citra/src/video_core/shader/shader_jit_x64.h

// Copyright 2015 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.

#pragma once

#include <set>
#include <utility>

#include <nihstro/shader_bytecode.h>

#include "common/x64/emitter.h"

#include "video_core/pica.h"
#include "video_core/shader/shader.h"

using nihstro::Instruction;
using nihstro::OpCode;
using nihstro::SwizzlePattern;

namespace Pica {

namespace Shader {

/// Memory needed to be available to compile the next shader (otherwise, clear the cache)
constexpr size_t jit_shader_size = 1024 * 512;
/// Memory allocated for the JIT code space cache
constexpr size_t jit_cache_size = 1024 * 1024 * 8;

using CompiledShader = void(void* registers);

/**
 * This class implements the shader JIT compiler. It recompiles a Pica shader program into x86_64
 * code that can be executed on the host machine directly.
 */
class JitCompiler : public Gen::XCodeBlock {
public:
    JitCompiler();

    CompiledShader* Compile();

    void Clear();

    void Compile_ADD(Instruction instr);
    void Compile_DP3(Instruction instr);
    void Compile_DP4(Instruction instr);
    void Compile_DPH(Instruction instr);
    void Compile_EX2(Instruction instr);
    void Compile_LG2(Instruction instr);
    void Compile_MUL(Instruction instr);
    void Compile_SGE(Instruction instr);
    void Compile_SLT(Instruction instr);
    void Compile_FLR(Instruction instr);
    void Compile_MAX(Instruction instr);
    void Compile_MIN(Instruction instr);
    void Compile_RCP(Instruction instr);
    void Compile_RSQ(Instruction instr);
    void Compile_MOVA(Instruction instr);
    void Compile_MOV(Instruction instr);
    void Compile_NOP(Instruction instr);
    void Compile_END(Instruction instr);
    void Compile_CALL(Instruction instr);
    void Compile_CALLC(Instruction instr);
    void Compile_CALLU(Instruction instr);
    void Compile_IF(Instruction instr);
    void Compile_LOOP(Instruction instr);
    void Compile_JMP(Instruction instr);
    void Compile_CMP(Instruction instr);
    void Compile_MAD(Instruction instr);

private:

    void Compile_Block(unsigned end);
    void Compile_NextInstr();

    void Compile_SwizzleSrc(Instruction instr, unsigned src_num, SourceRegister src_reg, Gen::X64Reg dest);
    void Compile_DestEnable(Instruction instr, Gen::X64Reg dest);

    /**
     * Compiles a `MUL src1, src2` operation, properly handling the PICA semantics when multiplying
     * zero by inf. Clobbers `src2` and `scratch`.
     */
    void Compile_SanitizedMul(Gen::X64Reg src1, Gen::X64Reg src2, Gen::X64Reg scratch);

    void Compile_EvaluateCondition(Instruction instr);
    void Compile_UniformCondition(Instruction instr);

    /**
     * Emits the code to conditionally return from a subroutine envoked by the `CALL` instruction.
     */
    void Compile_Return();

    BitSet32 PersistentCallerSavedRegs();

    /**
     * Analyzes the entire shader program for `CALL` instructions before emitting any code,
     * identifying the locations where a return needs to be inserted.
     */
    void FindReturnOffsets();

    /// Mapping of Pica VS instructions to pointers in the emitted code
    std::array<const u8*, 1024> code_ptr;

    /// Offsets in code where a return needs to be inserted
    std::set<unsigned> return_offsets;

    unsigned last_program_counter;  ///< Offset of the most recent instruction decoded
    unsigned program_counter;       ///< Offset of the next instruction to decode
    bool looping = false;           ///< True if compiling a loop, used to check for nested loops

    /// Branches that need to be fixed up once the entire shader program is compiled
    std::vector<std::pair<Gen::FixupBranch, unsigned>> fixup_branches;
};

} // Shader

} // Pica