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Diffstat (limited to 'compiler/rustc_codegen_gcc/Readme.md')
| -rw-r--r-- | compiler/rustc_codegen_gcc/Readme.md | 92 |
1 files changed, 86 insertions, 6 deletions
diff --git a/compiler/rustc_codegen_gcc/Readme.md b/compiler/rustc_codegen_gcc/Readme.md index fe23a2676..bb7419438 100644 --- a/compiler/rustc_codegen_gcc/Readme.md +++ b/compiler/rustc_codegen_gcc/Readme.md @@ -1,5 +1,7 @@ # WIP libgccjit codegen backend for rust +[](https://web.libera.chat/#rustc_codegen_gcc) + This is a GCC codegen for rustc, which means it can be loaded by the existing rustc frontend, but benefits from GCC: more architectures are supported and GCC's optimizations are used. **Despite its name, libgccjit can be used for ahead-of-time compilation, as is used here.** @@ -16,21 +18,61 @@ The patches in [this repository](https://github.com/antoyo/libgccjit-patches) ne (Those patches should work when applied on master, but in case it doesn't work, they are known to work when applied on 079c23cfe079f203d5df83fea8e92a60c7d7e878.) You can also use my [fork of gcc](https://github.com/antoyo/gcc) which already includes these patches.** +To build it (most of these instructions come from [here](https://gcc.gnu.org/onlinedocs/jit/internals/index.html), so don't hesitate to take a look there if you encounter an issue): + +```bash +$ git clone https://github.com/antoyo/gcc +$ sudo apt install flex libmpfr-dev libgmp-dev libmpc3 libmpc-dev +$ mkdir gcc-build gcc-install +$ cd gcc-build +$ ../gcc/configure \ + --enable-host-shared \ + --enable-languages=jit \ + --enable-checking=release \ # it enables extra checks which allow to find bugs + --disable-bootstrap \ + --disable-multilib \ + --prefix=$(pwd)/../gcc-install +$ make -j4 # You can replace `4` with another number depending on how many cores you have. +``` + +If you want to run libgccjit tests, you will need to also enable the C++ language in the `configure`: + +```bash +--enable-languages=jit,c++ +``` + +Then to run libgccjit tests: + +```bash +$ cd gcc # from the `gcc-build` folder +$ make check-jit +# To run one specific test: +$ make check-jit RUNTESTFLAGS="-v -v -v jit.exp=jit.dg/test-asm.cc" +``` + **Put the path to your custom build of libgccjit in the file `gcc_path`.** ```bash -$ git clone https://github.com/rust-lang/rustc_codegen_gcc.git -$ cd rustc_codegen_gcc +$ dirname $(readlink -f `find . -name libgccjit.so`) > gcc_path +``` + +You also need to set RUST_COMPILER_RT_ROOT: + +```bash $ git clone https://github.com/llvm/llvm-project llvm --depth 1 --single-branch $ export RUST_COMPILER_RT_ROOT="$PWD/llvm/compiler-rt" -$ ./prepare_build.sh # download and patch sysroot src -$ ./build.sh --release ``` -To run the tests: +Then you can run commands like this: ```bash $ ./prepare.sh # download and patch sysroot src and install hyperfine for benchmarking +$ LIBRARY_PATH=$(cat gcc_path) LD_LIBRARY_PATH=$(cat gcc_path) ./build.sh --release +``` + +To run the tests: + +```bash $ ./test.sh --release ``` @@ -120,13 +162,52 @@ To print a debug representation of a tree: debug_tree(expr); ``` +(defined in print-tree.h) + +To print a debug reprensentation of a gimple struct: + +```c +debug_gimple_stmt(gimple_struct) +``` + To get the `rustc` command to run in `gdb`, add the `--verbose` flag to `cargo build`. +To have the correct file paths in `gdb` instead of `/usr/src/debug/gcc/libstdc++-v3/libsupc++/eh_personality.cc`: + +Maybe by calling the following at the beginning of gdb: + +``` +set substitute-path /usr/src/debug/gcc /path/to/gcc-repo/gcc +``` + +TODO(antoyo): but that's not what I remember I was doing. + ### How to use a custom-build rustc * Build the stage2 compiler (`rustup toolchain link debug-current build/x86_64-unknown-linux-gnu/stage2`). * Clean and rebuild the codegen with `debug-current` in the file `rust-toolchain`. +### How to install a forked git-subtree + +Using git-subtree with `rustc` requires a patched git to make it work. +The PR that is needed is [here](https://github.com/gitgitgadget/git/pull/493). +Use the following instructions to install it: + +``` +git clone git@github.com:tqc/git.git +cd git +git checkout tqc/subtree +make +make install +cd contrib/subtree +make +cp git-subtree ~/bin +``` + +### How to use [mem-trace](https://github.com/antoyo/mem-trace) + +`rustc` needs to be built without `jemalloc` so that `mem-trace` can overload `malloc` since `jemalloc` is linked statically, so a `LD_PRELOAD`-ed library won't a chance to intercept the calls to `malloc`. + ### How to build a cross-compiling libgccjit #### Building libgccjit @@ -142,6 +223,5 @@ To get the `rustc` command to run in `gdb`, add the `--verbose` flag to `cargo b * Since rustc doesn't support this architecture yet, set it back to `TARGET_TRIPLE="mips-unknown-linux-gnu"` (or another target having the same attributes). Alternatively, create a [target specification file](https://book.avr-rust.com/005.1-the-target-specification-json-file.html) (note that the `arch` specified in this file must be supported by the rust compiler). * Set `linker='-Clinker=m68k-linux-gcc'`. * Set the path to the cross-compiling libgccjit in `gcc_path`. - * Disable the 128-bit integer types if the target doesn't support them by using `let i128_type = context.new_type::<i64>();` in `context.rs` (same for u128_type). * Comment the line: `context.add_command_line_option("-masm=intel");` in src/base.rs. * (might not be necessary) Disable the compilation of libstd.so (and possibly libcore.so?). |