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Diffstat (limited to 'contrib/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h')
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diff --git a/contrib/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h b/contrib/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h new file mode 100644 index 000000000000..5f9cdb69daf7 --- /dev/null +++ b/contrib/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h @@ -0,0 +1,1077 @@ +//===- SelectionDAGBuilder.h - Selection-DAG building -----------*- C++ -*-===// +// +// 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 LLVM_LIB_CODEGEN_SELECTIONDAG_SELECTIONDAGBUILDER_H +#define LLVM_LIB_CODEGEN_SELECTIONDAG_SELECTIONDAGBUILDER_H + +#include "StatepointLowering.h" +#include "llvm/ADT/APInt.h" +#include "llvm/ADT/ArrayRef.h" +#include "llvm/ADT/DenseMap.h" +#include "llvm/ADT/SmallVector.h" +#include "llvm/Analysis/AliasAnalysis.h" +#include "llvm/CodeGen/ISDOpcodes.h" +#include "llvm/CodeGen/SelectionDAG.h" +#include "llvm/CodeGen/SelectionDAGNodes.h" +#include "llvm/CodeGen/TargetLowering.h" +#include "llvm/CodeGen/ValueTypes.h" +#include "llvm/IR/CallSite.h" +#include "llvm/IR/DebugLoc.h" +#include "llvm/IR/Instruction.h" +#include "llvm/IR/Statepoint.h" +#include "llvm/Support/BranchProbability.h" +#include "llvm/Support/CodeGen.h" +#include "llvm/Support/ErrorHandling.h" +#include "llvm/Support/MachineValueType.h" +#include <algorithm> +#include <cassert> +#include <cstdint> +#include <utility> +#include <vector> + +namespace llvm { + +class AllocaInst; +class AtomicCmpXchgInst; +class AtomicRMWInst; +class BasicBlock; +class BranchInst; +class CallInst; +class CatchPadInst; +class CatchReturnInst; +class CatchSwitchInst; +class CleanupPadInst; +class CleanupReturnInst; +class Constant; +class ConstantInt; +class ConstrainedFPIntrinsic; +class DbgValueInst; +class DataLayout; +class DIExpression; +class DILocalVariable; +class DILocation; +class FenceInst; +class FunctionLoweringInfo; +class GCFunctionInfo; +class GCRelocateInst; +class GCResultInst; +class IndirectBrInst; +class InvokeInst; +class LandingPadInst; +class LLVMContext; +class LoadInst; +class MachineBasicBlock; +class PHINode; +class ResumeInst; +class ReturnInst; +class SDDbgValue; +class StoreInst; +class SwitchInst; +class TargetLibraryInfo; +class TargetMachine; +class Type; +class VAArgInst; +class UnreachableInst; +class Use; +class User; +class Value; + +//===----------------------------------------------------------------------===// +/// SelectionDAGBuilder - This is the common target-independent lowering +/// implementation that is parameterized by a TargetLowering object. +/// +class SelectionDAGBuilder { + /// CurInst - The current instruction being visited + const Instruction *CurInst = nullptr; + + 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 = nullptr; + DebugLoc dl; + unsigned SDNodeOrder = 0; + + public: + DanglingDebugInfo() = default; + DanglingDebugInfo(const DbgValueInst *di, DebugLoc DL, unsigned SDNO) + : DI(di), dl(std::move(DL)), SDNodeOrder(SDNO) {} + + const DbgValueInst* getDI() { return DI; } + DebugLoc getdl() { return dl; } + unsigned getSDNodeOrder() { return SDNodeOrder; } + }; + + /// DanglingDebugInfoVector - Helper type for DanglingDebugInfoMap. + typedef std::vector<DanglingDebugInfo> DanglingDebugInfoVector; + + /// 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*, DanglingDebugInfoVector> 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; + + /// State used while lowering a statepoint sequence (gc_statepoint, + /// gc_relocate, and gc_result). See StatepointLowering.hpp/cpp for details. + StatepointLoweringState StatepointLowering; + +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; + + enum CaseClusterKind { + /// A cluster of adjacent case labels with the same destination, or just one + /// case. + CC_Range, + /// A cluster of cases suitable for jump table lowering. + CC_JumpTable, + /// A cluster of cases suitable for bit test lowering. + CC_BitTests + }; + + /// A cluster of case labels. + struct CaseCluster { + CaseClusterKind Kind; + const ConstantInt *Low, *High; + union { + MachineBasicBlock *MBB; + unsigned JTCasesIndex; + unsigned BTCasesIndex; + }; + BranchProbability Prob; + + static CaseCluster range(const ConstantInt *Low, const ConstantInt *High, + MachineBasicBlock *MBB, BranchProbability Prob) { + CaseCluster C; + C.Kind = CC_Range; + C.Low = Low; + C.High = High; + C.MBB = MBB; + C.Prob = Prob; + return C; + } + + static CaseCluster jumpTable(const ConstantInt *Low, + const ConstantInt *High, unsigned JTCasesIndex, + BranchProbability Prob) { + CaseCluster C; + C.Kind = CC_JumpTable; + C.Low = Low; + C.High = High; + C.JTCasesIndex = JTCasesIndex; + C.Prob = Prob; + return C; + } + + static CaseCluster bitTests(const ConstantInt *Low, const ConstantInt *High, + unsigned BTCasesIndex, BranchProbability Prob) { + CaseCluster C; + C.Kind = CC_BitTests; + C.Low = Low; + C.High = High; + C.BTCasesIndex = BTCasesIndex; + C.Prob = Prob; + return C; + } + }; + + using CaseClusterVector = std::vector<CaseCluster>; + using CaseClusterIt = CaseClusterVector::iterator; + + struct CaseBits { + uint64_t Mask = 0; + MachineBasicBlock* BB = nullptr; + unsigned Bits = 0; + BranchProbability ExtraProb; + + CaseBits() = default; + CaseBits(uint64_t mask, MachineBasicBlock* bb, unsigned bits, + BranchProbability Prob): + Mask(mask), BB(bb), Bits(bits), ExtraProb(Prob) {} + }; + + using CaseBitsVector = std::vector<CaseBits>; + + /// Sort Clusters and merge adjacent cases. + void sortAndRangeify(CaseClusterVector &Clusters); + + /// 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 { + // 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; + + /// The debug location of the instruction this CaseBlock was + /// produced from. + SDLoc DL; + + // TrueProb/FalseProb - branch weights. + BranchProbability TrueProb, FalseProb; + + CaseBlock(ISD::CondCode cc, const Value *cmplhs, const Value *cmprhs, + const Value *cmpmiddle, MachineBasicBlock *truebb, + MachineBasicBlock *falsebb, MachineBasicBlock *me, + SDLoc dl, + BranchProbability trueprob = BranchProbability::getUnknown(), + BranchProbability falseprob = BranchProbability::getUnknown()) + : CC(cc), CmpLHS(cmplhs), CmpMHS(cmpmiddle), CmpRHS(cmprhs), + TrueBB(truebb), FalseBB(falsebb), ThisBB(me), DL(dl), + TrueProb(trueprob), FalseProb(falseprob) {} + }; + + struct JumpTable { + /// 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; + + JumpTable(unsigned R, unsigned J, MachineBasicBlock *M, + MachineBasicBlock *D): Reg(R), JTI(J), MBB(M), Default(D) {} + }; + struct JumpTableHeader { + APInt First; + APInt Last; + const Value *SValue; + MachineBasicBlock *HeaderBB; + bool Emitted; + + JumpTableHeader(APInt F, APInt L, const Value *SV, MachineBasicBlock *H, + bool E = false) + : First(std::move(F)), Last(std::move(L)), SValue(SV), HeaderBB(H), + Emitted(E) {} + }; + using JumpTableBlock = std::pair<JumpTableHeader, JumpTable>; + + struct BitTestCase { + uint64_t Mask; + MachineBasicBlock *ThisBB; + MachineBasicBlock *TargetBB; + BranchProbability ExtraProb; + + BitTestCase(uint64_t M, MachineBasicBlock* T, MachineBasicBlock* Tr, + BranchProbability Prob): + Mask(M), ThisBB(T), TargetBB(Tr), ExtraProb(Prob) {} + }; + + using BitTestInfo = SmallVector<BitTestCase, 3>; + + struct BitTestBlock { + APInt First; + APInt Range; + const Value *SValue; + unsigned Reg; + MVT RegVT; + bool Emitted; + bool ContiguousRange; + MachineBasicBlock *Parent; + MachineBasicBlock *Default; + BitTestInfo Cases; + BranchProbability Prob; + BranchProbability DefaultProb; + + BitTestBlock(APInt F, APInt R, const Value *SV, unsigned Rg, MVT RgVT, + bool E, bool CR, MachineBasicBlock *P, MachineBasicBlock *D, + BitTestInfo C, BranchProbability Pr) + : First(std::move(F)), Range(std::move(R)), SValue(SV), Reg(Rg), + RegVT(RgVT), Emitted(E), ContiguousRange(CR), Parent(P), Default(D), + Cases(std::move(C)), Prob(Pr) {} + }; + + /// Return the range of value in [First..Last]. + uint64_t getJumpTableRange(const CaseClusterVector &Clusters, unsigned First, + unsigned Last) const; + + /// Return the number of cases in [First..Last]. + uint64_t getJumpTableNumCases(const SmallVectorImpl<unsigned> &TotalCases, + unsigned First, unsigned Last) const; + + /// Build a jump table cluster from Clusters[First..Last]. Returns false if it + /// decides it's not a good idea. + bool buildJumpTable(const CaseClusterVector &Clusters, unsigned First, + unsigned Last, const SwitchInst *SI, + MachineBasicBlock *DefaultMBB, CaseCluster &JTCluster); + + /// Find clusters of cases suitable for jump table lowering. + void findJumpTables(CaseClusterVector &Clusters, const SwitchInst *SI, + MachineBasicBlock *DefaultMBB); + + /// Build a bit test cluster from Clusters[First..Last]. Returns false if it + /// decides it's not a good idea. + bool buildBitTests(CaseClusterVector &Clusters, unsigned First, unsigned Last, + const SwitchInst *SI, CaseCluster &BTCluster); + + /// Find clusters of cases suitable for bit test lowering. + void findBitTestClusters(CaseClusterVector &Clusters, const SwitchInst *SI); + + struct SwitchWorkListItem { + MachineBasicBlock *MBB; + CaseClusterIt FirstCluster; + CaseClusterIt LastCluster; + const ConstantInt *GE; + const ConstantInt *LT; + BranchProbability DefaultProb; + }; + using SwitchWorkList = SmallVector<SwitchWorkListItem, 4>; + + /// Determine the rank by weight of CC in [First,Last]. If CC has more weight + /// than each cluster in the range, its rank is 0. + static unsigned caseClusterRank(const CaseCluster &CC, CaseClusterIt First, + CaseClusterIt Last); + + /// Emit comparison and split W into two subtrees. + void splitWorkItem(SwitchWorkList &WorkList, const SwitchWorkListItem &W, + Value *Cond, MachineBasicBlock *SwitchMBB); + + /// Lower W. + void lowerWorkItem(SwitchWorkListItem W, Value *Cond, + MachineBasicBlock *SwitchMBB, + MachineBasicBlock *DefaultMBB); + + /// Peel the top probability case if it exceeds the threshold + MachineBasicBlock *peelDominantCaseCluster(const SwitchInst &SI, + CaseClusterVector &Clusters, + BranchProbability &PeeledCaseProb); + + /// A class which encapsulates all of the information needed to generate a + /// stack protector check and signals to isel via its state being initialized + /// that a stack protector needs to be generated. + /// + /// *NOTE* The following is a high level documentation of SelectionDAG Stack + /// Protector Generation. The reason that it is placed here is for a lack of + /// other good places to stick it. + /// + /// High Level Overview of SelectionDAG Stack Protector Generation: + /// + /// Previously, generation of stack protectors was done exclusively in the + /// pre-SelectionDAG Codegen LLVM IR Pass "Stack Protector". This necessitated + /// splitting basic blocks at the IR level to create the success/failure basic + /// blocks in the tail of the basic block in question. As a result of this, + /// calls that would have qualified for the sibling call optimization were no + /// longer eligible for optimization since said calls were no longer right in + /// the "tail position" (i.e. the immediate predecessor of a ReturnInst + /// instruction). + /// + /// Then it was noticed that since the sibling call optimization causes the + /// callee to reuse the caller's stack, if we could delay the generation of + /// the stack protector check until later in CodeGen after the sibling call + /// decision was made, we get both the tail call optimization and the stack + /// protector check! + /// + /// A few goals in solving this problem were: + /// + /// 1. Preserve the architecture independence of stack protector generation. + /// + /// 2. Preserve the normal IR level stack protector check for platforms like + /// OpenBSD for which we support platform-specific stack protector + /// generation. + /// + /// The main problem that guided the present solution is that one can not + /// solve this problem in an architecture independent manner at the IR level + /// only. This is because: + /// + /// 1. The decision on whether or not to perform a sibling call on certain + /// platforms (for instance i386) requires lower level information + /// related to available registers that can not be known at the IR level. + /// + /// 2. Even if the previous point were not true, the decision on whether to + /// perform a tail call is done in LowerCallTo in SelectionDAG which + /// occurs after the Stack Protector Pass. As a result, one would need to + /// put the relevant callinst into the stack protector check success + /// basic block (where the return inst is placed) and then move it back + /// later at SelectionDAG/MI time before the stack protector check if the + /// tail call optimization failed. The MI level option was nixed + /// immediately since it would require platform-specific pattern + /// matching. The SelectionDAG level option was nixed because + /// SelectionDAG only processes one IR level basic block at a time + /// implying one could not create a DAG Combine to move the callinst. + /// + /// To get around this problem a few things were realized: + /// + /// 1. While one can not handle multiple IR level basic blocks at the + /// SelectionDAG Level, one can generate multiple machine basic blocks + /// for one IR level basic block. This is how we handle bit tests and + /// switches. + /// + /// 2. At the MI level, tail calls are represented via a special return + /// MIInst called "tcreturn". Thus if we know the basic block in which we + /// wish to insert the stack protector check, we get the correct behavior + /// by always inserting the stack protector check right before the return + /// statement. This is a "magical transformation" since no matter where + /// the stack protector check intrinsic is, we always insert the stack + /// protector check code at the end of the BB. + /// + /// Given the aforementioned constraints, the following solution was devised: + /// + /// 1. On platforms that do not support SelectionDAG stack protector check + /// generation, allow for the normal IR level stack protector check + /// generation to continue. + /// + /// 2. On platforms that do support SelectionDAG stack protector check + /// generation: + /// + /// a. Use the IR level stack protector pass to decide if a stack + /// protector is required/which BB we insert the stack protector check + /// in by reusing the logic already therein. If we wish to generate a + /// stack protector check in a basic block, we place a special IR + /// intrinsic called llvm.stackprotectorcheck right before the BB's + /// returninst or if there is a callinst that could potentially be + /// sibling call optimized, before the call inst. + /// + /// b. Then when a BB with said intrinsic is processed, we codegen the BB + /// normally via SelectBasicBlock. In said process, when we visit the + /// stack protector check, we do not actually emit anything into the + /// BB. Instead, we just initialize the stack protector descriptor + /// class (which involves stashing information/creating the success + /// mbbb and the failure mbb if we have not created one for this + /// function yet) and export the guard variable that we are going to + /// compare. + /// + /// c. After we finish selecting the basic block, in FinishBasicBlock if + /// the StackProtectorDescriptor attached to the SelectionDAGBuilder is + /// initialized, we produce the validation code with one of these + /// techniques: + /// 1) with a call to a guard check function + /// 2) with inlined instrumentation + /// + /// 1) We insert a call to the check function before the terminator. + /// + /// 2) We first find a splice point in the parent basic block + /// before the terminator and then splice the terminator of said basic + /// block into the success basic block. Then we code-gen a new tail for + /// the parent basic block consisting of the two loads, the comparison, + /// and finally two branches to the success/failure basic blocks. We + /// conclude by code-gening the failure basic block if we have not + /// code-gened it already (all stack protector checks we generate in + /// the same function, use the same failure basic block). + class StackProtectorDescriptor { + public: + StackProtectorDescriptor() = default; + + /// Returns true if all fields of the stack protector descriptor are + /// initialized implying that we should/are ready to emit a stack protector. + bool shouldEmitStackProtector() const { + return ParentMBB && SuccessMBB && FailureMBB; + } + + bool shouldEmitFunctionBasedCheckStackProtector() const { + return ParentMBB && !SuccessMBB && !FailureMBB; + } + + /// Initialize the stack protector descriptor structure for a new basic + /// block. + void initialize(const BasicBlock *BB, MachineBasicBlock *MBB, + bool FunctionBasedInstrumentation) { + // Make sure we are not initialized yet. + assert(!shouldEmitStackProtector() && "Stack Protector Descriptor is " + "already initialized!"); + ParentMBB = MBB; + if (!FunctionBasedInstrumentation) { + SuccessMBB = AddSuccessorMBB(BB, MBB, /* IsLikely */ true); + FailureMBB = AddSuccessorMBB(BB, MBB, /* IsLikely */ false, FailureMBB); + } + } + + /// Reset state that changes when we handle different basic blocks. + /// + /// This currently includes: + /// + /// 1. The specific basic block we are generating a + /// stack protector for (ParentMBB). + /// + /// 2. The successor machine basic block that will contain the tail of + /// parent mbb after we create the stack protector check (SuccessMBB). This + /// BB is visited only on stack protector check success. + void resetPerBBState() { + ParentMBB = nullptr; + SuccessMBB = nullptr; + } + + /// Reset state that only changes when we switch functions. + /// + /// This currently includes: + /// + /// 1. FailureMBB since we reuse the failure code path for all stack + /// protector checks created in an individual function. + /// + /// 2.The guard variable since the guard variable we are checking against is + /// always the same. + void resetPerFunctionState() { + FailureMBB = nullptr; + } + + MachineBasicBlock *getParentMBB() { return ParentMBB; } + MachineBasicBlock *getSuccessMBB() { return SuccessMBB; } + MachineBasicBlock *getFailureMBB() { return FailureMBB; } + + private: + /// The basic block for which we are generating the stack protector. + /// + /// As a result of stack protector generation, we will splice the + /// terminators of this basic block into the successor mbb SuccessMBB and + /// replace it with a compare/branch to the successor mbbs + /// SuccessMBB/FailureMBB depending on whether or not the stack protector + /// was violated. + MachineBasicBlock *ParentMBB = nullptr; + + /// A basic block visited on stack protector check success that contains the + /// terminators of ParentMBB. + MachineBasicBlock *SuccessMBB = nullptr; + + /// This basic block visited on stack protector check failure that will + /// contain a call to __stack_chk_fail(). + MachineBasicBlock *FailureMBB = nullptr; + + /// Add a successor machine basic block to ParentMBB. If the successor mbb + /// has not been created yet (i.e. if SuccMBB = 0), then the machine basic + /// block will be created. Assign a large weight if IsLikely is true. + MachineBasicBlock *AddSuccessorMBB(const BasicBlock *BB, + MachineBasicBlock *ParentMBB, + bool IsLikely, + MachineBasicBlock *SuccMBB = nullptr); + }; + +private: + const TargetMachine &TM; + +public: + /// Lowest valid SDNodeOrder. The special case 0 is reserved for scheduling + /// nodes without a corresponding SDNode. + static const unsigned LowestSDNodeOrder = 1; + + SelectionDAG &DAG; + const DataLayout *DL = nullptr; + AliasAnalysis *AA = nullptr; + const TargetLibraryInfo *LibInfo; + + /// 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; + + /// A StackProtectorDescriptor structure used to communicate stack protector + /// information in between SelectBasicBlock and FinishBasicBlock. + StackProtectorDescriptor SPDescriptor; + + // 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; + + /// 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 = false; + + LLVMContext *Context; + + SelectionDAGBuilder(SelectionDAG &dag, FunctionLoweringInfo &funcinfo, + CodeGenOpt::Level ol) + : SDNodeOrder(LowestSDNodeOrder), TM(dag.getTarget()), DAG(dag), + FuncInfo(funcinfo) {} + + void init(GCFunctionInfo *gfi, AliasAnalysis *AA, + const TargetLibraryInfo *li); + + /// 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(); + + /// Clear the dangling debug information map. This function is separated 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(); + + /// 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(); + + /// 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(); + + SDLoc getCurSDLoc() const { + return SDLoc(CurInst, SDNodeOrder); + } + + DebugLoc getCurDebugLoc() const { + return CurInst ? CurInst->getDebugLoc() : DebugLoc(); + } + + void CopyValueToVirtualRegister(const Value *V, unsigned Reg); + + void visit(const Instruction &I); + + void visit(unsigned Opcode, const User &I); + + /// getCopyFromRegs - If there was virtual register allocated for the value V + /// emit CopyFromReg of the specified type Ty. Return empty SDValue() otherwise. + SDValue getCopyFromRegs(const Value *V, Type *Ty); + + /// If we have dangling debug info that describes \p Variable, or an + /// overlapping part of variable considering the \p Expr, then this method + /// weill drop that debug info as it isn't valid any longer. + void dropDanglingDebugInfo(const DILocalVariable *Variable, + const DIExpression *Expr); + + // 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); + bool findValue(const Value *V) const; + + /// Return the SDNode for the specified IR value if it exists. + SDNode *getNodeForIRValue(const Value *V) { + if (NodeMap.find(V) == NodeMap.end()) + return nullptr; + return NodeMap[V].getNode(); + } + + SDValue getNonRegisterValue(const Value *V); + SDValue getValueImpl(const Value *V); + + void setValue(const Value *V, SDValue NewN) { + SDValue &N = NodeMap[V]; + assert(!N.getNode() && "Already set a value for this node!"); + N = NewN; + } + + void setUnusedArgValue(const Value *V, SDValue NewN) { + SDValue &N = UnusedArgNodeMap[V]; + assert(!N.getNode() && "Already set a value for this node!"); + N = NewN; + } + + void FindMergedConditions(const Value *Cond, MachineBasicBlock *TBB, + MachineBasicBlock *FBB, MachineBasicBlock *CurBB, + MachineBasicBlock *SwitchBB, + Instruction::BinaryOps Opc, BranchProbability TProb, + BranchProbability FProb, bool InvertCond); + void EmitBranchForMergedCondition(const Value *Cond, MachineBasicBlock *TBB, + MachineBasicBlock *FBB, + MachineBasicBlock *CurBB, + MachineBasicBlock *SwitchBB, + BranchProbability TProb, BranchProbability FProb, + bool InvertCond); + 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, + const BasicBlock *EHPadBB = nullptr); + + // Lower range metadata from 0 to N to assert zext to an integer of nearest + // floor power of two. + SDValue lowerRangeToAssertZExt(SelectionDAG &DAG, const Instruction &I, + SDValue Op); + + void populateCallLoweringInfo(TargetLowering::CallLoweringInfo &CLI, + ImmutableCallSite CS, unsigned ArgIdx, + unsigned NumArgs, SDValue Callee, + Type *ReturnTy, bool IsPatchPoint); + + std::pair<SDValue, SDValue> + lowerInvokable(TargetLowering::CallLoweringInfo &CLI, + const BasicBlock *EHPadBB = nullptr); + + /// UpdateSplitBlock - When an MBB was split during scheduling, update the + /// references that need to refer to the last resulting block. + void UpdateSplitBlock(MachineBasicBlock *First, MachineBasicBlock *Last); + + /// Describes a gc.statepoint or a gc.statepoint like thing for the purposes + /// of lowering into a STATEPOINT node. + struct StatepointLoweringInfo { + /// Bases[i] is the base pointer for Ptrs[i]. Together they denote the set + /// of gc pointers this STATEPOINT has to relocate. + SmallVector<const Value *, 16> Bases; + SmallVector<const Value *, 16> Ptrs; + + /// The set of gc.relocate calls associated with this gc.statepoint. + SmallVector<const GCRelocateInst *, 16> GCRelocates; + + /// The full list of gc arguments to the gc.statepoint being lowered. + ArrayRef<const Use> GCArgs; + + /// The gc.statepoint instruction. + const Instruction *StatepointInstr = nullptr; + + /// The list of gc transition arguments present in the gc.statepoint being + /// lowered. + ArrayRef<const Use> GCTransitionArgs; + + /// The ID that the resulting STATEPOINT instruction has to report. + unsigned ID = -1; + + /// Information regarding the underlying call instruction. + TargetLowering::CallLoweringInfo CLI; + + /// The deoptimization state associated with this gc.statepoint call, if + /// any. + ArrayRef<const Use> DeoptState; + + /// Flags associated with the meta arguments being lowered. + uint64_t StatepointFlags = -1; + + /// The number of patchable bytes the call needs to get lowered into. + unsigned NumPatchBytes = -1; + + /// The exception handling unwind destination, in case this represents an + /// invoke of gc.statepoint. + const BasicBlock *EHPadBB = nullptr; + + explicit StatepointLoweringInfo(SelectionDAG &DAG) : CLI(DAG) {} + }; + + /// Lower \p SLI into a STATEPOINT instruction. + SDValue LowerAsSTATEPOINT(StatepointLoweringInfo &SI); + + // This function is responsible for the whole statepoint lowering process. + // It uniformly handles invoke and call statepoints. + void LowerStatepoint(ImmutableStatepoint ISP, + const BasicBlock *EHPadBB = nullptr); + + void LowerCallSiteWithDeoptBundle(ImmutableCallSite CS, SDValue Callee, + const BasicBlock *EHPadBB); + + void LowerDeoptimizeCall(const CallInst *CI); + void LowerDeoptimizingReturn(); + + void LowerCallSiteWithDeoptBundleImpl(ImmutableCallSite CS, SDValue Callee, + const BasicBlock *EHPadBB, + bool VarArgDisallowed, + bool ForceVoidReturnTy); + + /// Returns the type of FrameIndex and TargetFrameIndex nodes. + MVT getFrameIndexTy() { + return DAG.getTargetLoweringInfo().getFrameIndexTy(DAG.getDataLayout()); + } + +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); + void visitCleanupRet(const CleanupReturnInst &I); + void visitCatchSwitch(const CatchSwitchInst &I); + void visitCatchRet(const CatchReturnInst &I); + void visitCatchPad(const CatchPadInst &I); + void visitCleanupPad(const CleanupPadInst &CPI); + + BranchProbability getEdgeProbability(const MachineBasicBlock *Src, + const MachineBasicBlock *Dst) const; + void addSuccessorWithProb( + MachineBasicBlock *Src, MachineBasicBlock *Dst, + BranchProbability Prob = BranchProbability::getUnknown()); + +public: + void visitSwitchCase(CaseBlock &CB, + MachineBasicBlock *SwitchBB); + void visitSPDescriptorParent(StackProtectorDescriptor &SPD, + MachineBasicBlock *ParentBB); + void visitSPDescriptorFailure(StackProtectorDescriptor &SPD); + void visitBitTestHeader(BitTestBlock &B, MachineBasicBlock *SwitchBB); + void visitBitTestCase(BitTestBlock &BB, + MachineBasicBlock* NextMBB, + BranchProbability BranchProbToNext, + 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 visitUnary(const User &I, unsigned Opcode); + void visitFNeg(const User &I) { visitUnary(I, ISD::FNEG); } + + 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 visitAddrSpaceCast(const User &I); + + void visitExtractElement(const User &I); + void visitInsertElement(const User &I); + void visitShuffleVector(const User &I); + + void visitExtractValue(const User &I); + void visitInsertValue(const User &I); + void visitLandingPad(const LandingPadInst &LP); + + 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 visitMaskedLoad(const CallInst &I, bool IsExpanding = false); + void visitMaskedStore(const CallInst &I, bool IsCompressing = false); + void visitMaskedGather(const CallInst &I); + void visitMaskedScatter(const CallInst &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); + bool visitMemPCpyCall(const CallInst &I); + bool visitMemChrCall(const CallInst &I); + bool visitStrCpyCall(const CallInst &I, bool isStpcpy); + bool visitStrCmpCall(const CallInst &I); + bool visitStrLenCall(const CallInst &I); + bool visitStrNLenCall(const CallInst &I); + bool visitUnaryFloatCall(const CallInst &I, unsigned Opcode); + bool visitBinaryFloatCall(const CallInst &I, unsigned Opcode); + void visitAtomicLoad(const LoadInst &I); + void visitAtomicStore(const StoreInst &I); + void visitLoadFromSwiftError(const LoadInst &I); + void visitStoreToSwiftError(const StoreInst &I); + + void visitInlineAsm(ImmutableCallSite CS); + const char *visitIntrinsicCall(const CallInst &I, unsigned Intrinsic); + void visitTargetIntrinsic(const CallInst &I, unsigned Intrinsic); + void visitConstrainedFPIntrinsic(const ConstrainedFPIntrinsic &FPI); + + void visitVAStart(const CallInst &I); + void visitVAArg(const VAArgInst &I); + void visitVAEnd(const CallInst &I); + void visitVACopy(const CallInst &I); + void visitStackmap(const CallInst &I); + void visitPatchpoint(ImmutableCallSite CS, + const BasicBlock *EHPadBB = nullptr); + + // These two are implemented in StatepointLowering.cpp + void visitGCRelocate(const GCRelocateInst &Relocate); + void visitGCResult(const GCResultInst &I); + + void visitVectorReduce(const CallInst &I, unsigned Intrinsic); + + 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!"); + } + + void processIntegerCallValue(const Instruction &I, + SDValue Value, bool IsSigned); + + void HandlePHINodesInSuccessorBlocks(const BasicBlock *LLVMBB); + + void emitInlineAsmError(ImmutableCallSite CS, const Twine &Message); + + /// 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, DILocalVariable *Variable, + DIExpression *Expr, DILocation *DL, + bool IsDbgDeclare, const SDValue &N); + + /// Return the next block after MBB, or nullptr if there is none. + MachineBasicBlock *NextBlock(MachineBasicBlock *MBB); + + /// Update the DAG and DAG builder with the relevant information after + /// a new root node has been created which could be a tail call. + void updateDAGForMaybeTailCall(SDValue MaybeTC); + + /// Return the appropriate SDDbgValue based on N. + SDDbgValue *getDbgValue(SDValue N, DILocalVariable *Variable, + DIExpression *Expr, const DebugLoc &dl, + unsigned DbgSDNodeOrder); +}; + +/// RegsForValue - This struct represents the registers (physical or virtual) +/// that a particular set of values is assigned, and the type information about +/// the value. The most common situation is to represent one value at a time, +/// but struct or array values are handled element-wise as multiple values. The +/// splitting of aggregates is performed recursively, so that we never have +/// aggregate-typed registers. The values at this point do not necessarily have +/// legal types, so each value may require one or more registers of some legal +/// type. +/// +struct RegsForValue { + /// The value types of the values, which may not be legal, and + /// may need be promoted or synthesized from one or more registers. + SmallVector<EVT, 4> ValueVTs; + + /// The value types of the registers. This is the same size as ValueVTs and it + /// records, for each value, what the type of the assigned register or + /// registers are. (Individual values are never synthesized from more than one + /// type of register.) + /// + /// With virtual registers, the contents of RegVTs is redundant with TLI's + /// getRegisterType member function, however when with physical registers + /// it is necessary to have a separate record of the types. + SmallVector<MVT, 4> RegVTs; + + /// This list holds the registers assigned to the values. + /// Each legal or promoted value requires one register, and each + /// expanded value requires multiple registers. + SmallVector<unsigned, 4> Regs; + + /// This list holds the number of registers for each value. + SmallVector<unsigned, 4> RegCount; + + /// Records if this value needs to be treated in an ABI dependant manner, + /// different to normal type legalization. + Optional<CallingConv::ID> CallConv; + + RegsForValue() = default; + RegsForValue(const SmallVector<unsigned, 4> ®s, MVT regvt, EVT valuevt, + Optional<CallingConv::ID> CC = None); + RegsForValue(LLVMContext &Context, const TargetLowering &TLI, + const DataLayout &DL, unsigned Reg, Type *Ty, + Optional<CallingConv::ID> CC); + + bool isABIMangled() const { + return CallConv.hasValue(); + } + + /// Add the specified values to this one. + void append(const RegsForValue &RHS) { + ValueVTs.append(RHS.ValueVTs.begin(), RHS.ValueVTs.end()); + RegVTs.append(RHS.RegVTs.begin(), RHS.RegVTs.end()); + Regs.append(RHS.Regs.begin(), RHS.Regs.end()); + RegCount.push_back(RHS.Regs.size()); + } + + /// Emit a series of CopyFromReg nodes that copies from this value and returns + /// the result as a ValueVTs value. This uses Chain/Flag as the input and + /// updates them for the output Chain/Flag. If the Flag pointer is NULL, no + /// flag is used. + SDValue getCopyFromRegs(SelectionDAG &DAG, FunctionLoweringInfo &FuncInfo, + const SDLoc &dl, SDValue &Chain, SDValue *Flag, + const Value *V = nullptr) const; + + /// Emit a series of CopyToReg nodes that copies the specified value into the + /// registers specified by this object. This uses Chain/Flag as the input and + /// updates them for the output Chain/Flag. If the Flag pointer is nullptr, no + /// flag is used. If V is not nullptr, then it is used in printing better + /// diagnostic messages on error. + void getCopyToRegs(SDValue Val, SelectionDAG &DAG, const SDLoc &dl, + SDValue &Chain, SDValue *Flag, const Value *V = nullptr, + ISD::NodeType PreferredExtendType = ISD::ANY_EXTEND) const; + + /// Add this value to the specified inlineasm node operand list. This adds the + /// code marker, matching input operand index (if applicable), and includes + /// the number of values added into it. + void AddInlineAsmOperands(unsigned Code, bool HasMatching, + unsigned MatchingIdx, const SDLoc &dl, + SelectionDAG &DAG, std::vector<SDValue> &Ops) const; + + /// Check if the total RegCount is greater than one. + bool occupiesMultipleRegs() const { + return std::accumulate(RegCount.begin(), RegCount.end(), 0) > 1; + } + + /// Return a list of registers and their sizes. + SmallVector<std::pair<unsigned, unsigned>, 4> getRegsAndSizes() const; +}; + +} // end namespace llvm + +#endif // LLVM_LIB_CODEGEN_SELECTIONDAG_SELECTIONDAGBUILDER_H |