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interpret: use Either over Result when it is not representing an error condition

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This commit is contained in:
Ralf Jung 2022-11-18 10:18:32 +01:00
parent 83356b78c4
commit 4101889786
17 changed files with 130 additions and 98 deletions
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32
compiler/rustc_const_eval/src/interpret/operand.rs
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@ -1,6 +1,8 @@
//! Functions concerning immediate values and operands, and reading from operands.
//! All high-level functions to read from memory work on operands as sources.
use either::{Either, Left, Right};
use rustc_hir::def::Namespace;
use rustc_middle::ty::layout::{LayoutOf, PrimitiveExt, TyAndLayout};
use rustc_middle::ty::print::{FmtPrinter, PrettyPrinter};
@ -261,9 +263,9 @@ impl<'tcx, Prov: Provenance> OpTy<'tcx, Prov> {
layout: TyAndLayout<'tcx>,
cx: &impl HasDataLayout,
) -> InterpResult<'tcx, Self> {
match self.try_as_mplace() {
Ok(mplace) => Ok(mplace.offset_with_meta(offset, meta, layout, cx)?.into()),
Err(imm) => {
match self.as_mplace_or_imm() {
Left(mplace) => Ok(mplace.offset_with_meta(offset, meta, layout, cx)?.into()),
Right(imm) => {
assert!(
matches!(*imm, Immediate::Uninit),
"Scalar/ScalarPair cannot be offset into"
@ -353,8 +355,8 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
/// Try returning an immediate for the operand. If the layout does not permit loading this as an
/// immediate, return where in memory we can find the data.
/// Note that for a given layout, this operation will either always fail or always
/// succeed! Whether it succeeds depends on whether the layout can be represented
/// Note that for a given layout, this operation will either always return Left or Right!
/// succeed! Whether it returns Left depends on whether the layout can be represented
/// in an `Immediate`, not on which data is stored there currently.
///
/// This is an internal function that should not usually be used; call `read_immediate` instead.
@ -362,16 +364,16 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
pub fn read_immediate_raw(
&self,
src: &OpTy<'tcx, M::Provenance>,
) -> InterpResult<'tcx, Result<ImmTy<'tcx, M::Provenance>, MPlaceTy<'tcx, M::Provenance>>> {
Ok(match src.try_as_mplace() {
Ok(ref mplace) => {
) -> InterpResult<'tcx, Either<ImmTy<'tcx, M::Provenance>, MPlaceTy<'tcx, M::Provenance>>> {
Ok(match src.as_mplace_or_imm() {
Left(ref mplace) => {
if let Some(val) = self.read_immediate_from_mplace_raw(mplace)? {
Ok(val)
Left(val)
} else {
Err(*mplace)
Right(*mplace)
}
}
Err(val) => Ok(val),
Right(val) => Left(val),
})
}
@ -390,7 +392,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
) {
span_bug!(self.cur_span(), "primitive read not possible for type: {:?}", op.layout.ty);
}
let imm = self.read_immediate_raw(op)?.unwrap();
let imm = self.read_immediate_raw(op)?.left().unwrap();
if matches!(*imm, Immediate::Uninit) {
throw_ub!(InvalidUninitBytes(None));
}
@ -432,9 +434,9 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
// Basically we just transmute this place into an array following simd_size_and_type.
// This only works in memory, but repr(simd) types should never be immediates anyway.
assert!(op.layout.ty.is_simd());
match op.try_as_mplace() {
Ok(mplace) => self.mplace_to_simd(&mplace),
Err(imm) => match *imm {
match op.as_mplace_or_imm() {
Left(mplace) => self.mplace_to_simd(&mplace),
Right(imm) => match *imm {
Immediate::Uninit => {
throw_ub!(InvalidUninitBytes(None))
}