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