| use crate::back::write::create_informational_target_machine; |
| use crate::{llvm, llvm_util}; |
| use libc::c_int; |
| use libloading::Library; |
| use rustc_codegen_ssa::target_features::{ |
| supported_target_features, tied_target_features, RUSTC_SPECIFIC_FEATURES, |
| }; |
| use rustc_data_structures::fx::{FxHashMap, FxHashSet}; |
| use rustc_data_structures::small_c_str::SmallCStr; |
| use rustc_fs_util::path_to_c_string; |
| use rustc_middle::bug; |
| use rustc_session::config::PrintRequest; |
| use rustc_session::Session; |
| use rustc_span::symbol::Symbol; |
| use rustc_target::spec::{MergeFunctions, PanicStrategy}; |
| use smallvec::{smallvec, SmallVec}; |
| use std::ffi::{CStr, CString}; |
| use tracing::debug; |
| |
| use std::mem; |
| use std::path::Path; |
| use std::ptr; |
| use std::slice; |
| use std::str; |
| use std::sync::Once; |
| |
| static INIT: Once = Once::new(); |
| |
| pub(crate) fn init(sess: &Session) { |
| unsafe { |
| // Before we touch LLVM, make sure that multithreading is enabled. |
| if llvm::LLVMIsMultithreaded() != 1 { |
| bug!("LLVM compiled without support for threads"); |
| } |
| INIT.call_once(|| { |
| configure_llvm(sess); |
| }); |
| } |
| } |
| |
| fn require_inited() { |
| if !INIT.is_completed() { |
| bug!("LLVM is not initialized"); |
| } |
| } |
| |
| unsafe fn configure_llvm(sess: &Session) { |
| let n_args = sess.opts.cg.llvm_args.len() + sess.target.llvm_args.len(); |
| let mut llvm_c_strs = Vec::with_capacity(n_args + 1); |
| let mut llvm_args = Vec::with_capacity(n_args + 1); |
| |
| llvm::LLVMRustInstallFatalErrorHandler(); |
| // On Windows, an LLVM assertion will open an Abort/Retry/Ignore dialog |
| // box for the purpose of launching a debugger. However, on CI this will |
| // cause it to hang until it times out, which can take several hours. |
| if std::env::var_os("CI").is_some() { |
| llvm::LLVMRustDisableSystemDialogsOnCrash(); |
| } |
| |
| fn llvm_arg_to_arg_name(full_arg: &str) -> &str { |
| full_arg.trim().split(|c: char| c == '=' || c.is_whitespace()).next().unwrap_or("") |
| } |
| |
| let cg_opts = sess.opts.cg.llvm_args.iter().map(AsRef::as_ref); |
| let tg_opts = sess.target.llvm_args.iter().map(AsRef::as_ref); |
| let sess_args = cg_opts.chain(tg_opts); |
| |
| let user_specified_args: FxHashSet<_> = |
| sess_args.clone().map(|s| llvm_arg_to_arg_name(s)).filter(|s| !s.is_empty()).collect(); |
| |
| { |
| // This adds the given argument to LLVM. Unless `force` is true |
| // user specified arguments are *not* overridden. |
| let mut add = |arg: &str, force: bool| { |
| if force || !user_specified_args.contains(llvm_arg_to_arg_name(arg)) { |
| let s = CString::new(arg).unwrap(); |
| llvm_args.push(s.as_ptr()); |
| llvm_c_strs.push(s); |
| } |
| }; |
| // Set the llvm "program name" to make usage and invalid argument messages more clear. |
| add("rustc -Cllvm-args=\"...\" with", true); |
| if sess.time_llvm_passes() { |
| add("-time-passes", false); |
| } |
| if sess.print_llvm_passes() { |
| add("-debug-pass=Structure", false); |
| } |
| if sess.target.generate_arange_section |
| && !sess.opts.debugging_opts.no_generate_arange_section |
| { |
| add("-generate-arange-section", false); |
| } |
| |
| // Disable the machine outliner by default in LLVM versions 11 and LLVM |
| // version 12, where it leads to miscompilation. |
| // |
| // Ref: |
| // - https://github.com/rust-lang/rust/issues/85351 |
| // - https://reviews.llvm.org/D103167 |
| if llvm_util::get_version() < (13, 0, 0) { |
| add("-enable-machine-outliner=never", false); |
| } |
| |
| match sess.opts.debugging_opts.merge_functions.unwrap_or(sess.target.merge_functions) { |
| MergeFunctions::Disabled | MergeFunctions::Trampolines => {} |
| MergeFunctions::Aliases => { |
| add("-mergefunc-use-aliases", false); |
| } |
| } |
| |
| if sess.target.os == "emscripten" && sess.panic_strategy() == PanicStrategy::Unwind { |
| add("-enable-emscripten-cxx-exceptions", false); |
| } |
| |
| // HACK(eddyb) LLVM inserts `llvm.assume` calls to preserve align attributes |
| // during inlining. Unfortunately these may block other optimizations. |
| add("-preserve-alignment-assumptions-during-inlining=false", false); |
| |
| // Use non-zero `import-instr-limit` multiplier for cold callsites. |
| add("-import-cold-multiplier=0.1", false); |
| |
| for arg in sess_args { |
| add(&(*arg), true); |
| } |
| } |
| |
| if sess.opts.debugging_opts.llvm_time_trace { |
| llvm::LLVMTimeTraceProfilerInitialize(); |
| } |
| |
| llvm::LLVMInitializePasses(); |
| |
| // Use the legacy plugin registration if we don't use the new pass manager |
| if !should_use_new_llvm_pass_manager( |
| &sess.opts.debugging_opts.new_llvm_pass_manager, |
| &sess.target.arch, |
| ) { |
| // Register LLVM plugins by loading them into the compiler process. |
| for plugin in &sess.opts.debugging_opts.llvm_plugins { |
| let lib = Library::new(plugin).unwrap_or_else(|e| bug!("couldn't load plugin: {}", e)); |
| debug!("LLVM plugin loaded successfully {:?} ({})", lib, plugin); |
| |
| // Intentionally leak the dynamic library. We can't ever unload it |
| // since the library can make things that will live arbitrarily long. |
| mem::forget(lib); |
| } |
| } |
| |
| rustc_llvm::initialize_available_targets(); |
| |
| llvm::LLVMRustSetLLVMOptions(llvm_args.len() as c_int, llvm_args.as_ptr()); |
| } |
| |
| pub fn time_trace_profiler_finish(file_name: &Path) { |
| unsafe { |
| let file_name = path_to_c_string(file_name); |
| llvm::LLVMTimeTraceProfilerFinish(file_name.as_ptr()); |
| } |
| } |
| |
| // WARNING: the features after applying `to_llvm_features` must be known |
| // to LLVM or the feature detection code will walk past the end of the feature |
| // array, leading to crashes. |
| // |
| // To find a list of LLVM's names, check llvm-project/llvm/include/llvm/Support/*TargetParser.def |
| // where the * matches the architecture's name |
| // Beware to not use the llvm github project for this, but check the git submodule |
| // found in src/llvm-project |
| // Though note that Rust can also be build with an external precompiled version of LLVM |
| // which might lead to failures if the oldest tested / supported LLVM version |
| // doesn't yet support the relevant intrinsics |
| pub fn to_llvm_features<'a>(sess: &Session, s: &'a str) -> SmallVec<[&'a str; 2]> { |
| let arch = if sess.target.arch == "x86_64" { "x86" } else { &*sess.target.arch }; |
| match (arch, s) { |
| ("x86", "sse4.2") => { |
| if get_version() >= (14, 0, 0) { |
| smallvec!["sse4.2", "crc32"] |
| } else { |
| smallvec!["sse4.2"] |
| } |
| } |
| ("x86", "pclmulqdq") => smallvec!["pclmul"], |
| ("x86", "rdrand") => smallvec!["rdrnd"], |
| ("x86", "bmi1") => smallvec!["bmi"], |
| ("x86", "cmpxchg16b") => smallvec!["cx16"], |
| ("x86", "avx512vaes") => smallvec!["vaes"], |
| ("x86", "avx512gfni") => smallvec!["gfni"], |
| ("x86", "avx512vpclmulqdq") => smallvec!["vpclmulqdq"], |
| ("aarch64", "rcpc2") => smallvec!["rcpc-immo"], |
| ("aarch64", "dpb") => smallvec!["ccpp"], |
| ("aarch64", "dpb2") => smallvec!["ccdp"], |
| ("aarch64", "frintts") => smallvec!["fptoint"], |
| ("aarch64", "fcma") => smallvec!["complxnum"], |
| ("aarch64", "pmuv3") => smallvec!["perfmon"], |
| ("aarch64", "paca") => smallvec!["pauth"], |
| ("aarch64", "pacg") => smallvec!["pauth"], |
| // Rust ties fp and neon together. In LLVM neon implicitly enables fp, |
| // but we manually enable neon when a feature only implicitly enables fp |
| ("aarch64", "f32mm") => smallvec!["f32mm", "neon"], |
| ("aarch64", "f64mm") => smallvec!["f64mm", "neon"], |
| ("aarch64", "fhm") => smallvec!["fp16fml", "neon"], |
| ("aarch64", "fp16") => smallvec!["fullfp16", "neon"], |
| ("aarch64", "jsconv") => smallvec!["jsconv", "neon"], |
| ("aarch64", "sve") => smallvec!["sve", "neon"], |
| ("aarch64", "sve2") => smallvec!["sve2", "neon"], |
| ("aarch64", "sve2-aes") => smallvec!["sve2-aes", "neon"], |
| ("aarch64", "sve2-sm4") => smallvec!["sve2-sm4", "neon"], |
| ("aarch64", "sve2-sha3") => smallvec!["sve2-sha3", "neon"], |
| ("aarch64", "sve2-bitperm") => smallvec!["sve2-bitperm", "neon"], |
| (_, s) => smallvec![s], |
| } |
| } |
| |
| // Given a map from target_features to whether they are enabled or disabled, |
| // ensure only valid combinations are allowed. |
| pub fn check_tied_features( |
| sess: &Session, |
| features: &FxHashMap<&str, bool>, |
| ) -> Option<&'static [&'static str]> { |
| for tied in tied_target_features(sess) { |
| // Tied features must be set to the same value, or not set at all |
| let mut tied_iter = tied.iter(); |
| let enabled = features.get(tied_iter.next().unwrap()); |
| if tied_iter.any(|f| enabled != features.get(f)) { |
| return Some(tied); |
| } |
| } |
| None |
| } |
| |
| // Used to generate cfg variables and apply features |
| // Must express features in the way Rust understands them |
| pub fn target_features(sess: &Session) -> Vec<Symbol> { |
| let target_machine = create_informational_target_machine(sess); |
| let mut features: Vec<Symbol> = |
| supported_target_features(sess) |
| .iter() |
| .filter_map(|&(feature, gate)| { |
| if sess.is_nightly_build() || gate.is_none() { Some(feature) } else { None } |
| }) |
| .filter(|feature| { |
| // check that all features in a given smallvec are enabled |
| for llvm_feature in to_llvm_features(sess, feature) { |
| let cstr = SmallCStr::new(llvm_feature); |
| if !unsafe { llvm::LLVMRustHasFeature(target_machine, cstr.as_ptr()) } { |
| return false; |
| } |
| } |
| true |
| }) |
| .map(|feature| Symbol::intern(feature)) |
| .collect(); |
| |
| // LLVM 14 changed the ABI for i128 arguments to __float/__fix builtins on Win64 |
| // (see https://reviews.llvm.org/D110413). This unstable target feature is intended for use |
| // by compiler-builtins, to export the builtins with the expected, LLVM-version-dependent ABI. |
| // The target feature can be dropped once we no longer support older LLVM versions. |
| if sess.is_nightly_build() && get_version() >= (14, 0, 0) { |
| features.push(Symbol::intern("llvm14-builtins-abi")); |
| } |
| features |
| } |
| |
| pub fn print_version() { |
| let (major, minor, patch) = get_version(); |
| println!("LLVM version: {}.{}.{}", major, minor, patch); |
| } |
| |
| pub fn get_version() -> (u32, u32, u32) { |
| // Can be called without initializing LLVM |
| unsafe { |
| (llvm::LLVMRustVersionMajor(), llvm::LLVMRustVersionMinor(), llvm::LLVMRustVersionPatch()) |
| } |
| } |
| |
| pub fn print_passes() { |
| // Can be called without initializing LLVM |
| unsafe { |
| llvm::LLVMRustPrintPasses(); |
| } |
| } |
| |
| fn llvm_target_features(tm: &llvm::TargetMachine) -> Vec<(&str, &str)> { |
| let len = unsafe { llvm::LLVMRustGetTargetFeaturesCount(tm) }; |
| let mut ret = Vec::with_capacity(len); |
| for i in 0..len { |
| unsafe { |
| let mut feature = ptr::null(); |
| let mut desc = ptr::null(); |
| llvm::LLVMRustGetTargetFeature(tm, i, &mut feature, &mut desc); |
| if feature.is_null() || desc.is_null() { |
| bug!("LLVM returned a `null` target feature string"); |
| } |
| let feature = CStr::from_ptr(feature).to_str().unwrap_or_else(|e| { |
| bug!("LLVM returned a non-utf8 feature string: {}", e); |
| }); |
| let desc = CStr::from_ptr(desc).to_str().unwrap_or_else(|e| { |
| bug!("LLVM returned a non-utf8 feature string: {}", e); |
| }); |
| ret.push((feature, desc)); |
| } |
| } |
| ret |
| } |
| |
| fn print_target_features(sess: &Session, tm: &llvm::TargetMachine) { |
| let mut target_features = llvm_target_features(tm); |
| let mut rustc_target_features = supported_target_features(sess) |
| .iter() |
| .filter_map(|(feature, _gate)| { |
| for llvm_feature in to_llvm_features(sess, *feature) { |
| // LLVM asserts that these are sorted. LLVM and Rust both use byte comparison for these strings. |
| match target_features.binary_search_by_key(&llvm_feature, |(f, _d)| f).ok().map( |
| |index| { |
| let (_f, desc) = target_features.remove(index); |
| (*feature, desc) |
| }, |
| ) { |
| Some(v) => return Some(v), |
| None => {} |
| } |
| } |
| None |
| }) |
| .collect::<Vec<_>>(); |
| rustc_target_features.extend_from_slice(&[( |
| "crt-static", |
| "Enables C Run-time Libraries to be statically linked", |
| )]); |
| let max_feature_len = target_features |
| .iter() |
| .chain(rustc_target_features.iter()) |
| .map(|(feature, _desc)| feature.len()) |
| .max() |
| .unwrap_or(0); |
| |
| println!("Features supported by rustc for this target:"); |
| for (feature, desc) in &rustc_target_features { |
| println!(" {1:0$} - {2}.", max_feature_len, feature, desc); |
| } |
| println!("\nCode-generation features supported by LLVM for this target:"); |
| for (feature, desc) in &target_features { |
| println!(" {1:0$} - {2}.", max_feature_len, feature, desc); |
| } |
| if target_features.is_empty() { |
| println!(" Target features listing is not supported by this LLVM version."); |
| } |
| println!("\nUse +feature to enable a feature, or -feature to disable it."); |
| println!("For example, rustc -C target-cpu=mycpu -C target-feature=+feature1,-feature2\n"); |
| println!("Code-generation features cannot be used in cfg or #[target_feature],"); |
| println!("and may be renamed or removed in a future version of LLVM or rustc.\n"); |
| } |
| |
| pub(crate) fn print(req: PrintRequest, sess: &Session) { |
| require_inited(); |
| let tm = create_informational_target_machine(sess); |
| match req { |
| PrintRequest::TargetCPUs => unsafe { llvm::LLVMRustPrintTargetCPUs(tm) }, |
| PrintRequest::TargetFeatures => print_target_features(sess, tm), |
| _ => bug!("rustc_codegen_llvm can't handle print request: {:?}", req), |
| } |
| } |
| |
| fn handle_native(name: &str) -> &str { |
| if name != "native" { |
| return name; |
| } |
| |
| unsafe { |
| let mut len = 0; |
| let ptr = llvm::LLVMRustGetHostCPUName(&mut len); |
| str::from_utf8(slice::from_raw_parts(ptr as *const u8, len)).unwrap() |
| } |
| } |
| |
| pub fn target_cpu(sess: &Session) -> &str { |
| match sess.opts.cg.target_cpu { |
| Some(ref name) => handle_native(name), |
| None => handle_native(sess.target.cpu.as_ref()), |
| } |
| } |
| |
| /// The list of LLVM features computed from CLI flags (`-Ctarget-cpu`, `-Ctarget-feature`, |
| /// `--target` and similar). |
| pub(crate) fn global_llvm_features(sess: &Session, diagnostics: bool) -> Vec<String> { |
| // Features that come earlier are overridden by conflicting features later in the string. |
| // Typically we'll want more explicit settings to override the implicit ones, so: |
| // |
| // * Features from -Ctarget-cpu=*; are overridden by [^1] |
| // * Features implied by --target; are overridden by |
| // * Features from -Ctarget-feature; are overridden by |
| // * function specific features. |
| // |
| // [^1]: target-cpu=native is handled here, other target-cpu values are handled implicitly |
| // through LLVM TargetMachine implementation. |
| // |
| // FIXME(nagisa): it isn't clear what's the best interaction between features implied by |
| // `-Ctarget-cpu` and `--target` are. On one hand, you'd expect CLI arguments to always |
| // override anything that's implicit, so e.g. when there's no `--target` flag, features implied |
| // the host target are overridden by `-Ctarget-cpu=*`. On the other hand, what about when both |
| // `--target` and `-Ctarget-cpu=*` are specified? Both then imply some target features and both |
| // flags are specified by the user on the CLI. It isn't as clear-cut which order of precedence |
| // should be taken in cases like these. |
| let mut features = vec![]; |
| |
| // -Ctarget-cpu=native |
| match sess.opts.cg.target_cpu { |
| Some(ref s) if s == "native" => { |
| let features_string = unsafe { |
| let ptr = llvm::LLVMGetHostCPUFeatures(); |
| let features_string = if !ptr.is_null() { |
| CStr::from_ptr(ptr) |
| .to_str() |
| .unwrap_or_else(|e| { |
| bug!("LLVM returned a non-utf8 features string: {}", e); |
| }) |
| .to_owned() |
| } else { |
| bug!("could not allocate host CPU features, LLVM returned a `null` string"); |
| }; |
| |
| llvm::LLVMDisposeMessage(ptr); |
| |
| features_string |
| }; |
| features.extend(features_string.split(',').map(String::from)); |
| } |
| Some(_) | None => {} |
| }; |
| |
| // Features implied by an implicit or explicit `--target`. |
| features.extend( |
| sess.target |
| .features |
| .split(',') |
| .filter(|v| !v.is_empty() && backend_feature_name(v).is_some()) |
| .map(String::from), |
| ); |
| |
| // -Ctarget-features |
| let supported_features = supported_target_features(sess); |
| let feats = sess |
| .opts |
| .cg |
| .target_feature |
| .split(',') |
| .filter_map(|s| { |
| let enable_disable = match s.chars().next() { |
| None => return None, |
| Some(c @ '+' | c @ '-') => c, |
| Some(_) => { |
| if diagnostics { |
| let mut diag = sess.struct_warn(&format!( |
| "unknown feature specified for `-Ctarget-feature`: `{}`", |
| s |
| )); |
| diag.note("features must begin with a `+` to enable or `-` to disable it"); |
| diag.emit(); |
| } |
| return None; |
| } |
| }; |
| |
| let feature = backend_feature_name(s)?; |
| // Warn against use of LLVM specific feature names on the CLI. |
| if diagnostics && !supported_features.iter().any(|&(v, _)| v == feature) { |
| let rust_feature = supported_features.iter().find_map(|&(rust_feature, _)| { |
| let llvm_features = to_llvm_features(sess, rust_feature); |
| if llvm_features.contains(&feature) && !llvm_features.contains(&rust_feature) { |
| Some(rust_feature) |
| } else { |
| None |
| } |
| }); |
| let mut diag = sess.struct_warn(&format!( |
| "unknown feature specified for `-Ctarget-feature`: `{}`", |
| feature |
| )); |
| diag.note("it is still passed through to the codegen backend"); |
| if let Some(rust_feature) = rust_feature { |
| diag.help(&format!("you might have meant: `{}`", rust_feature)); |
| } else { |
| diag.note("consider filing a feature request"); |
| } |
| diag.emit(); |
| } |
| Some((enable_disable, feature)) |
| }) |
| .collect::<SmallVec<[(char, &str); 8]>>(); |
| |
| if diagnostics { |
| // FIXME(nagisa): figure out how to not allocate a full hashset here. |
| let featmap = feats.iter().map(|&(flag, feat)| (feat, flag == '+')).collect(); |
| if let Some(f) = check_tied_features(sess, &featmap) { |
| sess.err(&format!( |
| "target features {} must all be enabled or disabled together", |
| f.join(", ") |
| )); |
| } |
| } |
| |
| features.extend(feats.into_iter().flat_map(|(enable_disable, feature)| { |
| // rustc-specific features do not get passed down to LLVM… |
| if RUSTC_SPECIFIC_FEATURES.contains(&feature) { |
| return SmallVec::<[_; 2]>::new(); |
| } |
| // ... otherwise though we run through `to_llvm_features` when |
| // passing requests down to LLVM. This means that all in-language |
| // features also work on the command line instead of having two |
| // different names when the LLVM name and the Rust name differ. |
| to_llvm_features(sess, feature) |
| .into_iter() |
| .map(|f| format!("{}{}", enable_disable, f)) |
| .collect() |
| })); |
| features |
| } |
| |
| /// Returns a feature name for the given `+feature` or `-feature` string. |
| /// |
| /// Only allows features that are backend specific (i.e. not [`RUSTC_SPECIFIC_FEATURES`].) |
| fn backend_feature_name(s: &str) -> Option<&str> { |
| // features must start with a `+` or `-`. |
| let feature = s.strip_prefix(&['+', '-'][..]).unwrap_or_else(|| { |
| bug!("target feature `{}` must begin with a `+` or `-`", s); |
| }); |
| // Rustc-specific feature requests like `+crt-static` or `-crt-static` |
| // are not passed down to LLVM. |
| if RUSTC_SPECIFIC_FEATURES.contains(&feature) { |
| return None; |
| } |
| Some(feature) |
| } |
| |
| pub fn tune_cpu(sess: &Session) -> Option<&str> { |
| let name = sess.opts.debugging_opts.tune_cpu.as_ref()?; |
| Some(handle_native(name)) |
| } |
| |
| pub(crate) fn should_use_new_llvm_pass_manager(user_opt: &Option<bool>, target_arch: &str) -> bool { |
| // The new pass manager is enabled by default for LLVM >= 13. |
| // This matches Clang, which also enables it since Clang 13. |
| |
| // Since LLVM 15, the legacy pass manager is no longer supported. |
| if llvm_util::get_version() >= (15, 0, 0) { |
| return true; |
| } |
| |
| // There are some perf issues with the new pass manager when targeting |
| // s390x with LLVM 13, so enable the new pass manager only with LLVM 14. |
| // See https://github.com/rust-lang/rust/issues/89609. |
| let min_version = if target_arch == "s390x" { 14 } else { 13 }; |
| user_opt.unwrap_or_else(|| llvm_util::get_version() >= (min_version, 0, 0)) |
| } |
