are not emitted to the program immediately. We bunch
	/// them up and then emit token factor nodes when possible. This allows us to
	/// get simple disambiguation between loads without worrying about alias
	/// analysis.
	SmallVector<SDValue, 8> PendingLoads;
	private:

	/// PendingExports - CopyToReg nodes that copy values to virtual registers
	/// for export to other blocks need to be emitted before any terminator
	/// instruction, but they have no other ordering requirements. We bunch them
	/// up and the emit a single tokenfactor for them just before terminator
	/// instructions.
	SmallVector<SDValue, 8> PendingExports;

	/// SDNodeOrder - A unique monotonically increasing number used to order the
	/// SDNodes we create.
	unsigned SDNodeOrder;

	/// Case - A struct to record the Value for a switch case, and the
	/// case's target basic block.
	struct Case {
	Constant* Low;
	Constant* High;
	MachineBasicBlock* BB;
	uint32_t ExtraWeight;

	Case() : Low(0), High(0), BB(0), ExtraWeight(0) { }
	Case(Constant* low, Constant* high, MachineBasicBlock* bb,
	uint32_t extraweight) : Low(low), High(high), BB(bb),
	ExtraWeight(extraweight) { }

	APInt size() const {
	const APInt &rHigh = cast<ConstantInt>(High)->getValue();
	const APInt &rLow = cast<ConstantInt>(Low)->getValue();
	return (rHigh - rLow + 1ULL);
	}
	};

	struct CaseBits {
	uint64_t Mask;
	MachineBasicBlock* BB;
	unsigned Bits;

	CaseBits(uint64_t mask, MachineBasicBlock* bb, unsigned bits):
	Mask(mask), BB(bb), Bits(bits) { }
	};

	typedef std::vector<Case> CaseVector;
	typedef std::vector<CaseBits> CaseBitsVector;
	typedef CaseVector::iterator CaseItr;
	typedef std::pair<CaseItr, CaseItr> CaseRange;

	/// CaseRec - A struct with ctor used in lowering switches to a binary tree
	/// of conditional branches.
	struct CaseRec {
	CaseRec(MachineBasicBlock bb, const Constant lt, const Constant *ge,
	CaseRange r) :
	CaseBB(bb), LT(lt), GE(ge), Range(r) {}

	/// CaseBB - The MBB in which to emit the compare and branch
	MachineBasicBlock *CaseBB;
	/// LT, GE - If nonzero, we know the current case value must be less-than or
	/// greater-than-or-equal-to these Constants.
	const Constant *LT;
	const Constant *GE;
	/// Range - A pair of iterators representing the range of case values to be
	/// processed at this point in the binary search tree.
	CaseRange Range;
	};

	typedef std::vector<CaseRec> CaseRecVector;

	/// The comparison function for sorting the switch case values in the vector.
	/// WARNING: Case ranges should be disjoint!
	struct CaseCmp {
	bool operator()(const Case &C1, const Case &C2) {
	assert(isa<ConstantInt>(C1.Low) && isa<ConstantInt>(C2.High));
	const ConstantInt* CI1 = cast<const ConstantInt>(C1.Low);
	const ConstantInt* CI2 = cast<const ConstantInt>(C2.High);
	return CI1->getValue().slt(CI2->getValue());
	}
	};

	struct CaseBitsCmp {
	bool operator()(const CaseBits &C1, const CaseBits &C2) {
	return C1.Bits > C2.Bits;
	}
	};

	size_t Clusterify(CaseVector &Cases, const SwitchInst &SI);

	/// CaseBlock - This structure is used to communicate between
	/// SelectionDAGBuilder and SDISel for the code generation of additional basic
	/// blocks needed by multi-case switch statements.
	struct CaseBlock {
	CaseBlock(ISD::CondCode cc, const Value cmplhs, const Value cmprhs,
	const Value *cmpmiddle,
	MachineBasicBlock truebb, MachineBasicBlock falsebb,
	MachineBasicBlock *me,
	uint32_t trueweight = 0, uint32_t falseweight = 0)
	: CC(cc), CmpLHS(cmplhs), CmpMHS(cmpmiddle), CmpRHS(cmprhs),
	TrueBB(truebb), FalseBB(falsebb), ThisBB(me),
	TrueWeight(trueweight), FalseWeight(falseweight) { }

	// CC - the condition code to use for the case block's setcc node
	ISD::CondCode CC;

	// CmpLHS/CmpRHS/CmpMHS - The LHS/MHS/RHS of the comparison to emit.
	// Emit by default LHS op RHS. MHS is used for range comparisons:
	// If MHS is not null: (LHS <= MHS) and (MHS <= RHS).
	const Value CmpLHS, CmpMHS, *CmpRHS;

	// TrueBB/FalseBB - the block to branch to if the setcc is true/false.
	MachineBasicBlock TrueBB, FalseBB;

	// ThisBB - the block into which to emit the code for the setcc and branches
	MachineBasicBlock *ThisBB;

	// TrueWeight/FalseWeight - branch weights.
	uint32_t TrueWeight, FalseWeight;
	};

	struct JumpTable {
	JumpTable(unsigned R, unsigned J, MachineBasicBlock *M,
	MachineBasicBlock *D): Reg(R), JTI(J), MBB(M), Default(D) {}

	/// Reg - the virtual register containing the index of the jump table entry
	//. to jump to.
	unsigned Reg;
	/// JTI - the JumpTableIndex for this jump table in the function.
	unsigned JTI;
	/// MBB - the MBB into which to emit the code for the indirect jump.
	MachineBasicBlock *MBB;
	/// Default - the MBB of the default bb, which is a successor of the range
	/// check MBB. This is when updating PHI nodes in successors.
	MachineBasicBlock *Default;
	};
	struct JumpTableHeader {
	JumpTableHeader(APInt F, APInt L, const Value SV, MachineBasicBlock H,
	bool E = false):
	First(F), Last(L), SValue(SV), HeaderBB(H), Emitted(E) {}
	APInt First;
	APInt Last;
	const Value *SValue;
	MachineBasicBlock *HeaderBB;
	bool Emitted;
	};
	typedef std::pair<JumpTableHeader, JumpTable> JumpTableBlock;

	struct BitTestCase {
	BitTestCase(uint64_t M, MachineBasicBlock* T, MachineBasicBlock* Tr):
	Mask(M), ThisBB(T), TargetBB(Tr) { }
	uint64_t Mask;
	MachineBasicBlock *ThisBB;
	MachineBasicBlock *TargetBB;
	};

	typedef SmallVector<BitTestCase, 3> BitTestInfo;

	struct BitTestBlock {
	BitTestBlock(APInt F, APInt R, const Value* SV,
	unsigned Rg, EVT RgVT, bool E,
	MachineBasicBlock* P, MachineBasicBlock* D,
	const BitTestInfo& C):
	First(F), Range(R), SValue(SV), Reg(Rg), RegVT(RgVT), Emitted(E),
	Parent(P), Default(D), Cases(C) { }
	APInt First;
	APInt Range;
	const Value *SValue;
	unsigned Reg;
	EVT RegVT;
	bool Emitted;
	MachineBasicBlock *Parent;
	MachineBasicBlock *Default;
	BitTestInfo Cases;
	};

	public:
	// TLI - This is information that describes the available target features we
	// need for lowering. This indicates when operations are unavailable,
	// implemented with a libcall, etc.
	const TargetMachine &TM;
	const TargetLowering &TLI;
	SelectionDAG &DAG;
	const TargetData *TD;
	AliasAnalysis *AA;

	/// SwitchCases - Vector of CaseBlock structures used to communicate
	/// SwitchInst code generation information.
	std::vector<CaseBlock> SwitchCases;
	/// JTCases - Vector of JumpTable structures used to communicate
	/// SwitchInst code generation information.
	std::vector<JumpTableBlock> JTCases;
	/// BitTestCases - Vector of BitTestBlock structures used to communicate
	/// SwitchInst code generation information.
	std::vector<BitTestBlock> BitTestCases;

	// Emit PHI-node-operand constants only once even if used by multiple
	// PHI nodes.
	DenseMap<const Constant *, unsigned> ConstantsOut;

	/// FuncInfo - Information about the function as a whole.
	///
	FunctionLoweringInfo &FuncInfo;

	/// OptLevel - What optimization level we're generating code for.
	///
	CodeGenOpt::Level OptLevel;

	/// GFI - Garbage collection metadata for the function.
	GCFunctionInfo *GFI;

	/// LPadToCallSiteMap - Map a landing pad to the call site indexes.
	DenseMap<MachineBasicBlock*, SmallVector<unsigned, 4> > LPadToCallSiteMap;

	/// HasTailCall - This is set to true if a call in the current
	/// block has been translated as a tail call. In this case,
	/// no subsequent DAG nodes should be created.
	///
	bool HasTailCall;

	LLVMContext *Context;

	SelectionDAGBuilder(SelectionDAG &dag, FunctionLoweringInfo &funcinfo,
	CodeGenOpt::Level ol)
	: SDNodeOrder(0), TM(dag.getTarget()), TLI(dag.getTargetLoweringInfo()),
	DAG(dag), FuncInfo(funcinfo), OptLevel(ol),
	HasTailCall(false), Context(dag.getContext()) {
	}

	void init(GCFunctionInfo *gfi, AliasAnalysis &aa);

	/// clear - Clear out the current SelectionDAG and the associated
	/// state and prepare this SelectionDAGBuilder object to be used
	/// for a new block. This doesn't clear out information about
	/// additional blocks that are needed to complete switch lowering
	/// or PHI node updating; that information is cleared out as it is
	/// consumed.
	void clear();

	/// clearDanglingDebugInfo - Clear the dangling debug information
	/// map. This function is seperated from the clear so that debug
	/// information that is dangling in a basic block can be properly
	/// resolved in a different basic block. This allows the
	/// SelectionDAG to resolve dangling debug information attached
	/// to PHI nodes.
	void clearDanglingDebugInfo();

	/// getRoot - Return the current virtual root of the Selection DAG,
	/// flushing any PendingLoad items. This must be done before emitting
	/// a store or any other node that may need to be ordered after any
	/// prior load instructions.
	///
	SDValue getRoot();

	/// getControlRoot - Similar to getRoot, but instead of flushing all the
	/// PendingLoad items, flush all the PendingExports items. It is necessary
	/// to do this before emitting a terminator instruction.
	///
	SDValue getControlRoot();

	DebugLoc getCurDebugLoc() const { return CurDebugLoc; }

	unsigned getSDNodeOrder() const { return SDNodeOrder; }

	void CopyValueToVirtualRegister(const Value *V, unsigned Reg);

	/// AssignOrderingToNode - Assign an ordering to the node. The order is gotten
	/// from how the code appeared in the source. The ordering is used by the
	/// scheduler to effectively turn off scheduling.
	void AssignOrderingToNode(const SDNode *Node);

	void visit(const Instruction &I);

	void visit(unsigned Opcode, const User &I);

	// resolveDanglingDebugInfo - if we saw an earlier dbg_value referring to V,
	// generate the debug data structures now that we've seen its definition.
	void resolveDanglingDebugInfo(const Value *V, SDValue Val);
	SDValue getValue(const Value *V);
	SDValue getNonRegisterValue(const Value *V);
	SDValue getValueImpl(const Value *V);

	void setValue(const Value *V, SDValue NewN) {
	SDValue &N = NodeMap[V];
	assert(N.getNode() == 0 && "Already set a value for this node!");
	N = NewN;
	}

	void setUnusedArgValue(const Value *V, SDValue NewN) {
	SDValue &N = UnusedArgNodeMap[V];
	assert(N.getNode() == 0 && "Already set a value for this node!");
	N = NewN;
	}

	void FindMergedConditions(const Value Cond, MachineBasicBlock TBB,
	MachineBasicBlock FBB, MachineBasicBlock CurBB,
	MachineBasicBlock *SwitchBB, unsigned Opc);
	void EmitBranchForMergedCondition(const Value Cond, MachineBasicBlock TBB,
	MachineBasicBlock *FBB,
	MachineBasicBlock *CurBB,
	MachineBasicBlock *SwitchBB);
	bool ShouldEmitAsBranches(const std::vector<CaseBlock> &Cases);
	bool isExportableFromCurrentBlock(const Value V, const BasicBlock FromBB);
	void CopyToExportRegsIfNeeded(const Value *V);
	void ExportFromCurrentBlock(const Value *V);
	void LowerCallTo(ImmutableCallSite CS, SDValue Callee, bool IsTailCall,
	MachineBasicBlock *LandingPad = NULL);

	/// UpdateSplitBlock - When an MBB was split during scheduling, update the
	/// references that ned to refer to the last resulting block.
	void UpdateSplitBlock(MachineBasicBlock First, MachineBasicBlock Last);

	private:
	// Terminator instructions.
	void visitRet(const ReturnInst &I);
	void visitBr(const BranchInst &I);
	void visitSwitch(const SwitchInst &I);
	void visitIndirectBr(const IndirectBrInst &I);
	void visitUnreachable(const UnreachableInst &I) { /* noop */ }

	// Helpers for visitSwitch
	bool handleSmallSwitchRange(CaseRec& CR,
	CaseRecVector& WorkList,
	const Value* SV,
	MachineBasicBlock* Default,
	MachineBasicBlock *SwitchBB);
	bool handleJTSwitchCase(CaseRec& CR,
	CaseRecVector& WorkList,
	const Value* SV,
	MachineBasicBlock* Default,
	MachineBasicBlock *SwitchBB);
	bool handleBTSplitSwitchCase(CaseRec& CR,
	CaseRecVector& WorkList,
	const Value* SV,
	MachineBasicBlock* Default,
	MachineBasicBlock *SwitchBB);
	bool handleBitTestsSwitchCase(CaseRec& CR,
	CaseRecVector& WorkList,
	const Value* SV,
	MachineBasicBlock* Default,
	MachineBasicBlock *SwitchBB);

	uint32_t getEdgeWeight(MachineBasicBlock Src, MachineBasicBlock Dst);
	void addSuccessorWithWeight(MachineBasicBlock Src, MachineBasicBlock Dst,
	uint32_t Weight = 0);
	public:
	void visitSwitchCase(CaseBlock &CB,
	MachineBasicBlock *SwitchBB);
	void visitBitTestHeader(BitTestBlock &B, MachineBasicBlock *SwitchBB);
	void visitBitTestCase(BitTestBlock &BB,
	MachineBasicBlock* NextMBB,
	unsigned Reg,
	BitTestCase &B,
	MachineBasicBlock *SwitchBB);
	void visitJumpTable(JumpTable &JT);
	void visitJumpTableHeader(JumpTable &JT, JumpTableHeader &JTH,
	MachineBasicBlock *SwitchBB);

	private:
	// These all get lowered before this pass.
	void visitInvoke(const InvokeInst &I);
	void visitResume(const ResumeInst &I);
	void visitUnwind(const UnwindInst &I);

	void visitBinary(const User &I, unsigned OpCode);
	void visitShift(const User &I, unsigned Opcode);
	void visitAdd(const User &I) { visitBinary(I, ISD::ADD); }
	void visitFAdd(const User &I) { visitBinary(I, ISD::FADD); }
	void visitSub(const User &I) { visitBinary(I, ISD::SUB); }
	void visitFSub(const User &I);
	void visitMul(const User &I) { visitBinary(I, ISD::MUL); }
	void visitFMul(const User &I) { visitBinary(I, ISD::FMUL); }
	void visitURem(const User &I) { visitBinary(I, ISD::UREM); }
	void visitSRem(const User &I) { visitBinary(I, ISD::SREM); }
	void visitFRem(const User &I) { visitBinary(I, ISD::FREM); }
	void visitUDiv(const User &I) { visitBinary(I, ISD::UDIV); }
	void visitSDiv(const User &I);
	void visitFDiv(const User &I) { visitBinary(I, ISD::FDIV); }
	void visitAnd (const User &I) { visitBinary(I, ISD::AND); }
	void visitOr (const User &I) { visitBinary(I, ISD::OR); }
	void visitXor (const User &I) { visitBinary(I, ISD::XOR); }
	void visitShl (const User &I) { visitShift(I, ISD::SHL); }
	void visitLShr(const User &I) { visitShift(I, ISD::SRL); }
	void visitAShr(const User &I) { visitShift(I, ISD::SRA); }
	void visitICmp(const User &I);
	void visitFCmp(const User &I);
	// Visit the conversion instructions
	void visitTrunc(const User &I);
	void visitZExt(const User &I);
	void visitSExt(const User &I);
	void visitFPTrunc(const User &I);
	void visitFPExt(const User &I);
	void visitFPToUI(const User &I);
	void visitFPToSI(const User &I);
	void visitUIToFP(const User &I);
	void visitSIToFP(const User &I);
	void visitPtrToInt(const User &I);
	void visitIntToPtr(const User &I);
	void visitBitCast(const User &I);

	void visitExtractElement(const User &I);
	void visitInsertElement(const User &I);
	void visitShuffleVector(const User &I);

	void visitExtractValue(const ExtractValueInst &I);
	void visitInsertValue(const InsertValueInst &I);
	void visitLandingPad(const LandingPadInst &I);

	void visitGetElementPtr(const User &I);
	void visitSelect(const User &I);

	void visitAlloca(const AllocaInst &I);
	void visitLoad(const LoadInst &I);
	void visitStore(const StoreInst &I);
	void visitAtomicCmpXchg(const AtomicCmpXchgInst &I);
	void visitAtomicRMW(const AtomicRMWInst &I);
	void visitFence(const FenceInst &I);
	void visitPHI(const PHINode &I);
	void visitCall(const CallInst &I);
	bool visitMemCmpCall(const CallInst &I);
	void visitAtomicLoad(const LoadInst &I);
	void visitAtomicStore(const StoreInst &I);

	void visitInlineAsm(ImmutableCallSite CS);
	const char *visitIntrinsicCall(const CallInst &I, unsigned Intrinsic);
	void visitTargetIntrinsic(const CallInst &I, unsigned Intrinsic);

	void visitPow(const CallInst &I);
	void visitExp2(const CallInst &I);
	void visitExp(const CallInst &I);
	void visitLog(const CallInst &I);
	void visitLog2(const CallInst &I);
	void visitLog10(const CallInst &I);

	void visitVAStart(const CallInst &I);
	void visitVAArg(const VAArgInst &I);
	void visitVAEnd(const CallInst &I);
	void visitVACopy(const CallInst &I);

	void visitUserOp1(const Instruction &I) {
	llvm_unreachable("UserOp1 should not exist at instruction selection time!");
	}
	void visitUserOp2(const Instruction &I) {
	llvm_unreachable("UserOp2 should not exist at instruction selection time!");
	}

	const char *implVisitAluOverflow(const CallInst &I, ISD::NodeType Op);

	void HandlePHINodesInSuccessorBlocks(const BasicBlock *LLVMBB);

	/// EmitFuncArgumentDbgValue - If V is an function argument then create
	/// corresponding DBG_VALUE machine instruction for it now. At the end of
	/// instruction selection, they will be inserted to the entry BB.
	bool EmitFuncArgumentDbgValue(const Value V, MDNode Variable,
	int64_t Offset, const SDValue &N);
	};

	} // end namespace llvm

	#endif