diff options
Diffstat (limited to 'compiler/rustc_mir_transform/src/lower_intrinsics.rs')
| -rw-r--r-- | compiler/rustc_mir_transform/src/lower_intrinsics.rs | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/compiler/rustc_mir_transform/src/lower_intrinsics.rs b/compiler/rustc_mir_transform/src/lower_intrinsics.rs new file mode 100644 index 000000000..b7ba61651 --- /dev/null +++ b/compiler/rustc_mir_transform/src/lower_intrinsics.rs @@ -0,0 +1,156 @@ +//! Lowers intrinsic calls + +use crate::MirPass; +use rustc_middle::mir::*; +use rustc_middle::ty::subst::SubstsRef; +use rustc_middle::ty::{self, Ty, TyCtxt}; +use rustc_span::symbol::{sym, Symbol}; +use rustc_span::Span; + +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 func_ty = func.ty(local_decls, tcx); + let Some((intrinsic_name, substs)) = resolve_rust_intrinsic(tcx, func_ty) else { + continue; + }; + match intrinsic_name { + sym::unreachable => { + terminator.kind = TerminatorKind::Unreachable; + } + 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(Constant { + span: terminator.source_info.span, + user_ty: None, + literal: ConstantKind::zero_sized(tcx.types.unit), + }))), + ))), + }); + terminator.kind = TerminatorKind::Goto { target }; + } + } + sym::copy_nonoverlapping => { + let target = target.unwrap(); + let mut args = args.drain(..); + block.statements.push(Statement { + source_info: terminator.source_info, + kind: StatementKind::CopyNonOverlapping(Box::new( + rustc_middle::mir::CopyNonOverlapping { + src: args.next().unwrap(), + dst: args.next().unwrap(), + count: args.next().unwrap(), + }, + )), + }); + assert_eq!( + args.next(), + None, + "Extra argument for copy_non_overlapping intrinsic" + ); + drop(args); + terminator.kind = TerminatorKind::Goto { target }; + } + sym::wrapping_add | sym::wrapping_sub | sym::wrapping_mul => { + if let Some(target) = *target { + let lhs; + let rhs; + { + let mut args = args.drain(..); + lhs = args.next().unwrap(); + rhs = args.next().unwrap(); + } + let bin_op = match intrinsic_name { + sym::wrapping_add => BinOp::Add, + sym::wrapping_sub => BinOp::Sub, + sym::wrapping_mul => BinOp::Mul, + _ => 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, rhs))), + ))), + }); + terminator.kind = TerminatorKind::Goto { target }; + } + } + sym::add_with_overflow | sym::sub_with_overflow | sym::mul_with_overflow => { + // The checked binary operations are not suitable target for lowering here, + // since their semantics depend on the value of overflow-checks flag used + // during codegen. Issue #35310. + } + sym::size_of | sym::min_align_of => { + if let Some(target) = *target { + let tp_ty = substs.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::discriminant_value => { + if let (Some(target), Some(arg)) = (*target, args[0].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 }; + } + } + _ if intrinsic_name.as_str().starts_with("simd_shuffle") => { + validate_simd_shuffle(tcx, args, terminator.source_info.span); + } + _ => {} + } + } + } + } +} + +fn resolve_rust_intrinsic<'tcx>( + tcx: TyCtxt<'tcx>, + func_ty: Ty<'tcx>, +) -> Option<(Symbol, SubstsRef<'tcx>)> { + if let ty::FnDef(def_id, substs) = *func_ty.kind() { + if tcx.is_intrinsic(def_id) { + return Some((tcx.item_name(def_id), substs)); + } + } + None +} + +fn validate_simd_shuffle<'tcx>(tcx: TyCtxt<'tcx>, args: &[Operand<'tcx>], span: Span) { + match &args[2] { + Operand::Constant(_) => {} // all good + _ => { + let msg = "last argument of `simd_shuffle` is required to be a `const` item"; + tcx.sess.span_err(span, msg); + } + } +} |