src/librustc_codegen_llvm/llvm_util.rs

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