1use std::collections::VecDeque;
2use std::ffi::{CStr, CString};
3use std::fmt::Write;
4use std::path::Path;
5use std::sync::Once;
6use std::{ptr, slice, str};
7
8use libc::c_int;
9use rustc_codegen_ssa::TargetConfig;
10use rustc_codegen_ssa::base::wants_wasm_eh;
11use rustc_codegen_ssa::codegen_attrs::check_tied_features;
12use rustc_data_structures::fx::{FxHashMap, FxHashSet};
13use rustc_data_structures::small_c_str::SmallCStr;
14use rustc_data_structures::unord::UnordSet;
15use rustc_fs_util::path_to_c_string;
16use rustc_middle::bug;
17use rustc_session::Session;
18use rustc_session::config::{PrintKind, PrintRequest};
19use rustc_session::features::{StabilityExt, retpoline_features_by_flags};
20use rustc_span::Symbol;
21use rustc_target::spec::{MergeFunctions, PanicStrategy, SmallDataThresholdSupport};
22use rustc_target::target_features::{RUSTC_SPECIAL_FEATURES, RUSTC_SPECIFIC_FEATURES};
23use smallvec::{SmallVec, smallvec};
24
25use crate::back::write::create_informational_target_machine;
26use crate::errors::{
27 FixedX18InvalidArch, PossibleFeature, UnknownCTargetFeature, UnknownCTargetFeaturePrefix,
28};
29use crate::llvm;
30
31static INIT: Once = Once::new();
32
33pub(crate) fn init(sess: &Session) {
34 unsafe {
35 if llvm::LLVMIsMultithreaded() != 1 {
37 bug!("LLVM compiled without support for threads");
38 }
39 INIT.call_once(|| {
40 configure_llvm(sess);
41 });
42 }
43}
44
45fn require_inited() {
46 if !INIT.is_completed() {
47 bug!("LLVM is not initialized");
48 }
49}
50
51unsafe fn configure_llvm(sess: &Session) {
52 let n_args = sess.opts.cg.llvm_args.len() + sess.target.llvm_args.len();
53 let mut llvm_c_strs = Vec::with_capacity(n_args + 1);
54 let mut llvm_args = Vec::with_capacity(n_args + 1);
55
56 unsafe {
57 llvm::LLVMRustInstallErrorHandlers();
58 }
59 if std::env::var_os("CI").is_some() {
63 unsafe {
64 llvm::LLVMRustDisableSystemDialogsOnCrash();
65 }
66 }
67
68 fn llvm_arg_to_arg_name(full_arg: &str) -> &str {
69 full_arg.trim().split(|c: char| c == '=' || c.is_whitespace()).next().unwrap_or("")
70 }
71
72 let cg_opts = sess.opts.cg.llvm_args.iter().map(AsRef::as_ref);
73 let tg_opts = sess.target.llvm_args.iter().map(AsRef::as_ref);
74 let sess_args = cg_opts.chain(tg_opts);
75
76 let user_specified_args: FxHashSet<_> =
77 sess_args.clone().map(|s| llvm_arg_to_arg_name(s)).filter(|s| !s.is_empty()).collect();
78
79 {
80 let mut add = |arg: &str, force: bool| {
83 if force || !user_specified_args.contains(llvm_arg_to_arg_name(arg)) {
84 let s = CString::new(arg).unwrap();
85 llvm_args.push(s.as_ptr());
86 llvm_c_strs.push(s);
87 }
88 };
89 add("rustc -Cllvm-args=\"...\" with", true);
91 if sess.opts.unstable_opts.time_llvm_passes {
92 add("-time-passes", false);
93 }
94 if sess.opts.unstable_opts.print_llvm_passes {
95 add("-debug-pass=Structure", false);
96 }
97 if sess.target.generate_arange_section
98 && !sess.opts.unstable_opts.no_generate_arange_section
99 {
100 add("-generate-arange-section", false);
101 }
102
103 match sess.opts.unstable_opts.merge_functions.unwrap_or(sess.target.merge_functions) {
104 MergeFunctions::Disabled | MergeFunctions::Trampolines => {}
105 MergeFunctions::Aliases => {
106 add("-mergefunc-use-aliases", false);
107 }
108 }
109
110 if wants_wasm_eh(sess) {
111 add("-wasm-enable-eh", false);
112 }
113
114 if sess.target.os == "emscripten"
115 && !sess.opts.unstable_opts.emscripten_wasm_eh
116 && sess.panic_strategy() == PanicStrategy::Unwind
117 {
118 add("-enable-emscripten-cxx-exceptions", false);
119 }
120
121 add("-preserve-alignment-assumptions-during-inlining=false", false);
124
125 add("-import-cold-multiplier=0.1", false);
127
128 if sess.print_llvm_stats() {
129 add("-stats", false);
130 }
131
132 for arg in sess_args {
133 add(&(*arg), true);
134 }
135
136 match (
137 sess.opts.unstable_opts.small_data_threshold,
138 sess.target.small_data_threshold_support(),
139 ) {
140 (Some(threshold), SmallDataThresholdSupport::LlvmArg(arg)) => {
143 add(&format!("--{arg}={threshold}"), false)
144 }
145 _ => (),
146 };
147 }
148
149 if sess.opts.unstable_opts.llvm_time_trace {
150 unsafe { llvm::LLVMRustTimeTraceProfilerInitialize() };
151 }
152
153 rustc_llvm::initialize_available_targets();
154
155 unsafe { llvm::LLVMRustSetLLVMOptions(llvm_args.len() as c_int, llvm_args.as_ptr()) };
156}
157
158pub(crate) fn time_trace_profiler_finish(file_name: &Path) {
159 unsafe {
160 let file_name = path_to_c_string(file_name);
161 llvm::LLVMRustTimeTraceProfilerFinish(file_name.as_ptr());
162 }
163}
164
165enum TargetFeatureFoldStrength<'a> {
166 EnableOnly(&'a str),
169 Both(&'a str),
171}
172
173impl<'a> TargetFeatureFoldStrength<'a> {
174 fn as_str(&self) -> &'a str {
175 match self {
176 TargetFeatureFoldStrength::EnableOnly(feat) => feat,
177 TargetFeatureFoldStrength::Both(feat) => feat,
178 }
179 }
180}
181
182pub(crate) struct LLVMFeature<'a> {
183 llvm_feature_name: &'a str,
184 dependencies: SmallVec<[TargetFeatureFoldStrength<'a>; 1]>,
185}
186
187impl<'a> LLVMFeature<'a> {
188 fn new(llvm_feature_name: &'a str) -> Self {
189 Self { llvm_feature_name, dependencies: SmallVec::new() }
190 }
191
192 fn with_dependencies(
193 llvm_feature_name: &'a str,
194 dependencies: SmallVec<[TargetFeatureFoldStrength<'a>; 1]>,
195 ) -> Self {
196 Self { llvm_feature_name, dependencies }
197 }
198
199 fn contains(&'a self, feat: &str) -> bool {
200 self.iter().any(|dep| dep == feat)
201 }
202
203 fn iter(&'a self) -> impl Iterator<Item = &'a str> {
204 let dependencies = self.dependencies.iter().map(|feat| feat.as_str());
205 std::iter::once(self.llvm_feature_name).chain(dependencies)
206 }
207}
208
209impl<'a> IntoIterator for LLVMFeature<'a> {
210 type Item = &'a str;
211 type IntoIter = impl Iterator<Item = &'a str>;
212
213 fn into_iter(self) -> Self::IntoIter {
214 let dependencies = self.dependencies.into_iter().map(|feat| feat.as_str());
215 std::iter::once(self.llvm_feature_name).chain(dependencies)
216 }
217}
218
219pub(crate) fn to_llvm_features<'a>(sess: &Session, s: &'a str) -> Option<LLVMFeature<'a>> {
232 let arch = if sess.target.arch == "x86_64" {
233 "x86"
234 } else if sess.target.arch == "arm64ec" {
235 "aarch64"
236 } else if sess.target.arch == "sparc64" {
237 "sparc"
238 } else if sess.target.arch == "powerpc64" {
239 "powerpc"
240 } else {
241 &*sess.target.arch
242 };
243 match (arch, s) {
244 ("x86", "sse4.2") => Some(LLVMFeature::with_dependencies(
245 "sse4.2",
246 smallvec![TargetFeatureFoldStrength::EnableOnly("crc32")],
247 )),
248 ("x86", "pclmulqdq") => Some(LLVMFeature::new("pclmul")),
249 ("x86", "rdrand") => Some(LLVMFeature::new("rdrnd")),
250 ("x86", "bmi1") => Some(LLVMFeature::new("bmi")),
251 ("x86", "cmpxchg16b") => Some(LLVMFeature::new("cx16")),
252 ("x86", "lahfsahf") => Some(LLVMFeature::new("sahf")),
253 ("aarch64", "rcpc2") => Some(LLVMFeature::new("rcpc-immo")),
254 ("aarch64", "dpb") => Some(LLVMFeature::new("ccpp")),
255 ("aarch64", "dpb2") => Some(LLVMFeature::new("ccdp")),
256 ("aarch64", "frintts") => Some(LLVMFeature::new("fptoint")),
257 ("aarch64", "fcma") => Some(LLVMFeature::new("complxnum")),
258 ("aarch64", "pmuv3") => Some(LLVMFeature::new("perfmon")),
259 ("aarch64", "paca") => Some(LLVMFeature::new("pauth")),
260 ("aarch64", "pacg") => Some(LLVMFeature::new("pauth")),
261 ("aarch64", "sve-b16b16") if get_version().0 < 20 => Some(LLVMFeature::new("b16b16")),
263 ("aarch64", "sme-b16b16") if get_version().0 < 20 => Some(LLVMFeature::new("b16b16")),
264 ("aarch64", "flagm2") => Some(LLVMFeature::new("altnzcv")),
265 ("aarch64", "neon") => Some(LLVMFeature::with_dependencies(
267 "neon",
268 smallvec![TargetFeatureFoldStrength::Both("fp-armv8")],
269 )),
270 ("aarch64", "fhm") => Some(LLVMFeature::new("fp16fml")),
273 ("aarch64", "fp16") => Some(LLVMFeature::new("fullfp16")),
274 ("aarch64", "fpmr") => None, ("arm", "fp16") => Some(LLVMFeature::new("fullfp16")),
277 ("loongarch64", "div32" | "lam-bh" | "lamcas" | "ld-seq-sa" | "scq")
279 if get_version().0 < 20 =>
280 {
281 None
282 }
283 ("riscv32" | "riscv64", "zacas") if get_version().0 < 20 => None,
285 (
286 "s390x",
287 "message-security-assist-extension12"
288 | "concurrent-functions"
289 | "miscellaneous-extensions-4"
290 | "vector-enhancements-3"
291 | "vector-packed-decimal-enhancement-3",
292 ) if get_version().0 < 20 => None,
293 ("x86", s) if s.starts_with("avx512") => Some(LLVMFeature::with_dependencies(
295 s,
296 smallvec![TargetFeatureFoldStrength::EnableOnly("evex512")],
297 )),
298 ("wasm32" | "wasm64", "wide-arithmetic") if get_version() < (20, 0, 0) => None,
301 ("sparc", "leoncasa") => Some(LLVMFeature::new("hasleoncasa")),
302 ("sparc", "v8plus") if get_version().0 == 19 => Some(LLVMFeature::new("v9")),
307 ("powerpc", "power8-crypto") => Some(LLVMFeature::new("crypto")),
308 ("x86", "amx-avx512" | "amx-fp8" | "amx-movrs" | "amx-tf32" | "amx-transpose")
310 if get_version().0 < 20 =>
311 {
312 None
313 }
314 ("x86", "movrs") if get_version().0 < 20 => None,
315 ("x86", "avx10.1") => Some(LLVMFeature::new("avx10.1-512")),
316 ("x86", "avx10.2") if get_version().0 < 20 => None,
317 ("x86", "avx10.2") if get_version().0 >= 20 => Some(LLVMFeature::new("avx10.2-512")),
318 ("x86", "apxf") => Some(LLVMFeature::with_dependencies(
319 "egpr",
320 smallvec![
321 TargetFeatureFoldStrength::Both("push2pop2"),
322 TargetFeatureFoldStrength::Both("ppx"),
323 TargetFeatureFoldStrength::Both("ndd"),
324 TargetFeatureFoldStrength::Both("ccmp"),
325 TargetFeatureFoldStrength::Both("cf"),
326 TargetFeatureFoldStrength::Both("nf"),
327 TargetFeatureFoldStrength::Both("zu"),
328 ],
329 )),
330 (_, s) => Some(LLVMFeature::new(s)),
331 }
332}
333
334pub(crate) fn target_config(sess: &Session) -> TargetConfig {
339 let target_machine = create_informational_target_machine(sess, true);
346 let mut features: FxHashSet<Symbol> = sess
349 .target
350 .rust_target_features()
351 .iter()
352 .filter(|(feature, _, _)| {
353 if RUSTC_SPECIAL_FEATURES.contains(feature) {
355 return true;
356 }
357 if let Some(feat) = to_llvm_features(sess, feature) {
358 for llvm_feature in feat {
359 let cstr = SmallCStr::new(llvm_feature);
360 if !unsafe { llvm::LLVMRustHasFeature(target_machine.raw(), cstr.as_ptr()) } {
364 return false;
365 }
366 }
367 true
368 } else {
369 false
370 }
371 })
372 .map(|(feature, _, _)| Symbol::intern(feature))
373 .collect();
374
375 for (enabled, feature) in
377 sess.opts.cg.target_feature.split(',').filter_map(|s| match s.chars().next() {
378 Some('+') => Some((true, Symbol::intern(&s[1..]))),
379 Some('-') => Some((false, Symbol::intern(&s[1..]))),
380 _ => None,
381 })
382 {
383 if enabled {
384 #[allow(rustc::potential_query_instability)]
389 features.extend(
390 sess.target
391 .implied_target_features(feature.as_str())
392 .iter()
393 .map(|s| Symbol::intern(s)),
394 );
395 } else {
396 #[allow(rustc::potential_query_instability)]
401 features.retain(|f| {
402 if sess.target.implied_target_features(f.as_str()).contains(&feature.as_str()) {
403 false
406 } else {
407 true
409 }
410 });
411 }
412 }
413
414 let f = |allow_unstable| {
416 sess.target
417 .rust_target_features()
418 .iter()
419 .filter_map(|(feature, gate, _)| {
420 if allow_unstable
424 || (gate.in_cfg()
425 && (sess.is_nightly_build() || gate.requires_nightly().is_none()))
426 {
427 Some(Symbol::intern(feature))
428 } else {
429 None
430 }
431 })
432 .filter(|feature| features.contains(&feature))
433 .collect()
434 };
435
436 let target_features = f(false);
437 let unstable_target_features = f(true);
438 let mut cfg = TargetConfig {
439 target_features,
440 unstable_target_features,
441 has_reliable_f16: true,
442 has_reliable_f16_math: true,
443 has_reliable_f128: true,
444 has_reliable_f128_math: true,
445 };
446
447 update_target_reliable_float_cfg(sess, &mut cfg);
448 cfg
449}
450
451fn update_target_reliable_float_cfg(sess: &Session, cfg: &mut TargetConfig) {
453 let target_arch = sess.target.arch.as_ref();
454 let target_os = sess.target.options.os.as_ref();
455 let target_env = sess.target.options.env.as_ref();
456 let target_abi = sess.target.options.abi.as_ref();
457 let target_pointer_width = sess.target.pointer_width;
458
459 cfg.has_reliable_f16 = match (target_arch, target_os) {
460 ("s390x", _) => false,
462 ("arm64ec", _) => false,
464 ("x86_64", "windows") if target_env == "gnu" && target_abi != "llvm" => false,
466 ("csky", _) => false,
468 ("hexagon", _) => false,
469 ("powerpc" | "powerpc64", _) => false,
470 ("sparc" | "sparc64", _) => false,
471 ("wasm32" | "wasm64", _) => false,
472 _ => true,
476 };
477
478 cfg.has_reliable_f128 = match (target_arch, target_os) {
479 ("arm64ec", _) => false,
481 ("mips64" | "mips64r6", _) => false,
483 ("nvptx64", _) => false,
485 ("powerpc" | "powerpc64", _) => false,
488 ("sparc", _) => false,
490 ("x86", _) => false,
493 ("x86_64", "windows") if target_env == "gnu" && target_abi != "llvm" => false,
495 _ => true,
499 };
500
501 cfg.has_reliable_f16_math = cfg.has_reliable_f16;
504
505 cfg.has_reliable_f128_math = match (target_arch, target_os) {
506 ("x86_64", _) => false,
514 (_, "linux") if target_pointer_width == 64 => true,
515 _ => false,
516 } && cfg.has_reliable_f128;
517}
518
519pub(crate) fn print_version() {
520 let (major, minor, patch) = get_version();
521 println!("LLVM version: {major}.{minor}.{patch}");
522}
523
524pub(crate) fn get_version() -> (u32, u32, u32) {
525 unsafe {
527 (llvm::LLVMRustVersionMajor(), llvm::LLVMRustVersionMinor(), llvm::LLVMRustVersionPatch())
528 }
529}
530
531pub(crate) fn print_passes() {
532 unsafe {
534 llvm::LLVMRustPrintPasses();
535 }
536}
537
538fn llvm_target_features(tm: &llvm::TargetMachine) -> Vec<(&str, &str)> {
539 let len = unsafe { llvm::LLVMRustGetTargetFeaturesCount(tm) };
540 let mut ret = Vec::with_capacity(len);
541 for i in 0..len {
542 unsafe {
543 let mut feature = ptr::null();
544 let mut desc = ptr::null();
545 llvm::LLVMRustGetTargetFeature(tm, i, &mut feature, &mut desc);
546 if feature.is_null() || desc.is_null() {
547 bug!("LLVM returned a `null` target feature string");
548 }
549 let feature = CStr::from_ptr(feature).to_str().unwrap_or_else(|e| {
550 bug!("LLVM returned a non-utf8 feature string: {}", e);
551 });
552 let desc = CStr::from_ptr(desc).to_str().unwrap_or_else(|e| {
553 bug!("LLVM returned a non-utf8 feature string: {}", e);
554 });
555 ret.push((feature, desc));
556 }
557 }
558 ret
559}
560
561pub(crate) fn print(req: &PrintRequest, out: &mut String, sess: &Session) {
562 require_inited();
563 let tm = create_informational_target_machine(sess, false);
564 match req.kind {
565 PrintKind::TargetCPUs => print_target_cpus(sess, tm.raw(), out),
566 PrintKind::TargetFeatures => print_target_features(sess, tm.raw(), out),
567 _ => bug!("rustc_codegen_llvm can't handle print request: {:?}", req),
568 }
569}
570
571fn print_target_cpus(sess: &Session, tm: &llvm::TargetMachine, out: &mut String) {
572 let cpu_names = llvm::build_string(|s| unsafe {
573 llvm::LLVMRustPrintTargetCPUs(&tm, s);
574 })
575 .unwrap();
576
577 struct Cpu<'a> {
578 cpu_name: &'a str,
579 remark: String,
580 }
581 let target_cpu = handle_native(&sess.target.cpu);
583 let make_remark = |cpu_name| {
584 if cpu_name == target_cpu {
585 let target = &sess.target.llvm_target;
588 format!(
589 " - This is the default target CPU for the current build target (currently {target})."
590 )
591 } else {
592 "".to_owned()
593 }
594 };
595 let mut cpus = cpu_names
596 .lines()
597 .map(|cpu_name| Cpu { cpu_name, remark: make_remark(cpu_name) })
598 .collect::<VecDeque<_>>();
599
600 if sess.host.arch == sess.target.arch {
603 let host = get_host_cpu_name();
604 cpus.push_front(Cpu {
605 cpu_name: "native",
606 remark: format!(" - Select the CPU of the current host (currently {host})."),
607 });
608 }
609
610 let max_name_width = cpus.iter().map(|cpu| cpu.cpu_name.len()).max().unwrap_or(0);
611 writeln!(out, "Available CPUs for this target:").unwrap();
612 for Cpu { cpu_name, remark } in cpus {
613 let width = if remark.is_empty() { 0 } else { max_name_width };
615 writeln!(out, " {cpu_name:<width$}{remark}").unwrap();
616 }
617}
618
619fn print_target_features(sess: &Session, tm: &llvm::TargetMachine, out: &mut String) {
620 let mut llvm_target_features = llvm_target_features(tm);
621 let mut known_llvm_target_features = FxHashSet::<&'static str>::default();
622 let mut rustc_target_features = sess
623 .target
624 .rust_target_features()
625 .iter()
626 .filter_map(|(feature, gate, _implied)| {
627 if !gate.in_cfg() {
628 return None;
630 }
631 let llvm_feature = to_llvm_features(sess, *feature)?.llvm_feature_name;
634 let desc =
635 match llvm_target_features.binary_search_by_key(&llvm_feature, |(f, _d)| f).ok() {
636 Some(index) => {
637 known_llvm_target_features.insert(llvm_feature);
638 llvm_target_features[index].1
639 }
640 None => "",
641 };
642
643 Some((*feature, desc))
644 })
645 .collect::<Vec<_>>();
646
647 rustc_target_features.extend_from_slice(&[(
649 "crt-static",
650 "Enables C Run-time Libraries to be statically linked",
651 )]);
652 rustc_target_features.sort();
654
655 llvm_target_features.retain(|(f, _d)| !known_llvm_target_features.contains(f));
656
657 let max_feature_len = llvm_target_features
658 .iter()
659 .chain(rustc_target_features.iter())
660 .map(|(feature, _desc)| feature.len())
661 .max()
662 .unwrap_or(0);
663
664 writeln!(out, "Features supported by rustc for this target:").unwrap();
665 for (feature, desc) in &rustc_target_features {
666 writeln!(out, " {feature:max_feature_len$} - {desc}.").unwrap();
667 }
668 writeln!(out, "\nCode-generation features supported by LLVM for this target:").unwrap();
669 for (feature, desc) in &llvm_target_features {
670 writeln!(out, " {feature:max_feature_len$} - {desc}.").unwrap();
671 }
672 if llvm_target_features.is_empty() {
673 writeln!(out, " Target features listing is not supported by this LLVM version.")
674 .unwrap();
675 }
676 writeln!(out, "\nUse +feature to enable a feature, or -feature to disable it.").unwrap();
677 writeln!(out, "For example, rustc -C target-cpu=mycpu -C target-feature=+feature1,-feature2\n")
678 .unwrap();
679 writeln!(out, "Code-generation features cannot be used in cfg or #[target_feature],").unwrap();
680 writeln!(out, "and may be renamed or removed in a future version of LLVM or rustc.\n").unwrap();
681}
682
683fn get_host_cpu_name() -> &'static str {
685 let mut len = 0;
686 let slice: &'static [u8] = unsafe {
689 let ptr = llvm::LLVMRustGetHostCPUName(&mut len);
690 assert!(!ptr.is_null());
691 slice::from_raw_parts(ptr, len)
692 };
693 str::from_utf8(slice).expect("host CPU name should be UTF-8")
694}
695
696fn handle_native(cpu_name: &str) -> &str {
699 match cpu_name {
700 "native" => get_host_cpu_name(),
701 _ => cpu_name,
702 }
703}
704
705pub(crate) fn target_cpu(sess: &Session) -> &str {
706 let cpu_name = sess.opts.cg.target_cpu.as_deref().unwrap_or_else(|| &sess.target.cpu);
707 handle_native(cpu_name)
708}
709
710fn llvm_features_by_flags(sess: &Session) -> Vec<&str> {
711 let mut features: Vec<&str> = Vec::new();
712 retpoline_features_by_flags(sess, &mut features);
713 features
714}
715
716pub(crate) fn global_llvm_features(
719 sess: &Session,
720 diagnostics: bool,
721 only_base_features: bool,
722) -> Vec<String> {
723 let mut features = vec![];
742
743 match sess.opts.cg.target_cpu {
745 Some(ref s) if s == "native" => {
746 let features_string = unsafe {
752 let ptr = llvm::LLVMGetHostCPUFeatures();
753 let features_string = if !ptr.is_null() {
754 CStr::from_ptr(ptr)
755 .to_str()
756 .unwrap_or_else(|e| {
757 bug!("LLVM returned a non-utf8 features string: {}", e);
758 })
759 .to_owned()
760 } else {
761 bug!("could not allocate host CPU features, LLVM returned a `null` string");
762 };
763
764 llvm::LLVMDisposeMessage(ptr);
765
766 features_string
767 };
768 features.extend(features_string.split(',').map(String::from));
769 }
770 Some(_) | None => {}
771 };
772
773 features.extend(
775 sess.target
776 .features
777 .split(',')
778 .filter(|v| !v.is_empty())
779 .filter(|v| *v != "+v8plus" || get_version() >= (20, 0, 0))
781 .map(String::from),
782 );
783
784 if wants_wasm_eh(sess) && sess.panic_strategy() == PanicStrategy::Unwind {
785 features.push("+exception-handling".into());
786 }
787
788 if !only_base_features {
790 let known_features = sess.target.rust_target_features();
791 let mut featsmap = FxHashMap::default();
793
794 let mut all_rust_features = vec![];
796 for feature in sess.opts.cg.target_feature.split(',').chain(llvm_features_by_flags(sess)) {
797 if let Some(feature) = feature.strip_prefix('+') {
798 all_rust_features.extend(
799 UnordSet::from(sess.target.implied_target_features(feature))
800 .to_sorted_stable_ord()
801 .iter()
802 .map(|&&s| (true, s)),
803 )
804 } else if let Some(feature) = feature.strip_prefix('-') {
805 all_rust_features.push((false, feature));
809 } else if !feature.is_empty() {
810 if diagnostics {
811 sess.dcx().emit_warn(UnknownCTargetFeaturePrefix { feature });
812 }
813 }
814 }
815 all_rust_features.retain(|(_, feature)| {
817 !RUSTC_SPECIFIC_FEATURES.contains(feature)
819 });
820
821 if diagnostics {
823 for &(enable, feature) in &all_rust_features {
824 let feature_state = known_features.iter().find(|&&(v, _, _)| v == feature);
825 match feature_state {
826 None => {
827 let rust_feature =
828 known_features.iter().find_map(|&(rust_feature, _, _)| {
829 let llvm_features = to_llvm_features(sess, rust_feature)?;
830 if llvm_features.contains(feature)
831 && !llvm_features.contains(rust_feature)
832 {
833 Some(rust_feature)
834 } else {
835 None
836 }
837 });
838 let unknown_feature = if let Some(rust_feature) = rust_feature {
839 UnknownCTargetFeature {
840 feature,
841 rust_feature: PossibleFeature::Some { rust_feature },
842 }
843 } else {
844 UnknownCTargetFeature { feature, rust_feature: PossibleFeature::None }
845 };
846 sess.dcx().emit_warn(unknown_feature);
847 }
848 Some((_, stability, _)) => {
849 stability.verify_feature_enabled_by_flag(sess, enable, feature);
850 }
851 }
852
853 featsmap.insert(feature, enable);
855 }
856 }
857
858 let feats = all_rust_features
860 .iter()
861 .filter_map(|&(enable, feature)| {
862 let enable_disable = if enable { '+' } else { '-' };
863 let llvm_feature = to_llvm_features(sess, feature)?;
868
869 Some(
870 std::iter::once(format!(
871 "{}{}",
872 enable_disable, llvm_feature.llvm_feature_name
873 ))
874 .chain(llvm_feature.dependencies.into_iter().filter_map(
875 move |feat| match (enable, feat) {
876 (_, TargetFeatureFoldStrength::Both(f))
877 | (true, TargetFeatureFoldStrength::EnableOnly(f)) => {
878 Some(format!("{enable_disable}{f}"))
879 }
880 _ => None,
881 },
882 )),
883 )
884 })
885 .flatten();
886 features.extend(feats);
887
888 if diagnostics && let Some(f) = check_tied_features(sess, &featsmap) {
889 sess.dcx().emit_err(rustc_codegen_ssa::errors::TargetFeatureDisableOrEnable {
890 features: f,
891 span: None,
892 missing_features: None,
893 });
894 }
895 }
896
897 if sess.opts.unstable_opts.fixed_x18 {
899 if sess.target.arch != "aarch64" {
900 sess.dcx().emit_fatal(FixedX18InvalidArch { arch: &sess.target.arch });
901 } else {
902 features.push("+reserve-x18".into());
903 }
904 }
905
906 features
907}
908
909pub(crate) fn tune_cpu(sess: &Session) -> Option<&str> {
910 let name = sess.opts.unstable_opts.tune_cpu.as_ref()?;
911 Some(handle_native(name))
912}