bjoernager/rust
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Simplify aggregate projections.

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This commit is contained in:
Camille GILLOT 2023-09-16 09:35:46 +00:00
parent 692e528647
commit 48d2157a89
9 changed files with 192 additions and 119 deletions
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41
compiler/rustc_mir_transform/src/gvn.rs
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@ -276,6 +276,10 @@ impl<'body, 'tcx> VnState<'body, 'tcx> {
}
}
fn insert_scalar(&mut self, scalar: Scalar, ty: Ty<'tcx>) -> VnIndex {
self.insert(Value::Constant(Const::from_scalar(self.tcx, scalar, ty)))
}
#[instrument(level = "trace", skip(self), ret)]
fn eval_to_const(&mut self, value: VnIndex) -> Option<OpTy<'tcx>> {
use Value::*;
@ -483,12 +487,33 @@ impl<'body, 'tcx> VnState<'body, 'tcx> {
}
}
ProjectionElem::Downcast(name, index) => ProjectionElem::Downcast(name, index),
ProjectionElem::Field(f, ty) => ProjectionElem::Field(f, ty),
ProjectionElem::Field(f, ty) => {
if let Value::Aggregate(_, _, fields) = self.get(value) {
return Some(fields[f.as_usize()]);
} else if let Value::Projection(outer_value, ProjectionElem::Downcast(_, read_variant)) = self.get(value)
&& let Value::Aggregate(_, written_variant, fields) = self.get(*outer_value)
&& written_variant == read_variant
{
return Some(fields[f.as_usize()]);
}
ProjectionElem::Field(f, ty)
}
ProjectionElem::Index(idx) => {
let idx = self.locals[idx]?;
ProjectionElem::Index(idx)
}
ProjectionElem::ConstantIndex { offset, min_length, from_end } => {
match self.get(value) {
Value::Aggregate(ty, _, operands) if ty.is_array() => {
let offset = if from_end {
operands.len() - offset as usize
} else {
offset as usize
};
return operands.get(offset).copied();
}
_ => {}
};
ProjectionElem::ConstantIndex { offset, min_length, from_end }
}
ProjectionElem::Subslice { from, to, from_end } => {
@ -679,6 +704,9 @@ impl<'body, 'tcx> VnState<'body, 'tcx> {
}
Rvalue::Discriminant(ref mut place) => {
let place = self.simplify_place_value(place, location)?;
if let Some(discr) = self.simplify_discriminant(place) {
return Some(discr);
}
Value::Discriminant(place)
}
@ -688,6 +716,17 @@ impl<'body, 'tcx> VnState<'body, 'tcx> {
debug!(?value);
Some(self.insert(value))
}
fn simplify_discriminant(&mut self, place: VnIndex) -> Option<VnIndex> {
if let Value::Aggregate(enum_ty, variant, _) = *self.get(place)
&& enum_ty.is_enum()
{
let discr = self.ecx.discriminant_for_variant(enum_ty, variant).ok()?;
return Some(self.insert_scalar(discr.to_scalar(), discr.layout.ty));
}
None
}
}
fn op_to_prop_const<'tcx>(