From 222ce4fdb8fb5fbff8047014c3ffb73df0ef2693 Mon Sep 17 00:00:00 2001 From: Kjetil Kjeka Date: Tue, 6 Feb 2024 19:15:38 +0100 Subject: [PATCH] LLVM Bitcode Linker: Added crate --- Cargo.lock | 11 ++ Cargo.toml | 1 + src/bootstrap/src/core/build_steps/tool.rs | 1 + src/bootstrap/src/core/builder.rs | 1 + src/tools/llvm-bitcode-linker/Cargo.toml | 14 ++ src/tools/llvm-bitcode-linker/README.md | 5 + .../src/bin/llvm-bitcode-linker.rs | 62 +++++++ src/tools/llvm-bitcode-linker/src/lib.rs | 7 + src/tools/llvm-bitcode-linker/src/linker.rs | 163 ++++++++++++++++++ src/tools/llvm-bitcode-linker/src/opt.rs | 53 ++++++ src/tools/llvm-bitcode-linker/src/target.rs | 20 +++ 11 files changed, 338 insertions(+) create mode 100644 src/tools/llvm-bitcode-linker/Cargo.toml create mode 100644 src/tools/llvm-bitcode-linker/README.md create mode 100644 src/tools/llvm-bitcode-linker/src/bin/llvm-bitcode-linker.rs create mode 100644 src/tools/llvm-bitcode-linker/src/lib.rs create mode 100644 src/tools/llvm-bitcode-linker/src/linker.rs create mode 100644 src/tools/llvm-bitcode-linker/src/opt.rs create mode 100644 src/tools/llvm-bitcode-linker/src/target.rs diff --git a/Cargo.lock b/Cargo.lock index 3290741f128..53bd088b557 100644 --- a/Cargo.lock +++ b/Cargo.lock @@ -2265,6 +2265,17 @@ checksum = "f9d642685b028806386b2b6e75685faadd3eb65a85fff7df711ce18446a422da" name = "lld-wrapper" version = "0.1.0" +[[package]] +name = "llvm-bitcode-linker" +version = "0.0.1" +dependencies = [ + "anyhow", + "clap", + "thiserror", + "tracing", + "tracing-subscriber", +] + [[package]] name = "lock_api" version = "0.4.11" diff --git a/Cargo.toml b/Cargo.toml index 5847a817e76..5dd315ef2f7 100644 --- a/Cargo.toml +++ b/Cargo.toml @@ -34,6 +34,7 @@ members = [ "src/tools/expand-yaml-anchors", "src/tools/jsondocck", "src/tools/jsondoclint", + "src/tools/llvm-bitcode-linker", "src/tools/html-checker", "src/tools/bump-stage0", "src/tools/replace-version-placeholder", diff --git a/src/bootstrap/src/core/build_steps/tool.rs b/src/bootstrap/src/core/build_steps/tool.rs index 889876f461d..53dc1cff0ae 100644 --- a/src/bootstrap/src/core/build_steps/tool.rs +++ b/src/bootstrap/src/core/build_steps/tool.rs @@ -795,6 +795,7 @@ fn run(mut $sel, $builder: &Builder<'_>) -> PathBuf { Rls, "src/tools/rls", "rls", stable=true, tool_std=true; RustDemangler, "src/tools/rust-demangler", "rust-demangler", stable=false, tool_std=true; Rustfmt, "src/tools/rustfmt", "rustfmt", stable=true, add_bins_to_sysroot = ["rustfmt", "cargo-fmt"]; + LlvmBitcodeLinker, "src/tools/llvm-bitcode-linker", "llvm-bitcode-linker", stable=false, add_bins_to_sysroot = ["llvm-bitcode-linker"]; ); impl<'a> Builder<'a> { diff --git a/src/bootstrap/src/core/builder.rs b/src/bootstrap/src/core/builder.rs index 4927c837608..5e5d6d024ee 100644 --- a/src/bootstrap/src/core/builder.rs +++ b/src/bootstrap/src/core/builder.rs @@ -763,6 +763,7 @@ macro_rules! describe { tool::RustdocGUITest, tool::OptimizedDist, tool::CoverageDump, + tool::LlvmBitcodeLinker ), Kind::Check | Kind::Clippy | Kind::Fix => describe!( check::Std, diff --git a/src/tools/llvm-bitcode-linker/Cargo.toml b/src/tools/llvm-bitcode-linker/Cargo.toml new file mode 100644 index 00000000000..a9210b562f3 --- /dev/null +++ b/src/tools/llvm-bitcode-linker/Cargo.toml @@ -0,0 +1,14 @@ +[package] +name = "llvm-bitcode-linker" +version = "0.0.1" +description = "A self-contained linker for llvm bitcode" +license = "MIT OR Apache-2.0" +edition = "2021" +publish = false + +[dependencies] +anyhow = "1.0" +tracing = "0.1" +tracing-subscriber = {version = "0.3.0", features = ["std"] } +clap = { version = "4.3", features = ["derive"] } +thiserror = "1.0.24" diff --git a/src/tools/llvm-bitcode-linker/README.md b/src/tools/llvm-bitcode-linker/README.md new file mode 100644 index 00000000000..9b8719e3a77 --- /dev/null +++ b/src/tools/llvm-bitcode-linker/README.md @@ -0,0 +1,5 @@ +# LLVM Bitcode Linker +The LLVM bitcode linker can be used to link targets without any dependency on system libraries. +The code will be linked in llvm-bc before compiling to native code. For some of these targets +(e.g. ptx) there does not exist a sensible way to link the native format at all. A bitcode linker +is required to link code compiled for such targets. diff --git a/src/tools/llvm-bitcode-linker/src/bin/llvm-bitcode-linker.rs b/src/tools/llvm-bitcode-linker/src/bin/llvm-bitcode-linker.rs new file mode 100644 index 00000000000..a92af71a36e --- /dev/null +++ b/src/tools/llvm-bitcode-linker/src/bin/llvm-bitcode-linker.rs @@ -0,0 +1,62 @@ +use std::path::PathBuf; + +use clap::Parser; + +use llvm_bitcode_linker::{Optimization, Session, Target}; + +#[derive(Debug, Parser)] +/// Linker for embedded code without any system dependencies +pub struct Args { + /// Input files - objects, archives and static libraries. + /// + /// An archive can be, but not required to be, a Rust rlib. + files: Vec, + + /// A symbol that should be exported + #[arg(long)] + export_symbol: Vec, + + /// Input files directory + #[arg(short = 'L')] + input_dir: Vec, + + /// Target triple for which the code is compiled + #[arg(long)] + target: Target, + + /// The target cpu + #[arg(long)] + target_cpu: Option, + + /// Write output to the filename + #[arg(short, long)] + output: PathBuf, + + // Enable link time optimization + #[arg(long)] + lto: bool, + + /// Emit debug information + #[arg(long)] + debug: bool, + + /// The optimization level + #[arg(short = 'O', value_enum, default_value = "0")] + optimization: Optimization, +} + +fn main() -> anyhow::Result<()> { + tracing_subscriber::FmtSubscriber::builder().with_max_level(tracing::Level::DEBUG).init(); + + let args = Args::parse(); + + let mut linker = Session::new(args.target, args.target_cpu, args.output); + + linker.add_exported_symbols(args.export_symbol); + + for rlib in args.files { + linker.add_file(rlib); + } + + linker.lto(args.optimization, args.debug) +} diff --git a/src/tools/llvm-bitcode-linker/src/lib.rs b/src/tools/llvm-bitcode-linker/src/lib.rs new file mode 100644 index 00000000000..48f918f631c --- /dev/null +++ b/src/tools/llvm-bitcode-linker/src/lib.rs @@ -0,0 +1,7 @@ +mod linker; +mod opt; +mod target; + +pub use linker::Session; +pub use opt::Optimization; +pub use target::Target; diff --git a/src/tools/llvm-bitcode-linker/src/linker.rs b/src/tools/llvm-bitcode-linker/src/linker.rs new file mode 100644 index 00000000000..aa6b6443e4d --- /dev/null +++ b/src/tools/llvm-bitcode-linker/src/linker.rs @@ -0,0 +1,163 @@ +use std::path::PathBuf; + +use anyhow::Context; + +use crate::Optimization; +use crate::Target; + +#[derive(Debug)] +pub struct Session { + target: Target, + cpu: Option, + symbols: Vec, + + /// A file that `llvm-link` supports, like a bitcode file or an archive. + files: Vec, + + // Output files + link_path: PathBuf, + opt_path: PathBuf, + sym_path: PathBuf, + out_path: PathBuf, +} + +impl Session { + pub fn new(target: crate::Target, cpu: Option, out_path: PathBuf) -> Self { + let link_path = out_path.with_extension("o"); + let opt_path = out_path.with_extension("optimized.o"); + let sym_path = out_path.with_extension("symbols.txt"); + + Session { + target, + cpu, + symbols: Vec::new(), + files: Vec::new(), + link_path, + opt_path, + sym_path, + out_path, + } + } + + /// Add a file, like an rlib or bitcode file that should be linked + pub fn add_file(&mut self, path: PathBuf) { + self.files.push(path); + } + + /// Add a Vec of symbols to the list of exported symbols + pub fn add_exported_symbols(&mut self, symbols: Vec) { + self.symbols.extend(symbols); + } + + /// Reads every file that was added to the session and link them without optimization. + /// + /// The resulting artifact will be written to a file that can later be read to perform + /// optimizations and/or compilation from bitcode to the final artifact. + fn link(&mut self) -> anyhow::Result<()> { + tracing::info!("Linking {} files using llvm-link", self.files.len()); + + let llvm_link_output = std::process::Command::new("llvm-link") + .arg("--ignore-non-bitcode") + .args(&self.files) + .arg("-o") + .arg(&self.link_path) + .output() + .unwrap(); + + if !llvm_link_output.status.success() { + tracing::error!( + "llvm-link returned with Exit status: {}\n stdout: {}\n stderr: {}", + llvm_link_output.status, + String::from_utf8(llvm_link_output.stdout).unwrap(), + String::from_utf8(llvm_link_output.stderr).unwrap(), + ); + anyhow::bail!("llvm-link failed to link files {:?}", self.files); + } + + Ok(()) + } + + /// Optimize and compile to native format using `opt` and `llc` + /// + /// Before this can be called `link` needs to be called + fn optimize(&mut self, optimization: Optimization, mut debug: bool) -> anyhow::Result<()> { + let mut passes = format!("default<{}>", optimization); + + // FIXME(@kjetilkjeka) Debug symbol generation is broken for nvptx64 so we must remove them even in debug mode + if debug && self.target == crate::Target::Nvptx64NvidiaCuda { + tracing::warn!("nvptx64 target detected - stripping debug symbols"); + debug = false; + } + + // We add an internalize pass as the rust compiler as we require exported symbols to be explicitly marked + passes.push_str(",internalize,globaldce"); + let symbol_file_content = self.symbols.iter().fold(String::new(), |s, x| s + &x + "\n"); + std::fs::write(&self.sym_path, symbol_file_content) + .context(format!("Failed to write symbol file: {}", self.sym_path.display()))?; + + tracing::info!("optimizing bitcode with passes: {}", passes); + let mut opt_cmd = std::process::Command::new("opt"); + opt_cmd + .arg(&self.link_path) + .arg("-o") + .arg(&self.opt_path) + .arg(format!("--internalize-public-api-file={}", self.sym_path.display())) + .arg(format!("--passes={}", passes)); + + if !debug { + opt_cmd.arg("--strip-debug"); + } + + let opt_output = opt_cmd.output().unwrap(); + + if !opt_output.status.success() { + tracing::error!( + "opt returned with Exit status: {}\n stdout: {}\n stderr: {}", + opt_output.status, + String::from_utf8(opt_output.stdout).unwrap(), + String::from_utf8(opt_output.stderr).unwrap(), + ); + anyhow::bail!("opt failed optimize bitcode: {}", self.link_path.display()); + }; + + Ok(()) + } + + /// Compile the optimized bitcode file to native format using `llc` + /// + /// Before this can be called `optimize` needs to be called + fn compile(&mut self) -> anyhow::Result<()> { + let mut lcc_command = std::process::Command::new("llc"); + + if let Some(mcpu) = &self.cpu { + lcc_command.arg("--mcpu").arg(mcpu); + } + + let lcc_output = + lcc_command.arg(&self.opt_path).arg("-o").arg(&self.out_path).output().unwrap(); + + if !lcc_output.status.success() { + tracing::error!( + "llc returned with Exit status: {}\n stdout: {}\n stderr: {}", + lcc_output.status, + String::from_utf8(lcc_output.stdout).unwrap(), + String::from_utf8(lcc_output.stderr).unwrap(), + ); + + anyhow::bail!( + "llc failed to compile {} into {}", + self.opt_path.display(), + self.out_path.display() + ); + } + + Ok(()) + } + + /// Links, optimizes and compiles to the native format + pub fn lto(&mut self, optimization: crate::Optimization, debug: bool) -> anyhow::Result<()> { + self.link()?; + self.optimize(optimization, debug)?; + self.compile() + } +} diff --git a/src/tools/llvm-bitcode-linker/src/opt.rs b/src/tools/llvm-bitcode-linker/src/opt.rs new file mode 100644 index 00000000000..93f0ec7e2d6 --- /dev/null +++ b/src/tools/llvm-bitcode-linker/src/opt.rs @@ -0,0 +1,53 @@ +use std::fmt::Display; +use std::fmt::Formatter; + +#[derive(Debug, Clone, Copy, Default, Hash, Eq, PartialEq, clap::ValueEnum)] +pub enum Optimization { + #[default] + #[value(name = "0")] + O0, + #[value(name = "1")] + O1, + #[value(name = "2")] + O2, + #[value(name = "3")] + O3, + #[value(name = "s")] + Os, + #[value(name = "z")] + Oz, +} + +#[derive(Debug, Clone, Copy, thiserror::Error)] +/// An invalid optimization level +#[error("invalid optimization level")] +pub struct InvalidOptimizationLevel; + +impl std::str::FromStr for Optimization { + type Err = InvalidOptimizationLevel; + + fn from_str(s: &str) -> Result { + match s { + "0" | "O0" => Ok(Optimization::O0), + "1" | "O1" => Ok(Optimization::O1), + "2" | "O2" => Ok(Optimization::O2), + "3" | "O3" => Ok(Optimization::O3), + "s" | "Os" => Ok(Optimization::Os), + "z" | "Oz" => Ok(Optimization::Oz), + _ => Err(InvalidOptimizationLevel), + } + } +} + +impl Display for Optimization { + fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result { + match *self { + Optimization::O0 => write!(f, "O0"), + Optimization::O1 => write!(f, "O1"), + Optimization::O2 => write!(f, "O2"), + Optimization::O3 => write!(f, "O3"), + Optimization::Os => write!(f, "Os"), + Optimization::Oz => write!(f, "Oz"), + } + } +} diff --git a/src/tools/llvm-bitcode-linker/src/target.rs b/src/tools/llvm-bitcode-linker/src/target.rs new file mode 100644 index 00000000000..d9f8ff3852b --- /dev/null +++ b/src/tools/llvm-bitcode-linker/src/target.rs @@ -0,0 +1,20 @@ +#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash, clap::ValueEnum)] +pub enum Target { + Nvptx64NvidiaCuda, +} + +#[derive(Debug, Clone, Copy, thiserror::Error)] +/// The target is not supported by this linker +#[error("unsupported target")] +pub struct UnsupportedTarget; + +impl std::str::FromStr for Target { + type Err = UnsupportedTarget; + + fn from_str(s: &str) -> Result { + match s { + "nvptx64-nvidia-cuda" => Ok(Target::Nvptx64NvidiaCuda), + _ => Err(UnsupportedTarget), + } + } +}