compiler/rustc_codegen_llvm/src/back/write.rs

   1 use crate::back::lto::ThinBuffer;
   2 use crate::back::profiling::{
   3     selfprofile_after_pass_callback, selfprofile_before_pass_callback, LlvmSelfProfiler,
   4 };
   5 use crate::base;
   6 use crate::common;
   7 use crate::consts;
   8 use crate::errors::{
   9     CopyBitcode, FromLlvmDiag, FromLlvmOptimizationDiag, LlvmError, WithLlvmError, WriteBytecode,
  10 };
  11 use crate::llvm::{self, DiagnosticInfo, PassManager};
  12 use crate::llvm_util;
  13 use crate::type_::Type;
  14 use crate::LlvmCodegenBackend;
  15 use crate::ModuleLlvm;
  16 use rustc_codegen_ssa::back::link::ensure_removed;
  17 use rustc_codegen_ssa::back::write::{
  18     BitcodeSection, CodegenContext, EmitObj, ModuleConfig, TargetMachineFactoryConfig,
  19     TargetMachineFactoryFn,
  20 };
  21 use rustc_codegen_ssa::traits::*;
  22 use rustc_codegen_ssa::{CompiledModule, ModuleCodegen};
  23 use rustc_data_structures::profiling::SelfProfilerRef;
  24 use rustc_data_structures::small_c_str::SmallCStr;
  25 use rustc_errors::{FatalError, Handler, Level};
  26 use rustc_fs_util::{link_or_copy, path_to_c_string};
  27 use rustc_middle::ty::TyCtxt;
  28 use rustc_session::config::{self, Lto, OutputType, Passes, SplitDwarfKind, SwitchWithOptPath};
  29 use rustc_session::Session;
  30 use rustc_span::symbol::sym;
  31 use rustc_span::InnerSpan;
  32 use rustc_target::spec::{CodeModel, RelocModel, SanitizerSet, SplitDebuginfo};
  33
  34 use crate::llvm::diagnostic::OptimizationDiagnosticKind;
  35 use libc::{c_char, c_int, c_uint, c_void, size_t};
  36 use std::ffi::CString;
  37 use std::fs;
  38 use std::io::{self, Write};
  39 use std::path::{Path, PathBuf};
  40 use std::slice;
  41 use std::str;
  42 use std::sync::Arc;
  43
  44 pub fn llvm_err<'a>(handler: &rustc_errors::Handler, err: LlvmError<'a>) -> FatalError {
  45     match llvm::last_error() {
  46         Some(llvm_err) => handler.emit_almost_fatal(WithLlvmError(err, llvm_err)),
  47         None => handler.emit_almost_fatal(err),
  48     }
  49 }
  50
  51 pub fn write_output_file<'ll>(
  52     handler: &rustc_errors::Handler,
  53     target: &'ll llvm::TargetMachine,
  54     pm: &llvm::PassManager<'ll>,
  55     m: &'ll llvm::Module,
  56     output: &Path,
  57     dwo_output: Option<&Path>,
  58     file_type: llvm::FileType,
  59     self_profiler_ref: &SelfProfilerRef,
  60 ) -> Result<(), FatalError> {
  61     debug!("write_output_file output={:?} dwo_output={:?}", output, dwo_output);
  62     unsafe {
  63         let output_c = path_to_c_string(output);
  64         let dwo_output_c;
  65         let dwo_output_ptr = if let Some(dwo_output) = dwo_output {
  66             dwo_output_c = path_to_c_string(dwo_output);
  67             dwo_output_c.as_ptr()
  68         } else {
  69             std::ptr::null()
  70         };
  71         let result = llvm::LLVMRustWriteOutputFile(
  72             target,
  73             pm,
  74             m,
  75             output_c.as_ptr(),
  76             dwo_output_ptr,
  77             file_type,
  78         );
  79
  80         // Record artifact sizes for self-profiling
  81         if result == llvm::LLVMRustResult::Success {
  82             let artifact_kind = match file_type {
  83                 llvm::FileType::ObjectFile => "object_file",
  84                 llvm::FileType::AssemblyFile => "assembly_file",
  85             };
  86             record_artifact_size(self_profiler_ref, artifact_kind, output);
  87             if let Some(dwo_file) = dwo_output {
  88                 record_artifact_size(self_profiler_ref, "dwo_file", dwo_file);
  89             }
  90         }
  91
  92         result
  93             .into_result()
  94             .map_err(|()| llvm_err(handler, LlvmError::WriteOutput { path: output }))
  95     }
  96 }
  97
  98 pub fn create_informational_target_machine(sess: &Session) -> &'static mut llvm::TargetMachine {
  99     let config = TargetMachineFactoryConfig { split_dwarf_file: None };
 100     // Can't use query system here quite yet because this function is invoked before the query
 101     // system/tcx is set up.
 102     let features = llvm_util::global_llvm_features(sess, false);
 103     target_machine_factory(sess, config::OptLevel::No, &features)(config)
 104         .unwrap_or_else(|err| llvm_err(sess.diagnostic(), err).raise())
 105 }
 106
 107 pub fn create_target_machine(tcx: TyCtxt<'_>, mod_name: &str) -> &'static mut llvm::TargetMachine {
 108     let split_dwarf_file = if tcx.sess.target_can_use_split_dwarf() {
 109         tcx.output_filenames(()).split_dwarf_path(
 110             tcx.sess.split_debuginfo(),
 111             tcx.sess.opts.unstable_opts.split_dwarf_kind,
 112             Some(mod_name),
 113         )
 114     } else {
 115         None
 116     };
 117     let config = TargetMachineFactoryConfig { split_dwarf_file };
 118     target_machine_factory(
 119         &tcx.sess,
 120         tcx.backend_optimization_level(()),
 121         tcx.global_backend_features(()),
 122     )(config)
 123     .unwrap_or_else(|err| llvm_err(tcx.sess.diagnostic(), err).raise())
 124 }
 125
 126 pub fn to_llvm_opt_settings(
 127     cfg: config::OptLevel,
 128 ) -> (llvm::CodeGenOptLevel, llvm::CodeGenOptSize) {
 129     use self::config::OptLevel::*;
 130     match cfg {
 131         No => (llvm::CodeGenOptLevel::None, llvm::CodeGenOptSizeNone),
 132         Less => (llvm::CodeGenOptLevel::Less, llvm::CodeGenOptSizeNone),
 133         Default => (llvm::CodeGenOptLevel::Default, llvm::CodeGenOptSizeNone),
 134         Aggressive => (llvm::CodeGenOptLevel::Aggressive, llvm::CodeGenOptSizeNone),
 135         Size => (llvm::CodeGenOptLevel::Default, llvm::CodeGenOptSizeDefault),
 136         SizeMin => (llvm::CodeGenOptLevel::Default, llvm::CodeGenOptSizeAggressive),
 137     }
 138 }
 139
 140 fn to_pass_builder_opt_level(cfg: config::OptLevel) -> llvm::PassBuilderOptLevel {
 141     use config::OptLevel::*;
 142     match cfg {
 143         No => llvm::PassBuilderOptLevel::O0,
 144         Less => llvm::PassBuilderOptLevel::O1,
 145         Default => llvm::PassBuilderOptLevel::O2,
 146         Aggressive => llvm::PassBuilderOptLevel::O3,
 147         Size => llvm::PassBuilderOptLevel::Os,
 148         SizeMin => llvm::PassBuilderOptLevel::Oz,
 149     }
 150 }
 151
 152 fn to_llvm_relocation_model(relocation_model: RelocModel) -> llvm::RelocModel {
 153     match relocation_model {
 154         RelocModel::Static => llvm::RelocModel::Static,
 155         // LLVM doesn't have a PIE relocation model, it represents PIE as PIC with an extra attribute.
 156         RelocModel::Pic | RelocModel::Pie => llvm::RelocModel::PIC,
 157         RelocModel::DynamicNoPic => llvm::RelocModel::DynamicNoPic,
 158         RelocModel::Ropi => llvm::RelocModel::ROPI,
 159         RelocModel::Rwpi => llvm::RelocModel::RWPI,
 160         RelocModel::RopiRwpi => llvm::RelocModel::ROPI_RWPI,
 161     }
 162 }
 163
 164 pub(crate) fn to_llvm_code_model(code_model: Option<CodeModel>) -> llvm::CodeModel {
 165     match code_model {
 166         Some(CodeModel::Tiny) => llvm::CodeModel::Tiny,
 167         Some(CodeModel::Small) => llvm::CodeModel::Small,
 168         Some(CodeModel::Kernel) => llvm::CodeModel::Kernel,
 169         Some(CodeModel::Medium) => llvm::CodeModel::Medium,
 170         Some(CodeModel::Large) => llvm::CodeModel::Large,
 171         None => llvm::CodeModel::None,
 172     }
 173 }
 174
 175 pub fn target_machine_factory(
 176     sess: &Session,
 177     optlvl: config::OptLevel,
 178     target_features: &[String],
 179 ) -> TargetMachineFactoryFn<LlvmCodegenBackend> {
 180     let reloc_model = to_llvm_relocation_model(sess.relocation_model());
 181
 182     let (opt_level, _) = to_llvm_opt_settings(optlvl);
 183     let use_softfp = sess.opts.cg.soft_float;
 184
 185     let ffunction_sections =
 186         sess.opts.unstable_opts.function_sections.unwrap_or(sess.target.function_sections);
 187     let fdata_sections = ffunction_sections;
 188     let funique_section_names = !sess.opts.unstable_opts.no_unique_section_names;
 189
 190     let code_model = to_llvm_code_model(sess.code_model());
 191
 192     let mut singlethread = sess.target.singlethread;
 193
 194     // On the wasm target once the `atomics` feature is enabled that means that
 195     // we're no longer single-threaded, or otherwise we don't want LLVM to
 196     // lower atomic operations to single-threaded operations.
 197     if singlethread && sess.target.is_like_wasm && sess.target_features.contains(&sym::atomics) {
 198         singlethread = false;
 199     }
 200
 201     let triple = SmallCStr::new(&sess.target.llvm_target);
 202     let cpu = SmallCStr::new(llvm_util::target_cpu(sess));
 203     let features = CString::new(target_features.join(",")).unwrap();
 204     let abi = SmallCStr::new(&sess.target.llvm_abiname);
 205     let trap_unreachable =
 206         sess.opts.unstable_opts.trap_unreachable.unwrap_or(sess.target.trap_unreachable);
 207     let emit_stack_size_section = sess.opts.unstable_opts.emit_stack_sizes;
 208
 209     let asm_comments = sess.opts.unstable_opts.asm_comments;
 210     let relax_elf_relocations =
 211         sess.opts.unstable_opts.relax_elf_relocations.unwrap_or(sess.target.relax_elf_relocations);
 212
 213     let use_init_array =
 214         !sess.opts.unstable_opts.use_ctors_section.unwrap_or(sess.target.use_ctors_section);
 215
 216     let path_mapping = sess.source_map().path_mapping().clone();
 217
 218     let force_emulated_tls = sess.target.force_emulated_tls;
 219
 220     Arc::new(move |config: TargetMachineFactoryConfig| {
 221         let split_dwarf_file =
 222             path_mapping.map_prefix(config.split_dwarf_file.unwrap_or_default()).0;
 223         let split_dwarf_file = CString::new(split_dwarf_file.to_str().unwrap()).unwrap();
 224
 225         let tm = unsafe {
 226             llvm::LLVMRustCreateTargetMachine(
 227                 triple.as_ptr(),
 228                 cpu.as_ptr(),
 229                 features.as_ptr(),
 230                 abi.as_ptr(),
 231                 code_model,
 232                 reloc_model,
 233                 opt_level,
 234                 use_softfp,
 235                 ffunction_sections,
 236                 fdata_sections,
 237                 funique_section_names,
 238                 trap_unreachable,
 239                 singlethread,
 240                 asm_comments,
 241                 emit_stack_size_section,
 242                 relax_elf_relocations,
 243                 use_init_array,
 244                 split_dwarf_file.as_ptr(),
 245                 force_emulated_tls,
 246             )
 247         };
 248
 249         tm.ok_or_else(|| LlvmError::CreateTargetMachine { triple: triple.clone() })
 250     })
 251 }
 252
 253 pub(crate) fn save_temp_bitcode(
 254     cgcx: &CodegenContext<LlvmCodegenBackend>,
 255     module: &ModuleCodegen<ModuleLlvm>,
 256     name: &str,
 257 ) {
 258     if !cgcx.save_temps {
 259         return;
 260     }
 261     unsafe {
 262         let ext = format!("{}.bc", name);
 263         let cgu = Some(&module.name[..]);
 264         let path = cgcx.output_filenames.temp_path_ext(&ext, cgu);
 265         let cstr = path_to_c_string(&path);
 266         let llmod = module.module_llvm.llmod();
 267         llvm::LLVMWriteBitcodeToFile(llmod, cstr.as_ptr());
 268     }
 269 }
 270
 271 pub struct DiagnosticHandlers<'a> {
 272     data: *mut (&'a CodegenContext<LlvmCodegenBackend>, &'a Handler),
 273     llcx: &'a llvm::Context,
 274     old_handler: Option<&'a llvm::DiagnosticHandler>,
 275 }
 276
 277 impl<'a> DiagnosticHandlers<'a> {
 278     pub fn new(
 279         cgcx: &'a CodegenContext<LlvmCodegenBackend>,
 280         handler: &'a Handler,
 281         llcx: &'a llvm::Context,
 282     ) -> Self {
 283         let remark_passes_all: bool;
 284         let remark_passes: Vec<CString>;
 285         match &cgcx.remark {
 286             Passes::All => {
 287                 remark_passes_all = true;
 288                 remark_passes = Vec::new();
 289             }
 290             Passes::Some(passes) => {
 291                 remark_passes_all = false;
 292                 remark_passes =
 293                     passes.iter().map(|name| CString::new(name.as_str()).unwrap()).collect();
 294             }
 295         };
 296         let remark_passes: Vec<*const c_char> =
 297             remark_passes.iter().map(|name: &CString| name.as_ptr()).collect();
 298         let data = Box::into_raw(Box::new((cgcx, handler)));
 299         unsafe {
 300             let old_handler = llvm::LLVMRustContextGetDiagnosticHandler(llcx);
 301             llvm::LLVMRustContextConfigureDiagnosticHandler(
 302                 llcx,
 303                 diagnostic_handler,
 304                 data.cast(),
 305                 remark_passes_all,
 306                 remark_passes.as_ptr(),
 307                 remark_passes.len(),
 308             );
 309             DiagnosticHandlers { data, llcx, old_handler }
 310         }
 311     }
 312 }
 313
 314 impl<'a> Drop for DiagnosticHandlers<'a> {
 315     fn drop(&mut self) {
 316         unsafe {
 317             llvm::LLVMRustContextSetDiagnosticHandler(self.llcx, self.old_handler);
 318             drop(Box::from_raw(self.data));
 319         }
 320     }
 321 }
 322
 323 fn report_inline_asm(
 324     cgcx: &CodegenContext<LlvmCodegenBackend>,
 325     msg: String,
 326     level: llvm::DiagnosticLevel,
 327     mut cookie: c_uint,
 328     source: Option<(String, Vec<InnerSpan>)>,
 329 ) {
 330     // In LTO build we may get srcloc values from other crates which are invalid
 331     // since they use a different source map. To be safe we just suppress these
 332     // in LTO builds.
 333     if matches!(cgcx.lto, Lto::Fat | Lto::Thin) {
 334         cookie = 0;
 335     }
 336     let level = match level {
 337         llvm::DiagnosticLevel::Error => Level::Error { lint: false },
 338         llvm::DiagnosticLevel::Warning => Level::Warning(None),
 339         llvm::DiagnosticLevel::Note | llvm::DiagnosticLevel::Remark => Level::Note,
 340     };
 341     cgcx.diag_emitter.inline_asm_error(cookie as u32, msg, level, source);
 342 }
 343
 344 unsafe extern "C" fn diagnostic_handler(info: &DiagnosticInfo, user: *mut c_void) {
 345     if user.is_null() {
 346         return;
 347     }
 348     let (cgcx, diag_handler) = *(user as *const (&CodegenContext<LlvmCodegenBackend>, &Handler));
 349
 350     match llvm::diagnostic::Diagnostic::unpack(info) {
 351         llvm::diagnostic::InlineAsm(inline) => {
 352             report_inline_asm(cgcx, inline.message, inline.level, inline.cookie, inline.source);
 353         }
 354
 355         llvm::diagnostic::Optimization(opt) => {
 356             let enabled = match cgcx.remark {
 357                 Passes::All => true,
 358                 Passes::Some(ref v) => v.iter().any(|s| *s == opt.pass_name),
 359             };
 360
 361             if enabled {
 362                 diag_handler.emit_note(FromLlvmOptimizationDiag {
 363                     filename: &opt.filename,
 364                     line: opt.line,
 365                     column: opt.column,
 366                     pass_name: &opt.pass_name,
 367                     kind: match opt.kind {
 368                         OptimizationDiagnosticKind::OptimizationRemark => "success",
 369                         OptimizationDiagnosticKind::OptimizationMissed
 370                         | OptimizationDiagnosticKind::OptimizationFailure => "missed",
 371                         OptimizationDiagnosticKind::OptimizationAnalysis
 372                         | OptimizationDiagnosticKind::OptimizationAnalysisFPCommute
 373                         | OptimizationDiagnosticKind::OptimizationAnalysisAliasing => "analysis",
 374                         OptimizationDiagnosticKind::OptimizationRemarkOther => "other",
 375                     },
 376                     message: &opt.message,
 377                 });
 378             }
 379         }
 380         llvm::diagnostic::PGO(diagnostic_ref) | llvm::diagnostic::Linker(diagnostic_ref) => {
 381             let message = llvm::build_string(|s| {
 382                 llvm::LLVMRustWriteDiagnosticInfoToString(diagnostic_ref, s)
 383             })
 384             .expect("non-UTF8 diagnostic");
 385             diag_handler.emit_warning(FromLlvmDiag { message });
 386         }
 387         llvm::diagnostic::Unsupported(diagnostic_ref) => {
 388             let message = llvm::build_string(|s| {
 389                 llvm::LLVMRustWriteDiagnosticInfoToString(diagnostic_ref, s)
 390             })
 391             .expect("non-UTF8 diagnostic");
 392             diag_handler.emit_err(FromLlvmDiag { message });
 393         }
 394         llvm::diagnostic::UnknownDiagnostic(..) => {}
 395     }
 396 }
 397
 398 fn get_pgo_gen_path(config: &ModuleConfig) -> Option<CString> {
 399     match config.pgo_gen {
 400         SwitchWithOptPath::Enabled(ref opt_dir_path) => {
 401             let path = if let Some(dir_path) = opt_dir_path {
 402                 dir_path.join("default_%m.profraw")
 403             } else {
 404                 PathBuf::from("default_%m.profraw")
 405             };
 406
 407             Some(CString::new(format!("{}", path.display())).unwrap())
 408         }
 409         SwitchWithOptPath::Disabled => None,
 410     }
 411 }
 412
 413 fn get_pgo_use_path(config: &ModuleConfig) -> Option<CString> {
 414     config
 415         .pgo_use
 416         .as_ref()
 417         .map(|path_buf| CString::new(path_buf.to_string_lossy().as_bytes()).unwrap())
 418 }
 419
 420 fn get_pgo_sample_use_path(config: &ModuleConfig) -> Option<CString> {
 421     config
 422         .pgo_sample_use
 423         .as_ref()
 424         .map(|path_buf| CString::new(path_buf.to_string_lossy().as_bytes()).unwrap())
 425 }
 426
 427 fn get_instr_profile_output_path(config: &ModuleConfig) -> Option<CString> {
 428     config.instrument_coverage.then(|| CString::new("default_%m_%p.profraw").unwrap())
 429 }
 430
 431 pub(crate) unsafe fn llvm_optimize(
 432     cgcx: &CodegenContext<LlvmCodegenBackend>,
 433     diag_handler: &Handler,
 434     module: &ModuleCodegen<ModuleLlvm>,
 435     config: &ModuleConfig,
 436     opt_level: config::OptLevel,
 437     opt_stage: llvm::OptStage,
 438 ) -> Result<(), FatalError> {
 439     let unroll_loops =
 440         opt_level != config::OptLevel::Size && opt_level != config::OptLevel::SizeMin;
 441     let using_thin_buffers = opt_stage == llvm::OptStage::PreLinkThinLTO || config.bitcode_needed();
 442     let pgo_gen_path = get_pgo_gen_path(config);
 443     let pgo_use_path = get_pgo_use_path(config);
 444     let pgo_sample_use_path = get_pgo_sample_use_path(config);
 445     let is_lto = opt_stage == llvm::OptStage::ThinLTO || opt_stage == llvm::OptStage::FatLTO;
 446     let instr_profile_output_path = get_instr_profile_output_path(config);
 447     // Sanitizer instrumentation is only inserted during the pre-link optimization stage.
 448     let sanitizer_options = if !is_lto {
 449         Some(llvm::SanitizerOptions {
 450             sanitize_address: config.sanitizer.contains(SanitizerSet::ADDRESS),
 451             sanitize_address_recover: config.sanitizer_recover.contains(SanitizerSet::ADDRESS),
 452             sanitize_memory: config.sanitizer.contains(SanitizerSet::MEMORY),
 453             sanitize_memory_recover: config.sanitizer_recover.contains(SanitizerSet::MEMORY),
 454             sanitize_memory_track_origins: config.sanitizer_memory_track_origins as c_int,
 455             sanitize_thread: config.sanitizer.contains(SanitizerSet::THREAD),
 456             sanitize_hwaddress: config.sanitizer.contains(SanitizerSet::HWADDRESS),
 457             sanitize_hwaddress_recover: config.sanitizer_recover.contains(SanitizerSet::HWADDRESS),
 458             sanitize_kernel_address: config.sanitizer.contains(SanitizerSet::KERNELADDRESS),
 459             sanitize_kernel_address_recover: config
 460                 .sanitizer_recover
 461                 .contains(SanitizerSet::KERNELADDRESS),
 462         })
 463     } else {
 464         None
 465     };
 466
 467     let mut llvm_profiler = cgcx
 468         .prof
 469         .llvm_recording_enabled()
 470         .then(|| LlvmSelfProfiler::new(cgcx.prof.get_self_profiler().unwrap()));
 471
 472     let llvm_selfprofiler =
 473         llvm_profiler.as_mut().map(|s| s as *mut _ as *mut c_void).unwrap_or(std::ptr::null_mut());
 474
 475     let extra_passes = if !is_lto { config.passes.join(",") } else { "".to_string() };
 476
 477     let llvm_plugins = config.llvm_plugins.join(",");
 478
 479     // FIXME: NewPM doesn't provide a facility to pass custom InlineParams.
 480     // We would have to add upstream support for this first, before we can support
 481     // config.inline_threshold and our more aggressive default thresholds.
 482     let result = llvm::LLVMRustOptimize(
 483         module.module_llvm.llmod(),
 484         &*module.module_llvm.tm,
 485         to_pass_builder_opt_level(opt_level),
 486         opt_stage,
 487         config.no_prepopulate_passes,
 488         config.verify_llvm_ir,
 489         using_thin_buffers,
 490         config.merge_functions,
 491         unroll_loops,
 492         config.vectorize_slp,
 493         config.vectorize_loop,
 494         config.no_builtins,
 495         config.emit_lifetime_markers,
 496         sanitizer_options.as_ref(),
 497         pgo_gen_path.as_ref().map_or(std::ptr::null(), |s| s.as_ptr()),
 498         pgo_use_path.as_ref().map_or(std::ptr::null(), |s| s.as_ptr()),
 499         config.instrument_coverage,
 500         instr_profile_output_path.as_ref().map_or(std::ptr::null(), |s| s.as_ptr()),
 501         config.instrument_gcov,
 502         pgo_sample_use_path.as_ref().map_or(std::ptr::null(), |s| s.as_ptr()),
 503         config.debug_info_for_profiling,
 504         llvm_selfprofiler,
 505         selfprofile_before_pass_callback,
 506         selfprofile_after_pass_callback,
 507         extra_passes.as_ptr().cast(),
 508         extra_passes.len(),
 509         llvm_plugins.as_ptr().cast(),
 510         llvm_plugins.len(),
 511     );
 512     result.into_result().map_err(|()| llvm_err(diag_handler, LlvmError::RunLlvmPasses))
 513 }
 514
 515 // Unsafe due to LLVM calls.
 516 pub(crate) unsafe fn optimize(
 517     cgcx: &CodegenContext<LlvmCodegenBackend>,
 518     diag_handler: &Handler,
 519     module: &ModuleCodegen<ModuleLlvm>,
 520     config: &ModuleConfig,
 521 ) -> Result<(), FatalError> {
 522     let _timer = cgcx.prof.generic_activity_with_arg("LLVM_module_optimize", &*module.name);
 523
 524     let llmod = module.module_llvm.llmod();
 525     let llcx = &*module.module_llvm.llcx;
 526     let _handlers = DiagnosticHandlers::new(cgcx, diag_handler, llcx);
 527
 528     let module_name = module.name.clone();
 529     let module_name = Some(&module_name[..]);
 530
 531     if config.emit_no_opt_bc {
 532         let out = cgcx.output_filenames.temp_path_ext("no-opt.bc", module_name);
 533         let out = path_to_c_string(&out);
 534         llvm::LLVMWriteBitcodeToFile(llmod, out.as_ptr());
 535     }
 536
 537     if let Some(opt_level) = config.opt_level {
 538         let opt_stage = match cgcx.lto {
 539             Lto::Fat => llvm::OptStage::PreLinkFatLTO,
 540             Lto::Thin | Lto::ThinLocal => llvm::OptStage::PreLinkThinLTO,
 541             _ if cgcx.opts.cg.linker_plugin_lto.enabled() => llvm::OptStage::PreLinkThinLTO,
 542             _ => llvm::OptStage::PreLinkNoLTO,
 543         };
 544         return llvm_optimize(cgcx, diag_handler, module, config, opt_level, opt_stage);
 545     }
 546     Ok(())
 547 }
 548
 549 pub(crate) fn link(
 550     cgcx: &CodegenContext<LlvmCodegenBackend>,
 551     diag_handler: &Handler,
 552     mut modules: Vec<ModuleCodegen<ModuleLlvm>>,
 553 ) -> Result<ModuleCodegen<ModuleLlvm>, FatalError> {
 554     use super::lto::{Linker, ModuleBuffer};
 555     // Sort the modules by name to ensure deterministic behavior.
 556     modules.sort_by(|a, b| a.name.cmp(&b.name));
 557     let (first, elements) =
 558         modules.split_first().expect("Bug! modules must contain at least one module.");
 559
 560     let mut linker = Linker::new(first.module_llvm.llmod());
 561     for module in elements {
 562         let _timer = cgcx.prof.generic_activity_with_arg("LLVM_link_module", &*module.name);
 563         let buffer = ModuleBuffer::new(module.module_llvm.llmod());
 564         linker.add(buffer.data()).map_err(|()| {
 565             llvm_err(diag_handler, LlvmError::SerializeModule { name: &module.name })
 566         })?;
 567     }
 568     drop(linker);
 569     Ok(modules.remove(0))
 570 }
 571
 572 pub(crate) unsafe fn codegen(
 573     cgcx: &CodegenContext<LlvmCodegenBackend>,
 574     diag_handler: &Handler,
 575     module: ModuleCodegen<ModuleLlvm>,
 576     config: &ModuleConfig,
 577 ) -> Result<CompiledModule, FatalError> {
 578     let _timer = cgcx.prof.generic_activity_with_arg("LLVM_module_codegen", &*module.name);
 579     {
 580         let llmod = module.module_llvm.llmod();
 581         let llcx = &*module.module_llvm.llcx;
 582         let tm = &*module.module_llvm.tm;
 583         let module_name = module.name.clone();
 584         let module_name = Some(&module_name[..]);
 585         let handlers = DiagnosticHandlers::new(cgcx, diag_handler, llcx);
 586
 587         if cgcx.msvc_imps_needed {
 588             create_msvc_imps(cgcx, llcx, llmod);
 589         }
 590
 591         // A codegen-specific pass manager is used to generate object
 592         // files for an LLVM module.
 593         //
 594         // Apparently each of these pass managers is a one-shot kind of
 595         // thing, so we create a new one for each type of output. The
 596         // pass manager passed to the closure should be ensured to not
 597         // escape the closure itself, and the manager should only be
 598         // used once.
 599         unsafe fn with_codegen<'ll, F, R>(
 600             tm: &'ll llvm::TargetMachine,
 601             llmod: &'ll llvm::Module,
 602             no_builtins: bool,
 603             f: F,
 604         ) -> R
 605         where
 606             F: FnOnce(&'ll mut PassManager<'ll>) -> R,
 607         {
 608             let cpm = llvm::LLVMCreatePassManager();
 609             llvm::LLVMAddAnalysisPasses(tm, cpm);
 610             llvm::LLVMRustAddLibraryInfo(cpm, llmod, no_builtins);
 611             f(cpm)
 612         }
 613
 614         // Two things to note:
 615         // - If object files are just LLVM bitcode we write bitcode, copy it to
 616         //   the .o file, and delete the bitcode if it wasn't otherwise
 617         //   requested.
 618         // - If we don't have the integrated assembler then we need to emit
 619         //   asm from LLVM and use `gcc` to create the object file.
 620
 621         let bc_out = cgcx.output_filenames.temp_path(OutputType::Bitcode, module_name);
 622         let obj_out = cgcx.output_filenames.temp_path(OutputType::Object, module_name);
 623
 624         if config.bitcode_needed() {
 625             let _timer = cgcx
 626                 .prof
 627                 .generic_activity_with_arg("LLVM_module_codegen_make_bitcode", &*module.name);
 628             let thin = ThinBuffer::new(llmod, config.emit_thin_lto);
 629             let data = thin.data();
 630
 631             if let Some(bitcode_filename) = bc_out.file_name() {
 632                 cgcx.prof.artifact_size(
 633                     "llvm_bitcode",
 634                     bitcode_filename.to_string_lossy(),
 635                     data.len() as u64,
 636                 );
 637             }
 638
 639             if config.emit_bc || config.emit_obj == EmitObj::Bitcode {
 640                 let _timer = cgcx
 641                     .prof
 642                     .generic_activity_with_arg("LLVM_module_codegen_emit_bitcode", &*module.name);
 643                 if let Err(err) = fs::write(&bc_out, data) {
 644                     diag_handler.emit_err(WriteBytecode { path: &bc_out, err });
 645                 }
 646             }
 647
 648             if config.emit_obj == EmitObj::ObjectCode(BitcodeSection::Full) {
 649                 let _timer = cgcx
 650                     .prof
 651                     .generic_activity_with_arg("LLVM_module_codegen_embed_bitcode", &*module.name);
 652                 embed_bitcode(cgcx, llcx, llmod, &config.bc_cmdline, data);
 653             }
 654         }
 655
 656         if config.emit_ir {
 657             let _timer =
 658                 cgcx.prof.generic_activity_with_arg("LLVM_module_codegen_emit_ir", &*module.name);
 659             let out = cgcx.output_filenames.temp_path(OutputType::LlvmAssembly, module_name);
 660             let out_c = path_to_c_string(&out);
 661
 662             extern "C" fn demangle_callback(
 663                 input_ptr: *const c_char,
 664                 input_len: size_t,
 665                 output_ptr: *mut c_char,
 666                 output_len: size_t,
 667             ) -> size_t {
 668                 let input =
 669                     unsafe { slice::from_raw_parts(input_ptr as *const u8, input_len as usize) };
 670
 671                 let Ok(input) = str::from_utf8(input) else { return 0 };
 672
 673                 let output = unsafe {
 674                     slice::from_raw_parts_mut(output_ptr as *mut u8, output_len as usize)
 675                 };
 676                 let mut cursor = io::Cursor::new(output);
 677
 678                 let Ok(demangled) = rustc_demangle::try_demangle(input) else { return 0 };
 679
 680                 if write!(cursor, "{:#}", demangled).is_err() {
 681                     // Possible only if provided buffer is not big enough
 682                     return 0;
 683                 }
 684
 685                 cursor.position() as size_t
 686             }
 687
 688             let result = llvm::LLVMRustPrintModule(llmod, out_c.as_ptr(), demangle_callback);
 689
 690             if result == llvm::LLVMRustResult::Success {
 691                 record_artifact_size(&cgcx.prof, "llvm_ir", &out);
 692             }
 693
 694             result
 695                 .into_result()
 696                 .map_err(|()| llvm_err(diag_handler, LlvmError::WriteIr { path: &out }))?;
 697         }
 698
 699         if config.emit_asm {
 700             let _timer =
 701                 cgcx.prof.generic_activity_with_arg("LLVM_module_codegen_emit_asm", &*module.name);
 702             let path = cgcx.output_filenames.temp_path(OutputType::Assembly, module_name);
 703
 704             // We can't use the same module for asm and object code output,
 705             // because that triggers various errors like invalid IR or broken
 706             // binaries. So we must clone the module to produce the asm output
 707             // if we are also producing object code.
 708             let llmod = if let EmitObj::ObjectCode(_) = config.emit_obj {
 709                 llvm::LLVMCloneModule(llmod)
 710             } else {
 711                 llmod
 712             };
 713             with_codegen(tm, llmod, config.no_builtins, |cpm| {
 714                 write_output_file(
 715                     diag_handler,
 716                     tm,
 717                     cpm,
 718                     llmod,
 719                     &path,
 720                     None,
 721                     llvm::FileType::AssemblyFile,
 722                     &cgcx.prof,
 723                 )
 724             })?;
 725         }
 726
 727         match config.emit_obj {
 728             EmitObj::ObjectCode(_) => {
 729                 let _timer = cgcx
 730                     .prof
 731                     .generic_activity_with_arg("LLVM_module_codegen_emit_obj", &*module.name);
 732
 733                 let dwo_out = cgcx.output_filenames.temp_path_dwo(module_name);
 734                 let dwo_out = match (cgcx.split_debuginfo, cgcx.split_dwarf_kind) {
 735                     // Don't change how DWARF is emitted when disabled.
 736                     (SplitDebuginfo::Off, _) => None,
 737                     // Don't provide a DWARF object path if split debuginfo is enabled but this is
 738                     // a platform that doesn't support Split DWARF.
 739                     _ if !cgcx.target_can_use_split_dwarf => None,
 740                     // Don't provide a DWARF object path in single mode, sections will be written
 741                     // into the object as normal but ignored by linker.
 742                     (_, SplitDwarfKind::Single) => None,
 743                     // Emit (a subset of the) DWARF into a separate dwarf object file in split
 744                     // mode.
 745                     (_, SplitDwarfKind::Split) => Some(dwo_out.as_path()),
 746                 };
 747
 748                 with_codegen(tm, llmod, config.no_builtins, |cpm| {
 749                     write_output_file(
 750                         diag_handler,
 751                         tm,
 752                         cpm,
 753                         llmod,
 754                         &obj_out,
 755                         dwo_out,
 756                         llvm::FileType::ObjectFile,
 757                         &cgcx.prof,
 758                     )
 759                 })?;
 760             }
 761
 762             EmitObj::Bitcode => {
 763                 debug!("copying bitcode {:?} to obj {:?}", bc_out, obj_out);
 764                 if let Err(err) = link_or_copy(&bc_out, &obj_out) {
 765                     diag_handler.emit_err(CopyBitcode { err });
 766                 }
 767
 768                 if !config.emit_bc {
 769                     debug!("removing_bitcode {:?}", bc_out);
 770                     ensure_removed(diag_handler, &bc_out);
 771                 }
 772             }
 773
 774             EmitObj::None => {}
 775         }
 776
 777         record_llvm_cgu_instructions_stats(&cgcx.prof, llmod);
 778         drop(handlers);
 779     }
 780
 781     // `.dwo` files are only emitted if:
 782     //
 783     // - Object files are being emitted (i.e. bitcode only or metadata only compilations will not
 784     //   produce dwarf objects, even if otherwise enabled)
 785     // - Target supports Split DWARF
 786     // - Split debuginfo is enabled
 787     // - Split DWARF kind is `split` (i.e. debuginfo is split into `.dwo` files, not different
 788     //   sections in the `.o` files).
 789     let dwarf_object_emitted = matches!(config.emit_obj, EmitObj::ObjectCode(_))
 790         && cgcx.target_can_use_split_dwarf
 791         && cgcx.split_debuginfo != SplitDebuginfo::Off
 792         && cgcx.split_dwarf_kind == SplitDwarfKind::Split;
 793     Ok(module.into_compiled_module(
 794         config.emit_obj != EmitObj::None,
 795         dwarf_object_emitted,
 796         config.emit_bc,
 797         &cgcx.output_filenames,
 798     ))
 799 }
 800
 801 fn create_section_with_flags_asm(section_name: &str, section_flags: &str, data: &[u8]) -> Vec<u8> {
 802     let mut asm = format!(".section {},\"{}\"\n", section_name, section_flags).into_bytes();
 803     asm.extend_from_slice(b".ascii \"");
 804     asm.reserve(data.len());
 805     for &byte in data {
 806         if byte == b'\\' || byte == b'"' {
 807             asm.push(b'\\');
 808             asm.push(byte);
 809         } else if byte < 0x20 || byte >= 0x80 {
 810             // Avoid non UTF-8 inline assembly. Use octal escape sequence, because it is fixed
 811             // width, while hex escapes will consume following characters.
 812             asm.push(b'\\');
 813             asm.push(b'0' + ((byte >> 6) & 0x7));
 814             asm.push(b'0' + ((byte >> 3) & 0x7));
 815             asm.push(b'0' + ((byte >> 0) & 0x7));
 816         } else {
 817             asm.push(byte);
 818         }
 819     }
 820     asm.extend_from_slice(b"\"\n");
 821     asm
 822 }
 823
 824 /// Embed the bitcode of an LLVM module in the LLVM module itself.
 825 ///
 826 /// This is done primarily for iOS where it appears to be standard to compile C
 827 /// code at least with `-fembed-bitcode` which creates two sections in the
 828 /// executable:
 829 ///
 830 /// * __LLVM,__bitcode
 831 /// * __LLVM,__cmdline
 832 ///
 833 /// It appears *both* of these sections are necessary to get the linker to
 834 /// recognize what's going on. A suitable cmdline value is taken from the
 835 /// target spec.
 836 ///
 837 /// Furthermore debug/O1 builds don't actually embed bitcode but rather just
 838 /// embed an empty section.
 839 ///
 840 /// Basically all of this is us attempting to follow in the footsteps of clang
 841 /// on iOS. See #35968 for lots more info.
 842 unsafe fn embed_bitcode(
 843     cgcx: &CodegenContext<LlvmCodegenBackend>,
 844     llcx: &llvm::Context,
 845     llmod: &llvm::Module,
 846     cmdline: &str,
 847     bitcode: &[u8],
 848 ) {
 849     // We're adding custom sections to the output object file, but we definitely
 850     // do not want these custom sections to make their way into the final linked
 851     // executable. The purpose of these custom sections is for tooling
 852     // surrounding object files to work with the LLVM IR, if necessary. For
 853     // example rustc's own LTO will look for LLVM IR inside of the object file
 854     // in these sections by default.
 855     //
 856     // To handle this is a bit different depending on the object file format
 857     // used by the backend, broken down into a few different categories:
 858     //
 859     // * Mach-O - this is for macOS. Inspecting the source code for the native
 860     //   linker here shows that the `.llvmbc` and `.llvmcmd` sections are
 861     //   automatically skipped by the linker. In that case there's nothing extra
 862     //   that we need to do here.
 863     //
 864     // * Wasm - the native LLD linker is hard-coded to skip `.llvmbc` and
 865     //   `.llvmcmd` sections, so there's nothing extra we need to do.
 866     //
 867     // * COFF - if we don't do anything the linker will by default copy all
 868     //   these sections to the output artifact, not what we want! To subvert
 869     //   this we want to flag the sections we inserted here as
 870     //   `IMAGE_SCN_LNK_REMOVE`.
 871     //
 872     // * ELF - this is very similar to COFF above. One difference is that these
 873     //   sections are removed from the output linked artifact when
 874     //   `--gc-sections` is passed, which we pass by default. If that flag isn't
 875     //   passed though then these sections will show up in the final output.
 876     //   Additionally the flag that we need to set here is `SHF_EXCLUDE`.
 877     //
 878     // Unfortunately, LLVM provides no way to set custom section flags. For ELF
 879     // and COFF we emit the sections using module level inline assembly for that
 880     // reason (see issue #90326 for historical background).
 881     let is_apple = cgcx.opts.target_triple.triple().contains("-ios")
 882         || cgcx.opts.target_triple.triple().contains("-darwin")
 883         || cgcx.opts.target_triple.triple().contains("-tvos")
 884         || cgcx.opts.target_triple.triple().contains("-watchos");
 885     if is_apple
 886         || cgcx.opts.target_triple.triple().starts_with("wasm")
 887         || cgcx.opts.target_triple.triple().starts_with("asmjs")
 888     {
 889         // We don't need custom section flags, create LLVM globals.
 890         let llconst = common::bytes_in_context(llcx, bitcode);
 891         let llglobal = llvm::LLVMAddGlobal(
 892             llmod,
 893             common::val_ty(llconst),
 894             "rustc.embedded.module\0".as_ptr().cast(),
 895         );
 896         llvm::LLVMSetInitializer(llglobal, llconst);
 897
 898         let section = if is_apple { "__LLVM,__bitcode\0" } else { ".llvmbc\0" };
 899         llvm::LLVMSetSection(llglobal, section.as_ptr().cast());
 900         llvm::LLVMRustSetLinkage(llglobal, llvm::Linkage::PrivateLinkage);
 901         llvm::LLVMSetGlobalConstant(llglobal, llvm::True);
 902
 903         let llconst = common::bytes_in_context(llcx, cmdline.as_bytes());
 904         let llglobal = llvm::LLVMAddGlobal(
 905             llmod,
 906             common::val_ty(llconst),
 907             "rustc.embedded.cmdline\0".as_ptr().cast(),
 908         );
 909         llvm::LLVMSetInitializer(llglobal, llconst);
 910         let section = if is_apple { "__LLVM,__cmdline\0" } else { ".llvmcmd\0" };
 911         llvm::LLVMSetSection(llglobal, section.as_ptr().cast());
 912         llvm::LLVMRustSetLinkage(llglobal, llvm::Linkage::PrivateLinkage);
 913     } else {
 914         // We need custom section flags, so emit module-level inline assembly.
 915         let section_flags = if cgcx.is_pe_coff { "n" } else { "e" };
 916         let asm = create_section_with_flags_asm(".llvmbc", section_flags, bitcode);
 917         llvm::LLVMAppendModuleInlineAsm(llmod, asm.as_ptr().cast(), asm.len());
 918         let asm = create_section_with_flags_asm(".llvmcmd", section_flags, cmdline.as_bytes());
 919         llvm::LLVMAppendModuleInlineAsm(llmod, asm.as_ptr().cast(), asm.len());
 920     }
 921 }
 922
 923 // Create a `__imp_<symbol> = &symbol` global for every public static `symbol`.
 924 // This is required to satisfy `dllimport` references to static data in .rlibs
 925 // when using MSVC linker. We do this only for data, as linker can fix up
 926 // code references on its own.
 927 // See #26591, #27438
 928 fn create_msvc_imps(
 929     cgcx: &CodegenContext<LlvmCodegenBackend>,
 930     llcx: &llvm::Context,
 931     llmod: &llvm::Module,
 932 ) {
 933     if !cgcx.msvc_imps_needed {
 934         return;
 935     }
 936     // The x86 ABI seems to require that leading underscores are added to symbol
 937     // names, so we need an extra underscore on x86. There's also a leading
 938     // '\x01' here which disables LLVM's symbol mangling (e.g., no extra
 939     // underscores added in front).
 940     let prefix = if cgcx.target_arch == "x86" { "\x01__imp__" } else { "\x01__imp_" };
 941
 942     unsafe {
 943         let i8p_ty = Type::i8p_llcx(llcx);
 944         let globals = base::iter_globals(llmod)
 945             .filter(|&val| {
 946                 llvm::LLVMRustGetLinkage(val) == llvm::Linkage::ExternalLinkage
 947                     && llvm::LLVMIsDeclaration(val) == 0
 948             })
 949             .filter_map(|val| {
 950                 // Exclude some symbols that we know are not Rust symbols.
 951                 let name = llvm::get_value_name(val);
 952                 if ignored(name) { None } else { Some((val, name)) }
 953             })
 954             .map(move |(val, name)| {
 955                 let mut imp_name = prefix.as_bytes().to_vec();
 956                 imp_name.extend(name);
 957                 let imp_name = CString::new(imp_name).unwrap();
 958                 (imp_name, val)
 959             })
 960             .collect::<Vec<_>>();
 961
 962         for (imp_name, val) in globals {
 963             let imp = llvm::LLVMAddGlobal(llmod, i8p_ty, imp_name.as_ptr().cast());
 964             llvm::LLVMSetInitializer(imp, consts::ptrcast(val, i8p_ty));
 965             llvm::LLVMRustSetLinkage(imp, llvm::Linkage::ExternalLinkage);
 966         }
 967     }
 968
 969     // Use this function to exclude certain symbols from `__imp` generation.
 970     fn ignored(symbol_name: &[u8]) -> bool {
 971         // These are symbols generated by LLVM's profiling instrumentation
 972         symbol_name.starts_with(b"__llvm_profile_")
 973     }
 974 }
 975
 976 fn record_artifact_size(
 977     self_profiler_ref: &SelfProfilerRef,
 978     artifact_kind: &'static str,
 979     path: &Path,
 980 ) {
 981     // Don't stat the file if we are not going to record its size.
 982     if !self_profiler_ref.enabled() {
 983         return;
 984     }
 985
 986     if let Some(artifact_name) = path.file_name() {
 987         let file_size = std::fs::metadata(path).map(|m| m.len()).unwrap_or(0);
 988         self_profiler_ref.artifact_size(artifact_kind, artifact_name.to_string_lossy(), file_size);
 989     }
 990 }
 991
 992 fn record_llvm_cgu_instructions_stats(prof: &SelfProfilerRef, llmod: &llvm::Module) {
 993     if !prof.enabled() {
 994         return;
 995     }
 996
 997     let raw_stats =
 998         llvm::build_string(|s| unsafe { llvm::LLVMRustModuleInstructionStats(&llmod, s) })
 999             .expect("cannot get module instruction stats");
1000
1001     #[derive(serde::Deserialize)]
1002     struct InstructionsStats {
1003         module: String,
1004         total: u64,
1005     }
1006
1007     let InstructionsStats { module, total } =
1008         serde_json::from_str(&raw_stats).expect("cannot parse llvm cgu instructions stats");
1009     prof.artifact_size("cgu_instructions", module, total);
1010 }