Finish bumping stage0

[rust.git] / Readme.md

diff --git a/Readme.md b/Readme.md
index 44cb16334742fc227de254859dde833e0ee18229..fe23a26769663f3a2f61b1ccdf8a3d65ab975d70 100644 (file)
--- a/Readme.md
+++ b/Readme.md
@@ -12,15 +12,17 @@ A secondary goal is to check if using the gcc backend will provide any run-time
 ## Building
 
 **This requires a patched libgccjit in order to work.
-The patches in [this repostory](https://github.com/antoyo/libgccjit-patches) need to be applied.
+The patches in [this repository](https://github.com/antoyo/libgccjit-patches) need to be applied.
 (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.**
 
 **Put the path to your custom build of libgccjit in the file `gcc_path`.**
 
 ```bash
-$ git clone https://github.com/antoyo/rustc_codegen_gcc.git
+$ git clone https://github.com/rust-lang/rustc_codegen_gcc.git
 $ cd rustc_codegen_gcc
+$ 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
 ```
@@ -109,10 +111,37 @@ Or add a breakpoint to `add_error` in gdb and print the line number using:
 
 ```
 p loc->m_line
+p loc->m_filename->m_buffer
 ```
 
+To print a debug representation of a tree:
+
+```c
+debug_tree(expr);
+```
+
+To get the `rustc` command to run in `gdb`, add the `--verbose` flag to `cargo build`.
+
 ### How to use a custom-build rustc
 
- * Build the stage1 compiler (`rustup toolchain link debug-current stage2 build/x86_64-unknown-linux-gnu/stage1`).
+ * 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`.
- * Add `~/.rustup/toolchains/debug-current/lib/rustlib/x86_64-unknown-linux-gnu/lib` to `LD_LIBRARY_PATH`.
+
+### How to build a cross-compiling libgccjit
+
+#### 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).
+
+#### 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'`.
+ * 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?).