llvm/lib/Target/SPIRV/SPIRVModuleAnalysis.h

//===- SPIRVModuleAnalysis.h - analysis of global instrs & regs -*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// The analysis collects instructions that should be output at the module level
// and performs the global register numbering.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_LIB_TARGET_SPIRV_SPIRVMODULEANALYSIS_H
#define LLVM_LIB_TARGET_SPIRV_SPIRVMODULEANALYSIS_H

#include "MCTargetDesc/SPIRVBaseInfo.h"
#include "SPIRVGlobalRegistry.h"
#include "SPIRVUtils.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/SmallVector.h"

namespace llvm {
class SPIRVSubtarget;
class MachineFunction;
class MachineModuleInfo;

namespace SPIRV {
// The enum contains logical module sections for the instruction collection.
enum ModuleSectionType {
  //  MB_Capabilities, MB_Extensions, MB_ExtInstImports, MB_MemoryModel,
  MB_EntryPoints, // All OpEntryPoint instructions (if any).
  //  MB_ExecutionModes, MB_DebugSourceAndStrings,
  MB_DebugNames,           // All OpName and OpMemberName intrs.
  MB_DebugStrings,         // All OpString intrs.
  MB_DebugModuleProcessed, // All OpModuleProcessed instructions.
  MB_AliasingInsts,        // SPV_INTEL_memory_access_aliasing instructions.
  MB_Annotations,          // OpDecorate, OpMemberDecorate etc.
  MB_TypeConstVars,        // OpTypeXXX, OpConstantXXX, and global OpVariables.
  MB_NonSemanticGlobalDI,  // OpExtInst with e.g. DebugSource, DebugTypeBasic.
  MB_ExtFuncDecls,         // OpFunction etc. to declare for external funcs.
  NUM_MODULE_SECTIONS      // Total number of sections requiring basic blocks.
};

struct Requirements {
  const bool IsSatisfiable;
  const std::optional<Capability::Capability> Cap;
  const ExtensionList Exts;
  const VersionTuple MinVer; // 0 if no min version is required.
  const VersionTuple MaxVer; // 0 if no max version is required.

  Requirements(bool IsSatisfiable = false,
               std::optional<Capability::Capability> Cap = {},
               ExtensionList Exts = {}, VersionTuple MinVer = VersionTuple(),
               VersionTuple MaxVer = VersionTuple())
      : IsSatisfiable(IsSatisfiable), Cap(Cap), Exts(std::move(Exts)),
        MinVer(MinVer), MaxVer(MaxVer) {}
  Requirements(Capability::Capability Cap) : Requirements(true, {Cap}) {}
};

struct RequirementHandler {
private:
  CapabilityList MinimalCaps;

  // AllCaps and AvailableCaps are related but different. AllCaps is a subset of
  // AvailableCaps. AvailableCaps is the complete set of capabilities that are
  // available to the current target. AllCaps is the set of capabilities that
  // are required by the current module.
  SmallSet<Capability::Capability, 8> AllCaps;
  DenseSet<unsigned> AvailableCaps;

  SmallSet<Extension::Extension, 4> AllExtensions;
  VersionTuple MinVersion; // 0 if no min version is defined.
  VersionTuple MaxVersion; // 0 if no max version is defined.
  // Add capabilities to AllCaps, recursing through their implicitly declared
  // capabilities too.
  void recursiveAddCapabilities(const CapabilityList &ToPrune);

  void initAvailableCapabilitiesForOpenCL(const SPIRVSubtarget &ST);
  void initAvailableCapabilitiesForVulkan(const SPIRVSubtarget &ST);

public:
  RequirementHandler() = default;
  void clear() {
    MinimalCaps.clear();
    AllCaps.clear();
    AvailableCaps.clear();
    AllExtensions.clear();
    MinVersion = VersionTuple();
    MaxVersion = VersionTuple();
  }
  const CapabilityList &getMinimalCapabilities() const { return MinimalCaps; }
  const SmallSet<Extension::Extension, 4> &getExtensions() const {
    return AllExtensions;
  }
  // Add a list of capabilities, ensuring AllCaps captures all the implicitly
  // declared capabilities, and MinimalCaps has the minimal set of required
  // capabilities (so all implicitly declared ones are removed).
  void addCapabilities(const CapabilityList &ToAdd);
  void addCapability(Capability::Capability ToAdd) { addCapabilities({ToAdd}); }
  void addExtensions(const ExtensionList &ToAdd) {
    AllExtensions.insert_range(ToAdd);
  }
  void addExtension(Extension::Extension ToAdd) { AllExtensions.insert(ToAdd); }
  // Add the given requirements to the lists. If constraints conflict, or these
  // requirements cannot be satisfied, then abort the compilation.
  void addRequirements(const Requirements &Req);
  // Get requirement and add it to the list.
  void getAndAddRequirements(SPIRV::OperandCategory::OperandCategory Category,
                             uint32_t i, const SPIRVSubtarget &ST);
  // Check if all the requirements can be satisfied for the given subtarget, and
  // if not abort compilation.
  void checkSatisfiable(const SPIRVSubtarget &ST) const;
  void initAvailableCapabilities(const SPIRVSubtarget &ST);
  // Add the given capabilities to available and all their implicitly defined
  // capabilities too.
  void addAvailableCaps(const CapabilityList &ToAdd);
  bool isCapabilityAvailable(Capability::Capability Cap) const {
    return AvailableCaps.contains(Cap);
  }

  // Remove capability ToRemove, but only if IfPresent is present.
  void removeCapabilityIf(const Capability::Capability ToRemove,
                          const Capability::Capability IfPresent);
};

using InstrList = SmallVector<const MachineInstr *>;
// Maps a local register to the corresponding global alias.
using LocalToGlobalRegTable = std::map<Register, MCRegister>;
using RegisterAliasMapTy =
    std::map<const MachineFunction *, LocalToGlobalRegTable>;

// The struct contains results of the module analysis and methods
// to access them.
struct ModuleAnalysisInfo {
  RequirementHandler Reqs;
  MemoryModel::MemoryModel Mem;
  AddressingModel::AddressingModel Addr;
  SourceLanguage::SourceLanguage SrcLang;
  unsigned SrcLangVersion;
  StringSet<> SrcExt;
  // Maps ExtInstSet to corresponding ID register.
  DenseMap<unsigned, MCRegister> ExtInstSetMap;
  // Contains the list of all global OpVariables in the module.
  SmallVector<const MachineInstr *, 4> GlobalVarList;
  // Maps functions and global variables to corresponding ID registers.
  DenseMap<const GlobalObject *, MCRegister> GlobalObjMap;
  // The set contains machine instructions which are necessary
  // for correct MIR but will not be emitted in function bodies.
  DenseSet<const MachineInstr *> InstrsToDelete;
  // The table contains global aliases of local registers for each machine
  // function. The aliases are used to substitute local registers during
  // code emission.
  RegisterAliasMapTy RegisterAliasTable;
  // The counter holds the maximum ID we have in the module.
  unsigned MaxID;
  // The array contains lists of MIs for each module section.
  InstrList MS[NUM_MODULE_SECTIONS];
  // The table maps MBB number to SPIR-V unique ID register.
  DenseMap<std::pair<const MachineFunction *, int>, MCRegister> BBNumToRegMap;
  // The table maps function pointers to their default FP fast math info. It can
  // be assumed that the SmallVector is sorted by the bit width of the type. The
  // first element is the smallest bit width, and the last element is the
  // largest bit width, therefore, we will have {half, float, double} in
  // the order of their bit widths.
  DenseMap<const Function *, SPIRV::FPFastMathDefaultInfoVector>
      FPFastMathDefaultInfoMap;

  MCRegister getGlobalObjReg(const GlobalObject *GO) {
    assert(GO && "GlobalObject is null");
    return GlobalObjMap.lookup(GO);
  }
  MCRegister getExtInstSetReg(unsigned SetNum) { return ExtInstSetMap[SetNum]; }
  InstrList &getMSInstrs(unsigned MSType) { return MS[MSType]; }
  void setSkipEmission(const MachineInstr *MI) { InstrsToDelete.insert(MI); }
  bool getSkipEmission(const MachineInstr *MI) {
    return InstrsToDelete.contains(MI);
  }
  void setRegisterAlias(const MachineFunction *MF, Register Reg,
                        MCRegister AliasReg) {
    RegisterAliasTable[MF][Reg] = AliasReg;
  }
  MCRegister getRegisterAlias(const MachineFunction *MF, Register Reg) {
    auto &RegTable = RegisterAliasTable[MF];
    auto RI = RegTable.find(Reg);
    if (RI == RegTable.end()) {
      return MCRegister();
    }
    return RI->second;
  }
  bool hasRegisterAlias(const MachineFunction *MF, Register Reg) {
    auto RI = RegisterAliasTable.find(MF);
    if (RI == RegisterAliasTable.end())
      return false;
    return RI->second.find(Reg) != RI->second.end();
  }
  unsigned getNextID() { return MaxID++; }
  MCRegister getNextIDRegister() {
    return MCRegister((1U << 31) | getNextID());
  }
  bool hasMBBRegister(const MachineBasicBlock &MBB) {
    auto Key = std::make_pair(MBB.getParent(), MBB.getNumber());
    return BBNumToRegMap.contains(Key);
  }
  // Convert MBB's number to corresponding ID register.
  MCRegister getOrCreateMBBRegister(const MachineBasicBlock &MBB) {
    auto Key = std::make_pair(MBB.getParent(), MBB.getNumber());
    auto [It, Inserted] = BBNumToRegMap.try_emplace(Key);
    if (Inserted)
      It->second = getNextIDRegister();
    return It->second;
  }
};
} // namespace SPIRV

using InstrSignature = SmallVector<size_t>;
using InstrTraces = std::set<InstrSignature>;
using InstrGRegsMap = std::map<SmallVector<size_t>, unsigned>;

struct SPIRVModuleAnalysis : public ModulePass {
  static char ID;

public:
  SPIRVModuleAnalysis()
      : ModulePass(ID), ST(nullptr), GR(nullptr), TII(nullptr), MMI(nullptr) {}

  bool runOnModule(Module &M) override;
  void getAnalysisUsage(AnalysisUsage &AU) const override;
  SPIRV::ModuleAnalysisInfo MAI;

private:
  void setBaseInfo(const Module &M);
  void collectFuncNames(MachineInstr &MI, const Function *F);
  void processOtherInstrs(const Module &M);
  void numberRegistersGlobally(const Module &M);

  // analyze dependencies to collect module scope definitions
  void collectDeclarations(const Module &M);
  void visitDecl(const MachineRegisterInfo &MRI, InstrGRegsMap &SignatureToGReg,
                 std::map<const Value *, unsigned> &GlobalToGReg,
                 const MachineFunction *MF, const MachineInstr &MI);
  MCRegister handleVariable(const MachineFunction *MF, const MachineInstr &MI,
                            std::map<const Value *, unsigned> &GlobalToGReg);
  MCRegister handleTypeDeclOrConstant(const MachineInstr &MI,
                                      InstrGRegsMap &SignatureToGReg);
  MCRegister
  handleFunctionOrParameter(const MachineFunction *MF, const MachineInstr &MI,
                            std::map<const Value *, unsigned> &GlobalToGReg,
                            bool &IsFunDef);
  void visitFunPtrUse(Register OpReg, InstrGRegsMap &SignatureToGReg,
                      std::map<const Value *, unsigned> &GlobalToGReg,
                      const MachineFunction *MF, const MachineInstr &MI);
  bool isDeclSection(const MachineRegisterInfo &MRI, const MachineInstr &MI);

  const SPIRVSubtarget *ST;
  SPIRVGlobalRegistry *GR;
  const SPIRVInstrInfo *TII;
  MachineModuleInfo *MMI;
};
} // namespace llvm
#endif // LLVM_LIB_TARGET_SPIRV_SPIRVMODULEANALYSIS_H