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Ryan Houdek
b25f1c4e3b
When the `BT mem` operation was accessing memory where the bit offset wasn't a multiple of the access size, then we were dividing the offset by bytes and accessing bits at `mem[byteOffset] &= (BitOffset)`. BitOffset wasn't adjusted to compensate for the access size being added to the address. Causing a mismatch of testing the wrong bits. Unit tests didn't capture this. Trying to run glxgears on i965/iris showed extensive corruption because of it though.
FEXCore - Fast x86 Core emulation library
This is the core emulation library that is used for the FEX emulator project. This project aims to provide a fast and functional x86-64 emulation library that can meet and surpass other x86-64 emulation libraries.
Goals
- Be as fast as possible, beating and exceeding current options for x86-64 emulation
- 25% - 50% lower performance than native code would be desired target
- Use an IR to efficiently translate x86-64 to our host architecture
- Support a tiered recompiler to allow for fast runtime performance
- Support offline compilation and offline tooling for inspection and performance analysis
- Support threaded emulation. Including emulating x86-64's strong memory model on weak memory model architectures
- Support a significant portion of the x86-64 instruction space.
- Including MMX, SSE, SSE2, SSE3, SSSE3, and SSE4*
- Support fallback routines for uncommonly used x86-64 instructions
- Including x87 and 3DNow!
- Only support userspace emulation.
- All x86-64 instructions run as if they are under CPL-3(userland) security layer
- Minimal Linux Syscall emulation for testing purposes
- Portable library implementation in order to support easy integration in to applications
Target Host Architecture
The target host architecture for this library is AArch64. Specifically the ARMv8.1 version or newer. The CPU IR is designed with AArch64 in mind but there is a desire to run the recompiled code on other architectures as well. Multiple architecture support is desired for easier bringup and debugging, performance isn't as much of a priority there (ex. x86-64(guest) translated to x86-64(host))
Not currently goals but will be in the future
- 32bit x86 support
- This will be a desire in the future, but to lower the amount of work required, decided to push this off for now.
- Integration in to WINE
- Later generation of x86-64 instruction sets
- Including AVX, F16C, XOP, FMA, AVX2, etc
Not desired
- Kernel space emulation
- CPL0-2 emulation
- Real Mode, Protected Mode, Virtual-8086 Mode, System Management Mode
- IRQs
- SVM
- "Cycle Accurate" emulation
Dependencies
- SonicUtils
- LLVM
- clang-tidy if you want to ensure the code stays tidy
- cmake
- A C++17 compliant compiler (There are assumptions made about using Clang and LTO)