src/third_party/mozjs-45/js/src/jit/Registers.h

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * vim: set ts=8 sts=4 et sw=4 tw=99:
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef jit_Registers_h
#define jit_Registers_h

#include "mozilla/Array.h"

#include "jit/IonTypes.h"
#if defined(JS_CODEGEN_X86) || defined(JS_CODEGEN_X64)
# include "jit/x86-shared/Architecture-x86-shared.h"
#elif defined(JS_CODEGEN_ARM)
# include "jit/arm/Architecture-arm.h"
#elif defined(JS_CODEGEN_ARM64)
# include "jit/arm64/Architecture-arm64.h"
#elif defined(JS_CODEGEN_MIPS32)
# include "jit/mips32/Architecture-mips32.h"
#elif defined(JS_CODEGEN_MIPS64)
# include "jit/mips64/Architecture-mips64.h"
#elif defined(JS_CODEGEN_NONE)
# include "jit/none/Architecture-none.h"
#else
# error "Unknown architecture!"
#endif

namespace js {
namespace jit {

struct Register {
    typedef Registers Codes;
    typedef Codes::Encoding Encoding;
    typedef Codes::Code Code;
    typedef Codes::SetType SetType;

    Codes::Encoding reg_;
    static Register FromCode(Code i) {
        MOZ_ASSERT(i < Registers::Total);
        Register r = { Encoding(i) };
        return r;
    }
    static Register FromName(const char* name) {
        Code code = Registers::FromName(name);
        Register r = { Encoding(code) };
        return r;
    }
    MOZ_CONSTEXPR Code code() const {
        return Code(reg_);
    }
    Encoding encoding() const {
        MOZ_ASSERT(Code(reg_) < Registers::Total);
        return reg_;
    }
    const char* name() const {
        return Registers::GetName(code());
    }
    bool operator ==(Register other) const {
        return reg_ == other.reg_;
    }
    bool operator !=(Register other) const {
        return reg_ != other.reg_;
    }
    bool volatile_() const {
        return !!((SetType(1) << code()) & Registers::VolatileMask);
    }
    bool aliases(const Register& other) const {
        return reg_ == other.reg_;
    }
    uint32_t numAliased() const {
        return 1;
    }

    // N.B. FloatRegister is an explicit outparam here because msvc-2010
    // miscompiled it on win64 when the value was simply returned.  This
    // now has an explicit outparam for compatability.
    void aliased(uint32_t aliasIdx, Register* ret) const {
        MOZ_ASSERT(aliasIdx == 0);
        *ret = *this;
    }

    SetType alignedOrDominatedAliasedSet() const {
        return SetType(1) << code();
    }

    static uint32_t SetSize(SetType x) {
        return Codes::SetSize(x);
    }
    static uint32_t FirstBit(SetType x) {
        return Codes::FirstBit(x);
    }
    static uint32_t LastBit(SetType x) {
        return Codes::LastBit(x);
    }
};

struct Register64
{
#ifdef JS_PUNBOX64
    Register reg;
#else
    Register high;
    Register low;
#endif

#ifdef JS_PUNBOX64
    explicit MOZ_CONSTEXPR Register64(Register r)
      : reg(r)
    {}
#else
    MOZ_CONSTEXPR Register64(Register h, Register l)
      : high(h), low(l)
    {}
#endif
};

class RegisterDump
{
  public:
    typedef mozilla::Array<Registers::RegisterContent, Registers::Total> GPRArray;
    typedef mozilla::Array<FloatRegisters::RegisterContent, FloatRegisters::TotalPhys> FPUArray;

  protected: // Silence Clang warning.
    GPRArray regs_;
    FPUArray fpregs_;

  public:
    static size_t offsetOfRegister(Register reg) {
        return offsetof(RegisterDump, regs_) + reg.code() * sizeof(uintptr_t);
    }
    static size_t offsetOfRegister(FloatRegister reg) {
        return offsetof(RegisterDump, fpregs_) + reg.getRegisterDumpOffsetInBytes();
    }
};

// Information needed to recover machine register state. This records the
// location of spilled register and not the content of the spilled
// registers. Thus we can safely assume that this structure is unchanged, even
// if the GC pointers mapped by this structure are relocated.
class MachineState
{
    mozilla::Array<Registers::RegisterContent*, Registers::Total> regs_;
    mozilla::Array<FloatRegisters::RegisterContent*, FloatRegisters::Total> fpregs_;

  public:
    MachineState() {
#ifndef JS_CODEGEN_NONE
        for (unsigned i = 0; i < Registers::Total; i++)
            regs_[i] = reinterpret_cast<Registers::RegisterContent*>(i + 0x100);
        for (unsigned i = 0; i < FloatRegisters::Total; i++)
            fpregs_[i] = reinterpret_cast<FloatRegisters::RegisterContent*>(i + 0x200);
#endif
    }

    static MachineState FromBailout(RegisterDump::GPRArray& regs, RegisterDump::FPUArray& fpregs);

    void setRegisterLocation(Register reg, uintptr_t* up) {
        regs_[reg.code()] = (Registers::RegisterContent*) up;
    }
    void setRegisterLocation(FloatRegister reg, float* fp) {
        MOZ_ASSERT(reg.isSingle());
        fpregs_[reg.code()] = (FloatRegisters::RegisterContent*) fp;
    }
    void setRegisterLocation(FloatRegister reg, double* dp) {
        fpregs_[reg.code()] = (FloatRegisters::RegisterContent*) dp;
    }
    void setRegisterLocation(FloatRegister reg, FloatRegisters::RegisterContent* rp) {
        fpregs_[reg.code()] = rp;
    }

    bool has(Register reg) const {
        return regs_[reg.code()] != nullptr;
    }
    bool has(FloatRegister reg) const {
        return fpregs_[reg.code()] != nullptr;
    }
    uintptr_t read(Register reg) const {
        return regs_[reg.code()]->r;
    }
    double read(FloatRegister reg) const {
        return fpregs_[reg.code()]->d;
    }
    void write(Register reg, uintptr_t value) const {
        regs_[reg.code()]->r = value;
    }
    const FloatRegisters::RegisterContent* address(FloatRegister reg) const {
        return fpregs_[reg.code()];
    }
};

class MacroAssembler;

// Declares a register as owned within the scope of the object.
// In debug mode, owned register state is tracked within the MacroAssembler,
// and an assert will fire if ownership is conflicting.
// In contrast to ARM64's UseScratchRegisterScope, this class has no overhead
// in non-debug builds.
template <class RegisterType>
struct AutoGenericRegisterScope : public RegisterType
{
    // Prevent MacroAssembler templates from creating copies,
    // which causes the destructor to fire more than once.
    AutoGenericRegisterScope(const AutoGenericRegisterScope& other) = delete;

#ifdef DEBUG
    MacroAssembler& masm_;
    explicit AutoGenericRegisterScope(MacroAssembler& masm, RegisterType reg);
    ~AutoGenericRegisterScope();
#else
    MOZ_CONSTEXPR explicit AutoGenericRegisterScope(MacroAssembler& masm, RegisterType reg)
      : RegisterType(reg)
    { }
#endif
};

typedef AutoGenericRegisterScope<Register> AutoRegisterScope;
typedef AutoGenericRegisterScope<FloatRegister> AutoFloatRegisterScope;

} // namespace jit
} // namespace js

#endif /* jit_Registers_h */