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Allow clobbering unsupported registers in asm!

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Previously registers could only be marked as clobbered if the target feature for that register was enabled. This restriction is now removed.
This commit is contained in:
Amanieu d'Antras 2021-04-04 08:09:56 +01:00
parent cbd6ec7604
commit ddc53f809b
3 changed files with 97 additions and 33 deletions
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82
compiler/rustc_ast_lowering/src/expr.rs
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@ -1499,46 +1499,64 @@ impl<'hir> LoweringContext<'_, 'hir> {
// previous iteration.
required_features.clear();
// Validate register classes against currently enabled target
// features. We check that at least one type is available for
// the current target.
let reg_class = reg.reg_class();
if reg_class == asm::InlineAsmRegClass::Err {
continue;
}
for &(_, feature) in reg_class.supported_types(asm_arch.unwrap()) {
if let Some(feature) = feature {
if self.sess.target_features.contains(&Symbol::intern(feature)) {
// We ignore target feature requirements for clobbers: if the
// feature is disabled then the compiler doesn't care what we
// do with the registers.
//
// Note that this is only possible for explicit register
// operands, which cannot be used in the asm string.
let is_clobber = matches!(
op,
hir::InlineAsmOperand::Out {
reg: asm::InlineAsmRegOrRegClass::Reg(_),
late: _,
expr: None
}
);
if !is_clobber {
// Validate register classes against currently enabled target
// features. We check that at least one type is available for
// the current target.
for &(_, feature) in reg_class.supported_types(asm_arch.unwrap()) {
if let Some(feature) = feature {
if self.sess.target_features.contains(&Symbol::intern(feature)) {
required_features.clear();
break;
} else {
required_features.push(feature);
}
} else {
required_features.clear();
break;
} else {
required_features.push(feature);
}
} else {
required_features.clear();
break;
}
}
// We are sorting primitive strs here and can use unstable sort here
required_features.sort_unstable();
required_features.dedup();
match &required_features[..] {
[] => {}
[feature] => {
let msg = format!(
"register class `{}` requires the `{}` target feature",
reg_class.name(),
feature
);
sess.struct_span_err(op_sp, &msg).emit();
}
features => {
let msg = format!(
"register class `{}` requires at least one target feature: {}",
reg_class.name(),
features.join(", ")
);
sess.struct_span_err(op_sp, &msg).emit();
// We are sorting primitive strs here and can use unstable sort here
required_features.sort_unstable();
required_features.dedup();
match &required_features[..] {
[] => {}
[feature] => {
let msg = format!(
"register class `{}` requires the `{}` target feature",
reg_class.name(),
feature
);
sess.struct_span_err(op_sp, &msg).emit();
}
features => {
let msg = format!(
"register class `{}` requires at least one target feature: {}",
reg_class.name(),
features.join(", ")
);
sess.struct_span_err(op_sp, &msg).emit();
}
}
}