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//! Lowers intrinsic calls
use crate::take_array;
use rustc_middle::mir::*;
use rustc_middle::ty::{self, TyCtxt};
use rustc_middle::{bug, span_bug};
use rustc_span::symbol::sym;
pub struct LowerIntrinsics;
impl<'tcx> MirPass<'tcx> for LowerIntrinsics {
fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
let local_decls = &body.local_decls;
for block in body.basic_blocks.as_mut() {
let terminator = block.terminator.as_mut().unwrap();
if let TerminatorKind::Call { func, args, destination, target, .. } =
&mut terminator.kind
&& let ty::FnDef(def_id, generic_args) = *func.ty(local_decls, tcx).kind()
&& let Some(intrinsic) = tcx.intrinsic(def_id)
{
match intrinsic.name {
sym::unreachable => {
terminator.kind = TerminatorKind::Unreachable;
}
sym::ub_checks => {
let target = target.unwrap();
block.statements.push(Statement {
source_info: terminator.source_info,
kind: StatementKind::Assign(Box::new((
*destination,
Rvalue::NullaryOp(NullOp::UbChecks, tcx.types.bool),
))),
});
terminator.kind = TerminatorKind::Goto { target };
}
sym::forget => {
if let Some(target) = *target {
block.statements.push(Statement {
source_info: terminator.source_info,
kind: StatementKind::Assign(Box::new((
*destination,
Rvalue::Use(Operand::Constant(Box::new(ConstOperand {
span: terminator.source_info.span,
user_ty: None,
const_: Const::zero_sized(tcx.types.unit),
}))),
))),
});
terminator.kind = TerminatorKind::Goto { target };
}
}
sym::copy_nonoverlapping => {
let target = target.unwrap();
let Ok([src, dst, count]) = take_array(args) else {
bug!("Wrong arguments for copy_non_overlapping intrinsic");
};
block.statements.push(Statement {
source_info: terminator.source_info,
kind: StatementKind::Intrinsic(Box::new(
NonDivergingIntrinsic::CopyNonOverlapping(
rustc_middle::mir::CopyNonOverlapping {
src: src.node,
dst: dst.node,
count: count.node,
},
),
)),
});
terminator.kind = TerminatorKind::Goto { target };
}
sym::assume => {
let target = target.unwrap();
let Ok([arg]) = take_array(args) else {
bug!("Wrong arguments for assume intrinsic");
};
block.statements.push(Statement {
source_info: terminator.source_info,
kind: StatementKind::Intrinsic(Box::new(
NonDivergingIntrinsic::Assume(arg.node),
)),
});
terminator.kind = TerminatorKind::Goto { target };
}
sym::wrapping_add
| sym::wrapping_sub
| sym::wrapping_mul
| sym::three_way_compare
| sym::unchecked_add
| sym::unchecked_sub
| sym::unchecked_mul
| sym::unchecked_div
| sym::unchecked_rem
| sym::unchecked_shl
| sym::unchecked_shr => {
let target = target.unwrap();
let Ok([lhs, rhs]) = take_array(args) else {
bug!("Wrong arguments for {} intrinsic", intrinsic.name);
};
let bin_op = match intrinsic.name {
sym::wrapping_add => BinOp::Add,
sym::wrapping_sub => BinOp::Sub,
sym::wrapping_mul => BinOp::Mul,
sym::three_way_compare => BinOp::Cmp,
sym::unchecked_add => BinOp::AddUnchecked,
sym::unchecked_sub => BinOp::SubUnchecked,
sym::unchecked_mul => BinOp::MulUnchecked,
sym::unchecked_div => BinOp::Div,
sym::unchecked_rem => BinOp::Rem,
sym::unchecked_shl => BinOp::ShlUnchecked,
sym::unchecked_shr => BinOp::ShrUnchecked,
_ => bug!("unexpected intrinsic"),
};
block.statements.push(Statement {
source_info: terminator.source_info,
kind: StatementKind::Assign(Box::new((
*destination,
Rvalue::BinaryOp(bin_op, Box::new((lhs.node, rhs.node))),
))),
});
terminator.kind = TerminatorKind::Goto { target };
}
sym::add_with_overflow | sym::sub_with_overflow | sym::mul_with_overflow => {
if let Some(target) = *target {
let Ok([lhs, rhs]) = take_array(args) else {
bug!("Wrong arguments for {} intrinsic", intrinsic.name);
};
let bin_op = match intrinsic.name {
sym::add_with_overflow => BinOp::AddWithOverflow,
sym::sub_with_overflow => BinOp::SubWithOverflow,
sym::mul_with_overflow => BinOp::MulWithOverflow,
_ => bug!("unexpected intrinsic"),
};
block.statements.push(Statement {
source_info: terminator.source_info,
kind: StatementKind::Assign(Box::new((
*destination,
Rvalue::BinaryOp(bin_op, Box::new((lhs.node, rhs.node))),
))),
});
terminator.kind = TerminatorKind::Goto { target };
}
}
sym::size_of | sym::min_align_of => {
if let Some(target) = *target {
let tp_ty = generic_args.type_at(0);
let null_op = match intrinsic.name {
sym::size_of => NullOp::SizeOf,
sym::min_align_of => NullOp::AlignOf,
_ => bug!("unexpected intrinsic"),
};
block.statements.push(Statement {
source_info: terminator.source_info,
kind: StatementKind::Assign(Box::new((
*destination,
Rvalue::NullaryOp(null_op, tp_ty),
))),
});
terminator.kind = TerminatorKind::Goto { target };
}
}
sym::read_via_copy => {
let Ok([arg]) = take_array(args) else {
span_bug!(terminator.source_info.span, "Wrong number of arguments");
};
let derefed_place = if let Some(place) = arg.node.place()
&& let Some(local) = place.as_local()
{
tcx.mk_place_deref(local.into())
} else {
span_bug!(
terminator.source_info.span,
"Only passing a local is supported"
);
};
// Add new statement at the end of the block that does the read, and patch
// up the terminator.
block.statements.push(Statement {
source_info: terminator.source_info,
kind: StatementKind::Assign(Box::new((
*destination,
Rvalue::Use(Operand::Copy(derefed_place)),
))),
});
terminator.kind = match *target {
None => {
// No target means this read something uninhabited,
// so it must be unreachable.
TerminatorKind::Unreachable
}
Some(target) => TerminatorKind::Goto { target },
}
}
sym::write_via_move => {
let target = target.unwrap();
let Ok([ptr, val]) = take_array(args) else {
span_bug!(
terminator.source_info.span,
"Wrong number of arguments for write_via_move intrinsic",
);
};
let derefed_place = if let Some(place) = ptr.node.place()
&& let Some(local) = place.as_local()
{
tcx.mk_place_deref(local.into())
} else {
span_bug!(
terminator.source_info.span,
"Only passing a local is supported"
);
};
block.statements.push(Statement {
source_info: terminator.source_info,
kind: StatementKind::Assign(Box::new((
derefed_place,
Rvalue::Use(val.node),
))),
});
terminator.kind = TerminatorKind::Goto { target };
}
sym::discriminant_value => {
if let (Some(target), Some(arg)) = (*target, args[0].node.place()) {
let arg = tcx.mk_place_deref(arg);
block.statements.push(Statement {
source_info: terminator.source_info,
kind: StatementKind::Assign(Box::new((
*destination,
Rvalue::Discriminant(arg),
))),
});
terminator.kind = TerminatorKind::Goto { target };
}
}
sym::offset => {
let target = target.unwrap();
let Ok([ptr, delta]) = take_array(args) else {
span_bug!(
terminator.source_info.span,
"Wrong number of arguments for offset intrinsic",
);
};
block.statements.push(Statement {
source_info: terminator.source_info,
kind: StatementKind::Assign(Box::new((
*destination,
Rvalue::BinaryOp(BinOp::Offset, Box::new((ptr.node, delta.node))),
))),
});
terminator.kind = TerminatorKind::Goto { target };
}
sym::transmute | sym::transmute_unchecked => {
let dst_ty = destination.ty(local_decls, tcx).ty;
let Ok([arg]) = take_array(args) else {
span_bug!(
terminator.source_info.span,
"Wrong number of arguments for transmute intrinsic",
);
};
// Always emit the cast, even if we transmute to an uninhabited type,
// because that lets CTFE and codegen generate better error messages
// when such a transmute actually ends up reachable.
block.statements.push(Statement {
source_info: terminator.source_info,
kind: StatementKind::Assign(Box::new((
*destination,
Rvalue::Cast(CastKind::Transmute, arg.node, dst_ty),
))),
});
if let Some(target) = *target {
terminator.kind = TerminatorKind::Goto { target };
} else {
terminator.kind = TerminatorKind::Unreachable;
}
}
sym::aggregate_raw_ptr => {
let Ok([data, meta]) = take_array(args) else {
span_bug!(
terminator.source_info.span,
"Wrong number of arguments for aggregate_raw_ptr intrinsic",
);
};
let target = target.unwrap();
let pointer_ty = generic_args.type_at(0);
let kind = if let ty::RawPtr(pointee_ty, mutability) = pointer_ty.kind() {
AggregateKind::RawPtr(*pointee_ty, *mutability)
} else {
span_bug!(
terminator.source_info.span,
"Return type of aggregate_raw_ptr intrinsic must be a raw pointer",
);
};
let fields = [data.node, meta.node];
block.statements.push(Statement {
source_info: terminator.source_info,
kind: StatementKind::Assign(Box::new((
*destination,
Rvalue::Aggregate(Box::new(kind), fields.into()),
))),
});
terminator.kind = TerminatorKind::Goto { target };
}
sym::ptr_metadata => {
let Ok([ptr]) = take_array(args) else {
span_bug!(
terminator.source_info.span,
"Wrong number of arguments for ptr_metadata intrinsic",
);
};
let target = target.unwrap();
block.statements.push(Statement {
source_info: terminator.source_info,
kind: StatementKind::Assign(Box::new((
*destination,
Rvalue::UnaryOp(UnOp::PtrMetadata, ptr.node),
))),
});
terminator.kind = TerminatorKind::Goto { target };
}
_ => {}
}
}
}
}
}