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-rw-r--r--compiler/rustc_codegen_llvm/src/llvm_util.rs562
1 files changed, 562 insertions, 0 deletions
diff --git a/compiler/rustc_codegen_llvm/src/llvm_util.rs b/compiler/rustc_codegen_llvm/src/llvm_util.rs
new file mode 100644
index 000000000..a0a640473
--- /dev/null
+++ b/compiler/rustc_codegen_llvm/src/llvm_util.rs
@@ -0,0 +1,562 @@
+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.unstable_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.unstable_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.unstable_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.unstable_opts.new_llvm_pass_manager,
+ &sess.target.arch,
+ ) {
+ // Register LLVM plugins by loading them into the compiler process.
+ for plugin in &sess.opts.unstable_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]> {
+ if !features.is_empty() {
+ 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);
+ }
+ }
+ }
+ return None;
+}
+
+// Used to generate cfg variables and apply features
+// Must express features in the way Rust understands them
+pub fn target_features(sess: &Session, allow_unstable: bool) -> 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() || allow_unstable || 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 mut featsmap = FxHashMap::default();
+ 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();
+ }
+
+ if diagnostics {
+ // FIXME(nagisa): figure out how to not allocate a full hashset here.
+ featsmap.insert(feature, enable_disable == '+');
+ }
+
+ // rustc-specific features do not get passed down to LLVM…
+ if RUSTC_SPECIFIC_FEATURES.contains(&feature) {
+ return None;
+ }
+ // ... 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.
+ Some(
+ to_llvm_features(sess, feature)
+ .into_iter()
+ .map(move |f| format!("{}{}", enable_disable, f)),
+ )
+ })
+ .flatten();
+ features.extend(feats);
+
+ if diagnostics && let Some(f) = check_tied_features(sess, &featsmap) {
+ sess.err(&format!(
+ "target features {} must all be enabled or disabled together",
+ f.join(", ")
+ ));
+ }
+
+ 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.unstable_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))
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-06-12 05:55:41 +0000