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Add Zydis x86/x86-64 disassembler support #5128

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4 changes: 4 additions & 0 deletions .gitmodules
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Original file line number Diff line number Diff line change
Expand Up @@ -49,3 +49,7 @@
[submodule "External/range-v3"]
path = External/range-v3
url = https://github.com/ericniebler/range-v3.git
[submodule "External/zydis"]
shallow = true
path = External/zydis
url = https://github.com/zyantific/zydis.git
13 changes: 13 additions & 0 deletions CMakeLists.txt
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Expand Up @@ -28,6 +28,7 @@ option(ENABLE_LIBCXX "Enables LLVM libc++" FALSE)
option(ENABLE_CCACHE "Enables ccache for compile caching" TRUE)
option(ENABLE_VIXL_SIMULATOR "Enable use of VIXL simulator for emulation (only useful for CI testing)" FALSE)
option(ENABLE_VIXL_DISASSEMBLER "Enables debug disassembler output with VIXL" FALSE)
option(ENABLE_ZYDIS "Enables x86/x86-64 guest disassembler output with Zydis" FALSE)
option(USE_LEGACY_BINFMTMISC "Uses legacy method of setting up binfmt_misc" FALSE)
option(ENABLE_FEXCORE_PROFILER "Enables use of the FEXCore timeline profiling capabilities" FALSE)
set (FEXCORE_PROFILER_BACKEND "gpuvis" CACHE STRING "Set which backend to use for the FEXCore profiler (gpuvis, tracy)")
Expand Down Expand Up @@ -315,6 +316,18 @@ if (BUILD_TESTING OR ENABLE_VIXL_DISASSEMBLER OR ENABLE_VIXL_SIMULATOR)
include_directories(SYSTEM External/vixl/src/)
endif()

if (ENABLE_ZYDIS)
find_package(Zydis QUIET)
if (Zydis_FOUND)
message(STATUS "Using system Zydis")
else()
message(STATUS "Using bundled Zydis")
Comment on lines +320 to +324
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@neobrain neobrain Dec 18, 2025 •
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Unfortunately I realized Fedora does not actually ship a CMake config for Zydis, but only pkgconfig files. To add insult to injury, zycore uses a separate pkgconfig file, so this must be used instead:

Suggested change
find_package(Zydis QUIET)
if (Zydis_FOUND)
message(STATUS "Using system Zydis")
else()
message(STATUS "Using bundled Zydis")
pkg_search_module(Zydis QUIET IMPORTED_TARGET zydis)
pkg_search_module(Zycore QUIET IMPORTED_TARGET zycore)
if (TARGET PkgConfig::Zydis AND TARGET PkgConfig::Zycore AND NOT CMAKE_CROSSCOMPILING)
add_library(Zydis::Zydis ALIAS PkgConfig::Zydis)
add_library(Zycore::Zycore ALIAS PkgConfig::Zycore)
message(STATUS "Using system Zydis")
else()
message(STATUS "Using bundled Zydis")

None of the other distros that I use have that package to begin with so I don't know if CMake files are shipped anywhere. Might be interesting to check quickly on your systems, otherwise I wouldn't spend too much energy researching this.

One day we'll have nice things :(

set(ZYDIS_BUILD_TOOLS OFF CACHE BOOL "" FORCE)
set(ZYDIS_BUILD_EXAMPLES OFF CACHE BOOL "" FORCE)
add_subdirectory(External/zydis/)
endif()
endif()

if (ENABLE_FEXCORE_PROFILER AND FEXCORE_PROFILER_BACKEND STREQUAL "TRACY")
add_subdirectory(External/tracy)
endif()
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1 change: 1 addition & 0 deletions External/zydis
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Submodule zydis added at 9bfadd
8 changes: 8 additions & 0 deletions FEXCore/Source/CMakeLists.txt
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Expand Up @@ -96,6 +96,10 @@ if (ENABLE_VIXL_DISASSEMBLER)
list(APPEND DEFINES -DVIXL_DISASSEMBLER=1)
endif()

if (ENABLE_ZYDIS)
list(APPEND DEFINES -DZYDIS_DISASSEMBLER=1)
endif()

if (_M_ARM_64 AND HAS_CLANG_PRESERVE_ALL)
list(APPEND DEFINES "-DFEXCORE_PRESERVE_ALL_ATTR=__attribute__((preserve_all));-DFEXCORE_HAS_PRESERVE_ALL_ATTR=1")
else()
Expand All @@ -108,6 +112,10 @@ if (ENABLE_VIXL_DISASSEMBLER OR ENABLE_VIXL_SIMULATOR)
list (APPEND LIBS vixl)
endif()

if (ENABLE_ZYDIS)
list (APPEND LIBS Zydis)
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@neobrain neobrain Dec 18, 2025

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This should use the namespaced variant: Zydis::Zydis or Zycore::Zycore (they are robust against typos and unintentionally undeclared build targets; "Zydis" may fall back to purely linking against libZydis.so without propagating include directories etc)

endif()

if (NOT MINGW_BUILD)
list (APPEND LIBS dl)
else()
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8 changes: 8 additions & 0 deletions FEXCore/Source/Interface/Config/Config.json.in
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Expand Up @@ -334,6 +334,14 @@
"\tstats: Will print stats when disassembling the code"
]
},
"X86Disassemble": {
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@neobrain neobrain Dec 18, 2025

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Could you also briefly update the description of the Disassemble option to distinguish from this option / make it clear it only covers generated arm code?

"Type": "bool",
"Default": "false",
"Desc": [
"Enables x86/x86-64 guest disassembly output for compiled blocks.",
"Requires FEX to be built with -DENABLE_ZYDIS=TRUE"
]
},
"ForceSVEWidth": {
"Type": "uint32",
"Default": "0",
Expand Down
38 changes: 38 additions & 0 deletions FEXCore/Source/Interface/Core/Core.cpp
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Expand Up @@ -9,6 +9,9 @@ desc: Glues Frontend, OpDispatcher and IR Opts & Compilation, LookupCache, Dispa
*/

#include <cstdint>
#ifdef ZYDIS_DISASSEMBLER
#include <Zydis/Zydis.h>
#endif
#include "Interface/Core/ArchHelpers/Arm64Emitter.h"
#include "Interface/Core/LookupCache.h"
#include "Interface/Core/CPUBackend.h"
Expand Down Expand Up @@ -536,9 +539,25 @@ ContextImpl::GenerateIR(FEXCore::Core::InternalThreadState* Thread, uint64_t Gue

const auto GPRSize = Thread->OpDispatcher->GetGPROpSize();

#ifdef ZYDIS_DISASSEMBLER
FEX_CONFIG_OPT(X86Disassemble, X86DISASSEMBLE);
const auto ZydisMachineMode = Config.Is64BitMode ? ZYDIS_MACHINE_MODE_LONG_64 : ZYDIS_MACHINE_MODE_LEGACY_32;
if (X86Disassemble()) {
const uint64_t DecodedMin = Thread->FrontendDecoder->DecodedMinAddress;
const uint64_t DecodedMax = Thread->FrontendDecoder->DecodedMaxAddress;
LogMan::Msg::IFmt("Guest x86 Begin (RIP={:#x}, {:#x}-{:#x})", GuestRIP, DecodedMin, DecodedMax);
}
#endif

for (size_t j = 0; j < CodeBlocks->size(); ++j) {
const FEXCore::Frontend::Decoder::DecodedBlocks& Block = CodeBlocks->at(j);

#ifdef ZYDIS_DISASSEMBLER
if (X86Disassemble() && CodeBlocks->size() > 1) {
LogMan::Msg::IFmt(" Block {} Entry={:#x} NumInsts={}", j, Block.Entry, Block.NumInstructions);
}
#endif

bool BlockInForceTSOValidRange = false;
auto InstForceTSOIt = ForceTSOInstructions.end();
if (ForceTSOValidRanges.Contains({Block.Entry, Block.Entry + Block.Size})) {
Expand Down Expand Up @@ -570,6 +589,19 @@ ContextImpl::GenerateIR(FEXCore::Core::InternalThreadState* Thread, uint64_t Gue

TableInfo = Block.DecodedInstructions[i].TableInfo;
DecodedInfo = &Block.DecodedInstructions[i];

#ifdef ZYDIS_DISASSEMBLER
if (X86Disassemble()) {
const uint8_t* InstBytes = reinterpret_cast<const uint8_t*>(InstAddress);
ZydisDisassembledInstruction ZydisInst;
if (ZYAN_SUCCESS(ZydisDisassembleIntel(ZydisMachineMode, InstAddress, InstBytes, DecodedInfo->InstSize, &ZydisInst))) {
LogMan::Msg::IFmt("{:#x}: {}", InstAddress, ZydisInst.text);
} else {
LogMan::Msg::IFmt("{:#x}: (decode failed, {} bytes)", InstAddress, DecodedInfo->InstSize);
Comment on lines +598 to +600
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Suggested change
LogMan::Msg::IFmt("{:#x}: {}", InstAddress, ZydisInst.text);
} else {
LogMan::Msg::IFmt("{:#x}: (decode failed, {} bytes)", InstAddress, DecodedInfo->InstSize);
LogMan::Msg::IFmt(" {:#x}: {}", InstAddress, ZydisInst.text);
} else {
LogMan::Msg::IFmt(" {:#x}: (decode failed, {} bytes)", InstAddress, DecodedInfo->InstSize);

}
}
#endif

bool IsLocked = DecodedInfo->Flags & FEXCore::X86Tables::DecodeFlags::FLAG_LOCK;

// Do a partial register cache flush before every instruction. This
Expand Down Expand Up @@ -689,6 +721,12 @@ ContextImpl::GenerateIR(FEXCore::Core::InternalThreadState* Thread, uint64_t Gue
}
}

#ifdef ZYDIS_DISASSEMBLER
if (X86Disassemble()) {
LogMan::Msg::IFmt("Guest x86 End");
}
#endif

Thread->OpDispatcher->Finalize();

Thread->FrontendDecoder->DelayedDisownBuffer();
Expand Down
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