4 use rustc_ast::tokenstream::TokenStream;
5 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
6 use rustc_errors::{Applicability, DiagnosticBuilder};
7 use rustc_expand::base::{self, *};
8 use rustc_parse::parser::Parser;
9 use rustc_parse_format as parse;
10 use rustc_span::symbol::{kw, sym, Symbol};
11 use rustc_span::{InnerSpan, Span};
14 template: P<ast::Expr>,
15 operands: Vec<(ast::InlineAsmOperand, Span)>,
16 named_args: FxHashMap<Symbol, usize>,
17 reg_args: FxHashSet<usize>,
18 options: ast::InlineAsmOptions,
19 options_span: Option<Span>,
23 ecx: &mut ExtCtxt<'a>,
26 ) -> Result<AsmArgs, DiagnosticBuilder<'a>> {
27 let mut p = ecx.new_parser_from_tts(tts);
29 if p.token == token::Eof {
30 return Err(ecx.struct_span_err(sp, "requires at least a template string argument"));
33 // Detect use of the legacy llvm_asm! syntax (which used to be called asm!)
34 if p.look_ahead(1, |t| *t == token::Colon || *t == token::ModSep) {
36 ecx.struct_span_err(sp, "the legacy LLVM-style asm! syntax is no longer supported");
37 err.note("consider migrating to the new asm! syntax specified in RFC 2873");
38 err.note("alternatively, switch to llvm_asm! to keep your code working as it is");
40 // Find the span of the "asm!" so that we can offer an automatic suggestion
41 let asm_span = sp.from_inner(InnerSpan::new(0, 4));
42 if let Ok(s) = ecx.source_map().span_to_snippet(asm_span) {
48 Applicability::MachineApplicable,
55 let template = p.parse_expr()?;
56 let mut args = AsmArgs {
59 named_args: FxHashMap::default(),
60 reg_args: FxHashSet::default(),
61 options: ast::InlineAsmOptions::empty(),
66 while p.token != token::Eof {
67 if !p.eat(&token::Comma) {
69 // After `asm!(""` we always expect *only* a comma...
70 let mut err = ecx.struct_span_err(p.token.span, "expected token: `,`");
71 err.span_label(p.token.span, "expected `,`");
72 p.maybe_annotate_with_ascription(&mut err, false);
75 // ...after that delegate to `expect` to also include the other expected tokens.
76 return Err(p.expect(&token::Comma).err().unwrap());
80 if p.token == token::Eof {
82 } // accept trailing commas
85 if p.eat(&token::Ident(sym::options, false)) {
86 parse_options(&mut p, &mut args)?;
90 let span_start = p.token.span;
92 // Parse operand names
93 let name = if p.token.is_ident() && p.look_ahead(1, |t| *t == token::Eq) {
94 let (ident, _) = p.token.ident().unwrap();
96 p.expect(&token::Eq)?;
102 let mut explicit_reg = false;
103 let op = if p.eat(&token::Ident(kw::In, false)) {
104 let reg = parse_reg(&mut p, &mut explicit_reg)?;
105 let expr = p.parse_expr()?;
106 ast::InlineAsmOperand::In { reg, expr }
107 } else if p.eat(&token::Ident(sym::out, false)) {
108 let reg = parse_reg(&mut p, &mut explicit_reg)?;
109 let expr = if p.eat_keyword(kw::Underscore) { None } else { Some(p.parse_expr()?) };
110 ast::InlineAsmOperand::Out { reg, expr, late: false }
111 } else if p.eat(&token::Ident(sym::lateout, false)) {
112 let reg = parse_reg(&mut p, &mut explicit_reg)?;
113 let expr = if p.eat_keyword(kw::Underscore) { None } else { Some(p.parse_expr()?) };
114 ast::InlineAsmOperand::Out { reg, expr, late: true }
115 } else if p.eat(&token::Ident(sym::inout, false)) {
116 let reg = parse_reg(&mut p, &mut explicit_reg)?;
117 let expr = p.parse_expr()?;
118 if p.eat(&token::FatArrow) {
120 if p.eat_keyword(kw::Underscore) { None } else { Some(p.parse_expr()?) };
121 ast::InlineAsmOperand::SplitInOut { reg, in_expr: expr, out_expr, late: false }
123 ast::InlineAsmOperand::InOut { reg, expr, late: false }
125 } else if p.eat(&token::Ident(sym::inlateout, false)) {
126 let reg = parse_reg(&mut p, &mut explicit_reg)?;
127 let expr = p.parse_expr()?;
128 if p.eat(&token::FatArrow) {
130 if p.eat_keyword(kw::Underscore) { None } else { Some(p.parse_expr()?) };
131 ast::InlineAsmOperand::SplitInOut { reg, in_expr: expr, out_expr, late: true }
133 ast::InlineAsmOperand::InOut { reg, expr, late: true }
135 } else if p.eat(&token::Ident(kw::Const, false)) {
136 let expr = p.parse_expr()?;
137 ast::InlineAsmOperand::Const { expr }
138 } else if p.eat(&token::Ident(sym::sym, false)) {
139 let expr = p.parse_expr()?;
141 ast::ExprKind::Path(..) => {}
144 .struct_span_err(expr.span, "argument to `sym` must be a path expression");
148 ast::InlineAsmOperand::Sym { expr }
150 return Err(p.expect_one_of(&[], &[]).unwrap_err());
153 let span = span_start.to(p.prev_token.span);
154 let slot = args.operands.len();
155 args.operands.push((op, span));
157 // Validate the order of named, positional & explicit register operands and options. We do
158 // this at the end once we have the full span of the argument available.
159 if let Some(options_span) = args.options_span {
160 ecx.struct_span_err(span, "arguments are not allowed after options")
161 .span_label(options_span, "previous options")
162 .span_label(span, "argument")
167 ecx.struct_span_err(span, "explicit register arguments cannot have names").emit();
169 args.reg_args.insert(slot);
170 } else if let Some(name) = name {
171 if let Some(&prev) = args.named_args.get(&name) {
172 ecx.struct_span_err(span, &format!("duplicate argument named `{}`", name))
173 .span_label(args.operands[prev].1, "previously here")
174 .span_label(span, "duplicate argument")
178 if !args.reg_args.is_empty() {
179 let mut err = ecx.struct_span_err(
181 "named arguments cannot follow explicit register arguments",
183 err.span_label(span, "named argument");
184 for pos in &args.reg_args {
185 err.span_label(args.operands[*pos].1, "explicit register argument");
189 args.named_args.insert(name, slot);
191 if !args.named_args.is_empty() || !args.reg_args.is_empty() {
192 let mut err = ecx.struct_span_err(
194 "positional arguments cannot follow named arguments \
195 or explicit register arguments",
197 err.span_label(span, "positional argument");
198 for pos in args.named_args.values() {
199 err.span_label(args.operands[*pos].1, "named argument");
201 for pos in &args.reg_args {
202 err.span_label(args.operands[*pos].1, "explicit register argument");
209 if args.options.contains(ast::InlineAsmOptions::NOMEM)
210 && args.options.contains(ast::InlineAsmOptions::READONLY)
212 let span = args.options_span.unwrap();
213 ecx.struct_span_err(span, "the `nomem` and `readonly` options are mutually exclusive")
216 if args.options.contains(ast::InlineAsmOptions::PURE)
217 && args.options.contains(ast::InlineAsmOptions::NORETURN)
219 let span = args.options_span.unwrap();
220 ecx.struct_span_err(span, "the `pure` and `noreturn` options are mutually exclusive")
223 if args.options.contains(ast::InlineAsmOptions::PURE)
224 && !args.options.intersects(ast::InlineAsmOptions::NOMEM | ast::InlineAsmOptions::READONLY)
226 let span = args.options_span.unwrap();
229 "the `pure` option must be combined with either `nomem` or `readonly`",
234 let mut have_real_output = false;
235 let mut outputs_sp = vec![];
236 for (op, op_sp) in &args.operands {
238 ast::InlineAsmOperand::Out { expr, .. }
239 | ast::InlineAsmOperand::SplitInOut { out_expr: expr, .. } => {
240 outputs_sp.push(*op_sp);
241 have_real_output |= expr.is_some();
243 ast::InlineAsmOperand::InOut { .. } => {
244 outputs_sp.push(*op_sp);
245 have_real_output = true;
250 if args.options.contains(ast::InlineAsmOptions::PURE) && !have_real_output {
252 args.options_span.unwrap(),
253 "asm with `pure` option must have at least one output",
257 if args.options.contains(ast::InlineAsmOptions::NORETURN) && !outputs_sp.is_empty() {
259 .struct_span_err(outputs_sp, "asm outputs are not allowed with the `noreturn` option");
261 // Bail out now since this is likely to confuse MIR
268 fn parse_options<'a>(p: &mut Parser<'a>, args: &mut AsmArgs) -> Result<(), DiagnosticBuilder<'a>> {
269 let span_start = p.prev_token.span;
271 p.expect(&token::OpenDelim(token::DelimToken::Paren))?;
273 while !p.eat(&token::CloseDelim(token::DelimToken::Paren)) {
274 if p.eat(&token::Ident(sym::pure, false)) {
275 args.options |= ast::InlineAsmOptions::PURE;
276 } else if p.eat(&token::Ident(sym::nomem, false)) {
277 args.options |= ast::InlineAsmOptions::NOMEM;
278 } else if p.eat(&token::Ident(sym::readonly, false)) {
279 args.options |= ast::InlineAsmOptions::READONLY;
280 } else if p.eat(&token::Ident(sym::preserves_flags, false)) {
281 args.options |= ast::InlineAsmOptions::PRESERVES_FLAGS;
282 } else if p.eat(&token::Ident(sym::noreturn, false)) {
283 args.options |= ast::InlineAsmOptions::NORETURN;
284 } else if p.eat(&token::Ident(sym::nostack, false)) {
285 args.options |= ast::InlineAsmOptions::NOSTACK;
287 p.expect(&token::Ident(sym::att_syntax, false))?;
288 args.options |= ast::InlineAsmOptions::ATT_SYNTAX;
291 // Allow trailing commas
292 if p.eat(&token::CloseDelim(token::DelimToken::Paren)) {
295 p.expect(&token::Comma)?;
298 let new_span = span_start.to(p.prev_token.span);
299 if let Some(options_span) = args.options_span {
300 p.struct_span_err(new_span, "asm options cannot be specified multiple times")
301 .span_label(options_span, "previously here")
302 .span_label(new_span, "duplicate options")
305 args.options_span = Some(new_span);
313 explicit_reg: &mut bool,
314 ) -> Result<ast::InlineAsmRegOrRegClass, DiagnosticBuilder<'a>> {
315 p.expect(&token::OpenDelim(token::DelimToken::Paren))?;
316 let result = match p.token.kind {
317 token::Ident(name, false) => ast::InlineAsmRegOrRegClass::RegClass(name),
318 token::Literal(token::Lit { kind: token::LitKind::Str, symbol, suffix: _ }) => {
319 *explicit_reg = true;
320 ast::InlineAsmRegOrRegClass::Reg(symbol)
324 p.struct_span_err(p.token.span, "expected register class or explicit register")
329 p.expect(&token::CloseDelim(token::DelimToken::Paren))?;
333 fn expand_preparsed_asm(ecx: &mut ExtCtxt<'_>, sp: Span, args: AsmArgs) -> P<ast::Expr> {
334 let msg = "asm template must be a string literal";
335 let template_sp = args.template.span;
336 let (template_str, template_style, template_span) =
337 match expr_to_spanned_string(ecx, args.template, msg) {
338 Ok(template) => template,
340 if let Some(mut err) = err {
343 return DummyResult::raw_expr(sp, true);
347 let str_style = match template_style {
348 ast::StrStyle::Cooked => None,
349 ast::StrStyle::Raw(raw) => Some(raw as usize),
352 let template_str = &template_str.as_str();
353 let template_snippet = ecx.source_map().span_to_snippet(template_sp).ok();
354 let mut parser = parse::Parser::new(
359 parse::ParseMode::InlineAsm,
362 let mut unverified_pieces = Vec::new();
363 while let Some(piece) = parser.next() {
364 if !parser.errors.is_empty() {
367 unverified_pieces.push(piece);
371 if !parser.errors.is_empty() {
372 let err = parser.errors.remove(0);
373 let err_sp = template_span.from_inner(err.span);
375 .struct_span_err(err_sp, &format!("invalid asm template string: {}", err.description));
376 e.span_label(err_sp, err.label + " in asm template string");
377 if let Some(note) = err.note {
380 if let Some((label, span)) = err.secondary_label {
381 let err_sp = template_span.from_inner(span);
382 e.span_label(err_sp, label);
385 return DummyResult::raw_expr(sp, true);
388 // Register operands are implicitly used since they are not allowed to be
389 // referenced in the template string.
390 let mut used = vec![false; args.operands.len()];
391 for pos in &args.reg_args {
395 let named_pos: FxHashMap<usize, Symbol> =
396 args.named_args.iter().map(|(&sym, &idx)| (idx, sym)).collect();
397 let mut arg_spans = parser.arg_places.iter().map(|span| template_span.from_inner(*span));
398 let mut template = vec![];
399 for piece in unverified_pieces {
401 parse::Piece::String(s) => {
402 template.push(ast::InlineAsmTemplatePiece::String(s.to_string()))
404 parse::Piece::NextArgument(arg) => {
405 let span = arg_spans.next().unwrap_or(template_sp);
407 let operand_idx = match arg.position {
408 parse::ArgumentIs(idx) | parse::ArgumentImplicitlyIs(idx) => {
409 if idx >= args.operands.len()
410 || named_pos.contains_key(&idx)
411 || args.reg_args.contains(&idx)
413 let msg = format!("invalid reference to argument at index {}", idx);
414 let mut err = ecx.struct_span_err(span, &msg);
415 err.span_label(span, "from here");
417 let positional_args =
418 args.operands.len() - args.named_args.len() - args.reg_args.len();
419 let positional = if positional_args != args.operands.len() {
424 let msg = match positional_args {
425 0 => format!("no {}arguments were given", positional),
426 1 => format!("there is 1 {}argument", positional),
427 x => format!("there are {} {}arguments", x, positional),
431 if named_pos.contains_key(&idx) {
432 err.span_label(args.operands[idx].1, "named argument");
434 args.operands[idx].1,
435 "named arguments cannot be referenced by position",
437 } else if args.reg_args.contains(&idx) {
438 err.span_label(args.operands[idx].1, "explicit register argument");
440 args.operands[idx].1,
441 "explicit register arguments cannot be used in the asm template",
450 parse::ArgumentNamed(name) => match args.named_args.get(&name) {
451 Some(&idx) => Some(idx),
453 let msg = format!("there is no argument named `{}`", name);
454 ecx.struct_span_err(span, &msg[..]).emit();
460 let mut chars = arg.format.ty.chars();
461 let mut modifier = chars.next();
462 if chars.next().is_some() {
466 .map(|sp| template_sp.from_inner(sp))
467 .unwrap_or(template_sp);
468 ecx.struct_span_err(span, "asm template modifier must be a single character")
473 if let Some(operand_idx) = operand_idx {
474 used[operand_idx] = true;
475 template.push(ast::InlineAsmTemplatePiece::Placeholder {
485 let mut unused_operands = vec![];
486 let mut help_str = String::new();
487 for (idx, used) in used.into_iter().enumerate() {
489 let msg = if let Some(sym) = named_pos.get(&idx) {
490 help_str.push_str(&format!(" {{{}}}", sym));
491 "named argument never used"
493 help_str.push_str(&format!(" {{{}}}", idx));
494 "argument never used"
496 unused_operands.push((args.operands[idx].1, msg));
499 match unused_operands.len() {
502 let (sp, msg) = unused_operands.into_iter().next().unwrap();
503 let mut err = ecx.struct_span_err(sp, msg);
504 err.span_label(sp, msg);
506 "if this argument is intentionally unused, \
507 consider using it in an asm comment: `\"/*{} */\"`",
513 let mut err = ecx.struct_span_err(
514 unused_operands.iter().map(|&(sp, _)| sp).collect::<Vec<Span>>(),
515 "multiple unused asm arguments",
517 for (sp, msg) in unused_operands {
518 err.span_label(sp, msg);
521 "if these arguments are intentionally unused, \
522 consider using them in an asm comment: `\"/*{} */\"`",
529 let line_spans = if parser.line_spans.is_empty() {
532 parser.line_spans.iter().map(|span| template_span.from_inner(*span)).collect()
536 ast::InlineAsm { template, operands: args.operands, options: args.options, line_spans };
538 id: ast::DUMMY_NODE_ID,
539 kind: ast::ExprKind::InlineAsm(P(inline_asm)),
541 attrs: ast::AttrVec::new(),
546 pub fn expand_asm<'cx>(
547 ecx: &'cx mut ExtCtxt<'_>,
550 ) -> Box<dyn base::MacResult + 'cx> {
551 match parse_args(ecx, sp, tts) {
552 Ok(args) => MacEager::expr(expand_preparsed_asm(ecx, sp, args)),