src/librustc_driver/target_features.rs

   1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use syntax::{ast, attr};
  12 use llvm::LLVMRustHasFeature;
  13 use rustc::session::Session;
  14 use rustc_trans::back::write::create_target_machine;
  15 use syntax::parse::token::InternedString;
  16 use syntax::parse::token::intern_and_get_ident as intern;
  17 use libc::c_char;
  18
  19 // WARNING: the features must be known to LLVM or the feature
  20 // detection code will walk past the end of the feature array,
  21 // leading to crashes.
  22
  23 const ARM_WHITELIST: &'static [&'static str] = &["neon\0", "vfp2\0", "vfp3\0", "vfp4\0"];
  24
  25 const X86_WHITELIST: &'static [&'static str] = &["avx\0", "avx2\0", "bmi\0", "bmi2\0", "sse\0",
  26                                                  "sse2\0", "sse3\0", "sse4.1\0", "sse4.2\0",
  27                                                  "ssse3\0", "tbm\0"];
  28
  29 /// Add `target_feature = "..."` cfgs for a variety of platform
  30 /// specific features (SSE, NEON etc.).
  31 ///
  32 /// This is performed by checking whether a whitelisted set of
  33 /// features is available on the target machine, by querying LLVM.
  34 pub fn add_configuration(cfg: &mut ast::CrateConfig, sess: &Session) {
  35     let target_machine = create_target_machine(sess);
  36
  37     let whitelist = match &*sess.target.target.arch {
  38         "arm" => ARM_WHITELIST,
  39         "x86" | "x86_64" => X86_WHITELIST,
  40         _ => &[],
  41     };
  42
  43     let tf = InternedString::new("target_feature");
  44     for feat in whitelist {
  45         assert_eq!(feat.chars().last(), Some('\0'));
  46         if unsafe { LLVMRustHasFeature(target_machine, feat.as_ptr() as *const c_char) } {
  47             cfg.push(attr::mk_name_value_item_str(tf.clone(), intern(&feat[..feat.len() - 1])))
  48         }
  49     }
  50 }