a32_emit_x64: Implement fastmem

include/dynarmic/A32/config.h

@@ -101,6 +101,15 @@ struct UserConfig {
     ///       This can be avoided by carefully allocating the memory region.
     bool absolute_offset_page_table = false;
 
+    // Fastmem Pointer
+    // This should point to the beginning of a 4GB address space which is in arranged just like
+    // what you wish for emulated memory to be. If the host page faults on an address, the JIT
+    // will fallback to calling the MemoryRead*/MemoryWrite* callbacks.
+    void* fastmem_pointer = nullptr;
+    /// Determines if instructions that pagefault should cause recompilation of that block
+    /// with fastmem disabled.
+    bool recompile_on_fastmem_failure = true;
+
     // Coprocessors
     std::array<std::shared_ptr<Coprocessor>, 16> coprocessors{};
 

src/CMakeLists.txt

@@ -248,6 +248,7 @@ if (ARCHITECTURE_x86_64)
          backend/x64/emit_x64_sm4.cpp
          backend/x64/emit_x64_vector.cpp
          backend/x64/emit_x64_vector_floating_point.cpp
+         backend/x64/exception_handler.h
          backend/x64/hostloc.cpp
          backend/x64/hostloc.h
          backend/x64/jitstate_info.h

src/backend/x64/a32_emit_x64.cpp

@@ -72,6 +72,10 @@ A32EmitX64::A32EmitX64(BlockOfCode& code, A32::UserConfig config, A32::Jit* jit_
     GenTerminalHandlers();
     code.PreludeComplete();
     ClearFastDispatchTable();
+
+    exception_handler.SetFastmemCallback([this](u64 rip_){
+        return FastmemCallback(rip_);
+    });
 }
 
 A32EmitX64::~A32EmitX64() = default;
@@ -91,6 +95,9 @@ A32EmitX64::BlockDescriptor A32EmitX64::Emit(IR::Block& block) {
         if (config.page_table) {
             gprs.erase(std::find(gprs.begin(), gprs.end(), HostLoc::R14));
         }
+        if (config.fastmem_pointer) {
+            gprs.erase(std::find(gprs.begin(), gprs.end(), HostLoc::R13));
+        }
         return gprs;
     }();
 
@@ -146,6 +153,7 @@ void A32EmitX64::ClearCache() {
     EmitX64::ClearCache();
     block_ranges.ClearCache();
     ClearFastDispatchTable();
+    fastmem_patch_info.clear();
 }
 
 void A32EmitX64::InvalidateCacheRanges(const boost::icl::interval_set<u32>& ranges) {
@@ -777,6 +785,32 @@ void A32EmitX64::EmitA32SetExclusive(A32EmitContext& ctx, IR::Inst* inst) {
     code.mov(dword[r15 + offsetof(A32JitState, exclusive_address)], address);
 }
 
+std::optional<A32EmitX64::DoNotFastmemMarker> A32EmitX64::ShouldFastmem(A32EmitContext& ctx, IR::Inst* inst) const {
+    if (!config.fastmem_pointer || !exception_handler.SupportsFastmem()) {
+        return std::nullopt;
+    }
+
+    const auto marker = std::make_tuple(ctx.Location(), ctx.GetInstOffset(inst));
+    if (do_not_fastmem.count(marker) > 0) {
+        return std::nullopt;
+    }
+    return marker;
+}
+
+FakeCall A32EmitX64::FastmemCallback(u64 rip_) {
+    const auto iter = fastmem_patch_info.find(rip_);
+    ASSERT(iter != fastmem_patch_info.end());
+    if (config.recompile_on_fastmem_failure) {
+        const auto marker = iter->second.marker;
+        do_not_fastmem.emplace(marker);
+        InvalidateBasicBlocks({std::get<0>(marker)});
+    }
+    FakeCall ret;
+    ret.call_rip = iter->second.callback;
+    ret.ret_rip = iter->second.resume_rip;
+    return ret;
+}
+
 static Xbyak::RegExp EmitVAddrLookup(BlockOfCode& code, RegAlloc& reg_alloc,
                                      const A32::UserConfig& config, Xbyak::Label& abort,
                                      Xbyak::Reg64 vaddr,
@@ -823,13 +857,48 @@ void A32EmitX64::ReadMemory(A32EmitContext& ctx, IR::Inst* inst) {
         return;
     }
 
-    Xbyak::Label abort, end;
-
     const Xbyak::Reg64 vaddr = ctx.reg_alloc.UseGpr(args[0]);
     const Xbyak::Reg64 value = ctx.reg_alloc.ScratchGpr();
 
     const auto wrapped_fn = read_fallbacks[std::make_tuple(bitsize, vaddr.getIdx(), value.getIdx())];
 
+    if (const auto marker = ShouldFastmem(ctx, inst)) {
+        const auto location = code.getCurr();
+
+        switch (bitsize) {
+        case 8:
+            code.movzx(value.cvt32(), code.byte[r13 + vaddr]);
+            break;
+        case 16:
+            code.movzx(value.cvt32(), word[r13 + vaddr]);
+            break;
+        case 32:
+            code.mov(value.cvt32(), dword[r13 + vaddr]);
+            break;
+        case 64:
+            code.mov(value, qword[r13 + vaddr]);
+            break;
+        default:
+            ASSERT_MSG(false, "Invalid bitsize");
+            break;
+        }
+
+        ctx.reg_alloc.DefineValue(inst, value);
+
+        fastmem_patch_info.emplace(
+            Common::BitCast<u64>(location),
+            FastmemPatchInfo{
+                Common::BitCast<u64>(code.getCurr()),
+                Common::BitCast<u64>(wrapped_fn),
+                *marker,
+            }
+        );
+
+        return;
+    }
+
+    Xbyak::Label abort, end;
+
     const auto src_ptr = EmitVAddrLookup(code, ctx.reg_alloc, config, abort, vaddr, value);
     switch (bitsize) {
     case 8:
@@ -845,7 +914,7 @@ void A32EmitX64::ReadMemory(A32EmitContext& ctx, IR::Inst* inst) {
         code.mov(value, qword[src_ptr]);
         break;
     default:
-        ASSERT_MSG(false, "Invalid bit_size");
+        ASSERT_MSG(false, "Invalid bitsize");
         break;
     }
     code.jmp(end);
@@ -881,13 +950,46 @@ void A32EmitX64::WriteMemory(A32EmitContext& ctx, IR::Inst* inst) {
         return;
     }
 
-    Xbyak::Label abort, end;
-
     const Xbyak::Reg64 vaddr = ctx.reg_alloc.UseGpr(args[0]);
     const Xbyak::Reg64 value = ctx.reg_alloc.UseGpr(args[1]);
 
     const auto wrapped_fn = write_fallbacks[std::make_tuple(bitsize, vaddr.getIdx(), value.getIdx())];
 
+    if (const auto marker = ShouldFastmem(ctx, inst)) {
+        const auto location = code.getCurr();
+
+        switch (bitsize) {
+        case 8:
+            code.mov(code.byte[r13 + vaddr], value.cvt8());
+            break;
+        case 16:
+            code.mov(word[r13 + vaddr], value.cvt16());
+            break;
+        case 32:
+            code.mov(dword[r13 + vaddr], value.cvt32());
+            break;
+        case 64:
+            code.mov(qword[r13 + vaddr], value);
+            break;
+        default:
+            ASSERT_MSG(false, "Invalid bitsize");
+            break;
+        }
+
+        fastmem_patch_info.emplace(
+            Common::BitCast<u64>(location),
+            FastmemPatchInfo{
+                Common::BitCast<u64>(code.getCurr()),
+                Common::BitCast<u64>(wrapped_fn),
+                *marker,
+            }
+        );
+
+        return;
+    }
+
+    Xbyak::Label abort, end;
+
     const auto dest_ptr = EmitVAddrLookup(code, ctx.reg_alloc, config, abort, vaddr);
     switch (bitsize) {
     case 8:
@@ -903,7 +1005,7 @@ void A32EmitX64::WriteMemory(A32EmitContext& ctx, IR::Inst* inst) {
         code.mov(qword[dest_ptr], value);
         break;
     default:
-        ASSERT_MSG(false, "Invalid bit_size");
+        ASSERT_MSG(false, "Invalid bitsize");
         break;
     }
     code.jmp(end);

src/backend/x64/a32_emit_x64.h

@@ -7,6 +7,10 @@
 #pragma once
 
 #include <array>
+#include <optional>
+#include <set>
+#include <tuple>
+#include <unordered_map>
 
 #include <dynarmic/A32/a32.h>
 #include <dynarmic/A32/config.h>
@@ -46,7 +50,6 @@ protected:
     const A32::UserConfig config;
     A32::Jit* jit_interface;
     BlockRangeInformation<u32> block_ranges;
-    ExceptionHandler exception_handler;
 
     struct FastDispatchEntry {
         u64 location_descriptor;
@@ -78,6 +81,18 @@ protected:
     // Helpers
     std::string LocationDescriptorToFriendlyName(const IR::LocationDescriptor&) const override;
 
+    // Fastmem information
+    using DoNotFastmemMarker = std::tuple<IR::LocationDescriptor, std::ptrdiff_t>;
+    struct FastmemPatchInfo {
+        u64 resume_rip;
+        u64 callback;
+        DoNotFastmemMarker marker;
+    };
+    std::unordered_map<u64, FastmemPatchInfo> fastmem_patch_info;
+    std::set<DoNotFastmemMarker> do_not_fastmem;
+    std::optional<DoNotFastmemMarker> ShouldFastmem(A32EmitContext& ctx, IR::Inst* inst) const;
+    FakeCall FastmemCallback(u64 rip);
+
     // Memory access helpers
     template<std::size_t bitsize>
     void ReadMemory(A32EmitContext& ctx, IR::Inst* inst);

src/backend/x64/a32_interface.cpp

@@ -42,13 +42,13 @@ static RunCodeCallbacks GenRunCodeCallbacks(A32::UserCallbacks* cb, CodePtr (*Lo
 }
 
 static std::function<void(BlockOfCode&)> GenRCP(const A32::UserConfig& config) {
-    if (!config.page_table) {
-        return [](BlockOfCode&){};
+    return [config](BlockOfCode& code) {
+        if (config.page_table) {
+            code.mov(code.r14, Common::BitCast<u64>(config.page_table));
+        }
+        if (config.fastmem_pointer) {
+            code.mov(code.r13, Common::BitCast<u64>(config.fastmem_pointer));
         }
-
-    const u64 r14_value = Common::BitCast<u64>(config.page_table);
-    return [r14_value](BlockOfCode& code) {
-        code.mov(code.r14, r14_value);
     };
 }
 

src/backend/x64/emit_x64.cpp

@@ -4,6 +4,7 @@
  * General Public License version 2 or any later version.
  */
 
+#include <iterator>
 #include <unordered_map>
 
 #include "backend/x64/block_of_code.h"
@@ -28,6 +29,10 @@ using namespace Xbyak::util;
 EmitContext::EmitContext(RegAlloc& reg_alloc, IR::Block& block)
     : reg_alloc(reg_alloc), block(block) {}
 
+size_t EmitContext::GetInstOffset(IR::Inst* inst) const {
+    return static_cast<size_t>(std::distance(block.begin(), IR::Block::iterator(inst)));
+}
+
 void EmitContext::EraseInstruction(IR::Inst* inst) {
     block.Instructions().erase(inst);
     inst->ClearArgs();

src/backend/x64/emit_x64.h

@@ -43,6 +43,7 @@ using VectorArray = std::array<T, A64FullVectorWidth::value / Common::BitSize<T>
 struct EmitContext {
     EmitContext(RegAlloc& reg_alloc, IR::Block& block);
 
+    size_t GetInstOffset(IR::Inst* inst) const;
     void EraseInstruction(IR::Inst* inst);
 
     virtual FP::FPCR FPCR() const = 0;

src/backend/x64/exception_handler.h

@@ -6,18 +6,30 @@
 
 #pragma once
 
+#include <functional>
 #include <memory>
 
+#include "common/common_types.h"
+
 namespace Dynarmic::Backend::X64 {
 
 class BlockOfCode;
 
+struct FakeCall {
+    u64 call_rip;
+    u64 ret_rip;
+};
+
 class ExceptionHandler final {
 public:
     ExceptionHandler();
     ~ExceptionHandler();
 
     void Register(BlockOfCode& code);
+
+    bool SupportsFastmem() const noexcept;
+    void SetFastmemCallback(std::function<FakeCall(u64)> cb);
+
 private:
     struct Impl;
     std::unique_ptr<Impl> impl;

src/backend/x64/exception_handler_generic.cpp

@@ -18,4 +18,12 @@ void ExceptionHandler::Register(BlockOfCode&) {
     // Do nothing
 }
 
+bool ExceptionHandler::SupportsFastmem() const noexcept {
+    return false;
+}
+
+void ExceptionHandler::SetFastmemCallback(std::function<FakeCall(u64)>) {
+    // Do nothing
+}
+
 } // namespace Dynarmic::Backend::X64

src/backend/x64/exception_handler_windows.cpp

@@ -198,4 +198,12 @@ void ExceptionHandler::Register(BlockOfCode& code) {
     impl = std::make_unique<Impl>(rfuncs, code.getCode());
 }
 
+bool ExceptionHandler::SupportsFastmem() const noexcept {
+    return false;
+}
+
+void ExceptionHandler::SetFastmemCallback(std::function<FakeCall(u64)>) {
+    // Do nothing
+}
+
 } // namespace Dynarmic::Backend::X64

src/frontend/ir/location_descriptor.h

@@ -33,13 +33,17 @@ private:
 
 std::ostream& operator<<(std::ostream& o, const LocationDescriptor& descriptor);
 
+inline bool operator<(const LocationDescriptor& x, const LocationDescriptor& y) noexcept {
+    return x.Value() < y.Value();
+}
+
 } // namespace Dynarmic::IR
 
 namespace std {
 template <>
 struct less<Dynarmic::IR::LocationDescriptor> {
     bool operator()(const Dynarmic::IR::LocationDescriptor& x, const Dynarmic::IR::LocationDescriptor& y) const noexcept {
-        return x.Value() < y.Value();
+        return x < y;
     }
 };
 template <>