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// Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
/*
* Inline assembly support.
*/
use self::State::*;
use ast;
use codemap;
use codemap::Span;
use ext::base;
use ext::base::*;
use feature_gate;
use parse::token::{intern, InternedString};
use parse::token;
use ptr::P;
use str::slice_shift_char;
enum State {
Asm,
Outputs,
Inputs,
Clobbers,
Options,
StateNone
}
impl State {
fn next(&self) -> State {
match *self {
Asm => Outputs,
Outputs => Inputs,
Inputs => Clobbers,
Clobbers => Options,
Options => StateNone,
StateNone => StateNone
}
}
}
const OPTIONS: &'static [&'static str] = &["volatile", "alignstack", "intel"];
pub fn expand_asm<'cx>(cx: &'cx mut ExtCtxt, sp: Span, tts: &[ast::TokenTree])
-> Box<base::MacResult+'cx> {
if !cx.ecfg.enable_asm() {
feature_gate::emit_feature_err(
&cx.parse_sess.span_diagnostic, "asm", sp, feature_gate::EXPLAIN_ASM);
return DummyResult::expr(sp);
}
let mut p = cx.new_parser_from_tts(tts);
let mut asm = InternedString::new("");
let mut asm_str_style = None;
let mut outputs = Vec::new();
let mut inputs = Vec::new();
let mut clobs = Vec::new();
let mut volatile = false;
let mut alignstack = false;
let mut dialect = ast::AsmAtt;
let mut state = Asm;
'statement: loop {
match state {
Asm => {
if asm_str_style.is_some() {
// If we already have a string with instructions,
// ending up in Asm state again is an error.
cx.span_err(sp, "malformed inline assembly");
return DummyResult::expr(sp);
}
let (s, style) = match expr_to_string(cx, p.parse_expr(),
"inline assembly must be a string literal") {
Some((s, st)) => (s, st),
// let compilation continue
None => return DummyResult::expr(sp),
};
asm = s;
asm_str_style = Some(style);
}
Outputs => {
while p.token != token::Eof &&
p.token != token::Colon &&
p.token != token::ModSep {
if !outputs.is_empty() {
panictry!(p.eat(&token::Comma));
}
let (constraint, _str_style) = panictry!(p.parse_str());
let span = p.last_span;
panictry!(p.expect(&token::OpenDelim(token::Paren)));
let out = p.parse_expr();
panictry!(p.expect(&token::CloseDelim(token::Paren)));
// Expands a read+write operand into two operands.
//
// Use '+' modifier when you want the same expression
// to be both an input and an output at the same time.
// It's the opposite of '=&' which means that the memory
// cannot be shared with any other operand (usually when
// a register is clobbered early.)
let output = match slice_shift_char(&constraint) {
Some(('=', _)) => None,
Some(('+', operand)) => {
Some(token::intern_and_get_ident(&format!(
"={}", operand)))
}
_ => {
cx.span_err(span, "output operand constraint lacks '=' or '+'");
None
}
};
let is_rw = output.is_some();
outputs.push((output.unwrap_or(constraint), out, is_rw));
}
}
Inputs => {
while p.token != token::Eof &&
p.token != token::Colon &&
p.token != token::ModSep {
if !inputs.is_empty() {
panictry!(p.eat(&token::Comma));
}
let (constraint, _str_style) = panictry!(p.parse_str());
if constraint.starts_with("=") {
cx.span_err(p.last_span, "input operand constraint contains '='");
} else if constraint.starts_with("+") {
cx.span_err(p.last_span, "input operand constraint contains '+'");
}
panictry!(p.expect(&token::OpenDelim(token::Paren)));
let input = p.parse_expr();
panictry!(p.expect(&token::CloseDelim(token::Paren)));
inputs.push((constraint, input));
}
}
Clobbers => {
while p.token != token::Eof &&
p.token != token::Colon &&
p.token != token::ModSep {
if !clobs.is_empty() {
panictry!(p.eat(&token::Comma));
}
let (s, _str_style) = panictry!(p.parse_str());
if OPTIONS.iter().any(|&opt| s == opt) {
cx.span_warn(p.last_span, "expected a clobber, found an option");
}
clobs.push(s);
}
}
Options => {
let (option, _str_style) = panictry!(p.parse_str());
if option == "volatile" {
// Indicates that the inline assembly has side effects
// and must not be optimized out along with its outputs.
volatile = true;
} else if option == "alignstack" {
alignstack = true;
} else if option == "intel" {
dialect = ast::AsmIntel;
} else {
cx.span_warn(p.last_span, "unrecognized option");
}
if p.token == token::Comma {
panictry!(p.eat(&token::Comma));
}
}
StateNone => ()
}
loop {
// MOD_SEP is a double colon '::' without space in between.
// When encountered, the state must be advanced twice.
match (&p.token, state.next(), state.next().next()) {
(&token::Colon, StateNone, _) |
(&token::ModSep, _, StateNone) => {
panictry!(p.bump());
break 'statement;
}
(&token::Colon, st, _) |
(&token::ModSep, _, st) => {
panictry!(p.bump());
state = st;
}
(&token::Eof, _, _) => break 'statement,
_ => break
}
}
}
let expn_id = cx.codemap().record_expansion(codemap::ExpnInfo {
call_site: sp,
callee: codemap::NameAndSpan {
format: codemap::MacroBang(intern("asm")),
span: None,
allow_internal_unstable: false,
},
});
MacEager::expr(P(ast::Expr {
id: ast::DUMMY_NODE_ID,
node: ast::ExprInlineAsm(ast::InlineAsm {
asm: token::intern_and_get_ident(&asm),
asm_str_style: asm_str_style.unwrap(),
outputs: outputs,
inputs: inputs,
clobbers: clobs,
volatile: volatile,
alignstack: alignstack,
dialect: dialect,
expn_id: expn_id,
}),
span: sp
}))
}