src/librustc_back/target/mod.rs

   1 // Copyright 2014-2015 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 //! [Flexible target specification.](https://github.com/rust-lang/rfcs/pull/131)
  12 //!
  13 //! Rust targets a wide variety of usecases, and in the interest of flexibility,
  14 //! allows new target triples to be defined in configuration files. Most users
  15 //! will not need to care about these, but this is invaluable when porting Rust
  16 //! to a new platform, and allows for an unprecedented level of control over how
  17 //! the compiler works.
  18 //!
  19 //! # Using custom targets
  20 //!
  21 //! A target triple, as passed via `rustc --target=TRIPLE`, will first be
  22 //! compared against the list of built-in targets. This is to ease distributing
  23 //! rustc (no need for configuration files) and also to hold these built-in
  24 //! targets as immutable and sacred. If `TRIPLE` is not one of the built-in
  25 //! targets, rustc will check if a file named `TRIPLE` exists. If it does, it
  26 //! will be loaded as the target configuration. If the file does not exist,
  27 //! rustc will search each directory in the environment variable
  28 //! `RUST_TARGET_PATH` for a file named `TRIPLE.json`. The first one found will
  29 //! be loaded. If no file is found in any of those directories, a fatal error
  30 //! will be given.  `RUST_TARGET_PATH` includes `/etc/rustc` as its last entry,
  31 //! to be searched by default.
  32 //!
  33 //! Projects defining their own targets should use
  34 //! `--target=path/to/my-awesome-platform.json` instead of adding to
  35 //! `RUST_TARGET_PATH`.
  36 //!
  37 //! # Defining a new target
  38 //!
  39 //! Targets are defined using [JSON](http://json.org/). The `Target` struct in
  40 //! this module defines the format the JSON file should take, though each
  41 //! underscore in the field names should be replaced with a hyphen (`-`) in the
  42 //! JSON file. Some fields are required in every target specification, such as
  43 //! `data-layout`, `llvm-target`, `target-endian`, `target-pointer-width`, and
  44 //! `arch`. In general, options passed to rustc with `-C` override the target's
  45 //! settings, though `target-feature` and `link-args` will *add* to the list
  46 //! specified by the target, rather than replace.
  47
  48 use serialize::json::Json;
  49 use std::default::Default;
  50 use std::io::prelude::*;
  51 use syntax::abi;
  52
  53 mod android_base;
  54 mod apple_base;
  55 mod apple_ios_base;
  56 mod bitrig_base;
  57 mod dragonfly_base;
  58 mod freebsd_base;
  59 mod linux_base;
  60 mod openbsd_base;
  61 mod netbsd_base;
  62 mod windows_base;
  63 mod windows_msvc_base;
  64
  65 /// Everything `rustc` knows about how to compile for a specific target.
  66 ///
  67 /// Every field here must be specified, and has no default value.
  68 #[derive(Clone, Debug)]
  69 pub struct Target {
  70     /// Target triple to pass to LLVM.
  71     pub llvm_target: String,
  72     /// String to use as the `target_endian` `cfg` variable.
  73     pub target_endian: String,
  74     /// String to use as the `target_pointer_width` `cfg` variable.
  75     pub target_pointer_width: String,
  76     /// OS name to use for conditional compilation.
  77     pub target_os: String,
  78     /// Environment name to use for conditional compilation.
  79     pub target_env: String,
  80     /// Vendor name to use for conditional compilation.
  81     pub target_vendor: String,
  82     /// Architecture to use for ABI considerations. Valid options: "x86", "x86_64", "arm",
  83     /// "aarch64", "mips", "powerpc", "powerpc64" and "powerpc64le". "mips" includes "mipsel".
  84     pub arch: String,
  85     /// Optional settings with defaults.
  86     pub options: TargetOptions,
  87 }
  88
  89 /// Optional aspects of a target specification.
  90 ///
  91 /// This has an implementation of `Default`, see each field for what the default is. In general,
  92 /// these try to take "minimal defaults" that don't assume anything about the runtime they run in.
  93 #[derive(Clone, Debug)]
  94 pub struct TargetOptions {
  95     /// [Data layout](http://llvm.org/docs/LangRef.html#data-layout) to pass to LLVM.
  96     pub data_layout: Option<String>,
  97     /// Linker to invoke. Defaults to "cc".
  98     pub linker: String,
  99     /// Archive utility to use when managing archives. Defaults to "ar".
 100     pub ar: String,
 101
 102     /// Linker arguments that are unconditionally passed *before* any
 103     /// user-defined libraries.
 104     pub pre_link_args: Vec<String>,
 105     /// Objects to link before all others, always found within the
 106     /// sysroot folder.
 107     pub pre_link_objects_exe: Vec<String>, // ... when linking an executable
 108     pub pre_link_objects_dll: Vec<String>, // ... when linking a dylib
 109     /// Linker arguments that are unconditionally passed after any
 110     /// user-defined but before post_link_objects.  Standard platform
 111     /// libraries that should be always be linked to, usually go here.
 112     pub late_link_args: Vec<String>,
 113     /// Objects to link after all others, always found within the
 114     /// sysroot folder.
 115     pub post_link_objects: Vec<String>,
 116     /// Linker arguments that are unconditionally passed *after* any
 117     /// user-defined libraries.
 118     pub post_link_args: Vec<String>,
 119
 120     /// Default CPU to pass to LLVM. Corresponds to `llc -mcpu=$cpu`. Defaults
 121     /// to "default".
 122     pub cpu: String,
 123     /// Default target features to pass to LLVM. These features will *always* be
 124     /// passed, and cannot be disabled even via `-C`. Corresponds to `llc
 125     /// -mattr=$features`.
 126     pub features: String,
 127     /// Whether dynamic linking is available on this target. Defaults to false.
 128     pub dynamic_linking: bool,
 129     /// Whether executables are available on this target. iOS, for example, only allows static
 130     /// libraries. Defaults to false.
 131     pub executables: bool,
 132     /// Relocation model to use in object file. Corresponds to `llc
 133     /// -relocation-model=$relocation_model`. Defaults to "pic".
 134     pub relocation_model: String,
 135     /// Code model to use. Corresponds to `llc -code-model=$code_model`. Defaults to "default".
 136     pub code_model: String,
 137     /// Do not emit code that uses the "red zone", if the ABI has one. Defaults to false.
 138     pub disable_redzone: bool,
 139     /// Eliminate frame pointers from stack frames if possible. Defaults to true.
 140     pub eliminate_frame_pointer: bool,
 141     /// Emit each function in its own section. Defaults to true.
 142     pub function_sections: bool,
 143     /// String to prepend to the name of every dynamic library. Defaults to "lib".
 144     pub dll_prefix: String,
 145     /// String to append to the name of every dynamic library. Defaults to ".so".
 146     pub dll_suffix: String,
 147     /// String to append to the name of every executable.
 148     pub exe_suffix: String,
 149     /// String to prepend to the name of every static library. Defaults to "lib".
 150     pub staticlib_prefix: String,
 151     /// String to append to the name of every static library. Defaults to ".a".
 152     pub staticlib_suffix: String,
 153     /// OS family to use for conditional compilation. Valid options: "unix", "windows".
 154     pub target_family: Option<String>,
 155     /// Whether the target toolchain is like OSX's. Only useful for compiling against iOS/OS X, in
 156     /// particular running dsymutil and some other stuff like `-dead_strip`. Defaults to false.
 157     pub is_like_osx: bool,
 158     /// Whether the target toolchain is like Windows'. Only useful for compiling against Windows,
 159     /// only really used for figuring out how to find libraries, since Windows uses its own
 160     /// library naming convention. Defaults to false.
 161     pub is_like_windows: bool,
 162     pub is_like_msvc: bool,
 163     /// Whether the target toolchain is like Android's. Only useful for compiling against Android.
 164     /// Defaults to false.
 165     pub is_like_android: bool,
 166     /// Whether the linker support GNU-like arguments such as -O. Defaults to false.
 167     pub linker_is_gnu: bool,
 168     /// Whether the linker support rpaths or not. Defaults to false.
 169     pub has_rpath: bool,
 170     /// Whether to disable linking to compiler-rt. Defaults to false, as LLVM
 171     /// will emit references to the functions that compiler-rt provides.
 172     pub no_compiler_rt: bool,
 173     /// Whether to disable linking to the default libraries, typically corresponds
 174     /// to `-nodefaultlibs`. Defaults to true.
 175     pub no_default_libraries: bool,
 176     /// Dynamically linked executables can be compiled as position independent
 177     /// if the default relocation model of position independent code is not
 178     /// changed. This is a requirement to take advantage of ASLR, as otherwise
 179     /// the functions in the executable are not randomized and can be used
 180     /// during an exploit of a vulnerability in any code.
 181     pub position_independent_executables: bool,
 182     /// Format that archives should be emitted in. This affects whether we use
 183     /// LLVM to assemble an archive or fall back to the system linker, and
 184     /// currently only "gnu" is used to fall into LLVM. Unknown strings cause
 185     /// the system linker to be used.
 186     pub archive_format: String,
 187     /// Is asm!() allowed? Defaults to true.
 188     pub allow_asm: bool,
 189     /// Whether the target uses a custom unwind resumption routine.
 190     /// By default LLVM lowers `resume` instructions into calls to `_Unwind_Resume`
 191     /// defined in libgcc.  If this option is enabled, the target must provide
 192     /// `eh_unwind_resume` lang item.
 193     pub custom_unwind_resume: bool,
 194
 195     /// Default crate for allocation symbols to link against
 196     pub lib_allocation_crate: String,
 197     pub exe_allocation_crate: String,
 198
 199     /// Flag indicating whether ELF TLS (e.g. #[thread_local]) is available for
 200     /// this target.
 201     pub has_elf_tls: bool,
 202 }
 203
 204 impl Default for TargetOptions {
 205     /// Create a set of "sane defaults" for any target. This is still
 206     /// incomplete, and if used for compilation, will certainly not work.
 207     fn default() -> TargetOptions {
 208         TargetOptions {
 209             data_layout: None,
 210             linker: option_env!("CFG_DEFAULT_LINKER").unwrap_or("cc").to_string(),
 211             ar: option_env!("CFG_DEFAULT_AR").unwrap_or("ar").to_string(),
 212             pre_link_args: Vec::new(),
 213             post_link_args: Vec::new(),
 214             cpu: "generic".to_string(),
 215             features: "".to_string(),
 216             dynamic_linking: false,
 217             executables: false,
 218             relocation_model: "pic".to_string(),
 219             code_model: "default".to_string(),
 220             disable_redzone: false,
 221             eliminate_frame_pointer: true,
 222             function_sections: true,
 223             dll_prefix: "lib".to_string(),
 224             dll_suffix: ".so".to_string(),
 225             exe_suffix: "".to_string(),
 226             staticlib_prefix: "lib".to_string(),
 227             staticlib_suffix: ".a".to_string(),
 228             target_family: None,
 229             is_like_osx: false,
 230             is_like_windows: false,
 231             is_like_android: false,
 232             is_like_msvc: false,
 233             linker_is_gnu: false,
 234             has_rpath: false,
 235             no_compiler_rt: false,
 236             no_default_libraries: true,
 237             position_independent_executables: false,
 238             pre_link_objects_exe: Vec::new(),
 239             pre_link_objects_dll: Vec::new(),
 240             post_link_objects: Vec::new(),
 241             late_link_args: Vec::new(),
 242             archive_format: String::new(),
 243             custom_unwind_resume: false,
 244             lib_allocation_crate: "alloc_system".to_string(),
 245             exe_allocation_crate: "alloc_system".to_string(),
 246             allow_asm: true,
 247             has_elf_tls: false,
 248         }
 249     }
 250 }
 251
 252 impl Target {
 253     /// Given a function ABI, turn "System" into the correct ABI for this target.
 254     pub fn adjust_abi(&self, abi: abi::Abi) -> abi::Abi {
 255         match abi {
 256             abi::System => {
 257                 if self.options.is_like_windows && self.arch == "x86" {
 258                     abi::Stdcall
 259                 } else {
 260                     abi::C
 261                 }
 262             },
 263             abi => abi
 264         }
 265     }
 266
 267     /// Load a target descriptor from a JSON object.
 268     pub fn from_json(obj: Json) -> Target {
 269         // this is 1. ugly, 2. error prone.
 270
 271         let get_req_field = |name: &str| {
 272             match obj.find(name)
 273                      .map(|s| s.as_string())
 274                      .and_then(|os| os.map(|s| s.to_string())) {
 275                 Some(val) => val,
 276                 None => {
 277                     panic!("Field {} in target specification is required", name)
 278                 }
 279             }
 280         };
 281
 282         let get_opt_field = |name: &str, default: &str| {
 283             obj.find(name).and_then(|s| s.as_string())
 284                .map(|s| s.to_string())
 285                .unwrap_or(default.to_string())
 286         };
 287
 288         let mut base = Target {
 289             llvm_target: get_req_field("llvm-target"),
 290             target_endian: get_req_field("target-endian"),
 291             target_pointer_width: get_req_field("target-pointer-width"),
 292             arch: get_req_field("arch"),
 293             target_os: get_req_field("os"),
 294             target_env: get_opt_field("env", ""),
 295             target_vendor: get_opt_field("vendor", "unknown"),
 296             options: Default::default(),
 297         };
 298
 299         macro_rules! key {
 300             ($key_name:ident) => ( {
 301                 let name = (stringify!($key_name)).replace("_", "-");
 302                 obj.find(&name[..]).map(|o| o.as_string()
 303                                     .map(|s| base.options.$key_name = s.to_string()));
 304             } );
 305             ($key_name:ident, bool) => ( {
 306                 let name = (stringify!($key_name)).replace("_", "-");
 307                 obj.find(&name[..])
 308                     .map(|o| o.as_boolean()
 309                          .map(|s| base.options.$key_name = s));
 310             } );
 311             ($key_name:ident, list) => ( {
 312                 let name = (stringify!($key_name)).replace("_", "-");
 313                 obj.find(&name[..]).map(|o| o.as_array()
 314                     .map(|v| base.options.$key_name = v.iter()
 315                         .map(|a| a.as_string().unwrap().to_string()).collect()
 316                         )
 317                     );
 318             } );
 319             ($key_name:ident, optional) => ( {
 320                 let name = (stringify!($key_name)).replace("_", "-");
 321                 if let Some(o) = obj.find(&name[..]) {
 322                     base.options.$key_name = o
 323                         .as_string()
 324                         .map(|s| s.to_string() );
 325                 }
 326             } );
 327         }
 328
 329         key!(cpu);
 330         key!(ar);
 331         key!(linker);
 332         key!(relocation_model);
 333         key!(code_model);
 334         key!(dll_prefix);
 335         key!(dll_suffix);
 336         key!(exe_suffix);
 337         key!(staticlib_prefix);
 338         key!(staticlib_suffix);
 339         key!(features);
 340         key!(data_layout, optional);
 341         key!(dynamic_linking, bool);
 342         key!(executables, bool);
 343         key!(disable_redzone, bool);
 344         key!(eliminate_frame_pointer, bool);
 345         key!(function_sections, bool);
 346         key!(target_family, optional);
 347         key!(is_like_osx, bool);
 348         key!(is_like_windows, bool);
 349         key!(linker_is_gnu, bool);
 350         key!(has_rpath, bool);
 351         key!(no_compiler_rt, bool);
 352         key!(no_default_libraries, bool);
 353         key!(pre_link_args, list);
 354         key!(post_link_args, list);
 355         key!(archive_format);
 356         key!(allow_asm, bool);
 357         key!(custom_unwind_resume, bool);
 358
 359         base
 360     }
 361
 362     /// Search RUST_TARGET_PATH for a JSON file specifying the given target
 363     /// triple. Note that it could also just be a bare filename already, so also
 364     /// check for that. If one of the hardcoded targets we know about, just
 365     /// return it directly.
 366     ///
 367     /// The error string could come from any of the APIs called, including
 368     /// filesystem access and JSON decoding.
 369     pub fn search(target: &str) -> Result<Target, String> {
 370         use std::env;
 371         use std::ffi::OsString;
 372         use std::fs::File;
 373         use std::path::{Path, PathBuf};
 374         use serialize::json;
 375
 376         fn load_file(path: &Path) -> Result<Target, String> {
 377             let mut f = try!(File::open(path).map_err(|e| e.to_string()));
 378             let mut contents = Vec::new();
 379             try!(f.read_to_end(&mut contents).map_err(|e| e.to_string()));
 380             let obj = try!(json::from_reader(&mut &contents[..])
 381                                 .map_err(|e| e.to_string()));
 382             Ok(Target::from_json(obj))
 383         }
 384
 385         // this would use a match if stringify! were allowed in pattern position
 386         macro_rules! load_specific {
 387             ( $($name:ident),+ ) => (
 388                 {
 389                     $(mod $name;)*
 390                     let target = target.replace("-", "_");
 391                     if false { }
 392                     $(
 393                         else if target == stringify!($name) {
 394                             let t = $name::target();
 395                             debug!("Got builtin target: {:?}", t);
 396                             return Ok(t);
 397                         }
 398                     )*
 399                     else if target == "x86_64-w64-mingw32" {
 400                         let t = x86_64_pc_windows_gnu::target();
 401                         return Ok(t);
 402                     } else if target == "i686-w64-mingw32" {
 403                         let t = i686_pc_windows_gnu::target();
 404                         return Ok(t);
 405                     }
 406                 }
 407             )
 408         }
 409
 410         load_specific!(
 411             x86_64_unknown_linux_gnu,
 412             i686_unknown_linux_gnu,
 413             mips_unknown_linux_gnu,
 414             mipsel_unknown_linux_gnu,
 415             powerpc_unknown_linux_gnu,
 416             powerpc64_unknown_linux_gnu,
 417             powerpc64le_unknown_linux_gnu,
 418             arm_unknown_linux_gnueabi,
 419             arm_unknown_linux_gnueabihf,
 420             aarch64_unknown_linux_gnu,
 421             x86_64_unknown_linux_musl,
 422
 423             i686_linux_android,
 424             arm_linux_androideabi,
 425             aarch64_linux_android,
 426
 427             i686_unknown_freebsd,
 428             x86_64_unknown_freebsd,
 429
 430             i686_unknown_dragonfly,
 431             x86_64_unknown_dragonfly,
 432
 433             x86_64_unknown_bitrig,
 434             x86_64_unknown_openbsd,
 435             x86_64_unknown_netbsd,
 436             x86_64_rumprun_netbsd,
 437
 438             x86_64_apple_darwin,
 439             i686_apple_darwin,
 440
 441             i386_apple_ios,
 442             x86_64_apple_ios,
 443             aarch64_apple_ios,
 444             armv7_apple_ios,
 445             armv7s_apple_ios,
 446
 447             x86_64_pc_windows_gnu,
 448             i686_pc_windows_gnu,
 449
 450             x86_64_pc_windows_msvc,
 451             i686_pc_windows_msvc,
 452
 453             le32_unknown_nacl
 454         );
 455
 456
 457         let path = Path::new(target);
 458
 459         if path.is_file() {
 460             return load_file(&path);
 461         }
 462
 463         let path = {
 464             let mut target = target.to_string();
 465             target.push_str(".json");
 466             PathBuf::from(target)
 467         };
 468
 469         let target_path = env::var_os("RUST_TARGET_PATH")
 470                               .unwrap_or(OsString::new());
 471
 472         // FIXME 16351: add a sane default search path?
 473
 474         for dir in env::split_paths(&target_path) {
 475             let p =  dir.join(&path);
 476             if p.is_file() {
 477                 return load_file(&p);
 478             }
 479         }
 480
 481         Err(format!("Could not find specification for target {:?}", target))
 482     }
 483 }
 484
 485 fn maybe_jemalloc() -> String {
 486     if cfg!(disable_jemalloc) {
 487         "alloc_system".to_string()
 488     } else {
 489         "alloc_jemalloc".to_string()
 490     }
 491 }