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even tighter checks for layouts on immediate field projections

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This commit is contained in:
Ralf Jung 2022-05-10 13:24:39 +02:00
parent 79c169d5cf
commit 600d960261
1 changed files with 11 additions and 6 deletions
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17
compiler/rustc_const_eval/src/interpret/operand.rs
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@ -398,22 +398,27 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
};
let field_layout = base.layout.field(self, field);
if field_layout.is_zst() {
let immediate = Scalar::ZST.into();
return Ok(OpTy { op: Operand::Immediate(immediate), layout: field_layout });
}
let offset = base.layout.fields.offset(field);
// This makes several assumptions about what layouts we will encounter; we match what
// codegen does as good as we can (see `extract_field` in `rustc_codegen_ssa/src/mir/operand.rs`).
let field_val = match (*base, base.layout.abi) {
let field_val: Immediate<_> = match (*base, base.layout.abi) {
// the field contains no information
_ if field_layout.is_zst() => {
Scalar::ZST.into()
}
// the field covers the entire type
_ if field_layout.size == base.layout.size => {
assert!(match (base.layout.abi, field_layout.abi) {
(Abi::Scalar(..), Abi::Scalar(..)) => true,
(Abi::ScalarPair(..), Abi::ScalarPair(..)) => true,
_ => false,
});
assert!(offset.bytes() == 0);
*base
}
// extract fields from types with `ScalarPair` ABI
(Immediate::ScalarPair(a_val, b_val), Abi::ScalarPair(a, b)) => {
assert!(matches!(field_layout.abi, Abi::Scalar(..)));
Immediate::from(if offset.bytes() == 0 {
assert_eq!(field_layout.size, a.size(self));
a_val