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Simplify force_allocation_maybe_sized

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This commit is contained in:
Oliver Scherer 2019-12-14 00:05:04 +01:00
parent b5b5258d74
commit bb1ecee5b6
2 changed files with 4 additions and 15 deletions
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2
src/librustc_mir/interpret/eval_context.rs
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@ -118,7 +118,7 @@ pub struct LocalState<'tcx, Tag = (), Id = AllocId> {
}
/// Current value of a local variable
#[derive(Clone, PartialEq, Eq, Debug, HashStable)] // Miri debug-prints these
#[derive(Copy, Clone, PartialEq, Eq, Debug, HashStable)] // Miri debug-prints these
pub enum LocalValue<Tag = (), Id = AllocId> {
/// This local is not currently alive, and cannot be used at all.
Dead,

17
src/librustc_mir/interpret/place.rs
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@ -974,31 +974,20 @@ where
let (mplace, size) = match place.place {
Place::Local { frame, local } => {
match self.stack[frame].locals[local].access_mut()? {
Ok(local_val) => {
Ok(&mut local_val) => {
// We need to make an allocation.
// FIXME: Consider not doing anything for a ZST, and just returning
// a fake pointer? Are we even called for ZST?
// We cannot hold on to the reference `local_val` while allocating,
// but we can hold on to the value in there.
let old_val =
if let LocalValue::Live(Operand::Immediate(value)) = *local_val {
Some(value)
} else {
None
};
// We need the layout of the local. We can NOT use the layout we got,
// that might e.g., be an inner field of a struct with `Scalar` layout,
// that has different alignment than the outer field.
// We also need to support unsized types, and hence cannot use `allocate`.
let local_layout = self.layout_of_local(&self.stack[frame], local, None)?;
// We also need to support unsized types, and hence cannot use `allocate`.
let (size, align) = self
.size_and_align_of(meta, local_layout)?
.expect("Cannot allocate for non-dyn-sized type");
let ptr = self.memory.allocate(size, align, MemoryKind::Stack);
let mplace = MemPlace { ptr: ptr.into(), align, meta };
if let Some(value) = old_val {
if let LocalValue::Live(Operand::Immediate(value)) = local_val {
// Preserve old value.
// We don't have to validate as we can assume the local
// was already valid for its type.