bjoernager/rust
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avoid computing misalignment if we won't act on it

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This commit is contained in:
Ralf Jung 2023-09-05 21:54:14 +02:00
parent f3f9b795bd
commit cbf47a17d2
1 changed files with 11 additions and 6 deletions
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17
compiler/rustc_const_eval/src/interpret/memory.rs
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@ -424,7 +424,9 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
throw_ub!(DanglingIntPointer(addr, msg));
}
// Must be aligned.
self.check_misalign(Self::offset_misalignment(addr, align))?;
if M::enforce_alignment(self) && align.bytes() > 1 {
self.check_misalign(Self::offset_misalignment(addr, align))?;
}
None
}
Ok((alloc_id, offset, prov)) => {
@ -446,7 +448,9 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
}
// Test align. Check this last; if both bounds and alignment are violated
// we want the error to be about the bounds.
self.check_misalign(self.alloc_misalignment(ptr, offset, align, alloc_align))?;
if M::enforce_alignment(self) && align.bytes() > 1 {
self.check_misalign(self.alloc_misalignment(ptr, offset, align, alloc_align))?;
}
// We can still be zero-sized in this branch, in which case we have to
// return `None`.
@ -457,10 +461,8 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
#[inline(always)]
pub(super) fn check_misalign(&self, misaligned: Option<Misalignment>) -> InterpResult<'tcx> {
if M::enforce_alignment(self) {
if let Some(misaligned) = misaligned {
throw_ub!(AlignmentCheckFailed(misaligned))
}
if let Some(misaligned) = misaligned {
throw_ub!(AlignmentCheckFailed(misaligned))
}
Ok(())
}
@ -502,6 +504,9 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
ptr: Pointer<Option<M::Provenance>>,
align: Align,
) -> Option<Misalignment> {
if !M::enforce_alignment(self) {
return None;
}
match self.ptr_try_get_alloc_id(ptr) {
Err(addr) => Self::offset_misalignment(addr, align),
Ok((alloc_id, offset, _prov)) => {