73 lines
2.9 KiB
Markdown
73 lines
2.9 KiB
Markdown
# Tips
|
|
|
|
The following shows how to do different random small things we encountered and thought could
|
|
be useful.
|
|
|
|
### How to send arguments to the GCC linker
|
|
|
|
```
|
|
CG_RUSTFLAGS="-Clink-args=-save-temps -v" ../y.sh cargo build
|
|
```
|
|
|
|
### How to see the personality functions in the asm dump
|
|
|
|
```
|
|
CG_RUSTFLAGS="-Clink-arg=-save-temps -v -Clink-arg=-dA" ../y.sh cargo build
|
|
```
|
|
|
|
### How to see the LLVM IR for a sysroot crate
|
|
|
|
```
|
|
cargo build -v --target x86_64-unknown-linux-gnu -Zbuild-std
|
|
# Take the command from the output and add --emit=llvm-ir
|
|
```
|
|
|
|
### To prevent the linker from unmangling symbols
|
|
|
|
Run with:
|
|
|
|
```
|
|
COLLECT_NO_DEMANGLE=1
|
|
```
|
|
|
|
### 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 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 generate GIMPLE
|
|
|
|
If you need to check what gccjit is generating (GIMPLE), then take a look at how to
|
|
generate it in [gimple.md](./doc/gimple.md).
|
|
|
|
### How to build a cross-compiling libgccjit
|
|
|
|
#### Building libgccjit
|
|
|
|
* Follow the instructions on [this repo](https://github.com/cross-cg-gcc-tools/cross-gcc).
|
|
|
|
#### Configuring rustc_codegen_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` (in `config.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 ../y.sh cargo 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 ../y.sh cargo 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` (in `config.toml`) to the install directory.
|