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::base::wants_wasm_eh;
10use rustc_codegen_ssa::target_features::cfg_target_feature;
11use rustc_codegen_ssa::{TargetConfig, target_features};
12use rustc_data_structures::fx::FxHashSet;
13use rustc_data_structures::small_c_str::SmallCStr;
14use rustc_fs_util::path_to_c_string;
15use rustc_middle::bug;
16use rustc_session::Session;
17use rustc_session::config::{PrintKind, PrintRequest};
18use rustc_target::spec::{MergeFunctions, PanicStrategy, SmallDataThresholdSupport};
19use smallvec::{SmallVec, smallvec};
20
21use crate::back::write::create_informational_target_machine;
22use crate::{errors, llvm};
23
24static INIT: Once = Once::new();
25
26pub(crate) fn init(sess: &Session) {
27 unsafe {
28 if !llvm::LLVMIsMultithreaded().is_true() {
30 bug!("LLVM compiled without support for threads");
31 }
32 INIT.call_once(|| {
33 configure_llvm(sess);
34 });
35 }
36}
37
38fn require_inited() {
39 if !INIT.is_completed() {
40 bug!("LLVM is not initialized");
41 }
42}
43
44unsafe fn configure_llvm(sess: &Session) {
45 let n_args = sess.opts.cg.llvm_args.len() + sess.target.llvm_args.len();
46 let mut llvm_c_strs = Vec::with_capacity(n_args + 1);
47 let mut llvm_args = Vec::with_capacity(n_args + 1);
48
49 unsafe {
50 llvm::LLVMRustInstallErrorHandlers();
51 }
52 if std::env::var_os("CI").is_some() {
56 unsafe {
57 llvm::LLVMRustDisableSystemDialogsOnCrash();
58 }
59 }
60
61 fn llvm_arg_to_arg_name(full_arg: &str) -> &str {
62 full_arg.trim().split(|c: char| c == '=' || c.is_whitespace()).next().unwrap_or("")
63 }
64
65 let cg_opts = sess.opts.cg.llvm_args.iter().map(AsRef::as_ref);
66 let tg_opts = sess.target.llvm_args.iter().map(AsRef::as_ref);
67 let sess_args = cg_opts.chain(tg_opts);
68
69 let user_specified_args: FxHashSet<_> =
70 sess_args.clone().map(|s| llvm_arg_to_arg_name(s)).filter(|s| !s.is_empty()).collect();
71
72 {
73 let mut add = |arg: &str, force: bool| {
76 if force || !user_specified_args.contains(llvm_arg_to_arg_name(arg)) {
77 let s = CString::new(arg).unwrap();
78 llvm_args.push(s.as_ptr());
79 llvm_c_strs.push(s);
80 }
81 };
82 add("rustc -Cllvm-args=\"...\" with", true);
84 if sess.opts.unstable_opts.time_llvm_passes {
85 add("-time-passes", false);
86 }
87 if sess.opts.unstable_opts.print_llvm_passes {
88 add("-debug-pass=Structure", false);
89 }
90 if sess.target.generate_arange_section
91 && !sess.opts.unstable_opts.no_generate_arange_section
92 {
93 add("-generate-arange-section", false);
94 }
95
96 match sess.opts.unstable_opts.merge_functions.unwrap_or(sess.target.merge_functions) {
97 MergeFunctions::Disabled | MergeFunctions::Trampolines => {}
98 MergeFunctions::Aliases => {
99 add("-mergefunc-use-aliases", false);
100 }
101 }
102
103 if wants_wasm_eh(sess) {
104 add("-wasm-enable-eh", false);
105 }
106
107 if sess.target.os == "emscripten"
108 && !sess.opts.unstable_opts.emscripten_wasm_eh
109 && sess.panic_strategy().unwinds()
110 {
111 add("-enable-emscripten-cxx-exceptions", false);
112 }
113
114 add("-preserve-alignment-assumptions-during-inlining=false", false);
117
118 add("-import-cold-multiplier=0.1", false);
120
121 if sess.print_llvm_stats() {
122 add("-stats", false);
123 }
124
125 for arg in sess_args {
126 add(&(*arg), true);
127 }
128
129 match (
130 sess.opts.unstable_opts.small_data_threshold,
131 sess.target.small_data_threshold_support(),
132 ) {
133 (Some(threshold), SmallDataThresholdSupport::LlvmArg(arg)) => {
136 add(&format!("--{arg}={threshold}"), false)
137 }
138 _ => (),
139 };
140 }
141
142 if sess.opts.unstable_opts.llvm_time_trace {
143 unsafe { llvm::LLVMRustTimeTraceProfilerInitialize() };
144 }
145
146 rustc_llvm::initialize_available_targets();
147
148 unsafe { llvm::LLVMRustSetLLVMOptions(llvm_args.len() as c_int, llvm_args.as_ptr()) };
149}
150
151pub(crate) fn time_trace_profiler_finish(file_name: &Path) {
152 unsafe {
153 let file_name = path_to_c_string(file_name);
154 llvm::LLVMRustTimeTraceProfilerFinish(file_name.as_ptr());
155 }
156}
157
158enum TargetFeatureFoldStrength<'a> {
159 EnableOnly(&'a str),
162 Both(&'a str),
164}
165
166impl<'a> TargetFeatureFoldStrength<'a> {
167 fn as_str(&self) -> &'a str {
168 match self {
169 TargetFeatureFoldStrength::EnableOnly(feat) => feat,
170 TargetFeatureFoldStrength::Both(feat) => feat,
171 }
172 }
173}
174
175pub(crate) struct LLVMFeature<'a> {
176 llvm_feature_name: &'a str,
177 dependencies: SmallVec<[TargetFeatureFoldStrength<'a>; 1]>,
178}
179
180impl<'a> LLVMFeature<'a> {
181 fn new(llvm_feature_name: &'a str) -> Self {
182 Self { llvm_feature_name, dependencies: SmallVec::new() }
183 }
184
185 fn with_dependencies(
186 llvm_feature_name: &'a str,
187 dependencies: SmallVec<[TargetFeatureFoldStrength<'a>; 1]>,
188 ) -> Self {
189 Self { llvm_feature_name, dependencies }
190 }
191}
192
193impl<'a> IntoIterator for LLVMFeature<'a> {
194 type Item = &'a str;
195 type IntoIter = impl Iterator<Item = &'a str>;
196
197 fn into_iter(self) -> Self::IntoIter {
198 let dependencies = self.dependencies.into_iter().map(|feat| feat.as_str());
199 std::iter::once(self.llvm_feature_name).chain(dependencies)
200 }
201}
202
203pub(crate) fn to_llvm_features<'a>(sess: &Session, s: &'a str) -> Option<LLVMFeature<'a>> {
220 let raw_arch = &*sess.target.arch;
221 let arch = match raw_arch {
222 "x86_64" => "x86",
223 "arm64ec" => "aarch64",
224 "sparc64" => "sparc",
225 "powerpc64" => "powerpc",
226 _ => raw_arch,
227 };
228 let (major, _, _) = get_version();
229 match (arch, s) {
230 ("aarch64", "rcpc2") => Some(LLVMFeature::new("rcpc-immo")),
231 ("aarch64", "dpb") => Some(LLVMFeature::new("ccpp")),
232 ("aarch64", "dpb2") => Some(LLVMFeature::new("ccdp")),
233 ("aarch64", "frintts") => Some(LLVMFeature::new("fptoint")),
234 ("aarch64", "fcma") => Some(LLVMFeature::new("complxnum")),
235 ("aarch64", "pmuv3") => Some(LLVMFeature::new("perfmon")),
236 ("aarch64", "paca") => Some(LLVMFeature::new("pauth")),
237 ("aarch64", "pacg") => Some(LLVMFeature::new("pauth")),
238 ("aarch64", "flagm2") => Some(LLVMFeature::new("altnzcv")),
239 ("aarch64", "neon") => Some(LLVMFeature::with_dependencies(
241 "neon",
242 smallvec![TargetFeatureFoldStrength::Both("fp-armv8")],
243 )),
244 ("aarch64", "fhm") => Some(LLVMFeature::new("fp16fml")),
247 ("aarch64", "fp16") => Some(LLVMFeature::new("fullfp16")),
248 ("aarch64", "fpmr") => None, ("arm", "fp16") => Some(LLVMFeature::new("fullfp16")),
251 ("loongarch32" | "loongarch64", "32s") if major < 21 => None,
253 ("powerpc", "power8-crypto") => Some(LLVMFeature::new("crypto")),
254 ("sparc", "leoncasa") => Some(LLVMFeature::new("hasleoncasa")),
255 ("x86", "sse4.2") => Some(LLVMFeature::with_dependencies(
256 "sse4.2",
257 smallvec![TargetFeatureFoldStrength::EnableOnly("crc32")],
258 )),
259 ("x86", "pclmulqdq") => Some(LLVMFeature::new("pclmul")),
260 ("x86", "rdrand") => Some(LLVMFeature::new("rdrnd")),
261 ("x86", "bmi1") => Some(LLVMFeature::new("bmi")),
262 ("x86", "cmpxchg16b") => Some(LLVMFeature::new("cx16")),
263 ("x86", "lahfsahf") => Some(LLVMFeature::new("sahf")),
264 ("x86", s) if s.starts_with("avx512") => Some(LLVMFeature::with_dependencies(
266 s,
267 smallvec![TargetFeatureFoldStrength::EnableOnly("evex512")],
268 )),
269 ("x86", "avx10.1") => Some(LLVMFeature::new("avx10.1-512")),
270 ("x86", "avx10.2") => Some(LLVMFeature::new("avx10.2-512")),
271 ("x86", "apxf") => Some(LLVMFeature::with_dependencies(
272 "egpr",
273 smallvec![
274 TargetFeatureFoldStrength::Both("push2pop2"),
275 TargetFeatureFoldStrength::Both("ppx"),
276 TargetFeatureFoldStrength::Both("ndd"),
277 TargetFeatureFoldStrength::Both("ccmp"),
278 TargetFeatureFoldStrength::Both("cf"),
279 TargetFeatureFoldStrength::Both("nf"),
280 TargetFeatureFoldStrength::Both("zu"),
281 ],
282 )),
283 (_, s) => Some(LLVMFeature::new(s)),
284 }
285}
286
287pub(crate) fn target_config(sess: &Session) -> TargetConfig {
292 let target_machine = create_informational_target_machine(sess, true);
293
294 let (unstable_target_features, target_features) = cfg_target_feature(sess, |feature| {
295 if let Some(feat) = to_llvm_features(sess, feature) {
299 for llvm_feature in feat {
301 let cstr = SmallCStr::new(llvm_feature);
302 if !unsafe { llvm::LLVMRustHasFeature(target_machine.raw(), cstr.as_ptr()) } {
306 return false;
307 }
308 }
309 true
310 } else {
311 false
312 }
313 });
314
315 let mut cfg = TargetConfig {
316 target_features,
317 unstable_target_features,
318 has_reliable_f16: true,
319 has_reliable_f16_math: true,
320 has_reliable_f128: true,
321 has_reliable_f128_math: true,
322 };
323
324 update_target_reliable_float_cfg(sess, &mut cfg);
325 cfg
326}
327
328fn update_target_reliable_float_cfg(sess: &Session, cfg: &mut TargetConfig) {
330 let target_arch = sess.target.arch.as_ref();
331 let target_os = sess.target.options.os.as_ref();
332 let target_env = sess.target.options.env.as_ref();
333 let target_abi = sess.target.options.abi.as_ref();
334 let target_pointer_width = sess.target.pointer_width;
335 let version = get_version();
336 let lt_20_1_1 = version < (20, 1, 1);
337 let lt_21_0_0 = version < (21, 0, 0);
338
339 cfg.has_reliable_f16 = match (target_arch, target_os) {
340 ("aarch64", _)
342 if !cfg.target_features.iter().any(|f| f.as_str() == "neon") && lt_20_1_1 =>
343 {
344 false
345 }
346 ("arm64ec", _) => false,
348 ("s390x", _) if lt_21_0_0 => false,
350 ("x86_64", "windows") if target_env == "gnu" && target_abi != "llvm" => false,
352 ("csky", _) => false,
354 ("hexagon", _) if lt_21_0_0 => false, ("powerpc" | "powerpc64", _) => false,
356 ("sparc" | "sparc64", _) => false,
357 ("wasm32" | "wasm64", _) => false,
358 _ => true,
362 };
363
364 cfg.has_reliable_f128 = match (target_arch, target_os) {
365 ("arm64ec", _) => false,
367 ("mips64" | "mips64r6", _) if lt_20_1_1 => false,
369 ("nvptx64", _) => false,
372 ("amdgpu", _) => false,
374 ("powerpc" | "powerpc64", _) => false,
377 ("sparc", _) => false,
379 ("x86", _) if lt_21_0_0 => false,
382 ("x86_64", "windows") if target_env == "gnu" && target_abi != "llvm" => false,
384 _ => true,
388 };
389
390 cfg.has_reliable_f16_math = cfg.has_reliable_f16;
393
394 cfg.has_reliable_f128_math = match (target_arch, target_os) {
395 _ if target_env == "musl" => false,
405 ("x86_64", _) => false,
406 (_, "linux") if target_pointer_width == 64 => true,
407 _ => false,
408 } && cfg.has_reliable_f128;
409}
410
411pub(crate) fn print_version() {
412 let (major, minor, patch) = get_version();
413 println!("LLVM version: {major}.{minor}.{patch}");
414}
415
416pub(crate) fn get_version() -> (u32, u32, u32) {
417 unsafe {
419 (llvm::LLVMRustVersionMajor(), llvm::LLVMRustVersionMinor(), llvm::LLVMRustVersionPatch())
420 }
421}
422
423pub(crate) fn print_passes() {
424 unsafe {
426 llvm::LLVMRustPrintPasses();
427 }
428}
429
430fn llvm_target_features(tm: &llvm::TargetMachine) -> Vec<(&str, &str)> {
431 let len = unsafe { llvm::LLVMRustGetTargetFeaturesCount(tm) };
432 let mut ret = Vec::with_capacity(len);
433 for i in 0..len {
434 unsafe {
435 let mut feature = ptr::null();
436 let mut desc = ptr::null();
437 llvm::LLVMRustGetTargetFeature(tm, i, &mut feature, &mut desc);
438 if feature.is_null() || desc.is_null() {
439 bug!("LLVM returned a `null` target feature string");
440 }
441 let feature = CStr::from_ptr(feature).to_str().unwrap_or_else(|e| {
442 bug!("LLVM returned a non-utf8 feature string: {}", e);
443 });
444 let desc = CStr::from_ptr(desc).to_str().unwrap_or_else(|e| {
445 bug!("LLVM returned a non-utf8 feature string: {}", e);
446 });
447 ret.push((feature, desc));
448 }
449 }
450 ret
451}
452
453pub(crate) fn print(req: &PrintRequest, out: &mut String, sess: &Session) {
454 require_inited();
455 let tm = create_informational_target_machine(sess, false);
456 match req.kind {
457 PrintKind::TargetCPUs => print_target_cpus(sess, tm.raw(), out),
458 PrintKind::TargetFeatures => print_target_features(sess, tm.raw(), out),
459 _ => bug!("rustc_codegen_llvm can't handle print request: {:?}", req),
460 }
461}
462
463fn print_target_cpus(sess: &Session, tm: &llvm::TargetMachine, out: &mut String) {
464 let cpu_names = llvm::build_string(|s| unsafe {
465 llvm::LLVMRustPrintTargetCPUs(&tm, s);
466 })
467 .unwrap();
468
469 struct Cpu<'a> {
470 cpu_name: &'a str,
471 remark: String,
472 }
473 let target_cpu = handle_native(&sess.target.cpu);
475 let make_remark = |cpu_name| {
476 if cpu_name == target_cpu {
477 let target = &sess.target.llvm_target;
480 format!(
481 " - This is the default target CPU for the current build target (currently {target})."
482 )
483 } else {
484 "".to_owned()
485 }
486 };
487 let mut cpus = cpu_names
488 .lines()
489 .map(|cpu_name| Cpu { cpu_name, remark: make_remark(cpu_name) })
490 .collect::<VecDeque<_>>();
491
492 if sess.host.arch == sess.target.arch {
495 let host = get_host_cpu_name();
496 cpus.push_front(Cpu {
497 cpu_name: "native",
498 remark: format!(" - Select the CPU of the current host (currently {host})."),
499 });
500 }
501
502 let max_name_width = cpus.iter().map(|cpu| cpu.cpu_name.len()).max().unwrap_or(0);
503 writeln!(out, "Available CPUs for this target:").unwrap();
504 for Cpu { cpu_name, remark } in cpus {
505 let width = if remark.is_empty() { 0 } else { max_name_width };
507 writeln!(out, " {cpu_name:<width$}{remark}").unwrap();
508 }
509}
510
511fn print_target_features(sess: &Session, tm: &llvm::TargetMachine, out: &mut String) {
512 let mut llvm_target_features = llvm_target_features(tm);
513 let mut known_llvm_target_features = FxHashSet::<&'static str>::default();
514 let mut rustc_target_features = sess
515 .target
516 .rust_target_features()
517 .iter()
518 .filter_map(|(feature, gate, _implied)| {
519 if !gate.in_cfg() {
520 return None;
522 }
523 let llvm_feature = to_llvm_features(sess, *feature)?.llvm_feature_name;
526 let desc =
527 match llvm_target_features.binary_search_by_key(&llvm_feature, |(f, _d)| f).ok() {
528 Some(index) => {
529 known_llvm_target_features.insert(llvm_feature);
530 llvm_target_features[index].1
531 }
532 None => "",
533 };
534
535 Some((*feature, desc))
536 })
537 .collect::<Vec<_>>();
538
539 rustc_target_features.extend_from_slice(&[(
541 "crt-static",
542 "Enables C Run-time Libraries to be statically linked",
543 )]);
544 rustc_target_features.sort();
546
547 llvm_target_features.retain(|(f, _d)| !known_llvm_target_features.contains(f));
548
549 let max_feature_len = llvm_target_features
550 .iter()
551 .chain(rustc_target_features.iter())
552 .map(|(feature, _desc)| feature.len())
553 .max()
554 .unwrap_or(0);
555
556 writeln!(out, "Features supported by rustc for this target:").unwrap();
557 for (feature, desc) in &rustc_target_features {
558 writeln!(out, " {feature:max_feature_len$} - {desc}.").unwrap();
559 }
560 writeln!(out, "\nCode-generation features supported by LLVM for this target:").unwrap();
561 for (feature, desc) in &llvm_target_features {
562 writeln!(out, " {feature:max_feature_len$} - {desc}.").unwrap();
563 }
564 if llvm_target_features.is_empty() {
565 writeln!(out, " Target features listing is not supported by this LLVM version.")
566 .unwrap();
567 }
568 writeln!(out, "\nUse +feature to enable a feature, or -feature to disable it.").unwrap();
569 writeln!(out, "For example, rustc -C target-cpu=mycpu -C target-feature=+feature1,-feature2\n")
570 .unwrap();
571 writeln!(out, "Code-generation features cannot be used in cfg or #[target_feature],").unwrap();
572 writeln!(out, "and may be renamed or removed in a future version of LLVM or rustc.\n").unwrap();
573}
574
575fn get_host_cpu_name() -> &'static str {
577 let mut len = 0;
578 let slice: &'static [u8] = unsafe {
581 let ptr = llvm::LLVMRustGetHostCPUName(&mut len);
582 assert!(!ptr.is_null());
583 slice::from_raw_parts(ptr, len)
584 };
585 str::from_utf8(slice).expect("host CPU name should be UTF-8")
586}
587
588fn handle_native(cpu_name: &str) -> &str {
591 match cpu_name {
592 "native" => get_host_cpu_name(),
593 _ => cpu_name,
594 }
595}
596
597pub(crate) fn target_cpu(sess: &Session) -> &str {
598 let cpu_name = sess.opts.cg.target_cpu.as_deref().unwrap_or_else(|| &sess.target.cpu);
599 handle_native(cpu_name)
600}
601
602fn llvm_features_by_flags(sess: &Session, features: &mut Vec<String>) {
604 target_features::retpoline_features_by_flags(sess, features);
605
606 if sess.opts.unstable_opts.fixed_x18 {
608 if sess.target.arch != "aarch64" {
609 sess.dcx().emit_fatal(errors::FixedX18InvalidArch { arch: &sess.target.arch });
610 } else {
611 features.push("+reserve-x18".into());
612 }
613 }
614}
615
616pub(crate) fn global_llvm_features(
619 sess: &Session,
620 diagnostics: bool,
621 only_base_features: bool,
622) -> Vec<String> {
623 let mut features = vec![];
642
643 match sess.opts.cg.target_cpu {
645 Some(ref s) if s == "native" => {
646 let features_string = unsafe {
652 let ptr = llvm::LLVMGetHostCPUFeatures();
653 let features_string = if !ptr.is_null() {
654 CStr::from_ptr(ptr)
655 .to_str()
656 .unwrap_or_else(|e| {
657 bug!("LLVM returned a non-utf8 features string: {}", e);
658 })
659 .to_owned()
660 } else {
661 bug!("could not allocate host CPU features, LLVM returned a `null` string");
662 };
663
664 llvm::LLVMDisposeMessage(ptr);
665
666 features_string
667 };
668 features.extend(features_string.split(',').map(String::from));
669 }
670 Some(_) | None => {}
671 };
672
673 features.extend(sess.target.features.split(',').filter(|v| !v.is_empty()).map(String::from));
675
676 if wants_wasm_eh(sess) && sess.panic_strategy() == PanicStrategy::Unwind {
677 features.push("+exception-handling".into());
678 }
679
680 if !only_base_features {
682 target_features::flag_to_backend_features(
683 sess,
684 diagnostics,
685 |feature| {
686 to_llvm_features(sess, feature)
687 .map(|f| SmallVec::<[&str; 2]>::from_iter(f.into_iter()))
688 .unwrap_or_default()
689 },
690 |feature, enable| {
691 let enable_disable = if enable { '+' } else { '-' };
692 let Some(llvm_feature) = to_llvm_features(sess, feature) else { return };
697
698 features.extend(
699 std::iter::once(format!(
700 "{}{}",
701 enable_disable, llvm_feature.llvm_feature_name
702 ))
703 .chain(llvm_feature.dependencies.into_iter().filter_map(
704 move |feat| match (enable, feat) {
705 (_, TargetFeatureFoldStrength::Both(f))
706 | (true, TargetFeatureFoldStrength::EnableOnly(f)) => {
707 Some(format!("{enable_disable}{f}"))
708 }
709 _ => None,
710 },
711 )),
712 )
713 },
714 );
715 }
716
717 llvm_features_by_flags(sess, &mut features);
719
720 features
721}
722
723pub(crate) fn tune_cpu(sess: &Session) -> Option<&str> {
724 let name = sess.opts.unstable_opts.tune_cpu.as_ref()?;
725 Some(handle_native(name))
726}