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::{diagnostic, 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 windows_base;
  62
  63 /// Everything `rustc` knows about how to compile for a specific target.
  64 ///
  65 /// Every field here must be specified, and has no default value.
  66 #[derive(Clone, Debug)]
  67 pub struct Target {
  68     /// [Data layout](http://llvm.org/docs/LangRef.html#data-layout) to pass to LLVM.
  69     pub data_layout: String,
  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     /// Architecture to use for ABI considerations. Valid options: "x86", "x86_64", "arm",
  81     /// "aarch64", "mips", and "powerpc". "mips" includes "mipsel".
  82     pub arch: String,
  83     /// Optional settings with defaults.
  84     pub options: TargetOptions,
  85 }
  86
  87 /// Optional aspects of a target specification.
  88 ///
  89 /// This has an implementation of `Default`, see each field for what the default is. In general,
  90 /// these try to take "minimal defaults" that don't assume anything about the runtime they run in.
  91 #[derive(Clone, Debug)]
  92 pub struct TargetOptions {
  93     /// Linker to invoke. Defaults to "cc".
  94     pub linker: String,
  95     /// Linker arguments that are unconditionally passed *before* any
  96     /// user-defined libraries.
  97     pub pre_link_args: Vec<String>,
  98     /// Linker arguments that are unconditionally passed *after* any
  99     /// user-defined libraries.
 100     pub post_link_args: Vec<String>,
 101     /// Objects to link before and after all others, always found within the
 102     /// sysroot folder.
 103     pub pre_link_objects: Vec<String>,
 104     pub post_link_objects: Vec<String>,
 105     /// Default CPU to pass to LLVM. Corresponds to `llc -mcpu=$cpu`. Defaults
 106     /// to "default".
 107     pub cpu: String,
 108     /// Default target features to pass to LLVM. These features will *always* be
 109     /// passed, and cannot be disabled even via `-C`. Corresponds to `llc
 110     /// -mattr=$features`.
 111     pub features: String,
 112     /// Whether dynamic linking is available on this target. Defaults to false.
 113     pub dynamic_linking: bool,
 114     /// Whether executables are available on this target. iOS, for example, only allows static
 115     /// libraries. Defaults to false.
 116     pub executables: bool,
 117     /// Whether LLVM's segmented stack prelude is supported by whatever runtime is available.
 118     /// Will emit stack checks and calls to __morestack. Defaults to false.
 119     pub morestack: bool,
 120     /// Relocation model to use in object file. Corresponds to `llc
 121     /// -relocation-model=$relocation_model`. Defaults to "pic".
 122     pub relocation_model: String,
 123     /// Code model to use. Corresponds to `llc -code-model=$code_model`. Defaults to "default".
 124     pub code_model: String,
 125     /// Do not emit code that uses the "red zone", if the ABI has one. Defaults to false.
 126     pub disable_redzone: bool,
 127     /// Eliminate frame pointers from stack frames if possible. Defaults to true.
 128     pub eliminate_frame_pointer: bool,
 129     /// Emit each function in its own section. Defaults to true.
 130     pub function_sections: bool,
 131     /// String to prepend to the name of every dynamic library. Defaults to "lib".
 132     pub dll_prefix: String,
 133     /// String to append to the name of every dynamic library. Defaults to ".so".
 134     pub dll_suffix: String,
 135     /// String to append to the name of every executable.
 136     pub exe_suffix: String,
 137     /// String to prepend to the name of every static library. Defaults to "lib".
 138     pub staticlib_prefix: String,
 139     /// String to append to the name of every static library. Defaults to ".a".
 140     pub staticlib_suffix: String,
 141     /// Whether the target toolchain is like OSX's. Only useful for compiling against iOS/OS X, in
 142     /// particular running dsymutil and some other stuff like `-dead_strip`. Defaults to false.
 143     pub is_like_osx: bool,
 144     /// Whether the target toolchain is like Windows'. Only useful for compiling against Windows,
 145     /// only really used for figuring out how to find libraries, since Windows uses its own
 146     /// library naming convention. Defaults to false.
 147     pub is_like_windows: bool,
 148     /// Whether the target toolchain is like Android's. Only useful for compiling against Android.
 149     /// Defaults to false.
 150     pub is_like_android: bool,
 151     /// Whether the linker support GNU-like arguments such as -O. Defaults to false.
 152     pub linker_is_gnu: bool,
 153     /// Whether the linker support rpaths or not. Defaults to false.
 154     pub has_rpath: bool,
 155     /// Whether to disable linking to compiler-rt. Defaults to false, as LLVM will emit references
 156     /// to the functions that compiler-rt provides.
 157     pub no_compiler_rt: bool,
 158     /// Dynamically linked executables can be compiled as position independent if the default
 159     /// relocation model of position independent code is not changed. This is a requirement to take
 160     /// advantage of ASLR, as otherwise the functions in the executable are not randomized and can
 161     /// be used during an exploit of a vulnerability in any code.
 162     pub position_independent_executables: bool,
 163 }
 164
 165 impl Default for TargetOptions {
 166     /// Create a set of "sane defaults" for any target. This is still incomplete, and if used for
 167     /// compilation, will certainly not work.
 168     fn default() -> TargetOptions {
 169         TargetOptions {
 170             linker: "cc".to_string(),
 171             pre_link_args: Vec::new(),
 172             post_link_args: Vec::new(),
 173             cpu: "generic".to_string(),
 174             features: "".to_string(),
 175             dynamic_linking: false,
 176             executables: false,
 177             morestack: false,
 178             relocation_model: "pic".to_string(),
 179             code_model: "default".to_string(),
 180             disable_redzone: false,
 181             eliminate_frame_pointer: true,
 182             function_sections: true,
 183             dll_prefix: "lib".to_string(),
 184             dll_suffix: ".so".to_string(),
 185             exe_suffix: "".to_string(),
 186             staticlib_prefix: "lib".to_string(),
 187             staticlib_suffix: ".a".to_string(),
 188             is_like_osx: false,
 189             is_like_windows: false,
 190             is_like_android: false,
 191             linker_is_gnu: false,
 192             has_rpath: false,
 193             no_compiler_rt: false,
 194             position_independent_executables: false,
 195             pre_link_objects: Vec::new(),
 196             post_link_objects: Vec::new(),
 197         }
 198     }
 199 }
 200
 201 impl Target {
 202     /// Given a function ABI, turn "System" into the correct ABI for this target.
 203     pub fn adjust_abi(&self, abi: abi::Abi) -> abi::Abi {
 204         match abi {
 205             abi::System => {
 206                 if self.options.is_like_windows && self.arch == "x86" {
 207                     abi::Stdcall
 208                 } else {
 209                     abi::C
 210                 }
 211             },
 212             abi => abi
 213         }
 214     }
 215
 216     /// Load a target descriptor from a JSON object.
 217     pub fn from_json(obj: Json) -> Target {
 218         // this is 1. ugly, 2. error prone.
 219
 220
 221         let handler = diagnostic::default_handler(diagnostic::Auto, None, true);
 222
 223         let get_req_field = |name: &str| {
 224             match obj.find(name)
 225                      .map(|s| s.as_string())
 226                      .and_then(|os| os.map(|s| s.to_string())) {
 227                 Some(val) => val,
 228                 None =>
 229                     handler.fatal(&format!("Field {} in target specification is required", name))
 230             }
 231         };
 232
 233         let mut base = Target {
 234             data_layout: get_req_field("data-layout"),
 235             llvm_target: get_req_field("llvm-target"),
 236             target_endian: get_req_field("target-endian"),
 237             target_pointer_width: get_req_field("target-pointer-width"),
 238             arch: get_req_field("arch"),
 239             target_os: get_req_field("os"),
 240             target_env: obj.find("env").and_then(|s| s.as_string())
 241                            .map(|s| s.to_string()).unwrap_or(String::new()),
 242             options: Default::default(),
 243         };
 244
 245         macro_rules! key {
 246             ($key_name:ident) => ( {
 247                 let name = (stringify!($key_name)).replace("_", "-");
 248                 obj.find(&name[..]).map(|o| o.as_string()
 249                                     .map(|s| base.options.$key_name = s.to_string()));
 250             } );
 251             ($key_name:ident, bool) => ( {
 252                 let name = (stringify!($key_name)).replace("_", "-");
 253                 obj.find(&name[..])
 254                     .map(|o| o.as_boolean()
 255                          .map(|s| base.options.$key_name = s));
 256             } );
 257             ($key_name:ident, list) => ( {
 258                 let name = (stringify!($key_name)).replace("_", "-");
 259                 obj.find(&name[..]).map(|o| o.as_array()
 260                     .map(|v| base.options.$key_name = v.iter()
 261                         .map(|a| a.as_string().unwrap().to_string()).collect()
 262                         )
 263                     );
 264             } );
 265         }
 266
 267         key!(cpu);
 268         key!(linker);
 269         key!(relocation_model);
 270         key!(code_model);
 271         key!(dll_prefix);
 272         key!(dll_suffix);
 273         key!(exe_suffix);
 274         key!(staticlib_prefix);
 275         key!(staticlib_suffix);
 276         key!(features);
 277         key!(dynamic_linking, bool);
 278         key!(executables, bool);
 279         key!(morestack, bool);
 280         key!(disable_redzone, bool);
 281         key!(eliminate_frame_pointer, bool);
 282         key!(function_sections, bool);
 283         key!(is_like_osx, bool);
 284         key!(is_like_windows, bool);
 285         key!(linker_is_gnu, bool);
 286         key!(has_rpath, bool);
 287         key!(no_compiler_rt, bool);
 288         key!(pre_link_args, list);
 289         key!(post_link_args, list);
 290
 291         base
 292     }
 293
 294     /// Search RUST_TARGET_PATH for a JSON file specifying the given target
 295     /// triple. Note that it could also just be a bare filename already, so also
 296     /// check for that. If one of the hardcoded targets we know about, just
 297     /// return it directly.
 298     ///
 299     /// The error string could come from any of the APIs called, including
 300     /// filesystem access and JSON decoding.
 301     pub fn search(target: &str) -> Result<Target, String> {
 302         use std::env;
 303         use std::ffi::OsString;
 304         use std::fs::File;
 305         use std::path::{Path, PathBuf};
 306         use serialize::json;
 307
 308         fn load_file(path: &Path) -> Result<Target, String> {
 309             let mut f = try!(File::open(path).map_err(|e| e.to_string()));
 310             let mut contents = Vec::new();
 311             try!(f.read_to_end(&mut contents).map_err(|e| e.to_string()));
 312             let obj = try!(json::from_reader(&mut &contents[..])
 313                                 .map_err(|e| e.to_string()));
 314             Ok(Target::from_json(obj))
 315         }
 316
 317         // this would use a match if stringify! were allowed in pattern position
 318         macro_rules! load_specific {
 319             ( $($name:ident),+ ) => (
 320                 {
 321                     $(mod $name;)*
 322                     let target = target.replace("-", "_");
 323                     if false { }
 324                     $(
 325                         else if target == stringify!($name) {
 326                             let t = $name::target();
 327                             debug!("Got builtin target: {:?}", t);
 328                             return Ok(t);
 329                         }
 330                     )*
 331                     else if target == "x86_64-w64-mingw32" {
 332                         let t = x86_64_pc_windows_gnu::target();
 333                         return Ok(t);
 334                     } else if target == "i686-w64-mingw32" {
 335                         let t = i686_pc_windows_gnu::target();
 336                         return Ok(t);
 337                     }
 338                 }
 339             )
 340         }
 341
 342         load_specific!(
 343             x86_64_unknown_linux_gnu,
 344             i686_unknown_linux_gnu,
 345             mips_unknown_linux_gnu,
 346             mipsel_unknown_linux_gnu,
 347             powerpc_unknown_linux_gnu,
 348             arm_unknown_linux_gnueabi,
 349             arm_unknown_linux_gnueabihf,
 350             aarch64_unknown_linux_gnu,
 351             x86_64_unknown_linux_musl,
 352
 353             arm_linux_androideabi,
 354             aarch64_linux_android,
 355
 356             x86_64_unknown_freebsd,
 357
 358             i686_unknown_dragonfly,
 359             x86_64_unknown_dragonfly,
 360
 361             x86_64_unknown_bitrig,
 362             x86_64_unknown_openbsd,
 363
 364             x86_64_apple_darwin,
 365             i686_apple_darwin,
 366
 367             i386_apple_ios,
 368             x86_64_apple_ios,
 369             aarch64_apple_ios,
 370             armv7_apple_ios,
 371             armv7s_apple_ios,
 372
 373             x86_64_pc_windows_gnu,
 374             i686_pc_windows_gnu
 375         );
 376
 377
 378         let path = Path::new(target);
 379
 380         if path.is_file() {
 381             return load_file(&path);
 382         }
 383
 384         let path = {
 385             let mut target = target.to_string();
 386             target.push_str(".json");
 387             PathBuf::from(target)
 388         };
 389
 390         let target_path = env::var_os("RUST_TARGET_PATH")
 391                               .unwrap_or(OsString::new());
 392
 393         // FIXME 16351: add a sane default search path?
 394
 395         for dir in env::split_paths(&target_path) {
 396             let p =  dir.join(&path);
 397             if p.is_file() {
 398                 return load_file(&p);
 399             }
 400         }
 401
 402         Err(format!("Could not find specification for target {:?}", target))
 403     }
 404 }