mirror of
https://github.com/FEX-Emu/FEX.git
synced 2026-10-09 15:00:21 +02:00
Ryan Houdek
c82a683987
A source of overhead with multiblock is hitting instructions through a conditional branch that can never be executed. Usually AVX512 instructions in glibc. This causes us to emit partial blocks for a ton of targets that will never get executed. Instead, when we have multiblock enabled, if a block hits an instruction encoding we don't support, then remove all the decoded instructions from the block and early terminate it if it isn't the entry block. This resolves the issue of emitting a bunch of IR and code for blocks never executed. If the block of code has an invalid instruction in the entry block for decoding then it'll still emit code up to the invalid instruction and raise a SIGILL. This has the potential for generating some additional blocks of code if a game is abusing SIGILL, but since that's unlikely it's a good trade-off. Also removes a few log instructions that don't really provide anything anymore and just show up as confusing messages when multiblock is enabled.
127 lines
3.9 KiB
C++
127 lines
3.9 KiB
C++
// SPDX-License-Identifier: MIT
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#pragma once
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#include "Interface/Core/X86Tables/X86Tables.h"
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#include <FEXCore/HLE/SyscallHandler.h>
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#include <FEXCore/Utils/Telemetry.h>
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#include <FEXCore/fextl/set.h>
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#include <FEXCore/fextl/vector.h>
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#include <array>
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#include <cstdint>
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#include <stddef.h>
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namespace FEXCore::Context {
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class ContextImpl;
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}
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namespace FEXCore::Frontend {
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class Decoder final {
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public:
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// New Frontend decoding
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struct DecodedBlocks final {
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uint64_t Entry {};
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uint64_t NumInstructions {};
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FEXCore::X86Tables::DecodedInst* DecodedInstructions;
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bool HasInvalidInstruction {};
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};
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struct DecodedBlockInformation final {
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uint64_t TotalInstructionCount;
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fextl::vector<DecodedBlocks> Blocks;
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};
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Decoder(FEXCore::Context::ContextImpl* ctx);
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~Decoder();
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void DecodeInstructionsAtEntry(const uint8_t* InstStream, uint64_t PC, uint64_t MaxInst,
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std::function<void(uint64_t BlockEntry, uint64_t Start, uint64_t Length)> AddContainedCodePage);
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const DecodedBlockInformation* GetDecodedBlockInfo() const {
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return &BlockInfo;
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}
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uint64_t DecodedMinAddress {};
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uint64_t DecodedMaxAddress {~0ULL};
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void SetSectionMaxAddress(uint64_t v) {
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SectionMaxAddress = v;
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}
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void SetExternalBranches(fextl::set<uint64_t>* v) {
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ExternalBranches = v;
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}
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void DelayedDisownBuffer() {
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PoolObject.DelayedDisownBuffer();
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}
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private:
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// To pass any information from instruction prefixes
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// down into the actual instruction handling machinery.
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struct DecodedHeader {
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uint8_t vvvv; // Encoded operand in a VEX prefix.
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bool w; // VEX.W bit.
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bool L; // VEX.L bit (if set then 256 bit operation, if unset then scalar or 128-bit operation)
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};
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FEXCore::Context::ContextImpl* CTX;
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const FEXCore::HLE::SyscallOSABI OSABI {};
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bool DecodeInstruction(uint64_t PC);
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void BranchTargetInMultiblockRange();
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bool BranchTargetCanContinue(bool FinalInstruction) const;
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uint8_t ReadByte();
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uint8_t PeekByte(uint8_t Offset) const;
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uint64_t ReadData(uint8_t Size);
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void SkipBytes(uint8_t Size) {
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InstructionSize += Size;
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}
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bool NormalOp(const FEXCore::X86Tables::X86InstInfo* Info, uint16_t Op, DecodedHeader Options = {});
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bool NormalOpHeader(const FEXCore::X86Tables::X86InstInfo* Info, uint16_t Op);
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static constexpr size_t DefaultDecodedBufferSize = 0x10000;
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FEXCore::X86Tables::DecodedInst* DecodedBuffer {};
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Utils::FixedSizePooledAllocation<FEXCore::X86Tables::DecodedInst*, 5000, 500> PoolObject;
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size_t DecodedSize {};
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const uint8_t* InstStream;
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static constexpr size_t MAX_INST_SIZE = 15;
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uint8_t InstructionSize;
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std::array<uint8_t, MAX_INST_SIZE> Instruction;
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FEXCore::X86Tables::DecodedInst* DecodeInst;
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// This is for multiblock data tracking
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bool SymbolAvailable {false};
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uint64_t EntryPoint {};
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uint64_t MaxCondBranchForward {};
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uint64_t MaxCondBranchBackwards {~0ULL};
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uint64_t SymbolMaxAddress {};
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uint64_t SymbolMinAddress {~0ULL};
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uint64_t SectionMaxAddress {~0ULL};
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DecodedBlockInformation BlockInfo;
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fextl::set<uint64_t> CurrentBlockTargets;
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fextl::set<uint64_t> BlocksToDecode;
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fextl::set<uint64_t> HasBlocks;
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fextl::set<uint64_t>* ExternalBranches {nullptr};
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// ModRM rm decoding
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using DecodeModRMPtr = void (FEXCore::Frontend::Decoder::*)(X86Tables::DecodedOperand* Operand, X86Tables::ModRMDecoded ModRM);
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void DecodeModRM_16(X86Tables::DecodedOperand* Operand, X86Tables::ModRMDecoded ModRM);
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void DecodeModRM_64(X86Tables::DecodedOperand* Operand, X86Tables::ModRMDecoded ModRM);
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static constexpr std::array<DecodeModRMPtr, 2> DecodeModRMs_Disp {
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&FEXCore::Frontend::Decoder::DecodeModRM_64,
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&FEXCore::Frontend::Decoder::DecodeModRM_16,
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};
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const uint8_t* AdjustAddrForSpecialRegion(const uint8_t* _InstStream, uint64_t EntryPoint, uint64_t RIP);
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FEXCORE_TELEMETRY_INIT(EVEXOpTelem, TYPE_USES_EVEX_OPS);
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};
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} // namespace FEXCore::Frontend
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