Optimization: Read page-table directly for memory access

include/dynarmic/callbacks.h

@@ -6,6 +6,8 @@
 
 #pragma once
 
+#include <array>
+#include <cstddef>
 #include <cstdint>
 
 namespace Dynarmic {
@@ -30,6 +32,11 @@ struct UserCallbacks {
     void (*InterpreterFallback)(std::uint32_t pc, Jit* jit);
 
     bool (*CallSVC)(std::uint32_t swi);
+
+    // Page Table
+    static constexpr std::size_t PAGE_BITS = 12;
+    static constexpr std::size_t NUM_PAGE_TABLE_ENTRIES = 1 << (32 - PAGE_BITS);
+    std::array<std::uint8_t*, NUM_PAGE_TABLE_ENTRIES>* page_table = nullptr;
 };
 
 } // namespace Dynarmic

src/backend_x64/block_of_code.cpp

@@ -12,11 +12,12 @@
 #include "backend_x64/block_of_code.h"
 #include "backend_x64/jitstate.h"
 #include "common/assert.h"
+#include "dynarmic/callbacks.h"
 
 namespace Dynarmic {
 namespace BackendX64 {
 
-BlockOfCode::BlockOfCode() : Xbyak::CodeGenerator(128 * 1024 * 1024) {
+BlockOfCode::BlockOfCode(UserCallbacks cb) : Xbyak::CodeGenerator(128 * 1024 * 1024), cb(cb) {
     ClearCache(false);
 }
 
@@ -27,6 +28,7 @@ void BlockOfCode::ClearCache(bool poison_memory) {
     GenConstants();
     GenRunCode();
     GenReturnFromRunCode();
+    GenMemoryAccessors();
 }
 
 size_t BlockOfCode::RunCode(JitState* jit_state, CodePtr basic_block, size_t cycles_to_run) const {
@@ -118,6 +120,64 @@ void BlockOfCode::GenReturnFromRunCode() {
     ret();
 }
 
+void BlockOfCode::GenMemoryAccessors() {
+    align();
+    read_memory_8 = getCurr<const void*>();
+    ABI_PushCallerSaveRegistersAndAdjustStack(this);
+    CallFunction(cb.MemoryRead8);
+    ABI_PopCallerSaveRegistersAndAdjustStack(this);
+    ret();
+
+    align();
+    read_memory_16 = getCurr<const void*>();
+    ABI_PushCallerSaveRegistersAndAdjustStack(this);
+    CallFunction(cb.MemoryRead16);
+    ABI_PopCallerSaveRegistersAndAdjustStack(this);
+    ret();
+
+    align();
+    read_memory_32 = getCurr<const void*>();
+    ABI_PushCallerSaveRegistersAndAdjustStack(this);
+    CallFunction(cb.MemoryRead32);
+    ABI_PopCallerSaveRegistersAndAdjustStack(this);
+    ret();
+    
+    align();
+    read_memory_64 = getCurr<const void*>();
+    ABI_PushCallerSaveRegistersAndAdjustStack(this);
+    CallFunction(cb.MemoryRead64);
+    ABI_PopCallerSaveRegistersAndAdjustStack(this);
+    ret();
+
+    align();
+    write_memory_8 = getCurr<const void*>();
+    ABI_PushCallerSaveRegistersAndAdjustStack(this);
+    CallFunction(cb.MemoryWrite8);
+    ABI_PopCallerSaveRegistersAndAdjustStack(this);
+    ret();
+
+    align();
+    write_memory_16 = getCurr<const void*>();
+    ABI_PushCallerSaveRegistersAndAdjustStack(this);
+    CallFunction(cb.MemoryWrite16);
+    ABI_PopCallerSaveRegistersAndAdjustStack(this);
+    ret();
+
+    align();
+    write_memory_32 = getCurr<const void*>();
+    ABI_PushCallerSaveRegistersAndAdjustStack(this);
+    CallFunction(cb.MemoryWrite32);
+    ABI_PopCallerSaveRegistersAndAdjustStack(this);
+    ret();
+
+    align();
+    write_memory_64 = getCurr<const void*>();
+    ABI_PushCallerSaveRegistersAndAdjustStack(this);
+    CallFunction(cb.MemoryWrite64);
+    ABI_PopCallerSaveRegistersAndAdjustStack(this);
+    ret();
+}
+
 void BlockOfCode::SwitchMxcsrOnEntry() {
     stmxcsr(dword[r15 + offsetof(JitState, save_host_MXCSR)]);
     ldmxcsr(dword[r15 + offsetof(JitState, guest_MXCSR)]);

src/backend_x64/block_of_code.h

@@ -11,13 +11,14 @@
 
 #include "backend_x64/jitstate.h"
 #include "common/common_types.h"
+#include "dynarmic/callbacks.h"
 
 namespace Dynarmic {
 namespace BackendX64 {
 
 class BlockOfCode final : public Xbyak::CodeGenerator {
 public:
-    BlockOfCode();
+    explicit BlockOfCode(UserCallbacks cb);
 
     /// Clears this block of code and resets code pointer to beginning.
     void ClearCache(bool poison_memory);
@@ -93,6 +94,36 @@ public:
         return return_from_run_code;
     }
 
+    const void* GetMemoryReadCallback(size_t bit_size) const {
+        switch (bit_size) {
+        case 8:
+            return read_memory_8;
+        case 16:
+            return read_memory_16;
+        case 32:
+            return read_memory_32;
+        case 64:
+            return read_memory_64;
+        default:
+            return nullptr;
+        }
+    }
+
+    const void* GetMemoryWriteCallback(size_t bit_size) const {
+        switch (bit_size) {
+        case 8:
+            return write_memory_8;
+        case 16:
+            return write_memory_16;
+        case 32:
+            return write_memory_32;
+        case 64:
+            return write_memory_64;
+        default:
+            return nullptr;
+        }
+    }
+
     void int3() { db(0xCC); }
     void nop(size_t size = 1);
 
@@ -114,6 +145,8 @@ public:
 #endif
 
 private:
+    UserCallbacks cb;
+
     struct Consts {
         Xbyak::Label FloatPositiveZero32;
         Xbyak::Label FloatNegativeZero32;
@@ -138,6 +171,16 @@ private:
     const void* return_from_run_code = nullptr;
     const void* return_from_run_code_without_mxcsr_switch = nullptr;
     void GenReturnFromRunCode();
+
+    const void* read_memory_8 = nullptr;
+    const void* read_memory_16 = nullptr;
+    const void* read_memory_32 = nullptr;
+    const void* read_memory_64 = nullptr;
+    const void* write_memory_8 = nullptr;
+    const void* write_memory_16 = nullptr;
+    const void* write_memory_32 = nullptr;
+    const void* write_memory_64 = nullptr;
+    void GenMemoryAccessors();
 };
 
 } // namespace BackendX64

src/backend_x64/emit_x64.cpp

@@ -8,6 +8,7 @@
 #include <unordered_map>
 #include <common/bit_util.h>
 
+#include "backend_x64/abi.h"
 #include "backend_x64/emit_x64.h"
 #include "backend_x64/jitstate.h"
 #include "frontend/arm_types.h"
@@ -1829,52 +1830,133 @@ void EmitX64::EmitSetExclusive(IR::Block&, IR::Inst* inst) {
     code->mov(dword[r15 + offsetof(JitState, exclusive_address)], address);
 }
 
-void EmitX64::EmitReadMemory8(IR::Block&, IR::Inst* inst) {
+template <typename FunctionPointer>
-    reg_alloc.HostCall(inst, inst->GetArg(0));
+static void ReadMemory(BlockOfCode* code, RegAlloc& reg_alloc, IR::Inst* inst, UserCallbacks& cb, size_t bit_size, FunctionPointer fn) {
+    if (!cb.page_table) {
+        reg_alloc.HostCall(inst, inst->GetArg(0));
+        code->CallFunction(fn);
+        return;
+    }
 
-    code->CallFunction(cb.MemoryRead8);
+    using namespace Xbyak::util;
+
+    Xbyak::Reg64 result = reg_alloc.DefGpr(inst, { ABI_RETURN });
+    Xbyak::Reg32 vaddr = reg_alloc.UseScratchGpr(inst->GetArg(0), { ABI_PARAM1 }).cvt32();
+    Xbyak::Reg64 page_index = reg_alloc.ScratchGpr();
+    Xbyak::Reg64 page_offset = reg_alloc.ScratchGpr();
+
+    Xbyak::Label abort, end;
+
+    code->mov(rax, u64(cb.page_table));
+    code->mov(page_index.cvt32(), vaddr);
+    code->shr(page_index.cvt32(), 12);
+    code->mov(rax, qword[rax + page_index * 8]);
+    code->test(rax, rax);
+    code->jz(abort);
+    code->mov(page_offset.cvt32(), vaddr);
+    code->and_(page_offset.cvt32(), 4095);
+    switch (bit_size) {
+    case 8:
+        code->movzx(result, code->byte[rax + page_offset]);
+        break;
+    case 16:
+        code->movzx(result, word[rax + page_offset]);
+        break;
+    case 32:
+        code->mov(result.cvt32(), dword[rax + page_offset]);
+        break;
+    case 64:
+        code->mov(result.cvt64(), qword[rax + page_offset]);
+        break;
+    default:
+        ASSERT_MSG(false, "Invalid bit_size");
+        break;
+    }
+    code->jmp(end);
+    code->L(abort);
+    code->call(code->GetMemoryReadCallback(bit_size));
+    code->L(end);
+}
+
+template<typename FunctionPointer>
+static void WriteMemory(BlockOfCode* code, RegAlloc& reg_alloc, IR::Inst* inst, UserCallbacks& cb, size_t bit_size, FunctionPointer fn) {
+    if (!cb.page_table) {
+        reg_alloc.HostCall(inst, inst->GetArg(0), inst->GetArg(1));
+        code->CallFunction(fn);
+        return;
+    }
+
+    using namespace Xbyak::util;
+
+    reg_alloc.ScratchGpr({ HostLoc::RAX });
+    Xbyak::Reg32 vaddr = reg_alloc.UseScratchGpr(inst->GetArg(0), { ABI_PARAM1 }).cvt32();
+    Xbyak::Reg64 value = reg_alloc.UseScratchGpr(inst->GetArg(1), { ABI_PARAM2 });
+    Xbyak::Reg64 page_index = reg_alloc.ScratchGpr();
+    Xbyak::Reg64 page_offset = reg_alloc.ScratchGpr();
+
+    Xbyak::Label abort, end;
+
+    code->mov(rax, u64(cb.page_table));
+    code->mov(page_index.cvt32(), vaddr);
+    code->shr(page_index.cvt32(), 12);
+    code->mov(rax, qword[rax + page_index * 8]);
+    code->test(rax, rax);
+    code->jz(abort);
+    code->mov(page_offset.cvt32(), vaddr);
+    code->and_(page_offset.cvt32(), 4095);
+    switch (bit_size) {
+    case 8:
+        code->mov(code->byte[rax + page_offset], value.cvt8());
+        break;
+    case 16:
+        code->mov(word[rax + page_offset], value.cvt16());
+        break;
+    case 32:
+        code->mov(dword[rax + page_offset], value.cvt32());
+        break;
+    case 64:
+        code->mov(qword[rax + page_offset], value.cvt64());
+        break;
+    default:
+        ASSERT_MSG(false, "Invalid bit_size");
+        break;
+    }
+    code->jmp(end);
+    code->L(abort);
+    code->call(code->GetMemoryWriteCallback(bit_size));
+    code->L(end);
+}
+
+void EmitX64::EmitReadMemory8(IR::Block&, IR::Inst* inst) {
+    ReadMemory(code, reg_alloc, inst, cb, 8, cb.MemoryRead8);
 }
 
 void EmitX64::EmitReadMemory16(IR::Block&, IR::Inst* inst) {
-    reg_alloc.HostCall(inst, inst->GetArg(0));
+    ReadMemory(code, reg_alloc, inst, cb, 16, cb.MemoryRead16);
-
-    code->CallFunction(cb.MemoryRead16);
 }
 
 void EmitX64::EmitReadMemory32(IR::Block&, IR::Inst* inst) {
-    reg_alloc.HostCall(inst, inst->GetArg(0));
+    ReadMemory(code, reg_alloc, inst, cb, 32, cb.MemoryRead32);
-
-    code->CallFunction(cb.MemoryRead32);
 }
 
 void EmitX64::EmitReadMemory64(IR::Block&, IR::Inst* inst) {
-    reg_alloc.HostCall(inst, inst->GetArg(0));
+    ReadMemory(code, reg_alloc, inst, cb, 64, cb.MemoryRead64);
-
-    code->CallFunction(cb.MemoryRead64);
 }
 
 void EmitX64::EmitWriteMemory8(IR::Block&, IR::Inst* inst) {
-    reg_alloc.HostCall(nullptr, inst->GetArg(0), inst->GetArg(1));
+    WriteMemory(code, reg_alloc, inst, cb, 8, cb.MemoryWrite8);
-
-    code->CallFunction(cb.MemoryWrite8);
 }
 
 void EmitX64::EmitWriteMemory16(IR::Block&, IR::Inst* inst) {
-    reg_alloc.HostCall(nullptr, inst->GetArg(0), inst->GetArg(1));
+    WriteMemory(code, reg_alloc, inst, cb, 16, cb.MemoryWrite16);
-
-    code->CallFunction(cb.MemoryWrite16);
 }
 
 void EmitX64::EmitWriteMemory32(IR::Block&, IR::Inst* inst) {
-    reg_alloc.HostCall(nullptr, inst->GetArg(0), inst->GetArg(1));
+    WriteMemory(code, reg_alloc, inst, cb, 32, cb.MemoryWrite32);
-
-    code->CallFunction(cb.MemoryWrite32);
 }
 
 void EmitX64::EmitWriteMemory64(IR::Block&, IR::Inst* inst) {
-    reg_alloc.HostCall(nullptr, inst->GetArg(0), inst->GetArg(1));
+    WriteMemory(code, reg_alloc, inst, cb, 64, cb.MemoryWrite64);
-
-    code->CallFunction(cb.MemoryWrite64);
 }
 
 template <typename FunctionPointer>

src/backend_x64/interface_x64.cpp

@@ -31,7 +31,7 @@ using namespace BackendX64;
 
 struct Jit::Impl {
     Impl(Jit* jit, UserCallbacks callbacks)
-            : block_of_code()
+            : block_of_code(callbacks)
             , jit_state()
             , emitter(&block_of_code, callbacks, jit)
             , callbacks(callbacks)