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() != 1 {
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() == PanicStrategy::Unwind
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 arch = if sess.target.arch == "x86_64" {
221 "x86"
222 } else if sess.target.arch == "arm64ec" {
223 "aarch64"
224 } else if sess.target.arch == "sparc64" {
225 "sparc"
226 } else if sess.target.arch == "powerpc64" {
227 "powerpc"
228 } else {
229 &*sess.target.arch
230 };
231 match (arch, s) {
232 ("x86", "sse4.2") => Some(LLVMFeature::with_dependencies(
233 "sse4.2",
234 smallvec![TargetFeatureFoldStrength::EnableOnly("crc32")],
235 )),
236 ("x86", "pclmulqdq") => Some(LLVMFeature::new("pclmul")),
237 ("x86", "rdrand") => Some(LLVMFeature::new("rdrnd")),
238 ("x86", "bmi1") => Some(LLVMFeature::new("bmi")),
239 ("x86", "cmpxchg16b") => Some(LLVMFeature::new("cx16")),
240 ("x86", "lahfsahf") => Some(LLVMFeature::new("sahf")),
241 ("aarch64", "rcpc2") => Some(LLVMFeature::new("rcpc-immo")),
242 ("aarch64", "dpb") => Some(LLVMFeature::new("ccpp")),
243 ("aarch64", "dpb2") => Some(LLVMFeature::new("ccdp")),
244 ("aarch64", "frintts") => Some(LLVMFeature::new("fptoint")),
245 ("aarch64", "fcma") => Some(LLVMFeature::new("complxnum")),
246 ("aarch64", "pmuv3") => Some(LLVMFeature::new("perfmon")),
247 ("aarch64", "paca") => Some(LLVMFeature::new("pauth")),
248 ("aarch64", "pacg") => Some(LLVMFeature::new("pauth")),
249 ("aarch64", "sve-b16b16") if get_version().0 < 20 => Some(LLVMFeature::new("b16b16")),
251 ("aarch64", "sme-b16b16") if get_version().0 < 20 => Some(LLVMFeature::new("b16b16")),
252 ("aarch64", "flagm2") => Some(LLVMFeature::new("altnzcv")),
253 ("aarch64", "neon") => Some(LLVMFeature::with_dependencies(
255 "neon",
256 smallvec![TargetFeatureFoldStrength::Both("fp-armv8")],
257 )),
258 ("aarch64", "fhm") => Some(LLVMFeature::new("fp16fml")),
261 ("aarch64", "fp16") => Some(LLVMFeature::new("fullfp16")),
262 ("aarch64", "fpmr") => None, ("arm", "fp16") => Some(LLVMFeature::new("fullfp16")),
265 ("loongarch64", "div32" | "lam-bh" | "lamcas" | "ld-seq-sa" | "scq")
267 if get_version().0 < 20 =>
268 {
269 None
270 }
271 ("riscv32" | "riscv64", "zacas") if get_version().0 < 20 => None,
273 (
274 "s390x",
275 "message-security-assist-extension12"
276 | "concurrent-functions"
277 | "miscellaneous-extensions-4"
278 | "vector-enhancements-3"
279 | "vector-packed-decimal-enhancement-3",
280 ) if get_version().0 < 20 => None,
281 ("x86", s) if s.starts_with("avx512") => Some(LLVMFeature::with_dependencies(
283 s,
284 smallvec![TargetFeatureFoldStrength::EnableOnly("evex512")],
285 )),
286 ("wasm32" | "wasm64", "wide-arithmetic") if get_version() < (20, 0, 0) => None,
289 ("sparc", "leoncasa") => Some(LLVMFeature::new("hasleoncasa")),
290 ("sparc", "v8plus") if get_version().0 == 19 => Some(LLVMFeature::new("v9")),
295 ("powerpc", "power8-crypto") => Some(LLVMFeature::new("crypto")),
296 ("x86", "amx-avx512" | "amx-fp8" | "amx-movrs" | "amx-tf32" | "amx-transpose")
298 if get_version().0 < 20 =>
299 {
300 None
301 }
302 ("x86", "movrs") if get_version().0 < 20 => None,
303 ("x86", "avx10.1") => Some(LLVMFeature::new("avx10.1-512")),
304 ("x86", "avx10.2") if get_version().0 < 20 => None,
305 ("x86", "avx10.2") if get_version().0 >= 20 => Some(LLVMFeature::new("avx10.2-512")),
306 ("x86", "apxf") => Some(LLVMFeature::with_dependencies(
307 "egpr",
308 smallvec![
309 TargetFeatureFoldStrength::Both("push2pop2"),
310 TargetFeatureFoldStrength::Both("ppx"),
311 TargetFeatureFoldStrength::Both("ndd"),
312 TargetFeatureFoldStrength::Both("ccmp"),
313 TargetFeatureFoldStrength::Both("cf"),
314 TargetFeatureFoldStrength::Both("nf"),
315 TargetFeatureFoldStrength::Both("zu"),
316 ],
317 )),
318 (_, s) => Some(LLVMFeature::new(s)),
319 }
320}
321
322pub(crate) fn target_config(sess: &Session) -> TargetConfig {
327 let target_machine = create_informational_target_machine(sess, true);
334
335 let (unstable_target_features, target_features) = cfg_target_feature(sess, |feature| {
336 if let Some(feat) = to_llvm_features(sess, feature) {
337 for llvm_feature in feat {
339 let cstr = SmallCStr::new(llvm_feature);
340 if !unsafe { llvm::LLVMRustHasFeature(target_machine.raw(), cstr.as_ptr()) } {
344 return false;
345 }
346 }
347 true
348 } else {
349 false
350 }
351 });
352
353 let mut cfg = TargetConfig {
354 target_features,
355 unstable_target_features,
356 has_reliable_f16: true,
357 has_reliable_f16_math: true,
358 has_reliable_f128: true,
359 has_reliable_f128_math: true,
360 };
361
362 update_target_reliable_float_cfg(sess, &mut cfg);
363 cfg
364}
365
366fn update_target_reliable_float_cfg(sess: &Session, cfg: &mut TargetConfig) {
368 let target_arch = sess.target.arch.as_ref();
369 let target_os = sess.target.options.os.as_ref();
370 let target_env = sess.target.options.env.as_ref();
371 let target_abi = sess.target.options.abi.as_ref();
372 let target_pointer_width = sess.target.pointer_width;
373 let version = get_version();
374
375 cfg.has_reliable_f16 = match (target_arch, target_os) {
376 ("s390x", _) => false,
378 ("aarch64", _)
380 if !cfg.target_features.iter().any(|f| f.as_str() == "neon")
381 && version < (20, 1, 1) =>
382 {
383 false
384 }
385 ("arm64ec", _) => false,
387 ("x86_64", "windows") if target_env == "gnu" && target_abi != "llvm" => false,
389 ("csky", _) => false,
391 ("hexagon", _) => false,
392 ("powerpc" | "powerpc64", _) => false,
393 ("sparc" | "sparc64", _) => false,
394 ("wasm32" | "wasm64", _) => false,
395 _ => true,
399 };
400
401 cfg.has_reliable_f128 = match (target_arch, target_os) {
402 ("arm64ec", _) => false,
404 ("mips64" | "mips64r6", _) => false,
406 ("nvptx64", _) => false,
408 ("powerpc" | "powerpc64", _) => false,
411 ("sparc", _) => false,
413 ("x86", _) => false,
416 ("x86_64", "windows") if target_env == "gnu" && target_abi != "llvm" => false,
418 _ => true,
422 };
423
424 cfg.has_reliable_f16_math = cfg.has_reliable_f16;
427
428 cfg.has_reliable_f128_math = match (target_arch, target_os) {
429 ("x86_64", _) => false,
437 (_, "linux") if target_pointer_width == 64 => true,
438 _ => false,
439 } && cfg.has_reliable_f128;
440}
441
442pub(crate) fn print_version() {
443 let (major, minor, patch) = get_version();
444 println!("LLVM version: {major}.{minor}.{patch}");
445}
446
447pub(crate) fn get_version() -> (u32, u32, u32) {
448 unsafe {
450 (llvm::LLVMRustVersionMajor(), llvm::LLVMRustVersionMinor(), llvm::LLVMRustVersionPatch())
451 }
452}
453
454pub(crate) fn print_passes() {
455 unsafe {
457 llvm::LLVMRustPrintPasses();
458 }
459}
460
461fn llvm_target_features(tm: &llvm::TargetMachine) -> Vec<(&str, &str)> {
462 let len = unsafe { llvm::LLVMRustGetTargetFeaturesCount(tm) };
463 let mut ret = Vec::with_capacity(len);
464 for i in 0..len {
465 unsafe {
466 let mut feature = ptr::null();
467 let mut desc = ptr::null();
468 llvm::LLVMRustGetTargetFeature(tm, i, &mut feature, &mut desc);
469 if feature.is_null() || desc.is_null() {
470 bug!("LLVM returned a `null` target feature string");
471 }
472 let feature = CStr::from_ptr(feature).to_str().unwrap_or_else(|e| {
473 bug!("LLVM returned a non-utf8 feature string: {}", e);
474 });
475 let desc = CStr::from_ptr(desc).to_str().unwrap_or_else(|e| {
476 bug!("LLVM returned a non-utf8 feature string: {}", e);
477 });
478 ret.push((feature, desc));
479 }
480 }
481 ret
482}
483
484pub(crate) fn print(req: &PrintRequest, out: &mut String, sess: &Session) {
485 require_inited();
486 let tm = create_informational_target_machine(sess, false);
487 match req.kind {
488 PrintKind::TargetCPUs => print_target_cpus(sess, tm.raw(), out),
489 PrintKind::TargetFeatures => print_target_features(sess, tm.raw(), out),
490 _ => bug!("rustc_codegen_llvm can't handle print request: {:?}", req),
491 }
492}
493
494fn print_target_cpus(sess: &Session, tm: &llvm::TargetMachine, out: &mut String) {
495 let cpu_names = llvm::build_string(|s| unsafe {
496 llvm::LLVMRustPrintTargetCPUs(&tm, s);
497 })
498 .unwrap();
499
500 struct Cpu<'a> {
501 cpu_name: &'a str,
502 remark: String,
503 }
504 let target_cpu = handle_native(&sess.target.cpu);
506 let make_remark = |cpu_name| {
507 if cpu_name == target_cpu {
508 let target = &sess.target.llvm_target;
511 format!(
512 " - This is the default target CPU for the current build target (currently {target})."
513 )
514 } else {
515 "".to_owned()
516 }
517 };
518 let mut cpus = cpu_names
519 .lines()
520 .map(|cpu_name| Cpu { cpu_name, remark: make_remark(cpu_name) })
521 .collect::<VecDeque<_>>();
522
523 if sess.host.arch == sess.target.arch {
526 let host = get_host_cpu_name();
527 cpus.push_front(Cpu {
528 cpu_name: "native",
529 remark: format!(" - Select the CPU of the current host (currently {host})."),
530 });
531 }
532
533 let max_name_width = cpus.iter().map(|cpu| cpu.cpu_name.len()).max().unwrap_or(0);
534 writeln!(out, "Available CPUs for this target:").unwrap();
535 for Cpu { cpu_name, remark } in cpus {
536 let width = if remark.is_empty() { 0 } else { max_name_width };
538 writeln!(out, " {cpu_name:<width$}{remark}").unwrap();
539 }
540}
541
542fn print_target_features(sess: &Session, tm: &llvm::TargetMachine, out: &mut String) {
543 let mut llvm_target_features = llvm_target_features(tm);
544 let mut known_llvm_target_features = FxHashSet::<&'static str>::default();
545 let mut rustc_target_features = sess
546 .target
547 .rust_target_features()
548 .iter()
549 .filter_map(|(feature, gate, _implied)| {
550 if !gate.in_cfg() {
551 return None;
553 }
554 let llvm_feature = to_llvm_features(sess, *feature)?.llvm_feature_name;
557 let desc =
558 match llvm_target_features.binary_search_by_key(&llvm_feature, |(f, _d)| f).ok() {
559 Some(index) => {
560 known_llvm_target_features.insert(llvm_feature);
561 llvm_target_features[index].1
562 }
563 None => "",
564 };
565
566 Some((*feature, desc))
567 })
568 .collect::<Vec<_>>();
569
570 rustc_target_features.extend_from_slice(&[(
572 "crt-static",
573 "Enables C Run-time Libraries to be statically linked",
574 )]);
575 rustc_target_features.sort();
577
578 llvm_target_features.retain(|(f, _d)| !known_llvm_target_features.contains(f));
579
580 let max_feature_len = llvm_target_features
581 .iter()
582 .chain(rustc_target_features.iter())
583 .map(|(feature, _desc)| feature.len())
584 .max()
585 .unwrap_or(0);
586
587 writeln!(out, "Features supported by rustc for this target:").unwrap();
588 for (feature, desc) in &rustc_target_features {
589 writeln!(out, " {feature:max_feature_len$} - {desc}.").unwrap();
590 }
591 writeln!(out, "\nCode-generation features supported by LLVM for this target:").unwrap();
592 for (feature, desc) in &llvm_target_features {
593 writeln!(out, " {feature:max_feature_len$} - {desc}.").unwrap();
594 }
595 if llvm_target_features.is_empty() {
596 writeln!(out, " Target features listing is not supported by this LLVM version.")
597 .unwrap();
598 }
599 writeln!(out, "\nUse +feature to enable a feature, or -feature to disable it.").unwrap();
600 writeln!(out, "For example, rustc -C target-cpu=mycpu -C target-feature=+feature1,-feature2\n")
601 .unwrap();
602 writeln!(out, "Code-generation features cannot be used in cfg or #[target_feature],").unwrap();
603 writeln!(out, "and may be renamed or removed in a future version of LLVM or rustc.\n").unwrap();
604}
605
606fn get_host_cpu_name() -> &'static str {
608 let mut len = 0;
609 let slice: &'static [u8] = unsafe {
612 let ptr = llvm::LLVMRustGetHostCPUName(&mut len);
613 assert!(!ptr.is_null());
614 slice::from_raw_parts(ptr, len)
615 };
616 str::from_utf8(slice).expect("host CPU name should be UTF-8")
617}
618
619fn handle_native(cpu_name: &str) -> &str {
622 match cpu_name {
623 "native" => get_host_cpu_name(),
624 _ => cpu_name,
625 }
626}
627
628pub(crate) fn target_cpu(sess: &Session) -> &str {
629 let cpu_name = sess.opts.cg.target_cpu.as_deref().unwrap_or_else(|| &sess.target.cpu);
630 handle_native(cpu_name)
631}
632
633fn llvm_features_by_flags(sess: &Session, features: &mut Vec<String>) {
635 target_features::retpoline_features_by_flags(sess, features);
636
637 if sess.opts.unstable_opts.fixed_x18 {
639 if sess.target.arch != "aarch64" {
640 sess.dcx().emit_fatal(errors::FixedX18InvalidArch { arch: &sess.target.arch });
641 } else {
642 features.push("+reserve-x18".into());
643 }
644 }
645}
646
647pub(crate) fn global_llvm_features(
650 sess: &Session,
651 diagnostics: bool,
652 only_base_features: bool,
653) -> Vec<String> {
654 let mut features = vec![];
673
674 match sess.opts.cg.target_cpu {
676 Some(ref s) if s == "native" => {
677 let features_string = unsafe {
683 let ptr = llvm::LLVMGetHostCPUFeatures();
684 let features_string = if !ptr.is_null() {
685 CStr::from_ptr(ptr)
686 .to_str()
687 .unwrap_or_else(|e| {
688 bug!("LLVM returned a non-utf8 features string: {}", e);
689 })
690 .to_owned()
691 } else {
692 bug!("could not allocate host CPU features, LLVM returned a `null` string");
693 };
694
695 llvm::LLVMDisposeMessage(ptr);
696
697 features_string
698 };
699 features.extend(features_string.split(',').map(String::from));
700 }
701 Some(_) | None => {}
702 };
703
704 features.extend(
706 sess.target
707 .features
708 .split(',')
709 .filter(|v| !v.is_empty())
710 .filter(|v| *v != "+v8plus" || get_version() >= (20, 0, 0))
714 .map(String::from),
715 );
716
717 if wants_wasm_eh(sess) && sess.panic_strategy() == PanicStrategy::Unwind {
718 features.push("+exception-handling".into());
719 }
720
721 if !only_base_features {
723 target_features::flag_to_backend_features(
724 sess,
725 diagnostics,
726 |feature| {
727 to_llvm_features(sess, feature)
728 .map(|f| SmallVec::<[&str; 2]>::from_iter(f.into_iter()))
729 .unwrap_or_default()
730 },
731 |feature, enable| {
732 let enable_disable = if enable { '+' } else { '-' };
733 let Some(llvm_feature) = to_llvm_features(sess, feature) else { return };
738
739 features.extend(
740 std::iter::once(format!(
741 "{}{}",
742 enable_disable, llvm_feature.llvm_feature_name
743 ))
744 .chain(llvm_feature.dependencies.into_iter().filter_map(
745 move |feat| match (enable, feat) {
746 (_, TargetFeatureFoldStrength::Both(f))
747 | (true, TargetFeatureFoldStrength::EnableOnly(f)) => {
748 Some(format!("{enable_disable}{f}"))
749 }
750 _ => None,
751 },
752 )),
753 )
754 },
755 );
756 }
757
758 llvm_features_by_flags(sess, &mut features);
760
761 features
762}
763
764pub(crate) fn tune_cpu(sess: &Session) -> Option<&str> {
765 let name = sess.opts.unstable_opts.tune_cpu.as_ref()?;
766 Some(handle_native(name))
767}