compiler/rustc_llvm/build.rs

   1 use std::env;
   2 use std::path::{Path, PathBuf};
   3 use std::process::Command;
   4
   5 use build_helper::{output, tracked_env_var_os};
   6
   7 fn detect_llvm_link() -> (&'static str, &'static str) {
   8     // Force the link mode we want, preferring static by default, but
   9     // possibly overridden by `configure --enable-llvm-link-shared`.
  10     if tracked_env_var_os("LLVM_LINK_SHARED").is_some() {
  11         ("dylib", "--link-shared")
  12     } else {
  13         ("static", "--link-static")
  14     }
  15 }
  16
  17 fn main() {
  18     if tracked_env_var_os("RUST_CHECK").is_some() {
  19         // If we're just running `check`, there's no need for LLVM to be built.
  20         return;
  21     }
  22
  23     build_helper::restore_library_path();
  24
  25     let target = env::var("TARGET").expect("TARGET was not set");
  26     let llvm_config =
  27         tracked_env_var_os("LLVM_CONFIG").map(|x| Some(PathBuf::from(x))).unwrap_or_else(|| {
  28             if let Some(dir) = tracked_env_var_os("CARGO_TARGET_DIR").map(PathBuf::from) {
  29                 let to_test = dir
  30                     .parent()
  31                     .unwrap()
  32                     .parent()
  33                     .unwrap()
  34                     .join(&target)
  35                     .join("llvm/bin/llvm-config");
  36                 if Command::new(&to_test).output().is_ok() {
  37                     return Some(to_test);
  38                 }
  39             }
  40             None
  41         });
  42
  43     if let Some(llvm_config) = &llvm_config {
  44         println!("cargo:rerun-if-changed={}", llvm_config.display());
  45     }
  46     let llvm_config = llvm_config.unwrap_or_else(|| PathBuf::from("llvm-config"));
  47
  48     // Test whether we're cross-compiling LLVM. This is a pretty rare case
  49     // currently where we're producing an LLVM for a different platform than
  50     // what this build script is currently running on.
  51     //
  52     // In that case, there's no guarantee that we can actually run the target,
  53     // so the build system works around this by giving us the LLVM_CONFIG for
  54     // the host platform. This only really works if the host LLVM and target
  55     // LLVM are compiled the same way, but for us that's typically the case.
  56     //
  57     // We *want* detect this cross compiling situation by asking llvm-config
  58     // what its host-target is. If that's not the TARGET, then we're cross
  59     // compiling. Unfortunately `llvm-config` seems either be buggy, or we're
  60     // misconfiguring it, because the `i686-pc-windows-gnu` build of LLVM will
  61     // report itself with a `--host-target` of `x86_64-pc-windows-gnu`. This
  62     // tricks us into thinking we're doing a cross build when we aren't, so
  63     // havoc ensues.
  64     //
  65     // In any case, if we're cross compiling, this generally just means that we
  66     // can't trust all the output of llvm-config because it might be targeted
  67     // for the host rather than the target. As a result a bunch of blocks below
  68     // are gated on `if !is_crossed`
  69     let target = env::var("TARGET").expect("TARGET was not set");
  70     let host = env::var("HOST").expect("HOST was not set");
  71     let is_crossed = target != host;
  72
  73     let optional_components = &[
  74         "x86",
  75         "arm",
  76         "aarch64",
  77         "amdgpu",
  78         "avr",
  79         "m68k",
  80         "mips",
  81         "powerpc",
  82         "systemz",
  83         "jsbackend",
  84         "webassembly",
  85         "msp430",
  86         "sparc",
  87         "nvptx",
  88         "hexagon",
  89         "riscv",
  90         "bpf",
  91     ];
  92
  93     let required_components = &[
  94         "ipo",
  95         "bitreader",
  96         "bitwriter",
  97         "linker",
  98         "asmparser",
  99         "lto",
 100         "coverage",
 101         "instrumentation",
 102     ];
 103
 104     let components = output(Command::new(&llvm_config).arg("--components"));
 105     let mut components = components.split_whitespace().collect::<Vec<_>>();
 106     components.retain(|c| optional_components.contains(c) || required_components.contains(c));
 107
 108     for component in required_components {
 109         if !components.contains(component) {
 110             panic!("require llvm component {} but wasn't found", component);
 111         }
 112     }
 113
 114     for component in components.iter() {
 115         println!("cargo:rustc-cfg=llvm_component=\"{}\"", component);
 116     }
 117
 118     // Link in our own LLVM shims, compiled with the same flags as LLVM
 119     let mut cmd = Command::new(&llvm_config);
 120     cmd.arg("--cxxflags");
 121     let cxxflags = output(&mut cmd);
 122     let mut cfg = cc::Build::new();
 123     cfg.warnings(false);
 124     for flag in cxxflags.split_whitespace() {
 125         // Ignore flags like `-m64` when we're doing a cross build
 126         if is_crossed && flag.starts_with("-m") {
 127             continue;
 128         }
 129
 130         if flag.starts_with("-flto") {
 131             continue;
 132         }
 133
 134         // -Wdate-time is not supported by the netbsd cross compiler
 135         if is_crossed && target.contains("netbsd") && flag.contains("date-time") {
 136             continue;
 137         }
 138
 139         // Include path contains host directory, replace it with target
 140         if is_crossed && flag.starts_with("-I") {
 141             cfg.flag(&flag.replace(&host, &target));
 142             continue;
 143         }
 144
 145         cfg.flag(flag);
 146     }
 147
 148     for component in &components {
 149         let mut flag = String::from("LLVM_COMPONENT_");
 150         flag.push_str(&component.to_uppercase());
 151         cfg.define(&flag, None);
 152     }
 153
 154     if tracked_env_var_os("LLVM_RUSTLLVM").is_some() {
 155         cfg.define("LLVM_RUSTLLVM", None);
 156     }
 157
 158     if tracked_env_var_os("LLVM_NDEBUG").is_some() {
 159         cfg.define("NDEBUG", None);
 160         cfg.debug(false);
 161     }
 162
 163     build_helper::rerun_if_changed_anything_in_dir(Path::new("llvm-wrapper"));
 164     cfg.file("llvm-wrapper/PassWrapper.cpp")
 165         .file("llvm-wrapper/RustWrapper.cpp")
 166         .file("llvm-wrapper/ArchiveWrapper.cpp")
 167         .file("llvm-wrapper/CoverageMappingWrapper.cpp")
 168         .file("llvm-wrapper/Linker.cpp")
 169         .cpp(true)
 170         .cpp_link_stdlib(None) // we handle this below
 171         .compile("llvm-wrapper");
 172
 173     let (llvm_kind, llvm_link_arg) = detect_llvm_link();
 174
 175     // Link in all LLVM libraries, if we're using the "wrong" llvm-config then
 176     // we don't pick up system libs because unfortunately they're for the host
 177     // of llvm-config, not the target that we're attempting to link.
 178     let mut cmd = Command::new(&llvm_config);
 179     cmd.arg(llvm_link_arg).arg("--libs");
 180
 181     if !is_crossed {
 182         cmd.arg("--system-libs");
 183     } else if target.contains("windows-gnu") {
 184         println!("cargo:rustc-link-lib=shell32");
 185         println!("cargo:rustc-link-lib=uuid");
 186     } else if target.contains("netbsd") || target.contains("haiku") || target.contains("darwin") {
 187         println!("cargo:rustc-link-lib=z");
 188     }
 189     cmd.args(&components);
 190
 191     for lib in output(&mut cmd).split_whitespace() {
 192         let name = if let Some(stripped) = lib.strip_prefix("-l") {
 193             stripped
 194         } else if let Some(stripped) = lib.strip_prefix('-') {
 195             stripped
 196         } else if Path::new(lib).exists() {
 197             // On MSVC llvm-config will print the full name to libraries, but
 198             // we're only interested in the name part
 199             let name = Path::new(lib).file_name().unwrap().to_str().unwrap();
 200             name.trim_end_matches(".lib")
 201         } else if lib.ends_with(".lib") {
 202             // Some MSVC libraries just come up with `.lib` tacked on, so chop
 203             // that off
 204             lib.trim_end_matches(".lib")
 205         } else {
 206             continue;
 207         };
 208
 209         // Don't need or want this library, but LLVM's CMake build system
 210         // doesn't provide a way to disable it, so filter it here even though we
 211         // may or may not have built it. We don't reference anything from this
 212         // library and it otherwise may just pull in extra dependencies on
 213         // libedit which we don't want
 214         if name == "LLVMLineEditor" {
 215             continue;
 216         }
 217
 218         let kind = if name.starts_with("LLVM") { llvm_kind } else { "dylib" };
 219         println!("cargo:rustc-link-lib={}={}", kind, name);
 220     }
 221
 222     // LLVM ldflags
 223     //
 224     // If we're a cross-compile of LLVM then unfortunately we can't trust these
 225     // ldflags (largely where all the LLVM libs are located). Currently just
 226     // hack around this by replacing the host triple with the target and pray
 227     // that those -L directories are the same!
 228     let mut cmd = Command::new(&llvm_config);
 229     cmd.arg(llvm_link_arg).arg("--ldflags");
 230     for lib in output(&mut cmd).split_whitespace() {
 231         if is_crossed {
 232             if let Some(stripped) = lib.strip_prefix("-LIBPATH:") {
 233                 println!("cargo:rustc-link-search=native={}", stripped.replace(&host, &target));
 234             } else if let Some(stripped) = lib.strip_prefix("-L") {
 235                 println!("cargo:rustc-link-search=native={}", stripped.replace(&host, &target));
 236             }
 237         } else if let Some(stripped) = lib.strip_prefix("-LIBPATH:") {
 238             println!("cargo:rustc-link-search=native={}", stripped);
 239         } else if let Some(stripped) = lib.strip_prefix("-l") {
 240             println!("cargo:rustc-link-lib={}", stripped);
 241         } else if let Some(stripped) = lib.strip_prefix("-L") {
 242             println!("cargo:rustc-link-search=native={}", stripped);
 243         }
 244     }
 245
 246     // Some LLVM linker flags (-L and -l) may be needed even when linking
 247     // rustc_llvm, for example when using static libc++, we may need to
 248     // manually specify the library search path and -ldl -lpthread as link
 249     // dependencies.
 250     let llvm_linker_flags = tracked_env_var_os("LLVM_LINKER_FLAGS");
 251     if let Some(s) = llvm_linker_flags {
 252         for lib in s.into_string().unwrap().split_whitespace() {
 253             if let Some(stripped) = lib.strip_prefix("-l") {
 254                 println!("cargo:rustc-link-lib={}", stripped);
 255             } else if let Some(stripped) = lib.strip_prefix("-L") {
 256                 println!("cargo:rustc-link-search=native={}", stripped);
 257             }
 258         }
 259     }
 260
 261     let llvm_static_stdcpp = tracked_env_var_os("LLVM_STATIC_STDCPP");
 262     let llvm_use_libcxx = tracked_env_var_os("LLVM_USE_LIBCXX");
 263
 264     let stdcppname = if target.contains("openbsd") {
 265         if target.contains("sparc64") { "estdc++" } else { "c++" }
 266     } else if target.contains("freebsd") {
 267         "c++"
 268     } else if target.contains("darwin") {
 269         "c++"
 270     } else if target.contains("netbsd") && llvm_static_stdcpp.is_some() {
 271         // NetBSD uses a separate library when relocation is required
 272         "stdc++_pic"
 273     } else if llvm_use_libcxx.is_some() {
 274         "c++"
 275     } else {
 276         "stdc++"
 277     };
 278
 279     // RISC-V GCC erroneously requires libatomic for sub-word
 280     // atomic operations. FreeBSD uses Clang as its system
 281     // compiler and provides no libatomic in its base system so
 282     // does not want this.
 283     if !target.contains("freebsd") && target.starts_with("riscv") {
 284         println!("cargo:rustc-link-lib=atomic");
 285     }
 286
 287     // C++ runtime library
 288     if !target.contains("msvc") {
 289         if let Some(s) = llvm_static_stdcpp {
 290             assert!(!cxxflags.contains("stdlib=libc++"));
 291             let path = PathBuf::from(s);
 292             println!("cargo:rustc-link-search=native={}", path.parent().unwrap().display());
 293             if target.contains("windows") {
 294                 println!("cargo:rustc-link-lib=static:-bundle={}", stdcppname);
 295             } else {
 296                 println!("cargo:rustc-link-lib=static={}", stdcppname);
 297             }
 298         } else if cxxflags.contains("stdlib=libc++") {
 299             println!("cargo:rustc-link-lib=c++");
 300         } else {
 301             println!("cargo:rustc-link-lib={}", stdcppname);
 302         }
 303     }
 304
 305     // Libstdc++ depends on pthread which Rust doesn't link on MinGW
 306     // since nothing else requires it.
 307     if target.contains("windows-gnu") {
 308         println!("cargo:rustc-link-lib=static:-bundle=pthread");
 309     }
 310 }