src/libsyntax_ext/global_asm.rs

   1 // Copyright 2012-2013 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 /// Module-level assembly support.
  12 ///
  13 /// The macro defined here allows you to specify "top-level",
  14 /// "file-scoped", or "module-level" assembly. These synonyms
  15 /// all correspond to LLVM's module-level inline assembly instruction.
  16 ///
  17 /// For example, `global_asm!("some assembly here")` translates to
  18 /// LLVM's `module asm "some assembly here"`. All of LLVM's caveats
  19 /// therefore apply.
  20
  21 use syntax::ast;
  22 use syntax::ext::base;
  23 use syntax::ext::base::*;
  24 use syntax::feature_gate;
  25 use syntax::ptr::P;
  26 use syntax::symbol::Symbol;
  27 use syntax_pos::Span;
  28 use syntax::tokenstream;
  29
  30 use syntax::util::small_vector::SmallVector;
  31
  32 pub const MACRO: &'static str = "global_asm";
  33
  34 pub fn expand_global_asm<'cx>(cx: &'cx mut ExtCtxt,
  35                               sp: Span,
  36                               tts: &[tokenstream::TokenTree]) -> Box<base::MacResult + 'cx> {
  37     if !cx.ecfg.enable_global_asm() {
  38         feature_gate::emit_feature_err(&cx.parse_sess,
  39                                        MACRO,
  40                                        sp,
  41                                        feature_gate::GateIssue::Language,
  42                                        feature_gate::EXPLAIN_GLOBAL_ASM);
  43         return DummyResult::any(sp);
  44     }
  45
  46     let mut p = cx.new_parser_from_tts(tts);
  47     let (asm, _) = match expr_to_string(cx,
  48                                         panictry!(p.parse_expr()),
  49                                         "inline assembly must be a string literal") {
  50         Some((s, st)) => (s, st),
  51         None => return DummyResult::any(sp),
  52     };
  53
  54     MacEager::items(SmallVector::one(P(ast::Item {
  55         ident: ast::Ident::with_empty_ctxt(Symbol::intern("")),
  56         attrs: Vec::new(),
  57         id: ast::DUMMY_NODE_ID,
  58         node: ast::ItemKind::GlobalAsm(P(ast::GlobalAsm {
  59             asm,
  60             ctxt: cx.backtrace(),
  61         })),
  62         vis: ast::Visibility::Inherited,
  63         span: sp,
  64         tokens: None,
  65     })))
  66 }