1 VIXL: AArch64 Runtime Code Generation Library Version 1.4 2 ========================================================= 3 4 Contents: 5 6 * Requirements 7 * Overview 8 * Known limitations 9 * Usage 10 11 12 Requirements 13 ============ 14 15 To build VIXL the following software is required: 16 17 1. Python 2.7 18 2. SCons 2.0 19 3. GCC 4.4+ 20 21 A 64-bit host machine is required, implementing an LP64 data model. VIXL has 22 only been tested using GCC on Ubuntu systems. 23 24 To run the linter stage of the tests, the following software is also required: 25 26 1. Git 27 2. [Google's `cpplint.py`][cpplint] 28 29 Refer to the 'Usage' section for details. 30 31 32 Overview 33 ======== 34 35 VIXL is made of three components. 36 37 1. A programmatic assembler to generate A64 code at runtime. The assembler 38 abstracts some of the constraints of the A64 ISA, for example most 39 instructions support any immediate. 40 2. A disassembler which can print any instruction emitted by the assembler. 41 3. A simulator which can simulate any instruction emitted by the assembler. 42 The simulator allows generated code to be run on another architecture 43 without the need for a full ISA model. 44 45 The VIXL git repository can be found [on GitHub][vixl]. Changes from previous 46 versions of VIXL can be found in the [Changelog](doc/changelog.md). 47 48 49 Known Limitations 50 ================= 51 52 VIXL was developed to target JavaScript engines so a number of features from A64 53 were deemed unnecessary: 54 55 * No Advanced SIMD support. 56 * Limited rounding mode support for floating point. 57 * Limited support for synchronisation instructions. 58 * Limited support for system instructions. 59 * A few miscellaneous integer and floating point instructions are missing. 60 61 The VIXL simulator supports only those instructions that the VIXL assembler can 62 generate. The `doc` directory contains a 63 [list of supported instructions](doc/supported-instructions.md). 64 65 The VIXL simulator was developed to run on 64-bit amd64 platforms. Whilst it 66 builds and mostly works for 32-bit x86 platforms, there are a number of 67 floating-point operations which do not work correctly, and a number of tests 68 fail as a result. 69 70 Usage 71 ===== 72 73 74 Running all Tests 75 ----------------- 76 77 The helper script `tools/presubmit.py` will build and run every test that is 78 provided with VIXL, in both release and debug mode. It is a useful script for 79 verifying that all of VIXL's dependencies are in place and that VIXL is working 80 as it should. 81 82 By default, the `tools/presubmit.py` script runs a linter to check that the 83 source code conforms with the code style guide, and to detect several common 84 errors that the compiler may not warn about. This is most useful for VIXL 85 developers. The linter has the following dependencies: 86 87 1. Git must be installed, and the VIXL project must be in a valid Git 88 repository, such as one produced using `git clone`. 89 2. `cpplint.py`, [as provided by Google][cpplint], must be available (and 90 executable) on the `PATH`. Only revision 104 has been tested with VIXL. 91 92 It is possible to tell `tools/presubmit.py` to skip the linter stage by passing 93 `--nolint`. This removes the dependency on `cpplint.py` and Git. The `--nolint` 94 option is implied if the VIXL project is a snapshot (with no `.git` directory). 95 96 97 Building and Running the Benchmarks 98 ----------------------------------- 99 100 There are two very basic benchmarks provided with VIXL: 101 102 1. bench\_dataop, emitting adds 103 2. bench\_branch, emitting branches 104 105 To build one benchmark: `scons target=bench_xxx`, then run it as 106 `./bench_xxx_sim <number of iterations>`. The benchmarks do not report a 107 figure; they should be timed using the `time` command. 108 109 110 Getting Started 111 --------------- 112 113 A short introduction to using VIXL can be found [here](doc/getting-started.md). 114 Example source code is provided in the `examples` directory. Build this using 115 `scons target=examples` from the root directory. 116 117 118 119 [cpplint]: https://google-styleguide.googlecode.com/svn-history/r104/trunk/cpplint/cpplint.py 120 "Google's cpplint.py script." 121 122 [vixl]: https://github.com/armvixl/vixl 123 "The VIXL repository on GitHub." 124
