src/librustc_codegen_llvm/llvm_util.rs

   1 use crate::back::write::create_informational_target_machine;
   2 use crate::llvm;
   3 use libc::c_int;
   4 use rustc::bug;
   5 use rustc::session::config::PrintRequest;
   6 use rustc::session::Session;
   7 use rustc_data_structures::fx::FxHashSet;
   8 use rustc_feature::UnstableFeatures;
   9 use rustc_span::symbol::sym;
  10 use rustc_span::symbol::Symbol;
  11 use rustc_target::spec::{MergeFunctions, PanicStrategy};
  12 use std::ffi::CString;
  13
  14 use std::slice;
  15 use std::str;
  16 use std::sync::atomic::{AtomicBool, Ordering};
  17 use std::sync::Once;
  18
  19 static POISONED: AtomicBool = AtomicBool::new(false);
  20 static INIT: Once = Once::new();
  21
  22 pub(crate) fn init(sess: &Session) {
  23     unsafe {
  24         // Before we touch LLVM, make sure that multithreading is enabled.
  25         INIT.call_once(|| {
  26             if llvm::LLVMStartMultithreaded() != 1 {
  27                 // use an extra bool to make sure that all future usage of LLVM
  28                 // cannot proceed despite the Once not running more than once.
  29                 POISONED.store(true, Ordering::SeqCst);
  30             }
  31
  32             configure_llvm(sess);
  33         });
  34
  35         if POISONED.load(Ordering::SeqCst) {
  36             bug!("couldn't enable multi-threaded LLVM");
  37         }
  38     }
  39 }
  40
  41 fn require_inited() {
  42     INIT.call_once(|| bug!("llvm is not initialized"));
  43     if POISONED.load(Ordering::SeqCst) {
  44         bug!("couldn't enable multi-threaded LLVM");
  45     }
  46 }
  47
  48 unsafe fn configure_llvm(sess: &Session) {
  49     let n_args = sess.opts.cg.llvm_args.len();
  50     let mut llvm_c_strs = Vec::with_capacity(n_args + 1);
  51     let mut llvm_args = Vec::with_capacity(n_args + 1);
  52
  53     llvm::LLVMRustInstallFatalErrorHandler();
  54
  55     fn llvm_arg_to_arg_name(full_arg: &str) -> &str {
  56         full_arg.trim().split(|c: char| c == '=' || c.is_whitespace()).next().unwrap_or("")
  57     }
  58
  59     let user_specified_args: FxHashSet<_> = sess
  60         .opts
  61         .cg
  62         .llvm_args
  63         .iter()
  64         .map(|s| llvm_arg_to_arg_name(s))
  65         .filter(|s| s.len() > 0)
  66         .collect();
  67
  68     {
  69         // This adds the given argument to LLVM. Unless `force` is true
  70         // user specified arguments are *not* overridden.
  71         let mut add = |arg: &str, force: bool| {
  72             if force || !user_specified_args.contains(llvm_arg_to_arg_name(arg)) {
  73                 let s = CString::new(arg).unwrap();
  74                 llvm_args.push(s.as_ptr());
  75                 llvm_c_strs.push(s);
  76             }
  77         };
  78         add("rustc", true); // fake program name
  79         if sess.time_llvm_passes() {
  80             add("-time-passes", false);
  81         }
  82         if sess.print_llvm_passes() {
  83             add("-debug-pass=Structure", false);
  84         }
  85
  86         if sess.opts.debugging_opts.generate_arange_section {
  87             add("-generate-arange-section", false);
  88         }
  89         if get_major_version() >= 8 {
  90             match sess
  91                 .opts
  92                 .debugging_opts
  93                 .merge_functions
  94                 .unwrap_or(sess.target.target.options.merge_functions)
  95             {
  96                 MergeFunctions::Disabled | MergeFunctions::Trampolines => {}
  97                 MergeFunctions::Aliases => {
  98                     add("-mergefunc-use-aliases", false);
  99                 }
 100             }
 101         }
 102
 103         if sess.target.target.target_os == "emscripten"
 104             && sess.panic_strategy() == PanicStrategy::Unwind
 105         {
 106             add("-enable-emscripten-cxx-exceptions", false);
 107         }
 108
 109         // HACK(eddyb) LLVM inserts `llvm.assume` calls to preserve align attributes
 110         // during inlining. Unfortunately these may block other optimizations.
 111         add("-preserve-alignment-assumptions-during-inlining=false", false);
 112
 113         for arg in &sess.opts.cg.llvm_args {
 114             add(&(*arg), true);
 115         }
 116     }
 117
 118     llvm::LLVMInitializePasses();
 119
 120     ::rustc_llvm::initialize_available_targets();
 121
 122     llvm::LLVMRustSetLLVMOptions(llvm_args.len() as c_int, llvm_args.as_ptr());
 123 }
 124
 125 // WARNING: the features after applying `to_llvm_feature` must be known
 126 // to LLVM or the feature detection code will walk past the end of the feature
 127 // array, leading to crashes.
 128
 129 const ARM_WHITELIST: &[(&str, Option<Symbol>)] = &[
 130     ("aclass", Some(sym::arm_target_feature)),
 131     ("mclass", Some(sym::arm_target_feature)),
 132     ("rclass", Some(sym::arm_target_feature)),
 133     ("dsp", Some(sym::arm_target_feature)),
 134     ("neon", Some(sym::arm_target_feature)),
 135     ("crc", Some(sym::arm_target_feature)),
 136     ("crypto", Some(sym::arm_target_feature)),
 137     ("v5te", Some(sym::arm_target_feature)),
 138     ("v6", Some(sym::arm_target_feature)),
 139     ("v6k", Some(sym::arm_target_feature)),
 140     ("v6t2", Some(sym::arm_target_feature)),
 141     ("v7", Some(sym::arm_target_feature)),
 142     ("v8", Some(sym::arm_target_feature)),
 143     ("vfp2", Some(sym::arm_target_feature)),
 144     ("vfp3", Some(sym::arm_target_feature)),
 145     ("vfp4", Some(sym::arm_target_feature)),
 146 ];
 147
 148 const AARCH64_WHITELIST: &[(&str, Option<Symbol>)] = &[
 149     ("fp", Some(sym::aarch64_target_feature)),
 150     ("neon", Some(sym::aarch64_target_feature)),
 151     ("sve", Some(sym::aarch64_target_feature)),
 152     ("crc", Some(sym::aarch64_target_feature)),
 153     ("crypto", Some(sym::aarch64_target_feature)),
 154     ("ras", Some(sym::aarch64_target_feature)),
 155     ("lse", Some(sym::aarch64_target_feature)),
 156     ("rdm", Some(sym::aarch64_target_feature)),
 157     ("fp16", Some(sym::aarch64_target_feature)),
 158     ("rcpc", Some(sym::aarch64_target_feature)),
 159     ("dotprod", Some(sym::aarch64_target_feature)),
 160     ("v8.1a", Some(sym::aarch64_target_feature)),
 161     ("v8.2a", Some(sym::aarch64_target_feature)),
 162     ("v8.3a", Some(sym::aarch64_target_feature)),
 163 ];
 164
 165 const X86_WHITELIST: &[(&str, Option<Symbol>)] = &[
 166     ("adx", Some(sym::adx_target_feature)),
 167     ("aes", None),
 168     ("avx", None),
 169     ("avx2", None),
 170     ("avx512bw", Some(sym::avx512_target_feature)),
 171     ("avx512cd", Some(sym::avx512_target_feature)),
 172     ("avx512dq", Some(sym::avx512_target_feature)),
 173     ("avx512er", Some(sym::avx512_target_feature)),
 174     ("avx512f", Some(sym::avx512_target_feature)),
 175     ("avx512ifma", Some(sym::avx512_target_feature)),
 176     ("avx512pf", Some(sym::avx512_target_feature)),
 177     ("avx512vbmi", Some(sym::avx512_target_feature)),
 178     ("avx512vl", Some(sym::avx512_target_feature)),
 179     ("avx512vpopcntdq", Some(sym::avx512_target_feature)),
 180     ("bmi1", None),
 181     ("bmi2", None),
 182     ("cmpxchg16b", Some(sym::cmpxchg16b_target_feature)),
 183     ("f16c", Some(sym::f16c_target_feature)),
 184     ("fma", None),
 185     ("fxsr", None),
 186     ("lzcnt", None),
 187     ("mmx", Some(sym::mmx_target_feature)),
 188     ("movbe", Some(sym::movbe_target_feature)),
 189     ("pclmulqdq", None),
 190     ("popcnt", None),
 191     ("rdrand", None),
 192     ("rdseed", None),
 193     ("rtm", Some(sym::rtm_target_feature)),
 194     ("sha", None),
 195     ("sse", None),
 196     ("sse2", None),
 197     ("sse3", None),
 198     ("sse4.1", None),
 199     ("sse4.2", None),
 200     ("sse4a", Some(sym::sse4a_target_feature)),
 201     ("ssse3", None),
 202     ("tbm", Some(sym::tbm_target_feature)),
 203     ("xsave", None),
 204     ("xsavec", None),
 205     ("xsaveopt", None),
 206     ("xsaves", None),
 207 ];
 208
 209 const HEXAGON_WHITELIST: &[(&str, Option<Symbol>)] = &[
 210     ("hvx", Some(sym::hexagon_target_feature)),
 211     ("hvx-length128b", Some(sym::hexagon_target_feature)),
 212 ];
 213
 214 const POWERPC_WHITELIST: &[(&str, Option<Symbol>)] = &[
 215     ("altivec", Some(sym::powerpc_target_feature)),
 216     ("power8-altivec", Some(sym::powerpc_target_feature)),
 217     ("power9-altivec", Some(sym::powerpc_target_feature)),
 218     ("power8-vector", Some(sym::powerpc_target_feature)),
 219     ("power9-vector", Some(sym::powerpc_target_feature)),
 220     ("vsx", Some(sym::powerpc_target_feature)),
 221 ];
 222
 223 const MIPS_WHITELIST: &[(&str, Option<Symbol>)] =
 224     &[("fp64", Some(sym::mips_target_feature)), ("msa", Some(sym::mips_target_feature))];
 225
 226 const WASM_WHITELIST: &[(&str, Option<Symbol>)] =
 227     &[("simd128", Some(sym::wasm_target_feature)), ("atomics", Some(sym::wasm_target_feature))];
 228
 229 /// When rustdoc is running, provide a list of all known features so that all their respective
 230 /// primitives may be documented.
 231 ///
 232 /// IMPORTANT: If you're adding another whitelist to the above lists, make sure to add it to this
 233 /// iterator!
 234 pub fn all_known_features() -> impl Iterator<Item = (&'static str, Option<Symbol>)> {
 235     ARM_WHITELIST
 236         .iter()
 237         .cloned()
 238         .chain(AARCH64_WHITELIST.iter().cloned())
 239         .chain(X86_WHITELIST.iter().cloned())
 240         .chain(HEXAGON_WHITELIST.iter().cloned())
 241         .chain(POWERPC_WHITELIST.iter().cloned())
 242         .chain(MIPS_WHITELIST.iter().cloned())
 243         .chain(WASM_WHITELIST.iter().cloned())
 244 }
 245
 246 pub fn to_llvm_feature<'a>(sess: &Session, s: &'a str) -> &'a str {
 247     let arch = if sess.target.target.arch == "x86_64" { "x86" } else { &*sess.target.target.arch };
 248     match (arch, s) {
 249         ("x86", "pclmulqdq") => "pclmul",
 250         ("x86", "rdrand") => "rdrnd",
 251         ("x86", "bmi1") => "bmi",
 252         ("x86", "cmpxchg16b") => "cx16",
 253         ("aarch64", "fp") => "fp-armv8",
 254         ("aarch64", "fp16") => "fullfp16",
 255         (_, s) => s,
 256     }
 257 }
 258
 259 pub fn target_features(sess: &Session) -> Vec<Symbol> {
 260     let target_machine = create_informational_target_machine(sess, true);
 261     target_feature_whitelist(sess)
 262         .iter()
 263         .filter_map(|&(feature, gate)| {
 264             if UnstableFeatures::from_environment().is_nightly_build() || gate.is_none() {
 265                 Some(feature)
 266             } else {
 267                 None
 268             }
 269         })
 270         .filter(|feature| {
 271             let llvm_feature = to_llvm_feature(sess, feature);
 272             let cstr = CString::new(llvm_feature).unwrap();
 273             unsafe { llvm::LLVMRustHasFeature(target_machine, cstr.as_ptr()) }
 274         })
 275         .map(|feature| Symbol::intern(feature))
 276         .collect()
 277 }
 278
 279 pub fn target_feature_whitelist(sess: &Session) -> &'static [(&'static str, Option<Symbol>)] {
 280     match &*sess.target.target.arch {
 281         "arm" => ARM_WHITELIST,
 282         "aarch64" => AARCH64_WHITELIST,
 283         "x86" | "x86_64" => X86_WHITELIST,
 284         "hexagon" => HEXAGON_WHITELIST,
 285         "mips" | "mips64" => MIPS_WHITELIST,
 286         "powerpc" | "powerpc64" => POWERPC_WHITELIST,
 287         "wasm32" => WASM_WHITELIST,
 288         _ => &[],
 289     }
 290 }
 291
 292 pub fn print_version() {
 293     // Can be called without initializing LLVM
 294     unsafe {
 295         println!("LLVM version: {}.{}", llvm::LLVMRustVersionMajor(), llvm::LLVMRustVersionMinor());
 296     }
 297 }
 298
 299 pub fn get_major_version() -> u32 {
 300     unsafe { llvm::LLVMRustVersionMajor() }
 301 }
 302
 303 pub fn print_passes() {
 304     // Can be called without initializing LLVM
 305     unsafe {
 306         llvm::LLVMRustPrintPasses();
 307     }
 308 }
 309
 310 pub(crate) fn print(req: PrintRequest, sess: &Session) {
 311     require_inited();
 312     let tm = create_informational_target_machine(sess, true);
 313     unsafe {
 314         match req {
 315             PrintRequest::TargetCPUs => llvm::LLVMRustPrintTargetCPUs(tm),
 316             PrintRequest::TargetFeatures => llvm::LLVMRustPrintTargetFeatures(tm),
 317             _ => bug!("rustc_codegen_llvm can't handle print request: {:?}", req),
 318         }
 319     }
 320 }
 321
 322 pub fn target_cpu(sess: &Session) -> &str {
 323     let name = match sess.opts.cg.target_cpu {
 324         Some(ref s) => &**s,
 325         None => &*sess.target.target.options.cpu,
 326     };
 327     if name != "native" {
 328         return name;
 329     }
 330
 331     unsafe {
 332         let mut len = 0;
 333         let ptr = llvm::LLVMRustGetHostCPUName(&mut len);
 334         str::from_utf8(slice::from_raw_parts(ptr as *const u8, len)).unwrap()
 335     }
 336 }