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