rustc_ast_lowering/asm.rs
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535
use std::collections::hash_map::Entry;
use std::fmt::Write;
use rustc_ast::ptr::P;
use rustc_ast::*;
use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap};
use rustc_hir as hir;
use rustc_hir::def::{DefKind, Res};
use rustc_session::parse::feature_err;
use rustc_span::{Span, kw, sym};
use rustc_target::asm;
use super::LoweringContext;
use super::errors::{
AbiSpecifiedMultipleTimes, AttSyntaxOnlyX86, ClobberAbiNotSupported,
InlineAsmUnsupportedTarget, InvalidAbiClobberAbi, InvalidAsmTemplateModifierConst,
InvalidAsmTemplateModifierLabel, InvalidAsmTemplateModifierRegClass,
InvalidAsmTemplateModifierRegClassSub, InvalidAsmTemplateModifierSym, InvalidRegister,
InvalidRegisterClass, RegisterClassOnlyClobber, RegisterClassOnlyClobberStable,
RegisterConflict,
};
use crate::{
AllowReturnTypeNotation, ImplTraitContext, ImplTraitPosition, ParamMode,
ResolverAstLoweringExt, fluent_generated as fluent,
};
impl<'a, 'hir> LoweringContext<'a, 'hir> {
pub(crate) fn lower_inline_asm(
&mut self,
sp: Span,
asm: &InlineAsm,
) -> &'hir hir::InlineAsm<'hir> {
// Rustdoc needs to support asm! from foreign architectures: don't try
// lowering the register constraints in this case.
let asm_arch =
if self.tcx.sess.opts.actually_rustdoc { None } else { self.tcx.sess.asm_arch };
if asm_arch.is_none() && !self.tcx.sess.opts.actually_rustdoc {
self.dcx().emit_err(InlineAsmUnsupportedTarget { span: sp });
}
if let Some(asm_arch) = asm_arch {
// Inline assembly is currently only stable for these architectures.
let is_stable = matches!(
asm_arch,
asm::InlineAsmArch::X86
| asm::InlineAsmArch::X86_64
| asm::InlineAsmArch::Arm
| asm::InlineAsmArch::AArch64
| asm::InlineAsmArch::Arm64EC
| asm::InlineAsmArch::RiscV32
| asm::InlineAsmArch::RiscV64
| asm::InlineAsmArch::LoongArch64
| asm::InlineAsmArch::S390x
);
if !is_stable && !self.tcx.features().asm_experimental_arch() {
feature_err(
&self.tcx.sess,
sym::asm_experimental_arch,
sp,
fluent::ast_lowering_unstable_inline_assembly,
)
.emit();
}
}
let allow_experimental_reg = self.tcx.features().asm_experimental_reg();
if asm.options.contains(InlineAsmOptions::ATT_SYNTAX)
&& !matches!(asm_arch, Some(asm::InlineAsmArch::X86 | asm::InlineAsmArch::X86_64))
&& !self.tcx.sess.opts.actually_rustdoc
{
self.dcx().emit_err(AttSyntaxOnlyX86 { span: sp });
}
if asm.options.contains(InlineAsmOptions::MAY_UNWIND) && !self.tcx.features().asm_unwind() {
feature_err(
&self.tcx.sess,
sym::asm_unwind,
sp,
fluent::ast_lowering_unstable_may_unwind,
)
.emit();
}
let mut clobber_abis = FxIndexMap::default();
if let Some(asm_arch) = asm_arch {
for (abi_name, abi_span) in &asm.clobber_abis {
match asm::InlineAsmClobberAbi::parse(
asm_arch,
&self.tcx.sess.target,
&self.tcx.sess.unstable_target_features,
*abi_name,
) {
Ok(abi) => {
// If the abi was already in the list, emit an error
match clobber_abis.get(&abi) {
Some((prev_name, prev_sp)) => {
// Multiple different abi names may actually be the same ABI
// If the specified ABIs are not the same name, alert the user that they resolve to the same ABI
let source_map = self.tcx.sess.source_map();
let equivalent = source_map.span_to_snippet(*prev_sp)
!= source_map.span_to_snippet(*abi_span);
self.dcx().emit_err(AbiSpecifiedMultipleTimes {
abi_span: *abi_span,
prev_name: *prev_name,
prev_span: *prev_sp,
equivalent,
});
}
None => {
clobber_abis.insert(abi, (*abi_name, *abi_span));
}
}
}
Err(&[]) => {
self.dcx().emit_err(ClobberAbiNotSupported { abi_span: *abi_span });
}
Err(supported_abis) => {
let mut abis = format!("`{}`", supported_abis[0]);
for m in &supported_abis[1..] {
let _ = write!(abis, ", `{m}`");
}
self.dcx().emit_err(InvalidAbiClobberAbi {
abi_span: *abi_span,
supported_abis: abis,
});
}
}
}
}
// Lower operands to HIR. We use dummy register classes if an error
// occurs during lowering because we still need to be able to produce a
// valid HIR.
let sess = self.tcx.sess;
let mut operands: Vec<_> = asm
.operands
.iter()
.map(|(op, op_sp)| {
let lower_reg = |®: &_| match reg {
InlineAsmRegOrRegClass::Reg(reg) => {
asm::InlineAsmRegOrRegClass::Reg(if let Some(asm_arch) = asm_arch {
asm::InlineAsmReg::parse(asm_arch, reg).unwrap_or_else(|error| {
self.dcx().emit_err(InvalidRegister {
op_span: *op_sp,
reg,
error,
});
asm::InlineAsmReg::Err
})
} else {
asm::InlineAsmReg::Err
})
}
InlineAsmRegOrRegClass::RegClass(reg_class) => {
asm::InlineAsmRegOrRegClass::RegClass(if let Some(asm_arch) = asm_arch {
asm::InlineAsmRegClass::parse(asm_arch, reg_class).unwrap_or_else(
|error| {
self.dcx().emit_err(InvalidRegisterClass {
op_span: *op_sp,
reg_class,
error,
});
asm::InlineAsmRegClass::Err
},
)
} else {
asm::InlineAsmRegClass::Err
})
}
};
let op = match op {
InlineAsmOperand::In { reg, expr } => hir::InlineAsmOperand::In {
reg: lower_reg(reg),
expr: self.lower_expr(expr),
},
InlineAsmOperand::Out { reg, late, expr } => hir::InlineAsmOperand::Out {
reg: lower_reg(reg),
late: *late,
expr: expr.as_ref().map(|expr| self.lower_expr(expr)),
},
InlineAsmOperand::InOut { reg, late, expr } => hir::InlineAsmOperand::InOut {
reg: lower_reg(reg),
late: *late,
expr: self.lower_expr(expr),
},
InlineAsmOperand::SplitInOut { reg, late, in_expr, out_expr } => {
hir::InlineAsmOperand::SplitInOut {
reg: lower_reg(reg),
late: *late,
in_expr: self.lower_expr(in_expr),
out_expr: out_expr.as_ref().map(|expr| self.lower_expr(expr)),
}
}
InlineAsmOperand::Const { anon_const } => hir::InlineAsmOperand::Const {
anon_const: self.lower_anon_const_to_anon_const(anon_const),
},
InlineAsmOperand::Sym { sym } => {
let static_def_id = self
.resolver
.get_partial_res(sym.id)
.and_then(|res| res.full_res())
.and_then(|res| match res {
Res::Def(DefKind::Static { .. }, def_id) => Some(def_id),
_ => None,
});
if let Some(def_id) = static_def_id {
let path = self.lower_qpath(
sym.id,
&sym.qself,
&sym.path,
ParamMode::Optional,
AllowReturnTypeNotation::No,
ImplTraitContext::Disallowed(ImplTraitPosition::Path),
None,
);
hir::InlineAsmOperand::SymStatic { path, def_id }
} else {
// Replace the InlineAsmSym AST node with an
// Expr using the name node id.
let expr = Expr {
id: sym.id,
kind: ExprKind::Path(sym.qself.clone(), sym.path.clone()),
span: *op_sp,
attrs: AttrVec::new(),
tokens: None,
};
// Wrap the expression in an AnonConst.
let parent_def_id = self.current_hir_id_owner.def_id;
let node_id = self.next_node_id();
self.create_def(
parent_def_id,
node_id,
kw::Empty,
DefKind::AnonConst,
*op_sp,
);
let anon_const = AnonConst { id: node_id, value: P(expr) };
hir::InlineAsmOperand::SymFn {
anon_const: self.lower_anon_const_to_anon_const(&anon_const),
}
}
}
InlineAsmOperand::Label { block } => {
hir::InlineAsmOperand::Label { block: self.lower_block(block, false) }
}
};
(op, self.lower_span(*op_sp))
})
.collect();
// Validate template modifiers against the register classes for the operands
for p in &asm.template {
if let InlineAsmTemplatePiece::Placeholder {
operand_idx,
modifier: Some(modifier),
span: placeholder_span,
} = *p
{
let op_sp = asm.operands[operand_idx].1;
match &operands[operand_idx].0 {
hir::InlineAsmOperand::In { reg, .. }
| hir::InlineAsmOperand::Out { reg, .. }
| hir::InlineAsmOperand::InOut { reg, .. }
| hir::InlineAsmOperand::SplitInOut { reg, .. } => {
let class = reg.reg_class();
if class == asm::InlineAsmRegClass::Err {
continue;
}
let valid_modifiers = class.valid_modifiers(asm_arch.unwrap());
if !valid_modifiers.contains(&modifier) {
let sub = if !valid_modifiers.is_empty() {
let mut mods = format!("`{}`", valid_modifiers[0]);
for m in &valid_modifiers[1..] {
let _ = write!(mods, ", `{m}`");
}
InvalidAsmTemplateModifierRegClassSub::SupportModifier {
class_name: class.name(),
modifiers: mods,
}
} else {
InvalidAsmTemplateModifierRegClassSub::DoesNotSupportModifier {
class_name: class.name(),
}
};
self.dcx().emit_err(InvalidAsmTemplateModifierRegClass {
placeholder_span,
op_span: op_sp,
sub,
});
}
}
hir::InlineAsmOperand::Const { .. } => {
self.dcx().emit_err(InvalidAsmTemplateModifierConst {
placeholder_span,
op_span: op_sp,
});
}
hir::InlineAsmOperand::SymFn { .. }
| hir::InlineAsmOperand::SymStatic { .. } => {
self.dcx().emit_err(InvalidAsmTemplateModifierSym {
placeholder_span,
op_span: op_sp,
});
}
hir::InlineAsmOperand::Label { .. } => {
self.dcx().emit_err(InvalidAsmTemplateModifierLabel {
placeholder_span,
op_span: op_sp,
});
}
}
}
}
let mut used_input_regs = FxHashMap::default();
let mut used_output_regs = FxHashMap::default();
for (idx, &(ref op, op_sp)) in operands.iter().enumerate() {
if let Some(reg) = op.reg() {
let reg_class = reg.reg_class();
if reg_class == asm::InlineAsmRegClass::Err {
continue;
}
// Some register classes can only be used as clobbers. This
// means that we disallow passing a value in/out of the asm and
// require that the operand name an explicit register, not a
// register class.
if reg_class.is_clobber_only(asm_arch.unwrap(), allow_experimental_reg)
&& !op.is_clobber()
{
if allow_experimental_reg || reg_class.is_clobber_only(asm_arch.unwrap(), true)
{
// always clobber-only
self.dcx().emit_err(RegisterClassOnlyClobber {
op_span: op_sp,
reg_class_name: reg_class.name(),
});
} else {
// clobber-only in stable
self.tcx
.sess
.create_feature_err(
RegisterClassOnlyClobberStable {
op_span: op_sp,
reg_class_name: reg_class.name(),
},
sym::asm_experimental_reg,
)
.emit();
}
continue;
}
// Check for conflicts between explicit register operands.
if let asm::InlineAsmRegOrRegClass::Reg(reg) = reg {
let (input, output) = match op {
hir::InlineAsmOperand::In { .. } => (true, false),
// Late output do not conflict with inputs, but normal outputs do
hir::InlineAsmOperand::Out { late, .. } => (!late, true),
hir::InlineAsmOperand::InOut { .. }
| hir::InlineAsmOperand::SplitInOut { .. } => (true, true),
hir::InlineAsmOperand::Const { .. }
| hir::InlineAsmOperand::SymFn { .. }
| hir::InlineAsmOperand::SymStatic { .. }
| hir::InlineAsmOperand::Label { .. } => {
unreachable!("{op:?} is not a register operand");
}
};
// Flag to output the error only once per operand
let mut skip = false;
let mut check = |used_regs: &mut FxHashMap<asm::InlineAsmReg, usize>,
input,
r: asm::InlineAsmReg| {
match used_regs.entry(r) {
Entry::Occupied(o) => {
if skip {
return;
}
skip = true;
let idx2 = *o.get();
let (ref op2, op_sp2) = operands[idx2];
let in_out = match (op, op2) {
(
hir::InlineAsmOperand::In { .. },
hir::InlineAsmOperand::Out { late, .. },
)
| (
hir::InlineAsmOperand::Out { late, .. },
hir::InlineAsmOperand::In { .. },
) => {
assert!(!*late);
let out_op_sp = if input { op_sp2 } else { op_sp };
Some(out_op_sp)
}
_ => None,
};
let reg_str = |idx| -> &str {
// HIR asm doesn't preserve the original alias string of the explicit register,
// so we have to retrieve it from AST
let (op, _): &(InlineAsmOperand, Span) = &asm.operands[idx];
if let Some(ast::InlineAsmRegOrRegClass::Reg(reg_sym)) =
op.reg()
{
reg_sym.as_str()
} else {
unreachable!("{op:?} is not a register operand");
}
};
self.dcx().emit_err(RegisterConflict {
op_span1: op_sp,
op_span2: op_sp2,
reg1_name: reg_str(idx),
reg2_name: reg_str(idx2),
in_out,
});
}
Entry::Vacant(v) => {
if r == reg {
v.insert(idx);
}
}
}
};
let mut overlapping_with = vec![];
reg.overlapping_regs(|r| {
overlapping_with.push(r);
});
for r in overlapping_with {
if input {
check(&mut used_input_regs, true, r);
}
if output {
check(&mut used_output_regs, false, r);
}
}
}
}
}
// If a clobber_abi is specified, add the necessary clobbers to the
// operands list.
let mut clobbered = FxHashSet::default();
for (abi, (_, abi_span)) in clobber_abis {
for &clobber in abi.clobbered_regs() {
// Don't emit a clobber for a register already clobbered
if clobbered.contains(&clobber) {
continue;
}
let mut overlapping_with = vec![];
clobber.overlapping_regs(|reg| {
overlapping_with.push(reg);
});
let output_used =
overlapping_with.iter().any(|reg| used_output_regs.contains_key(®));
if !output_used {
operands.push((
hir::InlineAsmOperand::Out {
reg: asm::InlineAsmRegOrRegClass::Reg(clobber),
late: true,
expr: None,
},
self.lower_span(abi_span),
));
clobbered.insert(clobber);
}
}
}
// Feature gate checking for asm goto.
if let Some((_, op_sp)) =
operands.iter().find(|(op, _)| matches!(op, hir::InlineAsmOperand::Label { .. }))
{
if !self.tcx.features().asm_goto() {
feature_err(
sess,
sym::asm_goto,
*op_sp,
fluent::ast_lowering_unstable_inline_assembly_label_operands,
)
.emit();
}
// In addition, check if an output operand is used.
// This is gated behind an additional feature.
let output_operand_used = operands.iter().any(|(op, _)| {
matches!(
op,
hir::InlineAsmOperand::Out { expr: Some(_), .. }
| hir::InlineAsmOperand::InOut { .. }
| hir::InlineAsmOperand::SplitInOut { out_expr: Some(_), .. }
)
});
if output_operand_used && !self.tcx.features().asm_goto_with_outputs() {
feature_err(
sess,
sym::asm_goto_with_outputs,
*op_sp,
fluent::ast_lowering_unstable_inline_assembly_label_operand_with_outputs,
)
.emit();
}
}
let operands = self.arena.alloc_from_iter(operands);
let template = self.arena.alloc_from_iter(asm.template.iter().cloned());
let template_strs = self.arena.alloc_from_iter(
asm.template_strs
.iter()
.map(|(sym, snippet, span)| (*sym, *snippet, self.lower_span(*span))),
);
let line_spans =
self.arena.alloc_from_iter(asm.line_spans.iter().map(|span| self.lower_span(*span)));
let hir_asm = hir::InlineAsm {
asm_macro: asm.asm_macro,
template,
template_strs,
operands,
options: asm.options,
line_spans,
};
self.arena.alloc(hir_asm)
}
}