src/librustc_llvm/build.rs

   1 // Copyright 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 extern crate cc;
  12 extern crate build_helper;
  13
  14 use std::process::Command;
  15 use std::env;
  16 use std::path::{PathBuf, Path};
  17
  18 use build_helper::output;
  19
  20 fn detect_llvm_link() -> (&'static str, &'static str) {
  21     // Force the link mode we want, preferring static by default, but
  22     // possibly overridden by `configure --enable-llvm-link-shared`.
  23     if env::var_os("LLVM_LINK_SHARED").is_some() {
  24         ("dylib", "--link-shared")
  25     } else {
  26         ("static", "--link-static")
  27     }
  28 }
  29
  30 fn main() {
  31     let target = env::var("TARGET").expect("TARGET was not set");
  32     let llvm_config = env::var_os("LLVM_CONFIG")
  33         .map(PathBuf::from)
  34         .unwrap_or_else(|| {
  35             if let Some(dir) = env::var_os("CARGO_TARGET_DIR").map(PathBuf::from) {
  36                 let to_test = dir.parent()
  37                     .unwrap()
  38                     .parent()
  39                     .unwrap()
  40                     .join(&target)
  41                     .join("llvm/bin/llvm-config");
  42                 if Command::new(&to_test).output().is_ok() {
  43                     return to_test;
  44                 }
  45             }
  46             PathBuf::from("llvm-config")
  47         });
  48
  49     println!("cargo:rerun-if-changed={}", llvm_config.display());
  50     println!("cargo:rerun-if-env-changed=LLVM_CONFIG");
  51
  52     // Test whether we're cross-compiling LLVM. This is a pretty rare case
  53     // currently where we're producing an LLVM for a different platform than
  54     // what this build script is currently running on.
  55     //
  56     // In that case, there's no guarantee that we can actually run the target,
  57     // so the build system works around this by giving us the LLVM_CONFIG for
  58     // the host platform. This only really works if the host LLVM and target
  59     // LLVM are compiled the same way, but for us that's typically the case.
  60     //
  61     // We *want* detect this cross compiling situation by asking llvm-config
  62     // what it's host-target is. If that's not the TARGET, then we're cross
  63     // compiling. Unfortunately `llvm-config` seems either be buggy, or we're
  64     // misconfiguring it, because the `i686-pc-windows-gnu` build of LLVM will
  65     // report itself with a `--host-target` of `x86_64-pc-windows-gnu`. This
  66     // tricks us into thinking we're doing a cross build when we aren't, so
  67     // havoc ensues.
  68     //
  69     // In any case, if we're cross compiling, this generally just means that we
  70     // can't trust all the output of llvm-config becaues it might be targeted
  71     // for the host rather than the target. As a result a bunch of blocks below
  72     // are gated on `if !is_crossed`
  73     let target = env::var("TARGET").expect("TARGET was not set");
  74     let host = env::var("HOST").expect("HOST was not set");
  75     let is_crossed = target != host;
  76
  77     let mut optional_components =
  78         vec!["x86", "arm", "aarch64", "mips", "powerpc",
  79              "systemz", "jsbackend", "webassembly", "msp430", "sparc", "nvptx"];
  80
  81     let mut version_cmd = Command::new(&llvm_config);
  82     version_cmd.arg("--version");
  83     let version_output = output(&mut version_cmd);
  84     let mut parts = version_output.split('.').take(2)
  85         .filter_map(|s| s.parse::<u32>().ok());
  86     let (major, _minor) =
  87         if let (Some(major), Some(minor)) = (parts.next(), parts.next()) {
  88             (major, minor)
  89         } else {
  90             (3, 9)
  91         };
  92
  93     if major > 3 {
  94         optional_components.push("hexagon");
  95     }
  96
  97     // FIXME: surely we don't need all these components, right? Stuff like mcjit
  98     //        or interpreter the compiler itself never uses.
  99     let required_components = &["ipo",
 100                                 "bitreader",
 101                                 "bitwriter",
 102                                 "linker",
 103                                 "asmparser",
 104                                 "mcjit",
 105                                 "lto",
 106                                 "interpreter",
 107                                 "instrumentation"];
 108
 109     let components = output(Command::new(&llvm_config).arg("--components"));
 110     let mut components = components.split_whitespace().collect::<Vec<_>>();
 111     components.retain(|c| optional_components.contains(c) || required_components.contains(c));
 112
 113     for component in required_components {
 114         if !components.contains(component) {
 115             panic!("require llvm component {} but wasn't found", component);
 116         }
 117     }
 118
 119     for component in components.iter() {
 120         println!("cargo:rustc-cfg=llvm_component=\"{}\"", component);
 121     }
 122
 123     // Link in our own LLVM shims, compiled with the same flags as LLVM
 124     let mut cmd = Command::new(&llvm_config);
 125     cmd.arg("--cxxflags");
 126     let cxxflags = output(&mut cmd);
 127     let mut cfg = cc::Build::new();
 128     cfg.warnings(false);
 129     for flag in cxxflags.split_whitespace() {
 130         // Ignore flags like `-m64` when we're doing a cross build
 131         if is_crossed && flag.starts_with("-m") {
 132             continue;
 133         }
 134
 135         // -Wdate-time is not supported by the netbsd cross compiler
 136         if is_crossed && target.contains("netbsd") && flag.contains("date-time") {
 137             continue;
 138         }
 139
 140         cfg.flag(flag);
 141     }
 142
 143     for component in &components {
 144         let mut flag = String::from("LLVM_COMPONENT_");
 145         flag.push_str(&component.to_uppercase());
 146         cfg.define(&flag, None);
 147     }
 148
 149     println!("cargo:rerun-if-changed-env=LLVM_RUSTLLVM");
 150     if env::var_os("LLVM_RUSTLLVM").is_some() {
 151         cfg.define("LLVM_RUSTLLVM", None);
 152     }
 153
 154     build_helper::rerun_if_changed_anything_in_dir(Path::new("../rustllvm"));
 155     cfg.file("../rustllvm/PassWrapper.cpp")
 156        .file("../rustllvm/RustWrapper.cpp")
 157        .file("../rustllvm/ArchiveWrapper.cpp")
 158        .cpp(true)
 159        .cpp_link_stdlib(None) // we handle this below
 160        .compile("rustllvm");
 161
 162     let (llvm_kind, llvm_link_arg) = detect_llvm_link();
 163
 164     // Link in all LLVM libraries, if we're uwring the "wrong" llvm-config then
 165     // we don't pick up system libs because unfortunately they're for the host
 166     // of llvm-config, not the target that we're attempting to link.
 167     let mut cmd = Command::new(&llvm_config);
 168     cmd.arg(llvm_link_arg).arg("--libs");
 169
 170     if !is_crossed {
 171         cmd.arg("--system-libs");
 172     }
 173     cmd.args(&components);
 174
 175     for lib in output(&mut cmd).split_whitespace() {
 176         let name = if lib.starts_with("-l") {
 177             &lib[2..]
 178         } else if lib.starts_with("-") {
 179             &lib[1..]
 180         } else if Path::new(lib).exists() {
 181             // On MSVC llvm-config will print the full name to libraries, but
 182             // we're only interested in the name part
 183             let name = Path::new(lib).file_name().unwrap().to_str().unwrap();
 184             name.trim_right_matches(".lib")
 185         } else if lib.ends_with(".lib") {
 186             // Some MSVC libraries just come up with `.lib` tacked on, so chop
 187             // that off
 188             lib.trim_right_matches(".lib")
 189         } else {
 190             continue;
 191         };
 192
 193         // Don't need or want this library, but LLVM's CMake build system
 194         // doesn't provide a way to disable it, so filter it here even though we
 195         // may or may not have built it. We don't reference anything from this
 196         // library and it otherwise may just pull in extra dependencies on
 197         // libedit which we don't want
 198         if name == "LLVMLineEditor" {
 199             continue;
 200         }
 201
 202         let kind = if name.starts_with("LLVM") {
 203             llvm_kind
 204         } else {
 205             "dylib"
 206         };
 207         println!("cargo:rustc-link-lib={}={}", kind, name);
 208     }
 209
 210     // LLVM ldflags
 211     //
 212     // If we're a cross-compile of LLVM then unfortunately we can't trust these
 213     // ldflags (largely where all the LLVM libs are located). Currently just
 214     // hack around this by replacing the host triple with the target and pray
 215     // that those -L directories are the same!
 216     let mut cmd = Command::new(&llvm_config);
 217     cmd.arg(llvm_link_arg).arg("--ldflags");
 218     for lib in output(&mut cmd).split_whitespace() {
 219         if lib.starts_with("-LIBPATH:") {
 220             println!("cargo:rustc-link-search=native={}", &lib[9..]);
 221         } else if is_crossed {
 222             if lib.starts_with("-L") {
 223                 println!("cargo:rustc-link-search=native={}",
 224                          lib[2..].replace(&host, &target));
 225             }
 226         } else if lib.starts_with("-l") {
 227             println!("cargo:rustc-link-lib={}", &lib[2..]);
 228         } else if lib.starts_with("-L") {
 229             println!("cargo:rustc-link-search=native={}", &lib[2..]);
 230         }
 231     }
 232
 233     let llvm_static_stdcpp = env::var_os("LLVM_STATIC_STDCPP");
 234
 235     let stdcppname = if target.contains("openbsd") {
 236         // llvm-config on OpenBSD doesn't mention stdlib=libc++
 237         "c++"
 238     } else if target.contains("freebsd") {
 239         "c++"
 240     } else if target.contains("netbsd") && llvm_static_stdcpp.is_some() {
 241         // NetBSD uses a separate library when relocation is required
 242         "stdc++_pic"
 243     } else {
 244         "stdc++"
 245     };
 246
 247     // C++ runtime library
 248     if !target.contains("msvc") {
 249         if let Some(s) = llvm_static_stdcpp {
 250             assert!(!cxxflags.contains("stdlib=libc++"));
 251             let path = PathBuf::from(s);
 252             println!("cargo:rustc-link-search=native={}",
 253                      path.parent().unwrap().display());
 254             println!("cargo:rustc-link-lib=static={}", stdcppname);
 255         } else if cxxflags.contains("stdlib=libc++") {
 256             println!("cargo:rustc-link-lib=c++");
 257         } else {
 258             println!("cargo:rustc-link-lib={}", stdcppname);
 259         }
 260     }
 261
 262     // LLVM requires symbols from this library, but apparently they're not printed
 263     // during llvm-config?
 264     if target.contains("windows-gnu") {
 265         println!("cargo:rustc-link-lib=static-nobundle=gcc_s");
 266         println!("cargo:rustc-link-lib=static-nobundle=pthread");
 267     }
 268 }