bjoernager/rust
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Change enum->int casts to not go through MIR casts.

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Instead we generate a discriminant rvalue and cast the result of that.
This commit is contained in:
Oli Scherer 2022-06-29 14:18:55 +00:00
parent 0e674b3ec5
commit 7839cb963f
15 changed files with 221 additions and 132 deletions
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25
compiler/rustc_const_eval/src/interpret/cast.rs
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@ -8,7 +8,7 @@ use rustc_middle::mir::CastKind;
use rustc_middle::ty::adjustment::PointerCast;
use rustc_middle::ty::layout::{IntegerExt, LayoutOf, TyAndLayout};
use rustc_middle::ty::{self, FloatTy, Ty, TypeAndMut};
use rustc_target::abi::{Integer, Variants};
use rustc_target::abi::Integer;
use rustc_type_ir::sty::TyKind::*;
use super::{
@ -127,12 +127,10 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
Float(FloatTy::F64) => {
return Ok(self.cast_from_float(src.to_scalar()?.to_f64()?, cast_ty).into());
}
// The rest is integer/pointer-"like", including fn ptr casts and casts from enums that
// are represented as integers.
// The rest is integer/pointer-"like", including fn ptr casts
_ => assert!(
src.layout.ty.is_bool()
|| src.layout.ty.is_char()
|| src.layout.ty.is_enum()
|| src.layout.ty.is_integral()
|| src.layout.ty.is_any_ptr(),
"Unexpected cast from type {:?}",
@ -142,25 +140,6 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
// # First handle non-scalar source values.
// Handle cast from a ZST enum (0 or 1 variants).
match src.layout.variants {
Variants::Single { index } => {
if src.layout.abi.is_uninhabited() {
// This is dead code, because an uninhabited enum is UB to
// instantiate.
throw_ub!(Unreachable);
}
if let Some(discr) = src.layout.ty.discriminant_for_variant(*self.tcx, index) {
assert!(src.layout.is_zst());
let discr_layout = self.layout_of(discr.ty)?;
let scalar = Scalar::from_uint(discr.val, discr_layout.layout.size());
return Ok(self.cast_from_int_like(scalar, discr_layout, cast_ty)?.into());
}
}
Variants::Multiple { .. } => {}
}
// Handle casting any ptr to raw ptr (might be a fat ptr).
if src.layout.ty.is_any_ptr() && cast_ty.is_unsafe_ptr() {
let dest_layout = self.layout_of(cast_ty)?;