rustc_mir_transform/lower_intrinsics.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
//! Lowers intrinsic calls
use rustc_middle::mir::*;
use rustc_middle::ty::{self, TyCtxt};
use rustc_middle::{bug, span_bug};
use rustc_span::symbol::sym;
use crate::take_array;
pub(super) struct LowerIntrinsics;
impl<'tcx> crate::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 => {
let target = target.unwrap();
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 => {
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::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 => {
let target = target.unwrap();
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 => {
let target = target.unwrap();
let Ok([arg]) = take_array(args) else {
span_bug!(
terminator.source_info.span,
"Wrong arguments for discriminant_value intrinsic"
);
};
let arg = arg.node.place().unwrap();
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 };
}
_ => {}
}
}
}
}
}