rustc_ast_lowering/asm.rs
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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::symbol::kw;
use rustc_span::{Span, sym};
use rustc_target::asm;
use super::LoweringContext;
use super::errors::{
AbiSpecifiedMultipleTimes, AttSyntaxOnlyX86, ClobberAbiNotSupported,
InlineAsmUnsupportedTarget, InvalidAbiClobberAbi, InvalidAsmTemplateModifierConst,
InvalidAsmTemplateModifierLabel, InvalidAsmTemplateModifierRegClass,
InvalidAsmTemplateModifierRegClassSub, InvalidAsmTemplateModifierSym, InvalidRegister,
InvalidRegisterClass, RegisterClassOnlyClobber, 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();
}
}
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, *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_def_id_parent;
let node_id = self.next_node_id();
// HACK(min_generic_const_args): see lower_anon_const
if !expr.is_potential_trivial_const_arg(true) {
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 } => {
if !self.tcx.features().asm_goto() {
feature_err(
sess,
sym::asm_goto,
*op_sp,
fluent::ast_lowering_unstable_inline_assembly_label_operands,
)
.emit();
}
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()) && !op.is_clobber() {
self.dcx().emit_err(RegisterClassOnlyClobber {
op_span: op_sp,
reg_class_name: reg_class.name(),
});
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);
}
}
}
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)
}
}