https://github.com/ksco/rvemu

A simple and fast RISC-V JIT emulator.
https://github.com/ksco/rvemu

Last synced: 6 days ago
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A simple and fast RISC-V JIT emulator.

• Host: GitHub
• URL: https://github.com/ksco/rvemu
• Owner: ksco
• License: mit
• Created: 2023-01-04T15:28:41.000Z (almost 2 years ago)
• Default Branch: main
• Last Pushed: 2024-08-21T06:25:36.000Z (5 months ago)
• Last Synced: 2024-12-22T17:15:14.359Z (13 days ago)
• Language: C
• Homepage:
• Size: 116 KB
• Stars: 122
• Watchers: 2
• Forks: 23
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# `rvemu`

`rvemu` is a fast Linux emulator, which can run statically linked RV64 programs.

Yeah, it's a toy, but a fairly complete and fast one, which is perfect for learning how a JIT emulator works.

## Features

1. Faster than QEMU, can achieve native performance in some cases.

2. (Almost*) architecture independent, we've tested it under x86_64.

3. Tiny, and easy to understand.

4. Targeting RV64IMFDC w/ Newlib (only a small subset of syscalls is implemented, adding more).

> *Support for new architecture requires handling relocations in src/compile.c, but it's relatively easy. A few lines of code would do.

## Usage

```

make -j

riscv64-unknown-elf-gcc hello.c

./rvemu a.out

```

`rvemu` can only run under Linux, and `clang` needs to be installed to run, as rvemu uses `clang` to generate jit code.

## Showcase

### Running Lua 4.0.1

```

$ ./rvemu bin/lua -v

Lua 4.0.1  Copyright (C) 1994-2000 TeCGraf, PUC-Rio

$ ./rvemu bin/lua test/hello.lua

hello world, from Lua!

```

### Running Java (using [PitifulVM](https://github.com/sysprog21/pitifulvm))

```

$ javac tests/Hello.java

$ ./rvemu jvm tests/Hello.class

Hello, World!

```

## Notes

1. `rvemu` uses `clang -O3` to generate highly optimized target code.

2. `rvemu` uses hardfloat technique to gain more performance, just like [NEMU](https://github.com/OpenXiangShan/NEMU), this actually violates the RISC-V standard, but it produces correct results in most cases, and it's way faster than softfloat.

3. `rvemu` uses a linear-mapped MMU similar to [blink](https://github.com/jart/blink), which is really fast.

## Benchmark

> All the tests is compiled with `riscv64-unknown-elf-gcc -O3` for RISC-V and `clang-15` for x86 native, and run on Intel Xeon Platinum 8269CY.

- Test suite: [nbench](https://github.com/nfinit/ansibench/tree/master/nbench)

- Unit: iterations/second

### NUMERIC SORT

```

   rvemu | #######################################################      | 1595.92

    QEMU | ############################                                 | 821.9

  Native | ############################################################ | 1735.89

```

### STRING SORT

```

   rvemu | ###                                                          | 138.96

    QEMU | #                                                            | 25.24

  Native | ############################################################ | 2680.95

```

### BITFIELD

```

   rvemu | #########################################################    | 741057761.48

    QEMU | ###############################                              | 406495858.33

  Native | ############################################################ | 783239543.75

```

### FP EMULATION

```

   rvemu | ##################################                           | 591.06

    QEMU | #########                                                    | 162.26

  Native | ############################################################ | 1040.14

```

### FOURIER

```

   rvemu | ###                                                          | 6284.49

    QEMU | ##                                                           | 5867.78

  Native | ############################################################ | 147247.94

```

### ASSIGNMENT

```

   rvemu | ##################################################           | 84.68

    QEMU | ###################                                          | 31.98

  Native | ############################################################ | 102.54

```

### IDEA

```

   rvemu | #############################################                | 11070.72

    QEMU | #####################                                        | 5234.18

  Native | ############################################################ | 14832.27

```

### HUFFMAN

```

   rvemu | ############################################################ | 5070.87

    QEMU | ##########################                                   | 2205.89

  Native | ######################################################       | 4599.75

```

## Refs

Inspired by

1. https://github.com/gamozolabs/fuzz_with_emus

2. https://github.com/jart/blink

3. https://github.com/michaeljclark/rv8

4. https://github.com/OpenXiangShan/NEMU