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interpret: with enforce_number_validity, ensure integers are truly Scalar::Int (i.e., no pointers) #95340

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merged 2 commits into from
Mar 27, 2022
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interpret: with enforce_number_validity, ensure integers are truly Scalar::Int (i.e., no pointers) #95340

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78b680e
interpret: mark a dead match arm as dead
RalfJung Mar 26, 2022
3bbcf64
interpret: with enforce_number_validity, ensure integers are truly Sc…
RalfJung Mar 26, 2022
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3 changes: 2 additions & 1 deletion compiler/rustc_const_eval/src/interpret/eval_context.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -444,6 +444,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
match scalar.try_to_int() {
Ok(int) => int.is_null(),
Err(_) => {
// Can only happen during CTFE.
let ptr = self.scalar_to_ptr(scalar);
match self.memory.ptr_try_get_alloc(ptr) {
Ok((alloc_id, offset, _)) => {
Expand All @@ -455,7 +456,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
// Note that one-past-the-end (offset == size) is still inbounds, and never null.
offset > size
}
Err(offset) => offset == 0,
Err(_offset) => bug!("a non-int scalar is always a pointer"),
}
}
}
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9 changes: 6 additions & 3 deletions compiler/rustc_const_eval/src/interpret/validity.rs
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Expand Up @@ -21,7 +21,7 @@ use std::hash::Hash;

use super::{
alloc_range, CheckInAllocMsg, GlobalAlloc, InterpCx, InterpResult, MPlaceTy, Machine,
MemPlaceMeta, OpTy, ScalarMaybeUninit, ValueVisitor,
MemPlaceMeta, OpTy, Scalar, ScalarMaybeUninit, ValueVisitor,
};

macro_rules! throw_validation_failure {
Expand Down Expand Up @@ -521,8 +521,11 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
// NOTE: Keep this in sync with the array optimization for int/float
// types below!
if M::enforce_number_validity(self.ecx) {
// Integers/floats in CTFE: Must be scalar bits, pointers are dangerous
let is_bits = value.check_init().map_or(false, |v| v.try_to_int().is_ok());
// Integers/floats with number validity: Must be scalar bits, pointers are dangerous.
// As a special exception we *do* match on a `Scalar` here, since we truly want
// to know its underlying representation (and *not* cast it to an integer).
let is_bits =
value.check_init().map_or(false, |v| matches!(v, Scalar::Int(..)));
if !is_bits {
throw_validation_failure!(self.path,
{ "{:x}", value } expected { "initialized plain (non-pointer) bytes" }
Expand Down