diff options
Diffstat (limited to 'compiler/rustc_middle/src/ty/consts.rs')
| -rw-r--r-- | compiler/rustc_middle/src/ty/consts.rs | 160 |
1 files changed, 153 insertions, 7 deletions
diff --git a/compiler/rustc_middle/src/ty/consts.rs b/compiler/rustc_middle/src/ty/consts.rs index 44cdb9b1cd8..78943cb0ddb 100644 --- a/compiler/rustc_middle/src/ty/consts.rs +++ b/compiler/rustc_middle/src/ty/consts.rs @@ -1,6 +1,6 @@ use crate::middle::resolve_bound_vars as rbv; -use crate::mir::interpret::LitToConstInput; -use crate::ty::{self, InternalSubsts, ParamEnv, ParamEnvAnd, Ty, TyCtxt}; +use crate::mir::interpret::{AllocId, ConstValue, LitToConstInput, Scalar}; +use crate::ty::{self, InternalSubsts, ParamEnv, ParamEnvAnd, Ty, TyCtxt, TypeVisitableExt}; use rustc_data_structures::intern::Interned; use rustc_error_messages::MultiSpan; use rustc_hir as hir; @@ -14,9 +14,13 @@ mod valtree; pub use int::*; pub use kind::*; +use rustc_span::ErrorGuaranteed; use rustc_span::DUMMY_SP; +use rustc_target::abi::Size; pub use valtree::*; +use super::sty::ConstKind; + /// Use this rather than `ConstData`, whenever possible. #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, HashStable)] #[rustc_pass_by_value] @@ -32,6 +36,16 @@ pub struct ConstData<'tcx> { #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))] static_assert_size!(ConstData<'_>, 40); +enum EvalMode { + Typeck, + Mir, +} + +enum EvalResult<'tcx> { + ValTree(ty::ValTree<'tcx>), + ConstVal(ConstValue<'tcx>), +} + impl<'tcx> Const<'tcx> { #[inline] pub fn ty(self) -> Ty<'tcx> { @@ -40,7 +54,7 @@ impl<'tcx> Const<'tcx> { #[inline] pub fn kind(self) -> ConstKind<'tcx> { - self.0.kind + self.0.kind.clone() } #[inline] @@ -293,12 +307,12 @@ impl<'tcx> Const<'tcx> { assert_eq!(self.ty(), ty); let size = tcx.layout_of(param_env.with_reveal_all_normalized(tcx).and(ty)).ok()?.size; // if `ty` does not depend on generic parameters, use an empty param_env - self.kind().eval(tcx, param_env).try_to_bits(size) + self.eval(tcx, param_env).try_to_bits(size) } #[inline] pub fn try_eval_bool(self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Option<bool> { - self.kind().eval(tcx, param_env).try_to_bool() + self.eval(tcx, param_env).try_to_bool() } #[inline] @@ -307,14 +321,14 @@ impl<'tcx> Const<'tcx> { tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>, ) -> Option<u64> { - self.kind().eval(tcx, param_env).try_to_target_usize(tcx) + self.eval(tcx, param_env).try_to_target_usize(tcx) } #[inline] /// Tries to evaluate the constant if it is `Unevaluated`. If that doesn't succeed, return the /// unevaluated constant. pub fn eval(self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Const<'tcx> { - if let Some(val) = self.kind().try_eval_for_typeck(tcx, param_env) { + if let Some(val) = self.try_eval_for_typeck(tcx, param_env) { match val { Ok(val) => ty::Const::new_value(tcx, val, self.ty()), Err(guar) => ty::Const::new_error(tcx, guar, self.ty()), @@ -339,6 +353,138 @@ impl<'tcx> Const<'tcx> { .unwrap_or_else(|| bug!("expected usize, got {:#?}", self)) } + #[inline] + /// Tries to evaluate the constant if it is `Unevaluated`. If that isn't possible or necessary + /// return `None`. + // FIXME(@lcnr): Completely rework the evaluation/normalization system for `ty::Const` once valtrees are merged. + pub fn try_eval_for_mir( + self, + tcx: TyCtxt<'tcx>, + param_env: ParamEnv<'tcx>, + ) -> Option<Result<ConstValue<'tcx>, ErrorGuaranteed>> { + match self.try_eval_inner(tcx, param_env, EvalMode::Mir) { + Some(Ok(EvalResult::ValTree(_))) => unreachable!(), + Some(Ok(EvalResult::ConstVal(v))) => Some(Ok(v)), + Some(Err(e)) => Some(Err(e)), + None => None, + } + } + + #[inline] + /// Tries to evaluate the constant if it is `Unevaluated`. If that isn't possible or necessary + /// return `None`. + // FIXME(@lcnr): Completely rework the evaluation/normalization system for `ty::Const` once valtrees are merged. + pub fn try_eval_for_typeck( + self, + tcx: TyCtxt<'tcx>, + param_env: ParamEnv<'tcx>, + ) -> Option<Result<ty::ValTree<'tcx>, ErrorGuaranteed>> { + match self.try_eval_inner(tcx, param_env, EvalMode::Typeck) { + Some(Ok(EvalResult::ValTree(v))) => Some(Ok(v)), + Some(Ok(EvalResult::ConstVal(_))) => unreachable!(), + Some(Err(e)) => Some(Err(e)), + None => None, + } + } + + #[inline] + fn try_eval_inner( + self, + tcx: TyCtxt<'tcx>, + param_env: ParamEnv<'tcx>, + eval_mode: EvalMode, + ) -> Option<Result<EvalResult<'tcx>, ErrorGuaranteed>> { + assert!(!self.has_escaping_bound_vars(), "escaping vars in {self:?}"); + if let ConstKind::Unevaluated(unevaluated) = self.kind() { + use crate::mir::interpret::ErrorHandled; + + // HACK(eddyb) this erases lifetimes even though `const_eval_resolve` + // also does later, but we want to do it before checking for + // inference variables. + // Note that we erase regions *before* calling `with_reveal_all_normalized`, + // so that we don't try to invoke this query with + // any region variables. + + // HACK(eddyb) when the query key would contain inference variables, + // attempt using identity substs and `ParamEnv` instead, that will succeed + // when the expression doesn't depend on any parameters. + // FIXME(eddyb, skinny121) pass `InferCtxt` into here when it's available, so that + // we can call `infcx.const_eval_resolve` which handles inference variables. + let param_env_and = if (param_env, unevaluated).has_non_region_infer() { + tcx.param_env(unevaluated.def).and(ty::UnevaluatedConst { + def: unevaluated.def, + substs: InternalSubsts::identity_for_item(tcx, unevaluated.def), + }) + } else { + tcx.erase_regions(param_env) + .with_reveal_all_normalized(tcx) + .and(tcx.erase_regions(unevaluated)) + }; + + // FIXME(eddyb) maybe the `const_eval_*` methods should take + // `ty::ParamEnvAnd` instead of having them separate. + let (param_env, unevaluated) = param_env_and.into_parts(); + // try to resolve e.g. associated constants to their definition on an impl, and then + // evaluate the const. + match eval_mode { + EvalMode::Typeck => { + match tcx.const_eval_resolve_for_typeck(param_env, unevaluated, None) { + // NOTE(eddyb) `val` contains no lifetimes/types/consts, + // and we use the original type, so nothing from `substs` + // (which may be identity substs, see above), + // can leak through `val` into the const we return. + Ok(val) => Some(Ok(EvalResult::ValTree(val?))), + Err(ErrorHandled::TooGeneric) => None, + Err(ErrorHandled::Reported(e)) => Some(Err(e.into())), + } + } + EvalMode::Mir => { + match tcx.const_eval_resolve(param_env, unevaluated.expand(), None) { + // NOTE(eddyb) `val` contains no lifetimes/types/consts, + // and we use the original type, so nothing from `substs` + // (which may be identity substs, see above), + // can leak through `val` into the const we return. + Ok(val) => Some(Ok(EvalResult::ConstVal(val))), + Err(ErrorHandled::TooGeneric) => None, + Err(ErrorHandled::Reported(e)) => Some(Err(e.into())), + } + } + } + } else { + None + } + } + + #[inline] + pub fn try_to_value(self) -> Option<ty::ValTree<'tcx>> { + if let ConstKind::Value(val) = self.kind() { Some(val) } else { None } + } + + #[inline] + pub fn try_to_scalar(self) -> Option<Scalar<AllocId>> { + self.try_to_value()?.try_to_scalar() + } + + #[inline] + pub fn try_to_scalar_int(self) -> Option<ScalarInt> { + self.try_to_value()?.try_to_scalar_int() + } + + #[inline] + pub fn try_to_bits(self, size: Size) -> Option<u128> { + self.try_to_scalar_int()?.to_bits(size).ok() + } + + #[inline] + pub fn try_to_bool(self) -> Option<bool> { + self.try_to_scalar_int()?.try_into().ok() + } + + #[inline] + pub fn try_to_target_usize(self, tcx: TyCtxt<'tcx>) -> Option<u64> { + self.try_to_value()?.try_to_target_usize(tcx) + } + pub fn is_ct_infer(self) -> bool { matches!(self.kind(), ty::ConstKind::Infer(_)) } |