bjoernager/rust
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Remove bounds check with enum cast

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This commit is contained in:
ouz-a 2022-10-26 17:50:11 +03:00
parent 4596f4f8b5
commit a1672ad5b8
9 changed files with 120 additions and 19 deletions
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51
compiler/rustc_mir_build/src/build/expr/as_rvalue.rs
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@ -2,6 +2,7 @@
use rustc_index::vec::Idx;
use rustc_middle::ty::util::IntTypeExt;
use rustc_target::abi::{Abi, Primitive};
use crate::build::expr::as_place::PlaceBase;
use crate::build::expr::category::{Category, RvalueFunc};
@ -198,6 +199,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
let (source, ty) = if let ty::Adt(adt_def, ..) = source.ty.kind() && adt_def.is_enum() {
let discr_ty = adt_def.repr().discr_type().to_ty(this.tcx);
let temp = unpack!(block = this.as_temp(block, scope, source, Mutability::Not));
let layout = this.tcx.layout_of(this.param_env.and(source.ty));
let discr = this.temp(discr_ty, source.span);
this.cfg.push_assign(
block,
@ -205,8 +207,55 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
discr,
Rvalue::Discriminant(temp.into()),
);
let (op,ty) = (Operand::Move(discr), discr_ty);
if let Abi::Scalar(scalar) = layout.unwrap().abi{
if let Primitive::Int(_, signed) = scalar.primitive() {
let range = scalar.valid_range(&this.tcx);
// FIXME: Handle wraparound cases too.
if range.end >= range.start {
let mut assumer = |range: u128, bin_op: BinOp| {
// We will be overwriting this val if our scalar is signed value
// because sign extension on unsigned types might cause unintended things
let mut range_val =
ConstantKind::from_bits(this.tcx, range, ty::ParamEnv::empty().and(discr_ty));
let bool_ty = this.tcx.types.bool;
if signed {
let scalar_size_extend = scalar.size(&this.tcx).sign_extend(range);
let discr_layout = this.tcx.layout_of(this.param_env.and(discr_ty));
let truncated_val = discr_layout.unwrap().size.truncate(scalar_size_extend);
range_val = ConstantKind::from_bits(
this.tcx,
truncated_val,
ty::ParamEnv::empty().and(discr_ty),
);
}
let lit_op = this.literal_operand(expr.span, range_val);
let is_bin_op = this.temp(bool_ty, expr_span);
this.cfg.push_assign(
block,
source_info,
is_bin_op,
Rvalue::BinaryOp(bin_op, Box::new(((lit_op), (Operand::Copy(discr))))),
);
this.cfg.push(
block,
Statement {
source_info,
kind: StatementKind::Intrinsic(Box::new(NonDivergingIntrinsic::Assume(
Operand::Copy(is_bin_op),
))),
},
)
};
assumer(range.end, BinOp::Ge);
assumer(range.start, BinOp::Le);
}
}
}
(op,ty)
(Operand::Move(discr), discr_ty)
} else {
let ty = source.ty;
let source = unpack!(