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_span::Symbol;
20use rustc_target::spec::{MergeFunctions, PanicStrategy, SmallDataThresholdSupport};
21use rustc_target::target_features::{RUSTC_SPECIAL_FEATURES, RUSTC_SPECIFIC_FEATURES};
22use smallvec::{SmallVec, smallvec};
23
24use crate::back::write::create_informational_target_machine;
25use crate::errors::{
26 FixedX18InvalidArch, ForbiddenCTargetFeature, PossibleFeature, UnknownCTargetFeature,
27 UnknownCTargetFeaturePrefix, UnstableCTargetFeature,
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 ("x86", s) if s.starts_with("avx512") => Some(LLVMFeature::with_dependencies(
287 s,
288 smallvec![TargetFeatureFoldStrength::EnableOnly("evex512")],
289 )),
290 ("wasm32" | "wasm64", "wide-arithmetic") if get_version() < (20, 0, 0) => None,
293 ("sparc", "leoncasa") => Some(LLVMFeature::new("hasleoncasa")),
294 ("sparc", "v8plus") if get_version().0 == 19 => Some(LLVMFeature::new("v9")),
299 ("powerpc", "power8-crypto") => Some(LLVMFeature::new("crypto")),
300 ("x86", "amx-avx512" | "amx-fp8" | "amx-movrs" | "amx-tf32" | "amx-transpose")
302 if get_version().0 < 20 =>
303 {
304 None
305 }
306 ("x86", "movrs") if get_version().0 < 20 => None,
307 ("x86", "avx10.1") => Some(LLVMFeature::new("avx10.1-512")),
308 ("x86", "avx10.2") if get_version().0 < 20 => None,
309 ("x86", "avx10.2") if get_version().0 >= 20 => Some(LLVMFeature::new("avx10.2-512")),
310 ("x86", "apxf") => Some(LLVMFeature::with_dependencies(
311 "egpr",
312 smallvec![
313 TargetFeatureFoldStrength::Both("push2pop2"),
314 TargetFeatureFoldStrength::Both("ppx"),
315 TargetFeatureFoldStrength::Both("ndd"),
316 TargetFeatureFoldStrength::Both("ccmp"),
317 TargetFeatureFoldStrength::Both("cf"),
318 TargetFeatureFoldStrength::Both("nf"),
319 TargetFeatureFoldStrength::Both("zu"),
320 ],
321 )),
322 (_, s) => Some(LLVMFeature::new(s)),
323 }
324}
325
326pub(crate) fn target_config(sess: &Session) -> TargetConfig {
331 let target_machine = create_informational_target_machine(sess, true);
338 let mut features: FxHashSet<Symbol> = sess
341 .target
342 .rust_target_features()
343 .iter()
344 .filter(|(feature, _, _)| {
345 if RUSTC_SPECIAL_FEATURES.contains(feature) {
347 return true;
348 }
349 if let Some(feat) = to_llvm_features(sess, feature) {
350 for llvm_feature in feat {
351 let cstr = SmallCStr::new(llvm_feature);
352 if !unsafe { llvm::LLVMRustHasFeature(target_machine.raw(), cstr.as_ptr()) } {
356 return false;
357 }
358 }
359 true
360 } else {
361 false
362 }
363 })
364 .map(|(feature, _, _)| Symbol::intern(feature))
365 .collect();
366
367 for (enabled, feature) in
369 sess.opts.cg.target_feature.split(',').filter_map(|s| match s.chars().next() {
370 Some('+') => Some((true, Symbol::intern(&s[1..]))),
371 Some('-') => Some((false, Symbol::intern(&s[1..]))),
372 _ => None,
373 })
374 {
375 if enabled {
376 #[allow(rustc::potential_query_instability)]
381 features.extend(
382 sess.target
383 .implied_target_features(feature.as_str())
384 .iter()
385 .map(|s| Symbol::intern(s)),
386 );
387 } else {
388 #[allow(rustc::potential_query_instability)]
393 features.retain(|f| {
394 if sess.target.implied_target_features(f.as_str()).contains(&feature.as_str()) {
395 false
398 } else {
399 true
401 }
402 });
403 }
404 }
405
406 let f = |allow_unstable| {
408 sess.target
409 .rust_target_features()
410 .iter()
411 .filter_map(|(feature, gate, _)| {
412 if allow_unstable
416 || (gate.in_cfg()
417 && (sess.is_nightly_build() || gate.requires_nightly().is_none()))
418 {
419 Some(Symbol::intern(feature))
420 } else {
421 None
422 }
423 })
424 .filter(|feature| features.contains(&feature))
425 .collect()
426 };
427
428 let target_features = f(false);
429 let unstable_target_features = f(true);
430 let mut cfg = TargetConfig {
431 target_features,
432 unstable_target_features,
433 has_reliable_f16: true,
434 has_reliable_f16_math: true,
435 has_reliable_f128: true,
436 has_reliable_f128_math: true,
437 };
438
439 update_target_reliable_float_cfg(sess, &mut cfg);
440 cfg
441}
442
443fn update_target_reliable_float_cfg(sess: &Session, cfg: &mut TargetConfig) {
445 let target_arch = sess.target.arch.as_ref();
446 let target_os = sess.target.options.os.as_ref();
447 let target_env = sess.target.options.env.as_ref();
448 let target_abi = sess.target.options.abi.as_ref();
449 let target_pointer_width = sess.target.pointer_width;
450
451 cfg.has_reliable_f16 = match (target_arch, target_os) {
452 ("s390x", _) => false,
454 ("arm64ec", _) => false,
456 ("x86_64", "windows") if target_env == "gnu" && target_abi != "llvm" => false,
458 ("csky", _) => false,
460 ("hexagon", _) => false,
461 ("powerpc" | "powerpc64", _) => false,
462 ("sparc" | "sparc64", _) => false,
463 ("wasm32" | "wasm64", _) => false,
464 _ => true,
468 };
469
470 cfg.has_reliable_f128 = match (target_arch, target_os) {
471 ("arm64ec", _) => false,
473 ("mips64" | "mips64r6", _) => false,
475 ("nvptx64", _) => false,
477 ("powerpc" | "powerpc64", _) => false,
480 ("sparc", _) => false,
482 ("x86", _) => false,
485 ("x86_64", "windows") if target_env == "gnu" && target_abi != "llvm" => false,
487 _ => true,
491 };
492
493 cfg.has_reliable_f16_math = cfg.has_reliable_f16;
496
497 cfg.has_reliable_f128_math = match (target_arch, target_os) {
498 ("x86_64", _) => false,
506 (_, "linux") if target_pointer_width == 64 => true,
507 _ => false,
508 } && cfg.has_reliable_f128;
509}
510
511pub(crate) fn print_version() {
512 let (major, minor, patch) = get_version();
513 println!("LLVM version: {major}.{minor}.{patch}");
514}
515
516pub(crate) fn get_version() -> (u32, u32, u32) {
517 unsafe {
519 (llvm::LLVMRustVersionMajor(), llvm::LLVMRustVersionMinor(), llvm::LLVMRustVersionPatch())
520 }
521}
522
523pub(crate) fn print_passes() {
524 unsafe {
526 llvm::LLVMRustPrintPasses();
527 }
528}
529
530fn llvm_target_features(tm: &llvm::TargetMachine) -> Vec<(&str, &str)> {
531 let len = unsafe { llvm::LLVMRustGetTargetFeaturesCount(tm) };
532 let mut ret = Vec::with_capacity(len);
533 for i in 0..len {
534 unsafe {
535 let mut feature = ptr::null();
536 let mut desc = ptr::null();
537 llvm::LLVMRustGetTargetFeature(tm, i, &mut feature, &mut desc);
538 if feature.is_null() || desc.is_null() {
539 bug!("LLVM returned a `null` target feature string");
540 }
541 let feature = CStr::from_ptr(feature).to_str().unwrap_or_else(|e| {
542 bug!("LLVM returned a non-utf8 feature string: {}", e);
543 });
544 let desc = CStr::from_ptr(desc).to_str().unwrap_or_else(|e| {
545 bug!("LLVM returned a non-utf8 feature string: {}", e);
546 });
547 ret.push((feature, desc));
548 }
549 }
550 ret
551}
552
553pub(crate) fn print(req: &PrintRequest, out: &mut String, sess: &Session) {
554 require_inited();
555 let tm = create_informational_target_machine(sess, false);
556 match req.kind {
557 PrintKind::TargetCPUs => print_target_cpus(sess, tm.raw(), out),
558 PrintKind::TargetFeatures => print_target_features(sess, tm.raw(), out),
559 _ => bug!("rustc_codegen_llvm can't handle print request: {:?}", req),
560 }
561}
562
563fn print_target_cpus(sess: &Session, tm: &llvm::TargetMachine, out: &mut String) {
564 let cpu_names = llvm::build_string(|s| unsafe {
565 llvm::LLVMRustPrintTargetCPUs(&tm, s);
566 })
567 .unwrap();
568
569 struct Cpu<'a> {
570 cpu_name: &'a str,
571 remark: String,
572 }
573 let target_cpu = handle_native(&sess.target.cpu);
575 let make_remark = |cpu_name| {
576 if cpu_name == target_cpu {
577 let target = &sess.target.llvm_target;
580 format!(
581 " - This is the default target CPU for the current build target (currently {target})."
582 )
583 } else {
584 "".to_owned()
585 }
586 };
587 let mut cpus = cpu_names
588 .lines()
589 .map(|cpu_name| Cpu { cpu_name, remark: make_remark(cpu_name) })
590 .collect::<VecDeque<_>>();
591
592 if sess.host.arch == sess.target.arch {
595 let host = get_host_cpu_name();
596 cpus.push_front(Cpu {
597 cpu_name: "native",
598 remark: format!(" - Select the CPU of the current host (currently {host})."),
599 });
600 }
601
602 let max_name_width = cpus.iter().map(|cpu| cpu.cpu_name.len()).max().unwrap_or(0);
603 writeln!(out, "Available CPUs for this target:").unwrap();
604 for Cpu { cpu_name, remark } in cpus {
605 let width = if remark.is_empty() { 0 } else { max_name_width };
607 writeln!(out, " {cpu_name:<width$}{remark}").unwrap();
608 }
609}
610
611fn print_target_features(sess: &Session, tm: &llvm::TargetMachine, out: &mut String) {
612 let mut llvm_target_features = llvm_target_features(tm);
613 let mut known_llvm_target_features = FxHashSet::<&'static str>::default();
614 let mut rustc_target_features = sess
615 .target
616 .rust_target_features()
617 .iter()
618 .filter_map(|(feature, gate, _implied)| {
619 if !gate.in_cfg() {
620 return None;
622 }
623 let llvm_feature = to_llvm_features(sess, *feature)?.llvm_feature_name;
626 let desc =
627 match llvm_target_features.binary_search_by_key(&llvm_feature, |(f, _d)| f).ok() {
628 Some(index) => {
629 known_llvm_target_features.insert(llvm_feature);
630 llvm_target_features[index].1
631 }
632 None => "",
633 };
634
635 Some((*feature, desc))
636 })
637 .collect::<Vec<_>>();
638
639 rustc_target_features.extend_from_slice(&[(
641 "crt-static",
642 "Enables C Run-time Libraries to be statically linked",
643 )]);
644 rustc_target_features.sort();
646
647 llvm_target_features.retain(|(f, _d)| !known_llvm_target_features.contains(f));
648
649 let max_feature_len = llvm_target_features
650 .iter()
651 .chain(rustc_target_features.iter())
652 .map(|(feature, _desc)| feature.len())
653 .max()
654 .unwrap_or(0);
655
656 writeln!(out, "Features supported by rustc for this target:").unwrap();
657 for (feature, desc) in &rustc_target_features {
658 writeln!(out, " {feature:max_feature_len$} - {desc}.").unwrap();
659 }
660 writeln!(out, "\nCode-generation features supported by LLVM for this target:").unwrap();
661 for (feature, desc) in &llvm_target_features {
662 writeln!(out, " {feature:max_feature_len$} - {desc}.").unwrap();
663 }
664 if llvm_target_features.is_empty() {
665 writeln!(out, " Target features listing is not supported by this LLVM version.")
666 .unwrap();
667 }
668 writeln!(out, "\nUse +feature to enable a feature, or -feature to disable it.").unwrap();
669 writeln!(out, "For example, rustc -C target-cpu=mycpu -C target-feature=+feature1,-feature2\n")
670 .unwrap();
671 writeln!(out, "Code-generation features cannot be used in cfg or #[target_feature],").unwrap();
672 writeln!(out, "and may be renamed or removed in a future version of LLVM or rustc.\n").unwrap();
673}
674
675fn get_host_cpu_name() -> &'static str {
677 let mut len = 0;
678 let slice: &'static [u8] = unsafe {
681 let ptr = llvm::LLVMRustGetHostCPUName(&mut len);
682 assert!(!ptr.is_null());
683 slice::from_raw_parts(ptr, len)
684 };
685 str::from_utf8(slice).expect("host CPU name should be UTF-8")
686}
687
688fn handle_native(cpu_name: &str) -> &str {
691 match cpu_name {
692 "native" => get_host_cpu_name(),
693 _ => cpu_name,
694 }
695}
696
697pub(crate) fn target_cpu(sess: &Session) -> &str {
698 let cpu_name = sess.opts.cg.target_cpu.as_deref().unwrap_or_else(|| &sess.target.cpu);
699 handle_native(cpu_name)
700}
701
702pub(crate) fn global_llvm_features(
705 sess: &Session,
706 diagnostics: bool,
707 only_base_features: bool,
708) -> Vec<String> {
709 let mut features = vec![];
728
729 match sess.opts.cg.target_cpu {
731 Some(ref s) if s == "native" => {
732 let features_string = unsafe {
738 let ptr = llvm::LLVMGetHostCPUFeatures();
739 let features_string = if !ptr.is_null() {
740 CStr::from_ptr(ptr)
741 .to_str()
742 .unwrap_or_else(|e| {
743 bug!("LLVM returned a non-utf8 features string: {}", e);
744 })
745 .to_owned()
746 } else {
747 bug!("could not allocate host CPU features, LLVM returned a `null` string");
748 };
749
750 llvm::LLVMDisposeMessage(ptr);
751
752 features_string
753 };
754 features.extend(features_string.split(',').map(String::from));
755 }
756 Some(_) | None => {}
757 };
758
759 features.extend(
761 sess.target
762 .features
763 .split(',')
764 .filter(|v| !v.is_empty())
765 .filter(|v| *v != "+v8plus" || get_version() >= (20, 0, 0))
767 .map(String::from),
768 );
769
770 if wants_wasm_eh(sess) && sess.panic_strategy() == PanicStrategy::Unwind {
771 features.push("+exception-handling".into());
772 }
773
774 if !only_base_features {
776 let known_features = sess.target.rust_target_features();
777 let mut featsmap = FxHashMap::default();
779
780 let mut all_rust_features = vec![];
782 for feature in sess.opts.cg.target_feature.split(',') {
783 if let Some(feature) = feature.strip_prefix('+') {
784 all_rust_features.extend(
785 UnordSet::from(sess.target.implied_target_features(feature))
786 .to_sorted_stable_ord()
787 .iter()
788 .map(|&&s| (true, s)),
789 )
790 } else if let Some(feature) = feature.strip_prefix('-') {
791 all_rust_features.push((false, feature));
795 } else if !feature.is_empty() {
796 if diagnostics {
797 sess.dcx().emit_warn(UnknownCTargetFeaturePrefix { feature });
798 }
799 }
800 }
801 all_rust_features.retain(|(_, feature)| {
803 !RUSTC_SPECIFIC_FEATURES.contains(feature)
805 });
806
807 if diagnostics {
809 for &(enable, feature) in &all_rust_features {
810 let feature_state = known_features.iter().find(|&&(v, _, _)| v == feature);
811 match feature_state {
812 None => {
813 let rust_feature =
814 known_features.iter().find_map(|&(rust_feature, _, _)| {
815 let llvm_features = to_llvm_features(sess, rust_feature)?;
816 if llvm_features.contains(feature)
817 && !llvm_features.contains(rust_feature)
818 {
819 Some(rust_feature)
820 } else {
821 None
822 }
823 });
824 let unknown_feature = if let Some(rust_feature) = rust_feature {
825 UnknownCTargetFeature {
826 feature,
827 rust_feature: PossibleFeature::Some { rust_feature },
828 }
829 } else {
830 UnknownCTargetFeature { feature, rust_feature: PossibleFeature::None }
831 };
832 sess.dcx().emit_warn(unknown_feature);
833 }
834 Some((_, stability, _)) => {
835 if let Err(reason) = stability.toggle_allowed() {
836 sess.dcx().emit_warn(ForbiddenCTargetFeature {
837 feature,
838 enabled: if enable { "enabled" } else { "disabled" },
839 reason,
840 });
841 } else if stability.requires_nightly().is_some() {
842 sess.dcx().emit_warn(UnstableCTargetFeature { feature });
846 }
847 }
848 }
849
850 featsmap.insert(feature, enable);
852 }
853 }
854
855 let feats = all_rust_features
857 .iter()
858 .filter_map(|&(enable, feature)| {
859 let enable_disable = if enable { '+' } else { '-' };
860 let llvm_feature = to_llvm_features(sess, feature)?;
865
866 Some(
867 std::iter::once(format!(
868 "{}{}",
869 enable_disable, llvm_feature.llvm_feature_name
870 ))
871 .chain(llvm_feature.dependencies.into_iter().filter_map(
872 move |feat| match (enable, feat) {
873 (_, TargetFeatureFoldStrength::Both(f))
874 | (true, TargetFeatureFoldStrength::EnableOnly(f)) => {
875 Some(format!("{enable_disable}{f}"))
876 }
877 _ => None,
878 },
879 )),
880 )
881 })
882 .flatten();
883 features.extend(feats);
884
885 if diagnostics && let Some(f) = check_tied_features(sess, &featsmap) {
886 sess.dcx().emit_err(rustc_codegen_ssa::errors::TargetFeatureDisableOrEnable {
887 features: f,
888 span: None,
889 missing_features: None,
890 });
891 }
892 }
893
894 if sess.opts.unstable_opts.fixed_x18 {
896 if sess.target.arch != "aarch64" {
897 sess.dcx().emit_fatal(FixedX18InvalidArch { arch: &sess.target.arch });
898 } else {
899 features.push("+reserve-x18".into());
900 }
901 }
902
903 features
904}
905
906pub(crate) fn tune_cpu(sess: &Session) -> Option<&str> {
907 let name = sess.opts.unstable_opts.tune_cpu.as_ref()?;
908 Some(handle_native(name))
909}