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interpret: sanity-check that required_consts captures all consts that can fail

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This commit is contained in:
Ralf Jung 2024-03-14 07:28:25 +01:00
parent b2b617a88e
commit bf021ea625
7 changed files with 62 additions and 34 deletions
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19
compiler/rustc_mir_transform/src/inline.rs
View file

@ -720,18 +720,8 @@ impl<'tcx> Inliner<'tcx> {
kind: TerminatorKind::Goto { target: integrator.map_block(START_BLOCK) },
});
// Copy only unevaluated constants from the callee_body into the caller_body.
// Although we are only pushing `ConstKind::Unevaluated` consts to
// `required_consts`, here we may not only have `ConstKind::Unevaluated`
// because we are calling `instantiate_and_normalize_erasing_regions`.
caller_body.required_consts.extend(callee_body.required_consts.iter().copied().filter(
|&ct| match ct.const_ {
Const::Ty(_) => {
bug!("should never encounter ty::UnevaluatedConst in `required_consts`")
}
Const::Val(..) | Const::Unevaluated(..) => true,
},
));
// Copy required constants from the callee_body into the caller_body.
caller_body.required_consts.extend(callee_body.required_consts);
// Now that we incorporated the callee's `required_consts`, we can remove the callee from
// `mentioned_items` -- but we have to take their `mentioned_items` in return. This does
// some extra work here to save the monomorphization collector work later. It helps a lot,
@ -747,8 +737,9 @@ impl<'tcx> Inliner<'tcx> {
caller_body.mentioned_items.remove(idx);
caller_body.mentioned_items.extend(callee_body.mentioned_items);
} else {
// If we can't find the callee, there's no point in adding its items.
// Probably it already got removed by being inlined elsewhere in the same function.
// If we can't find the callee, there's no point in adding its items. Probably it
// already got removed by being inlined elsewhere in the same function, so we already
// took its items.
}
}

22
compiler/rustc_mir_transform/src/required_consts.rs
View file

@ -1,6 +1,6 @@
use rustc_middle::mir::visit::Visitor;
use rustc_middle::mir::{Const, ConstOperand, Location};
use rustc_middle::ty::ConstKind;
use rustc_middle::ty;
pub struct RequiredConstsVisitor<'a, 'tcx> {
required_consts: &'a mut Vec<ConstOperand<'tcx>>,
@ -14,14 +14,22 @@ impl<'a, 'tcx> RequiredConstsVisitor<'a, 'tcx> {
impl<'tcx> Visitor<'tcx> for RequiredConstsVisitor<'_, 'tcx> {
fn visit_constant(&mut self, constant: &ConstOperand<'tcx>, _: Location) {
let const_ = constant.const_;
match const_ {
// Only unevaluated consts have to be added to `required_consts` as only those can possibly
// still have latent const-eval errors.
let is_required = match constant.const_ {
Const::Ty(c) => match c.kind() {
ConstKind::Param(_) | ConstKind::Error(_) | ConstKind::Value(_) => {}
_ => bug!("only ConstKind::Param/Value should be encountered here, got {:#?}", c),
ty::ConstKind::Value(_) => false, // already a value, cannot error
ty::ConstKind::Param(_) | ty::ConstKind::Error(_) => true, // these are errors or could be replaced by errors
_ => bug!(
"only ConstKind::Param/Value/Error should be encountered here, got {:#?}",
c
),
},
Const::Unevaluated(..) => self.required_consts.push(*constant),
Const::Val(..) => {}
Const::Unevaluated(..) => true,
Const::Val(..) => false, // already a value, cannot error
};
if is_required {
self.required_consts.push(*constant);
}
}
}