bjoernager/rust
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Auto merge of #115705 - cjgillot:const-prop-aggregate, r=oli-obk

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Read from non-scalar constants and statics in dataflow const-prop

DataflowConstProp is designed to handle scalar values. When MIR features an assignment from a non-scalar constant, we need to manually decompose it into the custom state space.

This PR tweaks interpreter callbacks to allow reusing `eval_mir_constant` without having a stack frame to get a span from.

r? `@oli-obk`
cc `@jachris`
This commit is contained in:
bors 2023-09-12 09:02:27 +00:00
commit cc7a9d6972
26 changed files with 1072 additions and 144 deletions
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7
compiler/rustc_const_eval/src/interpret/discriminant.rs
View file

@ -247,9 +247,9 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
&self,
layout: TyAndLayout<'tcx>,
variant: VariantIdx,
) -> InterpResult<'tcx, Scalar<M::Provenance>> {
) -> InterpResult<'tcx, ImmTy<'tcx, M::Provenance>> {
let discr_layout = self.layout_of(layout.ty.discriminant_ty(*self.tcx))?;
Ok(match layout.ty.discriminant_for_variant(*self.tcx, variant) {
let discr_value = match layout.ty.discriminant_for_variant(*self.tcx, variant) {
Some(discr) => {
// This type actually has discriminants.
assert_eq!(discr.ty, discr_layout.ty);
@ -260,6 +260,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
assert_eq!(variant.as_u32(), 0);
Scalar::from_uint(variant.as_u32(), discr_layout.size)
}
})
};
Ok(ImmTy::from_scalar(discr_value, discr_layout))
}
}

2
compiler/rustc_const_eval/src/interpret/intrinsics.rs
View file

@ -222,7 +222,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
let place = self.deref_pointer(&args[0])?;
let variant = self.read_discriminant(&place)?;
let discr = self.discriminant_for_variant(place.layout, variant)?;
self.write_scalar(discr, dest)?;
self.write_immediate(*discr, dest)?;
}
sym::exact_div => {
let l = self.read_immediate(&args[0])?;

2
compiler/rustc_const_eval/src/interpret/step.rs
View file

@ -301,7 +301,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
let op = self.eval_place_to_op(place, None)?;
let variant = self.read_discriminant(&op)?;
let discr = self.discriminant_for_variant(op.layout, variant)?;
self.write_scalar(discr, &dest)?;
self.write_immediate(*discr, &dest)?;
}
}