rust/compiler/rustc_builtin_macros/src/global_asm.rs
Aaron Hill c1011165e6
Attach TokenStream to ast::Visibility
A `Visibility` does not have outer attributes, so we only capture tokens
when parsing a `macro_rules!` matcher
2020-09-10 17:33:06 -04:00

69 lines
2.1 KiB
Rust

//! Module-level assembly support.
//!
//! The macro defined here allows you to specify "top-level",
//! "file-scoped", or "module-level" assembly. These synonyms
//! all correspond to LLVM's module-level inline assembly instruction.
//!
//! For example, `global_asm!("some assembly here")` codegens to
//! LLVM's `module asm "some assembly here"`. All of LLVM's caveats
//! therefore apply.
use rustc_ast as ast;
use rustc_ast::ptr::P;
use rustc_ast::token;
use rustc_ast::tokenstream::TokenStream;
use rustc_errors::DiagnosticBuilder;
use rustc_expand::base::{self, *};
use rustc_span::symbol::Ident;
use rustc_span::Span;
use smallvec::smallvec;
pub fn expand_global_asm<'cx>(
cx: &'cx mut ExtCtxt<'_>,
sp: Span,
tts: TokenStream,
) -> Box<dyn base::MacResult + 'cx> {
match parse_global_asm(cx, sp, tts) {
Ok(Some(global_asm)) => MacEager::items(smallvec![P(ast::Item {
ident: Ident::invalid(),
attrs: Vec::new(),
id: ast::DUMMY_NODE_ID,
kind: ast::ItemKind::GlobalAsm(P(global_asm)),
vis: ast::Visibility {
span: sp.shrink_to_lo(),
kind: ast::VisibilityKind::Inherited,
tokens: None,
},
span: cx.with_def_site_ctxt(sp),
tokens: None,
})]),
Ok(None) => DummyResult::any(sp),
Err(mut err) => {
err.emit();
DummyResult::any(sp)
}
}
}
fn parse_global_asm<'a>(
cx: &mut ExtCtxt<'a>,
sp: Span,
tts: TokenStream,
) -> Result<Option<ast::GlobalAsm>, DiagnosticBuilder<'a>> {
let mut p = cx.new_parser_from_tts(tts);
if p.token == token::Eof {
let mut err = cx.struct_span_err(sp, "macro requires a string literal as an argument");
err.span_label(sp, "string literal required");
return Err(err);
}
let expr = p.parse_expr()?;
let (asm, _) = match expr_to_string(cx, expr, "inline assembly must be a string literal") {
Some((s, st)) => (s, st),
None => return Ok(None),
};
Ok(Some(ast::GlobalAsm { asm }))
}