diff --git a/src/tools/compiletest/src/command-list.rs b/src/tools/compiletest/src/command-list.rs index 7f8080235c87..a559d6f81a24 100644 --- a/src/tools/compiletest/src/command-list.rs +++ b/src/tools/compiletest/src/command-list.rs @@ -141,6 +141,7 @@ const KNOWN_DIRECTIVE_NAMES: &[&str] = &[ "needs-force-clang-based-tests", "needs-git-hash", "needs-llvm-components", + "needs-llvm-zstd", "needs-profiler-support", "needs-relocation-model-pic", "needs-run-enabled", diff --git a/src/tools/compiletest/src/header.rs b/src/tools/compiletest/src/header.rs index 1fc24301c85e..933913eb47c3 100644 --- a/src/tools/compiletest/src/header.rs +++ b/src/tools/compiletest/src/header.rs @@ -1203,6 +1203,107 @@ pub fn extract_llvm_version_from_binary(binary_path: &str) -> Option { None } +/// For tests using the `needs-llvm-zstd` directive: +/// - for local LLVM builds, try to find the static zstd library in the llvm-config system libs. +/// - for `download-ci-llvm`, see if `lld` was built with zstd support. +pub fn llvm_has_libzstd(config: &Config) -> bool { + // Strategy 1: works for local builds but not with `download-ci-llvm`. + // + // We check whether `llvm-config` returns the zstd library. Bootstrap's `llvm.libzstd` will only + // ask to statically link it when building LLVM, so we only check if the list of system libs + // contains a path to that static lib, and that it exists. + // + // See compiler/rustc_llvm/build.rs for more details and similar expectations. + fn is_zstd_in_config(llvm_bin_dir: &Path) -> Option<()> { + let llvm_config_path = llvm_bin_dir.join("llvm-config"); + let output = Command::new(llvm_config_path).arg("--system-libs").output().ok()?; + assert!(output.status.success(), "running llvm-config --system-libs failed"); + + let libs = String::from_utf8(output.stdout).ok()?; + for lib in libs.split_whitespace() { + if lib.ends_with("libzstd.a") && Path::new(lib).exists() { + return Some(()); + } + } + + None + } + + // Strategy 2: `download-ci-llvm`'s `llvm-config --system-libs` will not return any libs to + // use. + // + // The CI artifacts also don't contain the bootstrap config used to build them: otherwise we + // could have looked at the `llvm.libzstd` config. + // + // We infer whether `LLVM_ENABLE_ZSTD` was used to build LLVM as a byproduct of testing whether + // `lld` supports it. If not, an error will be emitted: "LLVM was not built with + // LLVM_ENABLE_ZSTD or did not find zstd at build time". + #[cfg(unix)] + fn is_lld_built_with_zstd(llvm_bin_dir: &Path) -> Option<()> { + let lld_path = llvm_bin_dir.join("lld"); + if lld_path.exists() { + // We can't call `lld` as-is, it expects to be invoked by a compiler driver using a + // different name. Prepare a temporary symlink to do that. + let lld_symlink_path = llvm_bin_dir.join("ld.lld"); + if !lld_symlink_path.exists() { + std::os::unix::fs::symlink(lld_path, &lld_symlink_path).ok()?; + } + + // Run `lld` with a zstd flag. We expect this command to always error here, we don't + // want to link actual files and don't pass any. + let output = Command::new(&lld_symlink_path) + .arg("--compress-debug-sections=zstd") + .output() + .ok()?; + assert!(!output.status.success()); + + // Look for a specific error caused by LLVM not being built with zstd support. We could + // also look for the "no input files" message, indicating the zstd flag was accepted. + let stderr = String::from_utf8(output.stderr).ok()?; + let zstd_available = !stderr.contains("LLVM was not built with LLVM_ENABLE_ZSTD"); + + // We don't particularly need to clean the link up (so the previous commands could fail + // in theory but won't in practice), but we can try. + std::fs::remove_file(lld_symlink_path).ok()?; + + if zstd_available { + return Some(()); + } + } + + None + } + + #[cfg(not(unix))] + fn is_lld_built_with_zstd(_llvm_bin_dir: &Path) -> Option<()> { + None + } + + if let Some(llvm_bin_dir) = &config.llvm_bin_dir { + // Strategy 1: for local LLVM builds. + if is_zstd_in_config(llvm_bin_dir).is_some() { + return true; + } + + // Strategy 2: for LLVM artifacts built on CI via `download-ci-llvm`. + // + // It doesn't work for cases where the artifacts don't contain the linker, but it's + // best-effort: CI has `llvm.libzstd` and `lld` enabled on the x64 linux artifacts, so it + // will at least work there. + // + // If this can be improved and expanded to less common cases in the future, it should. + if config.target == "x86_64-unknown-linux-gnu" + && config.host == config.target + && is_lld_built_with_zstd(llvm_bin_dir).is_some() + { + return true; + } + } + + // Otherwise, all hope is lost. + false +} + /// Takes a directive of the form " [- ]", /// returns the numeric representation of and as /// tuple: ( as u32, as u32) diff --git a/src/tools/compiletest/src/header/needs.rs b/src/tools/compiletest/src/header/needs.rs index 8f935d5b7444..e04abea0bf98 100644 --- a/src/tools/compiletest/src/header/needs.rs +++ b/src/tools/compiletest/src/header/needs.rs @@ -1,5 +1,5 @@ use crate::common::{Config, Sanitizer}; -use crate::header::IgnoreDecision; +use crate::header::{llvm_has_libzstd, IgnoreDecision}; pub(super) fn handle_needs( cache: &CachedNeedsConditions, @@ -144,6 +144,11 @@ pub(super) fn handle_needs( condition: cache.symlinks, ignore_reason: "ignored if symlinks are unavailable", }, + Need { + name: "needs-llvm-zstd", + condition: cache.llvm_zstd, + ignore_reason: "ignored if LLVM wasn't build with zstd for ELF section compression", + }, ]; let (name, comment) = match ln.split_once([':', ' ']) { @@ -210,6 +215,8 @@ pub(super) struct CachedNeedsConditions { rust_lld: bool, dlltool: bool, symlinks: bool, + /// Whether LLVM built with zstd, for the `needs-llvm-zstd` directive. + llvm_zstd: bool, } impl CachedNeedsConditions { @@ -253,6 +260,7 @@ impl CachedNeedsConditions { .join(if config.host.contains("windows") { "rust-lld.exe" } else { "rust-lld" }) .exists(), + llvm_zstd: llvm_has_libzstd(&config), dlltool: find_dlltool(&config), symlinks: has_symlinks(), }