text: // WebAssemblyMachineFunctionInfo.h-WebAssembly machine function info-*- C++ -*-
  //
  //                     The LLVM Compiler Infrastructure
  //
  // This file is distributed under the University of Illinois Open Source
  // License. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  ///
  /// \file
  /// This file declares WebAssembly-specific per-machine-function
  /// information.
  ///
  //===----------------------------------------------------------------------===//
  
  #ifndef LLVM_LIB_TARGET_WEBASSEMBLY_WEBASSEMBLYMACHINEFUNCTIONINFO_H
  #define LLVM_LIB_TARGET_WEBASSEMBLY_WEBASSEMBLYMACHINEFUNCTIONINFO_H
  
  #include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
  #include "llvm/BinaryFormat/Wasm.h"
  #include "llvm/CodeGen/MachineRegisterInfo.h"
  #include "llvm/MC/MCSymbolWasm.h"
  
  namespace llvm {
  
  /// This class is derived from MachineFunctionInfo and contains private
  /// WebAssembly-specific information for each MachineFunction.
  class WebAssemblyFunctionInfo final : public MachineFunctionInfo {
    MachineFunction &MF;
  
    std::vector<MVT> Params;
    std::vector<MVT> Results;
    std::vector<MVT> Locals;
  
    /// A mapping from CodeGen vreg index to WebAssembly register number.
    std::vector<unsigned> WARegs;
  
    /// A mapping from CodeGen vreg index to a boolean value indicating whether
    /// the given register is considered to be "stackified", meaning it has been
    /// determined or made to meet the stack requirements:
    ///   - single use (per path)
    ///   - single def (per path)
    ///   - defined and used in LIFO order with other stack registers
    BitVector VRegStackified;
  
    // A virtual register holding the pointer to the vararg buffer for vararg
    // functions. It is created and set in TLI::LowerFormalArguments and read by
    // TLI::LowerVASTART
    unsigned VarargVreg = -1U;
  
    // A virtual register holding the base pointer for functions that have
    // overaligned values on the user stack.
    unsigned BasePtrVreg = -1U;
  
  public:
    explicit WebAssemblyFunctionInfo(MachineFunction &MF) : MF(MF) {}
    ~WebAssemblyFunctionInfo() override;
  
    void addParam(MVT VT) { Params.push_back(VT); }
    const std::vector<MVT> &getParams() const { return Params; }
  
    void addResult(MVT VT) { Results.push_back(VT); }
    const std::vector<MVT> &getResults() const { return Results; }
  
    void clearParamsAndResults() {
      Params.clear();
      Results.clear();
    }
  
    void setNumLocals(size_t NumLocals) { Locals.resize(NumLocals, MVT::i32); }
    void setLocal(size_t i, MVT VT) { Locals[i] = VT; }
    void addLocal(MVT VT) { Locals.push_back(VT); }
    const std::vector<MVT> &getLocals() const { return Locals; }
  
    unsigned getVarargBufferVreg() const {
      assert(VarargVreg != -1U && "Vararg vreg hasn't been set");
      return VarargVreg;
    }
    void setVarargBufferVreg(unsigned Reg) { VarargVreg = Reg; }
  
    unsigned getBasePointerVreg() const {
      assert(BasePtrVreg != -1U && "Base ptr vreg hasn't been set");
      return BasePtrVreg;
    }
    void setBasePointerVreg(unsigned Reg) { BasePtrVreg = Reg; }
  
    static const unsigned UnusedReg = -1u;
  
    void stackifyVReg(unsigned VReg) {
      assert(MF.getRegInfo().getUniqueVRegDef(VReg));
      auto I = TargetRegisterInfo::virtReg2Index(VReg);
      if (I >= VRegStackified.size())
        VRegStackified.resize(I + 1);
      VRegStackified.set(I);
    }
    bool isVRegStackified(unsigned VReg) const {
      auto I = TargetRegisterInfo::virtReg2Index(VReg);
      if (I >= VRegStackified.size())
        return false;
      return VRegStackified.test(I);
    }
  
    void initWARegs();
    void setWAReg(unsigned VReg, unsigned WAReg) {
      assert(WAReg != UnusedReg);
      auto I = TargetRegisterInfo::virtReg2Index(VReg);
      assert(I < WARegs.size());
      WARegs[I] = WAReg;
    }
    unsigned getWAReg(unsigned VReg) const {
      auto I = TargetRegisterInfo::virtReg2Index(VReg);
      assert(I < WARegs.size());
      return WARegs[I];
    }
  
    // For a given stackified WAReg, return the id number to print with push/pop.
    static unsigned getWARegStackId(unsigned Reg) {
      assert(Reg & INT32_MIN);
      return Reg & INT32_MAX;
    }
  };
  
  void ComputeLegalValueVTs(const Function &F, const TargetMachine &TM, Type *Ty,
                            SmallVectorImpl<MVT> &ValueVTs);
  
  // Compute the signature for a given FunctionType (Ty). Note that it's not the
  // signature for F (F is just used to get varous context)
  void ComputeSignatureVTs(const FunctionType *Ty, const Function &F,
                           const TargetMachine &TM, SmallVectorImpl<MVT> &Params,
                           SmallVectorImpl<MVT> &Results);
  
  std::unique_ptr<wasm::WasmSignature>
  SignatureFromMVTs(const SmallVectorImpl<MVT> &Results,
                    const SmallVectorImpl<MVT> &Params);
  
  } // end namespace llvm
  
  #endif
  