src/librustc_codegen_llvm/back/write.rs

   1 use crate::attributes;
   2 use crate::back::bytecode;
   3 use crate::back::lto::ThinBuffer;
   4 use crate::base;
   5 use crate::consts;
   6 use crate::llvm::{self, DiagnosticInfo, PassManager, SMDiagnostic};
   7 use crate::llvm_util;
   8 use crate::ModuleLlvm;
   9 use crate::type_::Type;
  10 use crate::context::{is_pie_binary, get_reloc_model};
  11 use crate::common;
  12 use crate::LlvmCodegenBackend;
  13 use rustc::bug;
  14 use rustc::hir::def_id::LOCAL_CRATE;
  15 use rustc_codegen_ssa::back::write::{CodegenContext, ModuleConfig, run_assembler};
  16 use rustc_codegen_ssa::traits::*;
  17 use rustc::session::config::{self, OutputType, Passes, Lto, Sanitizer, SwitchWithOptPath};
  18 use rustc::session::Session;
  19 use rustc::ty::TyCtxt;
  20 use rustc_codegen_ssa::{RLIB_BYTECODE_EXTENSION, ModuleCodegen, CompiledModule};
  21 use rustc::util::common::time_ext;
  22 use rustc_fs_util::{path_to_c_string, link_or_copy};
  23 use rustc_data_structures::small_c_str::SmallCStr;
  24 use rustc_errors::{Handler, FatalError};
  25 use log::debug;
  26
  27 use std::ffi::CString;
  28 use std::fs;
  29 use std::io::{self, Write};
  30 use std::path::{Path, PathBuf};
  31 use std::str;
  32 use std::sync::Arc;
  33 use std::slice;
  34 use libc::{c_int, c_uint, c_void, c_char, size_t};
  35
  36 pub const RELOC_MODEL_ARGS : [(&str, llvm::RelocMode); 7] = [
  37     ("pic", llvm::RelocMode::PIC),
  38     ("static", llvm::RelocMode::Static),
  39     ("default", llvm::RelocMode::Default),
  40     ("dynamic-no-pic", llvm::RelocMode::DynamicNoPic),
  41     ("ropi", llvm::RelocMode::ROPI),
  42     ("rwpi", llvm::RelocMode::RWPI),
  43     ("ropi-rwpi", llvm::RelocMode::ROPI_RWPI),
  44 ];
  45
  46 pub const CODE_GEN_MODEL_ARGS: &[(&str, llvm::CodeModel)] = &[
  47     ("small", llvm::CodeModel::Small),
  48     ("kernel", llvm::CodeModel::Kernel),
  49     ("medium", llvm::CodeModel::Medium),
  50     ("large", llvm::CodeModel::Large),
  51 ];
  52
  53 pub const TLS_MODEL_ARGS : [(&str, llvm::ThreadLocalMode); 4] = [
  54     ("global-dynamic", llvm::ThreadLocalMode::GeneralDynamic),
  55     ("local-dynamic", llvm::ThreadLocalMode::LocalDynamic),
  56     ("initial-exec", llvm::ThreadLocalMode::InitialExec),
  57     ("local-exec", llvm::ThreadLocalMode::LocalExec),
  58 ];
  59
  60 pub fn llvm_err(handler: &rustc_errors::Handler, msg: &str) -> FatalError {
  61     match llvm::last_error() {
  62         Some(err) => handler.fatal(&format!("{}: {}", msg, err)),
  63         None => handler.fatal(&msg),
  64     }
  65 }
  66
  67 pub fn write_output_file(
  68         handler: &rustc_errors::Handler,
  69         target: &'ll llvm::TargetMachine,
  70         pm: &llvm::PassManager<'ll>,
  71         m: &'ll llvm::Module,
  72         output: &Path,
  73         file_type: llvm::FileType) -> Result<(), FatalError> {
  74     unsafe {
  75         let output_c = path_to_c_string(output);
  76         let result = llvm::LLVMRustWriteOutputFile(target, pm, m, output_c.as_ptr(), file_type);
  77         result.into_result().map_err(|()| {
  78             let msg = format!("could not write output to {}", output.display());
  79             llvm_err(handler, &msg)
  80         })
  81     }
  82 }
  83
  84 pub fn create_informational_target_machine(
  85     sess: &Session,
  86     find_features: bool,
  87 ) -> &'static mut llvm::TargetMachine {
  88     target_machine_factory(sess, config::OptLevel::No, find_features)().unwrap_or_else(|err| {
  89         llvm_err(sess.diagnostic(), &err).raise()
  90     })
  91 }
  92
  93 pub fn create_target_machine(
  94     tcx: TyCtxt<'_>,
  95     find_features: bool,
  96 ) -> &'static mut llvm::TargetMachine {
  97     target_machine_factory(&tcx.sess, tcx.backend_optimization_level(LOCAL_CRATE), find_features)()
  98     .unwrap_or_else(|err| {
  99         llvm_err(tcx.sess.diagnostic(), &err).raise()
 100     })
 101 }
 102
 103 pub fn to_llvm_opt_settings(cfg: config::OptLevel) -> (llvm::CodeGenOptLevel, llvm::CodeGenOptSize)
 104 {
 105     use self::config::OptLevel::*;
 106     match cfg {
 107         No => (llvm::CodeGenOptLevel::None, llvm::CodeGenOptSizeNone),
 108         Less => (llvm::CodeGenOptLevel::Less, llvm::CodeGenOptSizeNone),
 109         Default => (llvm::CodeGenOptLevel::Default, llvm::CodeGenOptSizeNone),
 110         Aggressive => (llvm::CodeGenOptLevel::Aggressive, llvm::CodeGenOptSizeNone),
 111         Size => (llvm::CodeGenOptLevel::Default, llvm::CodeGenOptSizeDefault),
 112         SizeMin => (llvm::CodeGenOptLevel::Default, llvm::CodeGenOptSizeAggressive),
 113     }
 114 }
 115
 116 // If find_features is true this won't access `sess.crate_types` by assuming
 117 // that `is_pie_binary` is false. When we discover LLVM target features
 118 // `sess.crate_types` is uninitialized so we cannot access it.
 119 pub fn target_machine_factory(sess: &Session, optlvl: config::OptLevel, find_features: bool)
 120     -> Arc<dyn Fn() -> Result<&'static mut llvm::TargetMachine, String> + Send + Sync>
 121 {
 122     let reloc_model = get_reloc_model(sess);
 123
 124     let (opt_level, _) = to_llvm_opt_settings(optlvl);
 125     let use_softfp = sess.opts.cg.soft_float;
 126
 127     let ffunction_sections = sess.target.target.options.function_sections;
 128     let fdata_sections = ffunction_sections;
 129
 130     let code_model_arg = sess.opts.cg.code_model.as_ref().or(
 131         sess.target.target.options.code_model.as_ref(),
 132     );
 133
 134     let code_model = match code_model_arg {
 135         Some(s) => {
 136             match CODE_GEN_MODEL_ARGS.iter().find(|arg| arg.0 == s) {
 137                 Some(x) => x.1,
 138                 _ => {
 139                     sess.err(&format!("{:?} is not a valid code model",
 140                                       code_model_arg));
 141                     sess.abort_if_errors();
 142                     bug!();
 143                 }
 144             }
 145         }
 146         None => llvm::CodeModel::None,
 147     };
 148
 149     let features = attributes::llvm_target_features(sess).collect::<Vec<_>>();
 150     let mut singlethread = sess.target.target.options.singlethread;
 151
 152     // On the wasm target once the `atomics` feature is enabled that means that
 153     // we're no longer single-threaded, or otherwise we don't want LLVM to
 154     // lower atomic operations to single-threaded operations.
 155     if singlethread &&
 156         sess.target.target.llvm_target.contains("wasm32") &&
 157         features.iter().any(|s| *s == "+atomics")
 158     {
 159         singlethread = false;
 160     }
 161
 162     let triple = SmallCStr::new(&sess.target.target.llvm_target);
 163     let cpu = SmallCStr::new(llvm_util::target_cpu(sess));
 164     let features = features.join(",");
 165     let features = CString::new(features).unwrap();
 166     let abi = SmallCStr::new(&sess.target.target.options.llvm_abiname);
 167     let is_pie_binary = !find_features && is_pie_binary(sess);
 168     let trap_unreachable = sess.target.target.options.trap_unreachable;
 169     let emit_stack_size_section = sess.opts.debugging_opts.emit_stack_sizes;
 170
 171     let asm_comments = sess.asm_comments();
 172     let relax_elf_relocations = sess.target.target.options.relax_elf_relocations;
 173     Arc::new(move || {
 174         let tm = unsafe {
 175             llvm::LLVMRustCreateTargetMachine(
 176                 triple.as_ptr(), cpu.as_ptr(), features.as_ptr(), abi.as_ptr(),
 177                 code_model,
 178                 reloc_model,
 179                 opt_level,
 180                 use_softfp,
 181                 is_pie_binary,
 182                 ffunction_sections,
 183                 fdata_sections,
 184                 trap_unreachable,
 185                 singlethread,
 186                 asm_comments,
 187                 emit_stack_size_section,
 188                 relax_elf_relocations,
 189             )
 190         };
 191
 192         tm.ok_or_else(|| {
 193             format!("Could not create LLVM TargetMachine for triple: {}",
 194                     triple.to_str().unwrap())
 195         })
 196     })
 197 }
 198
 199 pub(crate) fn save_temp_bitcode(
 200     cgcx: &CodegenContext<LlvmCodegenBackend>,
 201     module: &ModuleCodegen<ModuleLlvm>,
 202     name: &str
 203 ) {
 204     if !cgcx.save_temps {
 205         return
 206     }
 207     unsafe {
 208         let ext = format!("{}.bc", name);
 209         let cgu = Some(&module.name[..]);
 210         let path = cgcx.output_filenames.temp_path_ext(&ext, cgu);
 211         let cstr = path_to_c_string(&path);
 212         let llmod = module.module_llvm.llmod();
 213         llvm::LLVMWriteBitcodeToFile(llmod, cstr.as_ptr());
 214     }
 215 }
 216
 217 pub struct DiagnosticHandlers<'a> {
 218     data: *mut (&'a CodegenContext<LlvmCodegenBackend>, &'a Handler),
 219     llcx: &'a llvm::Context,
 220 }
 221
 222 impl<'a> DiagnosticHandlers<'a> {
 223     pub fn new(cgcx: &'a CodegenContext<LlvmCodegenBackend>,
 224                handler: &'a Handler,
 225                llcx: &'a llvm::Context) -> Self {
 226         let data = Box::into_raw(Box::new((cgcx, handler)));
 227         unsafe {
 228             llvm::LLVMRustSetInlineAsmDiagnosticHandler(llcx, inline_asm_handler, data.cast());
 229             llvm::LLVMContextSetDiagnosticHandler(llcx, diagnostic_handler, data.cast());
 230         }
 231         DiagnosticHandlers { data, llcx }
 232     }
 233 }
 234
 235 impl<'a> Drop for DiagnosticHandlers<'a> {
 236     fn drop(&mut self) {
 237         use std::ptr::null_mut;
 238         unsafe {
 239             llvm::LLVMRustSetInlineAsmDiagnosticHandler(self.llcx, inline_asm_handler, null_mut());
 240             llvm::LLVMContextSetDiagnosticHandler(self.llcx, diagnostic_handler, null_mut());
 241             drop(Box::from_raw(self.data));
 242         }
 243     }
 244 }
 245
 246 unsafe extern "C" fn report_inline_asm(cgcx: &CodegenContext<LlvmCodegenBackend>,
 247                                        msg: &str,
 248                                        cookie: c_uint) {
 249     cgcx.diag_emitter.inline_asm_error(cookie as u32, msg.to_owned());
 250 }
 251
 252 unsafe extern "C" fn inline_asm_handler(diag: &SMDiagnostic,
 253                                         user: *const c_void,
 254                                         cookie: c_uint) {
 255     if user.is_null() {
 256         return
 257     }
 258     let (cgcx, _) = *(user as *const (&CodegenContext<LlvmCodegenBackend>, &Handler));
 259
 260     let msg = llvm::build_string(|s| llvm::LLVMRustWriteSMDiagnosticToString(diag, s))
 261         .expect("non-UTF8 SMDiagnostic");
 262
 263     report_inline_asm(cgcx, &msg, cookie);
 264 }
 265
 266 unsafe extern "C" fn diagnostic_handler(info: &DiagnosticInfo, user: *mut c_void) {
 267     if user.is_null() {
 268         return
 269     }
 270     let (cgcx, diag_handler) = *(user as *const (&CodegenContext<LlvmCodegenBackend>, &Handler));
 271
 272     match llvm::diagnostic::Diagnostic::unpack(info) {
 273         llvm::diagnostic::InlineAsm(inline) => {
 274             report_inline_asm(cgcx,
 275                               &llvm::twine_to_string(inline.message),
 276                               inline.cookie);
 277         }
 278
 279         llvm::diagnostic::Optimization(opt) => {
 280             let enabled = match cgcx.remark {
 281                 Passes::All => true,
 282                 Passes::Some(ref v) => v.iter().any(|s| *s == opt.pass_name),
 283             };
 284
 285             if enabled {
 286                 diag_handler.note_without_error(&format!("optimization {} for {} at {}:{}:{}: {}",
 287                                                 opt.kind.describe(),
 288                                                 opt.pass_name,
 289                                                 opt.filename,
 290                                                 opt.line,
 291                                                 opt.column,
 292                                                 opt.message));
 293             }
 294         }
 295         llvm::diagnostic::PGO(diagnostic_ref) |
 296         llvm::diagnostic::Linker(diagnostic_ref) => {
 297             let msg = llvm::build_string(|s| {
 298                 llvm::LLVMRustWriteDiagnosticInfoToString(diagnostic_ref, s)
 299             }).expect("non-UTF8 diagnostic");
 300             diag_handler.warn(&msg);
 301         }
 302         llvm::diagnostic::UnknownDiagnostic(..) => {},
 303     }
 304 }
 305
 306 // Unsafe due to LLVM calls.
 307 pub(crate) unsafe fn optimize(cgcx: &CodegenContext<LlvmCodegenBackend>,
 308                    diag_handler: &Handler,
 309                    module: &ModuleCodegen<ModuleLlvm>,
 310                    config: &ModuleConfig)
 311     -> Result<(), FatalError>
 312 {
 313     let _timer = cgcx.prof.generic_activity("LLVM_module_optimize");
 314
 315     let llmod = module.module_llvm.llmod();
 316     let llcx = &*module.module_llvm.llcx;
 317     let tm = &*module.module_llvm.tm;
 318     let _handlers = DiagnosticHandlers::new(cgcx, diag_handler, llcx);
 319
 320     let module_name = module.name.clone();
 321     let module_name = Some(&module_name[..]);
 322
 323     if config.emit_no_opt_bc {
 324         let out = cgcx.output_filenames.temp_path_ext("no-opt.bc", module_name);
 325         let out = path_to_c_string(&out);
 326         llvm::LLVMWriteBitcodeToFile(llmod, out.as_ptr());
 327     }
 328
 329     if let Some(opt_level) = config.opt_level {
 330         // Create the two optimizing pass managers. These mirror what clang
 331         // does, and are by populated by LLVM's default PassManagerBuilder.
 332         // Each manager has a different set of passes, but they also share
 333         // some common passes.
 334         let fpm = llvm::LLVMCreateFunctionPassManagerForModule(llmod);
 335         let mpm = llvm::LLVMCreatePassManager();
 336
 337         {
 338             let find_pass = |pass_name: &str| {
 339                 let pass_name = SmallCStr::new(pass_name);
 340                 llvm::LLVMRustFindAndCreatePass(pass_name.as_ptr())
 341             };
 342
 343             if config.verify_llvm_ir {
 344                 // Verification should run as the very first pass.
 345                 llvm::LLVMRustAddPass(fpm, find_pass("verify").unwrap());
 346             }
 347
 348             let mut extra_passes = Vec::new();
 349             let mut have_name_anon_globals_pass = false;
 350
 351             for pass_name in &config.passes {
 352                 if pass_name == "lint" {
 353                     // Linting should also be performed early, directly on the generated IR.
 354                     llvm::LLVMRustAddPass(fpm, find_pass("lint").unwrap());
 355                     continue;
 356                 }
 357
 358                 if let Some(pass) = find_pass(pass_name) {
 359                     extra_passes.push(pass);
 360                 } else {
 361                     diag_handler.warn(&format!("unknown pass `{}`, ignoring", pass_name));
 362                 }
 363
 364                 if pass_name == "name-anon-globals" {
 365                     have_name_anon_globals_pass = true;
 366                 }
 367             }
 368
 369             add_sanitizer_passes(config, &mut extra_passes);
 370
 371             // Some options cause LLVM bitcode to be emitted, which uses ThinLTOBuffers, so we need
 372             // to make sure we run LLVM's NameAnonGlobals pass when emitting bitcode; otherwise
 373             // we'll get errors in LLVM.
 374             let using_thin_buffers = config.bitcode_needed();
 375             if !config.no_prepopulate_passes {
 376                 llvm::LLVMAddAnalysisPasses(tm, fpm);
 377                 llvm::LLVMAddAnalysisPasses(tm, mpm);
 378                 let opt_level = to_llvm_opt_settings(opt_level).0;
 379                 let prepare_for_thin_lto = cgcx.lto == Lto::Thin || cgcx.lto == Lto::ThinLocal ||
 380                     (cgcx.lto != Lto::Fat && cgcx.opts.cg.linker_plugin_lto.enabled());
 381                 with_llvm_pmb(llmod, &config, opt_level, prepare_for_thin_lto, &mut |b| {
 382                     llvm::LLVMRustAddLastExtensionPasses(
 383                         b, extra_passes.as_ptr(), extra_passes.len() as size_t);
 384                     llvm::LLVMPassManagerBuilderPopulateFunctionPassManager(b, fpm);
 385                     llvm::LLVMPassManagerBuilderPopulateModulePassManager(b, mpm);
 386                 });
 387
 388                 have_name_anon_globals_pass = have_name_anon_globals_pass || prepare_for_thin_lto;
 389                 if using_thin_buffers && !prepare_for_thin_lto {
 390                     llvm::LLVMRustAddPass(mpm, find_pass("name-anon-globals").unwrap());
 391                     have_name_anon_globals_pass = true;
 392                 }
 393             } else {
 394                 // If we don't use the standard pipeline, directly populate the MPM
 395                 // with the extra passes.
 396                 for pass in extra_passes {
 397                     llvm::LLVMRustAddPass(mpm, pass);
 398                 }
 399             }
 400
 401             if using_thin_buffers && !have_name_anon_globals_pass {
 402                 // As described above, this will probably cause an error in LLVM
 403                 if config.no_prepopulate_passes {
 404                     diag_handler.err("The current compilation is going to use thin LTO buffers \
 405                                       without running LLVM's NameAnonGlobals pass. \
 406                                       This will likely cause errors in LLVM. Consider adding \
 407                                       -C passes=name-anon-globals to the compiler command line.");
 408                 } else {
 409                     bug!("We are using thin LTO buffers without running the NameAnonGlobals pass. \
 410                           This will likely cause errors in LLVM and should never happen.");
 411                 }
 412             }
 413         }
 414
 415         diag_handler.abort_if_errors();
 416
 417         // Finally, run the actual optimization passes
 418         {
 419             let _timer = cgcx.prof.generic_activity("LLVM_module_optimize_function_passes");
 420             time_ext(config.time_passes,
 421                         &format!("llvm function passes [{}]", module_name.unwrap()),
 422                         || {
 423                 llvm::LLVMRustRunFunctionPassManager(fpm, llmod)
 424             });
 425         }
 426         {
 427             let _timer = cgcx.prof.generic_activity("LLVM_module_optimize_module_passes");
 428             time_ext(config.time_passes,
 429                     &format!("llvm module passes [{}]", module_name.unwrap()),
 430                     || {
 431                 llvm::LLVMRunPassManager(mpm, llmod)
 432             });
 433         }
 434
 435         // Deallocate managers that we're now done with
 436         llvm::LLVMDisposePassManager(fpm);
 437         llvm::LLVMDisposePassManager(mpm);
 438     }
 439     Ok(())
 440 }
 441
 442 unsafe fn add_sanitizer_passes(config: &ModuleConfig,
 443                                passes: &mut Vec<&'static mut llvm::Pass>) {
 444
 445     let sanitizer = match &config.sanitizer {
 446         None => return,
 447         Some(s) => s,
 448     };
 449
 450     let recover = config.sanitizer_recover.contains(sanitizer);
 451     match sanitizer {
 452         Sanitizer::Address => {
 453             passes.push(llvm::LLVMRustCreateAddressSanitizerFunctionPass(recover));
 454             passes.push(llvm::LLVMRustCreateModuleAddressSanitizerPass(recover));
 455         }
 456         Sanitizer::Memory => {
 457             let track_origins = config.sanitizer_memory_track_origins as c_int;
 458             passes.push(llvm::LLVMRustCreateMemorySanitizerPass(track_origins, recover));
 459         }
 460         Sanitizer::Thread => {
 461             passes.push(llvm::LLVMRustCreateThreadSanitizerPass());
 462         }
 463         Sanitizer::Leak => {}
 464     }
 465 }
 466
 467 pub(crate) unsafe fn codegen(cgcx: &CodegenContext<LlvmCodegenBackend>,
 468                   diag_handler: &Handler,
 469                   module: ModuleCodegen<ModuleLlvm>,
 470                   config: &ModuleConfig)
 471     -> Result<CompiledModule, FatalError>
 472 {
 473     let _timer = cgcx.prof.generic_activity("LLVM_module_codegen");
 474     {
 475         let llmod = module.module_llvm.llmod();
 476         let llcx = &*module.module_llvm.llcx;
 477         let tm = &*module.module_llvm.tm;
 478         let module_name = module.name.clone();
 479         let module_name = Some(&module_name[..]);
 480         let handlers = DiagnosticHandlers::new(cgcx, diag_handler, llcx);
 481
 482         if cgcx.msvc_imps_needed {
 483             create_msvc_imps(cgcx, llcx, llmod);
 484         }
 485
 486         // A codegen-specific pass manager is used to generate object
 487         // files for an LLVM module.
 488         //
 489         // Apparently each of these pass managers is a one-shot kind of
 490         // thing, so we create a new one for each type of output. The
 491         // pass manager passed to the closure should be ensured to not
 492         // escape the closure itself, and the manager should only be
 493         // used once.
 494         unsafe fn with_codegen<'ll, F, R>(tm: &'ll llvm::TargetMachine,
 495                                           llmod: &'ll llvm::Module,
 496                                           no_builtins: bool,
 497                                           f: F) -> R
 498             where F: FnOnce(&'ll mut PassManager<'ll>) -> R,
 499         {
 500             let cpm = llvm::LLVMCreatePassManager();
 501             llvm::LLVMAddAnalysisPasses(tm, cpm);
 502             llvm::LLVMRustAddLibraryInfo(cpm, llmod, no_builtins);
 503             f(cpm)
 504         }
 505
 506         // If we don't have the integrated assembler, then we need to emit asm
 507         // from LLVM and use `gcc` to create the object file.
 508         let asm_to_obj = config.emit_obj && config.no_integrated_as;
 509
 510         // Change what we write and cleanup based on whether obj files are
 511         // just llvm bitcode. In that case write bitcode, and possibly
 512         // delete the bitcode if it wasn't requested. Don't generate the
 513         // machine code, instead copy the .o file from the .bc
 514         let write_bc = config.emit_bc || config.obj_is_bitcode;
 515         let rm_bc = !config.emit_bc && config.obj_is_bitcode;
 516         let write_obj = config.emit_obj && !config.obj_is_bitcode && !asm_to_obj;
 517         let copy_bc_to_obj = config.emit_obj && config.obj_is_bitcode;
 518
 519         let bc_out = cgcx.output_filenames.temp_path(OutputType::Bitcode, module_name);
 520         let obj_out = cgcx.output_filenames.temp_path(OutputType::Object, module_name);
 521
 522
 523         if write_bc || config.emit_bc_compressed || config.embed_bitcode {
 524             let _timer = cgcx.prof.generic_activity("LLVM_module_codegen_make_bitcode");
 525             let thin = ThinBuffer::new(llmod);
 526             let data = thin.data();
 527
 528             if write_bc {
 529                 let _timer = cgcx.prof.generic_activity("LLVM_module_codegen_emit_bitcode");
 530                 if let Err(e) = fs::write(&bc_out, data) {
 531                     let msg = format!("failed to write bytecode to {}: {}", bc_out.display(), e);
 532                     diag_handler.err(&msg);
 533                 }
 534             }
 535
 536             if config.embed_bitcode {
 537                 let _timer = cgcx.prof.generic_activity("LLVM_module_codegen_embed_bitcode");
 538                 embed_bitcode(cgcx, llcx, llmod, Some(data));
 539             }
 540
 541             if config.emit_bc_compressed {
 542                 let _timer =
 543                     cgcx.prof.generic_activity("LLVM_module_codegen_emit_compressed_bitcode");
 544                 let dst = bc_out.with_extension(RLIB_BYTECODE_EXTENSION);
 545                 let data = bytecode::encode(&module.name, data);
 546                 if let Err(e) = fs::write(&dst, data) {
 547                     let msg = format!("failed to write bytecode to {}: {}", dst.display(), e);
 548                     diag_handler.err(&msg);
 549                 }
 550             }
 551         } else if config.embed_bitcode_marker {
 552             embed_bitcode(cgcx, llcx, llmod, None);
 553         }
 554
 555         time_ext(config.time_passes, &format!("codegen passes [{}]", module_name.unwrap()),
 556             || -> Result<(), FatalError> {
 557             if config.emit_ir {
 558                 let _timer = cgcx.prof.generic_activity("LLVM_module_codegen_emit_ir");
 559                 let out = cgcx.output_filenames.temp_path(OutputType::LlvmAssembly, module_name);
 560                 let out_c = path_to_c_string(&out);
 561
 562                 extern "C" fn demangle_callback(input_ptr: *const c_char,
 563                                                 input_len: size_t,
 564                                                 output_ptr: *mut c_char,
 565                                                 output_len: size_t) -> size_t {
 566                     let input = unsafe {
 567                         slice::from_raw_parts(input_ptr as *const u8, input_len as usize)
 568                     };
 569
 570                     let input = match str::from_utf8(input) {
 571                         Ok(s) => s,
 572                         Err(_) => return 0,
 573                     };
 574
 575                     let output = unsafe {
 576                         slice::from_raw_parts_mut(output_ptr as *mut u8, output_len as usize)
 577                     };
 578                     let mut cursor = io::Cursor::new(output);
 579
 580                     let demangled = match rustc_demangle::try_demangle(input) {
 581                         Ok(d) => d,
 582                         Err(_) => return 0,
 583                     };
 584
 585                     if let Err(_) = write!(cursor, "{:#}", demangled) {
 586                         // Possible only if provided buffer is not big enough
 587                         return 0;
 588                     }
 589
 590                     cursor.position() as size_t
 591                 }
 592
 593                 let result =
 594                     llvm::LLVMRustPrintModule(llmod, out_c.as_ptr(), demangle_callback);
 595                 result.into_result().map_err(|()| {
 596                     let msg = format!("failed to write LLVM IR to {}", out.display());
 597                     llvm_err(diag_handler, &msg)
 598                 })?;
 599             }
 600
 601             if config.emit_asm || asm_to_obj {
 602                 let _timer = cgcx.prof.generic_activity("LLVM_module_codegen_emit_asm");
 603                 let path = cgcx.output_filenames.temp_path(OutputType::Assembly, module_name);
 604
 605                 // We can't use the same module for asm and binary output, because that triggers
 606                 // various errors like invalid IR or broken binaries, so we might have to clone the
 607                 // module to produce the asm output
 608                 let llmod = if config.emit_obj {
 609                     llvm::LLVMCloneModule(llmod)
 610                 } else {
 611                     llmod
 612                 };
 613                 with_codegen(tm, llmod, config.no_builtins, |cpm| {
 614                     write_output_file(diag_handler, tm, cpm, llmod, &path,
 615                                       llvm::FileType::AssemblyFile)
 616                 })?;
 617             }
 618
 619             if write_obj {
 620                 let _timer = cgcx.prof.generic_activity("LLVM_module_codegen_emit_obj");
 621                 with_codegen(tm, llmod, config.no_builtins, |cpm| {
 622                     write_output_file(diag_handler, tm, cpm, llmod, &obj_out,
 623                                       llvm::FileType::ObjectFile)
 624                 })?;
 625             } else if asm_to_obj {
 626                 let _timer = cgcx.prof.generic_activity("LLVM_module_codegen_asm_to_obj");
 627                 let assembly = cgcx.output_filenames.temp_path(OutputType::Assembly, module_name);
 628                 run_assembler(cgcx, diag_handler, &assembly, &obj_out);
 629
 630                 if !config.emit_asm && !cgcx.save_temps {
 631                     drop(fs::remove_file(&assembly));
 632                 }
 633             }
 634
 635             Ok(())
 636         })?;
 637
 638         if copy_bc_to_obj {
 639             debug!("copying bitcode {:?} to obj {:?}", bc_out, obj_out);
 640             if let Err(e) = link_or_copy(&bc_out, &obj_out) {
 641                 diag_handler.err(&format!("failed to copy bitcode to object file: {}", e));
 642             }
 643         }
 644
 645         if rm_bc {
 646             debug!("removing_bitcode {:?}", bc_out);
 647             if let Err(e) = fs::remove_file(&bc_out) {
 648                 diag_handler.err(&format!("failed to remove bitcode: {}", e));
 649             }
 650         }
 651
 652         drop(handlers);
 653     }
 654     Ok(module.into_compiled_module(config.emit_obj,
 655                                    config.emit_bc,
 656                                    config.emit_bc_compressed,
 657                                    &cgcx.output_filenames))
 658 }
 659
 660 /// Embed the bitcode of an LLVM module in the LLVM module itself.
 661 ///
 662 /// This is done primarily for iOS where it appears to be standard to compile C
 663 /// code at least with `-fembed-bitcode` which creates two sections in the
 664 /// executable:
 665 ///
 666 /// * __LLVM,__bitcode
 667 /// * __LLVM,__cmdline
 668 ///
 669 /// It appears *both* of these sections are necessary to get the linker to
 670 /// recognize what's going on. For us though we just always throw in an empty
 671 /// cmdline section.
 672 ///
 673 /// Furthermore debug/O1 builds don't actually embed bitcode but rather just
 674 /// embed an empty section.
 675 ///
 676 /// Basically all of this is us attempting to follow in the footsteps of clang
 677 /// on iOS. See #35968 for lots more info.
 678 unsafe fn embed_bitcode(cgcx: &CodegenContext<LlvmCodegenBackend>,
 679                         llcx: &llvm::Context,
 680                         llmod: &llvm::Module,
 681                         bitcode: Option<&[u8]>) {
 682     let llconst = common::bytes_in_context(llcx, bitcode.unwrap_or(&[]));
 683     let llglobal = llvm::LLVMAddGlobal(
 684         llmod,
 685         common::val_ty(llconst),
 686         "rustc.embedded.module\0".as_ptr().cast(),
 687     );
 688     llvm::LLVMSetInitializer(llglobal, llconst);
 689
 690     let is_apple = cgcx.opts.target_triple.triple().contains("-ios") ||
 691                    cgcx.opts.target_triple.triple().contains("-darwin");
 692
 693     let section = if is_apple {
 694         "__LLVM,__bitcode\0"
 695     } else {
 696         ".llvmbc\0"
 697     };
 698     llvm::LLVMSetSection(llglobal, section.as_ptr().cast());
 699     llvm::LLVMRustSetLinkage(llglobal, llvm::Linkage::PrivateLinkage);
 700     llvm::LLVMSetGlobalConstant(llglobal, llvm::True);
 701
 702     let llconst = common::bytes_in_context(llcx, &[]);
 703     let llglobal = llvm::LLVMAddGlobal(
 704         llmod,
 705         common::val_ty(llconst),
 706         "rustc.embedded.cmdline\0".as_ptr().cast(),
 707     );
 708     llvm::LLVMSetInitializer(llglobal, llconst);
 709     let section = if  is_apple {
 710         "__LLVM,__cmdline\0"
 711     } else {
 712         ".llvmcmd\0"
 713     };
 714     llvm::LLVMSetSection(llglobal, section.as_ptr().cast());
 715     llvm::LLVMRustSetLinkage(llglobal, llvm::Linkage::PrivateLinkage);
 716 }
 717
 718 pub unsafe fn with_llvm_pmb(llmod: &llvm::Module,
 719                             config: &ModuleConfig,
 720                             opt_level: llvm::CodeGenOptLevel,
 721                             prepare_for_thin_lto: bool,
 722                             f: &mut dyn FnMut(&llvm::PassManagerBuilder)) {
 723     use std::ptr;
 724
 725     // Create the PassManagerBuilder for LLVM. We configure it with
 726     // reasonable defaults and prepare it to actually populate the pass
 727     // manager.
 728     let builder = llvm::LLVMPassManagerBuilderCreate();
 729     let opt_size = config.opt_size.map(|x| to_llvm_opt_settings(x).1)
 730         .unwrap_or(llvm::CodeGenOptSizeNone);
 731     let inline_threshold = config.inline_threshold;
 732
 733     let pgo_gen_path = match config.pgo_gen {
 734         SwitchWithOptPath::Enabled(ref opt_dir_path) => {
 735             let path = if let Some(dir_path) = opt_dir_path {
 736                 dir_path.join("default_%m.profraw")
 737             } else {
 738                 PathBuf::from("default_%m.profraw")
 739             };
 740
 741             Some(CString::new(format!("{}", path.display())).unwrap())
 742         }
 743         SwitchWithOptPath::Disabled => {
 744             None
 745         }
 746     };
 747
 748     let pgo_use_path = config.pgo_use.as_ref().map(|path_buf| {
 749         CString::new(path_buf.to_string_lossy().as_bytes()).unwrap()
 750     });
 751
 752     llvm::LLVMRustConfigurePassManagerBuilder(
 753         builder,
 754         opt_level,
 755         config.merge_functions,
 756         config.vectorize_slp,
 757         config.vectorize_loop,
 758         prepare_for_thin_lto,
 759         pgo_gen_path.as_ref().map_or(ptr::null(), |s| s.as_ptr()),
 760         pgo_use_path.as_ref().map_or(ptr::null(), |s| s.as_ptr()),
 761     );
 762
 763     llvm::LLVMPassManagerBuilderSetSizeLevel(builder, opt_size as u32);
 764
 765     if opt_size != llvm::CodeGenOptSizeNone {
 766         llvm::LLVMPassManagerBuilderSetDisableUnrollLoops(builder, 1);
 767     }
 768
 769     llvm::LLVMRustAddBuilderLibraryInfo(builder, llmod, config.no_builtins);
 770
 771     // Here we match what clang does (kinda). For O0 we only inline
 772     // always-inline functions (but don't add lifetime intrinsics), at O1 we
 773     // inline with lifetime intrinsics, and O2+ we add an inliner with a
 774     // thresholds copied from clang.
 775     match (opt_level, opt_size, inline_threshold) {
 776         (.., Some(t)) => {
 777             llvm::LLVMPassManagerBuilderUseInlinerWithThreshold(builder, t as u32);
 778         }
 779         (llvm::CodeGenOptLevel::Aggressive, ..) => {
 780             llvm::LLVMPassManagerBuilderUseInlinerWithThreshold(builder, 275);
 781         }
 782         (_, llvm::CodeGenOptSizeDefault, _) => {
 783             llvm::LLVMPassManagerBuilderUseInlinerWithThreshold(builder, 75);
 784         }
 785         (_, llvm::CodeGenOptSizeAggressive, _) => {
 786             llvm::LLVMPassManagerBuilderUseInlinerWithThreshold(builder, 25);
 787         }
 788         (llvm::CodeGenOptLevel::None, ..) => {
 789             llvm::LLVMRustAddAlwaysInlinePass(builder, false);
 790         }
 791         (llvm::CodeGenOptLevel::Less, ..) => {
 792             llvm::LLVMRustAddAlwaysInlinePass(builder, true);
 793         }
 794         (llvm::CodeGenOptLevel::Default, ..) => {
 795             llvm::LLVMPassManagerBuilderUseInlinerWithThreshold(builder, 225);
 796         }
 797         (llvm::CodeGenOptLevel::Other, ..) => {
 798             bug!("CodeGenOptLevel::Other selected")
 799         }
 800     }
 801
 802     f(builder);
 803     llvm::LLVMPassManagerBuilderDispose(builder);
 804 }
 805
 806 // Create a `__imp_<symbol> = &symbol` global for every public static `symbol`.
 807 // This is required to satisfy `dllimport` references to static data in .rlibs
 808 // when using MSVC linker.  We do this only for data, as linker can fix up
 809 // code references on its own.
 810 // See #26591, #27438
 811 fn create_msvc_imps(
 812     cgcx: &CodegenContext<LlvmCodegenBackend>,
 813     llcx: &llvm::Context,
 814     llmod: &llvm::Module
 815 ) {
 816     if !cgcx.msvc_imps_needed {
 817         return
 818     }
 819     // The x86 ABI seems to require that leading underscores are added to symbol
 820     // names, so we need an extra underscore on x86. There's also a leading
 821     // '\x01' here which disables LLVM's symbol mangling (e.g., no extra
 822     // underscores added in front).
 823     let prefix = if cgcx.target_arch == "x86" {
 824         "\x01__imp__"
 825     } else {
 826         "\x01__imp_"
 827     };
 828
 829     unsafe {
 830         let i8p_ty = Type::i8p_llcx(llcx);
 831         let globals = base::iter_globals(llmod)
 832             .filter(|&val| {
 833                 llvm::LLVMRustGetLinkage(val) == llvm::Linkage::ExternalLinkage &&
 834                     llvm::LLVMIsDeclaration(val) == 0
 835             })
 836             .filter_map(|val| {
 837                 // Exclude some symbols that we know are not Rust symbols.
 838                 let name = llvm::get_value_name(val);
 839                 if ignored(name) {
 840                     None
 841                 } else {
 842                     Some((val, name))
 843                 }
 844             })
 845             .map(move |(val, name)| {
 846                 let mut imp_name = prefix.as_bytes().to_vec();
 847                 imp_name.extend(name);
 848                 let imp_name = CString::new(imp_name).unwrap();
 849                 (imp_name, val)
 850             })
 851             .collect::<Vec<_>>();
 852
 853         for (imp_name, val) in globals {
 854             let imp = llvm::LLVMAddGlobal(llmod,
 855                                           i8p_ty,
 856                                           imp_name.as_ptr().cast());
 857             llvm::LLVMSetInitializer(imp, consts::ptrcast(val, i8p_ty));
 858             llvm::LLVMRustSetLinkage(imp, llvm::Linkage::ExternalLinkage);
 859         }
 860     }
 861
 862     // Use this function to exclude certain symbols from `__imp` generation.
 863     fn ignored(symbol_name: &[u8]) -> bool {
 864         // These are symbols generated by LLVM's profiling instrumentation
 865         symbol_name.starts_with(b"__llvm_profile_")
 866     }
 867 }