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Diffstat (limited to 'compiler/rustc_codegen_gcc/Readme.md')
| -rw-r--r-- | compiler/rustc_codegen_gcc/Readme.md | 52 |
1 files changed, 36 insertions, 16 deletions
diff --git a/compiler/rustc_codegen_gcc/Readme.md b/compiler/rustc_codegen_gcc/Readme.md index f001c83b08d..95fc6374c09 100644 --- a/compiler/rustc_codegen_gcc/Readme.md +++ b/compiler/rustc_codegen_gcc/Readme.md @@ -55,13 +55,6 @@ $ make check-jit RUNTESTFLAGS="-v -v -v jit.exp=jit.dg/test-asm.cc" $ 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" -``` - Then you can run commands like this: ```bash @@ -91,9 +84,17 @@ $ CHANNEL="release" $CG_GCCJIT_DIR/cargo.sh run If you compiled cg_gccjit in debug mode (aka you didn't pass `--release` to `./test.sh`) you should use `CHANNEL="debug"` instead or omit `CHANNEL="release"` completely. +### LTO + To use LTO, you need to set the variable `FAT_LTO=1` and `EMBED_LTO_BITCODE=1` in addition to setting `lto = "fat"` in the `Cargo.toml`. Don't set `FAT_LTO` when compiling the sysroot, though: only set `EMBED_LTO_BITCODE=1`. +Failing to set `EMBED_LTO_BITCODE` will give you the following error: + +``` +error: failed to copy bitcode to object file: No such file or directory (os error 2) +``` + ### Rustc > You should prefer using the Cargo method. @@ -286,6 +287,16 @@ git checkout sync_branch_name git merge master ``` +To send the changes to the rust repo: + +```bash +cd ../rust +git pull origin master +git checkout -b subtree-update_cg_gcc_YYYY-MM-DD +PATH="$HOME/bin:$PATH" ~/bin/git-subtree pull --prefix=compiler/rustc_codegen_gcc/ https://github.com/rust-lang/rustc_codegen_gcc.git master +git push +``` + TODO: write a script that does the above. https://rust-lang.zulipchat.com/#narrow/stream/301329-t-devtools/topic/subtree.20madness/near/258877725 @@ -303,16 +314,25 @@ generate it in [gimple.md](./doc/gimple.md). #### Building libgccjit - * Follow these instructions: https://preshing.com/20141119/how-to-build-a-gcc-cross-compiler/ with the following changes: - * Configure gcc with `../gcc/configure --enable-host-shared --disable-multilib --enable-languages=c,jit,c++ --disable-bootstrap --enable-checking=release --prefix=/opt/m68k-gcc/ --target=m68k-linux --without-headers`. - * Some shells, like fish, don't define the environment variable `$MACHTYPE`. - * Add `CFLAGS="-Wno-error=attributes -g -O2"` at the end of the configure command for building glibc (`CFLAGS="-Wno-error=attributes -Wno-error=array-parameter -Wno-error=stringop-overflow -Wno-error=array-bounds -g -O2"` for glibc 2.31, which is useful for Debian). + * Follow the instructions on [this repo](https://github.com/cross-cg-gcc-tools/cross-gcc). #### Configuring rustc_codegen_gcc - * Set `TARGET_TRIPLE="m68k-unknown-linux-gnu"` in config.sh. - * 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'`. + * Run `./y.sh prepare --cross` so that the sysroot is patched for the cross-compiling case. * Set the path to the cross-compiling libgccjit in `gcc_path`. - * 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?): Remove dylib from build_sysroot/sysroot_src/library/std/Cargo.toml. + * Make sure you have the linker for your target (for instance `m68k-unknown-linux-gnu-gcc`) in your `$PATH`. Currently, the linker name is hardcoded as being `$TARGET-gcc`. Specify the target when building the sysroot: `./y.sh build --target-triple m68k-unknown-linux-gnu`. + * Build your project by specifying the target: `OVERWRITE_TARGET_TRIPLE=m68k-unknown-linux-gnu ../cargo.sh build --target m68k-unknown-linux-gnu`. + +If the target is not yet supported by the Rust compiler, create a [target specification file](https://docs.rust-embedded.org/embedonomicon/custom-target.html) (note that the `arch` specified in this file must be supported by the rust compiler). +Then, you can use it the following way: + + * Add the target specification file using `--target` as an **absolute** path to build the sysroot: `./y.sh build --target-triple m68k-unknown-linux-gnu --target $(pwd)/m68k-unknown-linux-gnu.json` + * Build your project by specifying the target specification file: `OVERWRITE_TARGET_TRIPLE=m68k-unknown-linux-gnu ../cargo.sh build --target path/to/m68k-unknown-linux-gnu.json`. + +If you get the following error: + +``` +/usr/bin/ld: unrecognised emulation mode: m68kelf +``` + +Make sure you set `gcc_path` to the install directory. |