diff options
| -rw-r--r-- | compiler/rustc_middle/src/mir/consts.rs | 414 | ||||
| -rw-r--r-- | compiler/rustc_middle/src/mir/mod.rs | 417 |
2 files changed, 422 insertions, 409 deletions
diff --git a/compiler/rustc_middle/src/mir/consts.rs b/compiler/rustc_middle/src/mir/consts.rs new file mode 100644 index 00000000000..92c6828a0b4 --- /dev/null +++ b/compiler/rustc_middle/src/mir/consts.rs @@ -0,0 +1,414 @@ +use std::fmt::{self, Debug, Display, Formatter}; + +use rustc_hir; +use rustc_hir::def_id::{DefId, LocalDefId}; +use rustc_hir::{self as hir}; +use rustc_span::Span; +use rustc_target::abi::Size; + +use crate::mir::interpret::{ConstValue, ErrorHandled, GlobalAlloc, Scalar}; +use crate::mir::{interpret, pretty_print_const, pretty_print_const_value, Promoted}; +use crate::ty::{self, List, Ty, TyCtxt}; +use crate::ty::{GenericArgs, GenericArgsRef}; +use crate::ty::{ScalarInt, UserTypeAnnotationIndex}; + +/////////////////////////////////////////////////////////////////////////// +/// Constants +/// +/// Two constants are equal if they are the same constant. Note that +/// this does not necessarily mean that they are `==` in Rust. In +/// particular, one must be wary of `NaN`! + +#[derive(Clone, Copy, PartialEq, TyEncodable, TyDecodable, Hash, HashStable)] +#[derive(TypeFoldable, TypeVisitable)] +pub struct Constant<'tcx> { + pub span: Span, + + /// Optional user-given type: for something like + /// `collect::<Vec<_>>`, this would be present and would + /// indicate that `Vec<_>` was explicitly specified. + /// + /// Needed for NLL to impose user-given type constraints. + pub user_ty: Option<UserTypeAnnotationIndex>, + + pub literal: ConstantKind<'tcx>, +} + +#[derive(Clone, Copy, PartialEq, Eq, TyEncodable, TyDecodable, Hash, HashStable, Debug)] +#[derive(TypeFoldable, TypeVisitable)] +pub enum ConstantKind<'tcx> { + /// This constant came from the type system. + /// + /// Any way of turning `ty::Const` into `ConstValue` should go through `valtree_to_const_val`; + /// this ensures that we consistently produce "clean" values without data in the padding or + /// anything like that. + Ty(ty::Const<'tcx>), + + /// An unevaluated mir constant which is not part of the type system. + Unevaluated(UnevaluatedConst<'tcx>, Ty<'tcx>), + + /// This constant cannot go back into the type system, as it represents + /// something the type system cannot handle (e.g. pointers). + Val(interpret::ConstValue<'tcx>, Ty<'tcx>), +} + +impl<'tcx> Constant<'tcx> { + pub fn check_static_ptr(&self, tcx: TyCtxt<'_>) -> Option<DefId> { + match self.literal.try_to_scalar() { + Some(Scalar::Ptr(ptr, _size)) => match tcx.global_alloc(ptr.provenance) { + GlobalAlloc::Static(def_id) => { + assert!(!tcx.is_thread_local_static(def_id)); + Some(def_id) + } + _ => None, + }, + _ => None, + } + } + #[inline] + pub fn ty(&self) -> Ty<'tcx> { + self.literal.ty() + } +} + +impl<'tcx> ConstantKind<'tcx> { + #[inline(always)] + pub fn ty(&self) -> Ty<'tcx> { + match self { + ConstantKind::Ty(c) => c.ty(), + ConstantKind::Val(_, ty) | ConstantKind::Unevaluated(_, ty) => *ty, + } + } + + #[inline] + pub fn try_to_scalar(self) -> Option<Scalar> { + match self { + ConstantKind::Ty(c) => match c.kind() { + ty::ConstKind::Value(valtree) => match valtree { + ty::ValTree::Leaf(scalar_int) => Some(Scalar::Int(scalar_int)), + ty::ValTree::Branch(_) => None, + }, + _ => None, + }, + ConstantKind::Val(val, _) => val.try_to_scalar(), + ConstantKind::Unevaluated(..) => None, + } + } + + #[inline] + pub fn try_to_scalar_int(self) -> Option<ScalarInt> { + self.try_to_scalar()?.try_to_int().ok() + } + + #[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 eval( + self, + tcx: TyCtxt<'tcx>, + param_env: ty::ParamEnv<'tcx>, + span: Option<Span>, + ) -> Result<interpret::ConstValue<'tcx>, ErrorHandled> { + match self { + ConstantKind::Ty(c) => { + // We want to consistently have a "clean" value for type system constants (i.e., no + // data hidden in the padding), so we always go through a valtree here. + let val = c.eval(tcx, param_env, span)?; + Ok(tcx.valtree_to_const_val((self.ty(), val))) + } + ConstantKind::Unevaluated(uneval, _) => { + // FIXME: We might want to have a `try_eval`-like function on `Unevaluated` + tcx.const_eval_resolve(param_env, uneval, span) + } + ConstantKind::Val(val, _) => Ok(val), + } + } + + /// Normalizes the constant to a value or an error if possible. + #[inline] + pub fn normalize(self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> Self { + match self.eval(tcx, param_env, None) { + Ok(val) => Self::Val(val, self.ty()), + Err(ErrorHandled::Reported(guar, _span)) => { + Self::Ty(ty::Const::new_error(tcx, guar.into(), self.ty())) + } + Err(ErrorHandled::TooGeneric(_span)) => self, + } + } + + #[inline] + pub fn try_eval_scalar( + self, + tcx: TyCtxt<'tcx>, + param_env: ty::ParamEnv<'tcx>, + ) -> Option<Scalar> { + self.eval(tcx, param_env, None).ok()?.try_to_scalar() + } + + #[inline] + pub fn try_eval_scalar_int( + self, + tcx: TyCtxt<'tcx>, + param_env: ty::ParamEnv<'tcx>, + ) -> Option<ScalarInt> { + self.try_eval_scalar(tcx, param_env)?.try_to_int().ok() + } + + #[inline] + pub fn try_eval_bits( + &self, + tcx: TyCtxt<'tcx>, + param_env: ty::ParamEnv<'tcx>, + ty: Ty<'tcx>, + ) -> Option<u128> { + let int = self.try_eval_scalar_int(tcx, param_env)?; + assert_eq!(self.ty(), ty); + let size = tcx.layout_of(param_env.with_reveal_all_normalized(tcx).and(ty)).ok()?.size; + int.to_bits(size).ok() + } + + /// Panics if the value cannot be evaluated or doesn't contain a valid integer of the given type. + #[inline] + pub fn eval_bits(self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>, ty: Ty<'tcx>) -> u128 { + self.try_eval_bits(tcx, param_env, ty) + .unwrap_or_else(|| bug!("expected bits of {:#?}, got {:#?}", ty, self)) + } + + #[inline] + pub fn try_eval_target_usize( + self, + tcx: TyCtxt<'tcx>, + param_env: ty::ParamEnv<'tcx>, + ) -> Option<u64> { + self.try_eval_scalar_int(tcx, param_env)?.try_to_target_usize(tcx).ok() + } + + #[inline] + /// Panics if the value cannot be evaluated or doesn't contain a valid `usize`. + pub fn eval_target_usize(self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> u64 { + self.try_eval_target_usize(tcx, param_env) + .unwrap_or_else(|| bug!("expected usize, got {:#?}", self)) + } + + #[inline] + pub fn try_eval_bool(self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> Option<bool> { + self.try_eval_scalar_int(tcx, param_env)?.try_into().ok() + } + + #[inline] + pub fn from_value(val: ConstValue<'tcx>, ty: Ty<'tcx>) -> Self { + Self::Val(val, ty) + } + + pub fn from_bits( + tcx: TyCtxt<'tcx>, + bits: u128, + param_env_ty: ty::ParamEnvAnd<'tcx, Ty<'tcx>>, + ) -> Self { + let size = tcx + .layout_of(param_env_ty) + .unwrap_or_else(|e| { + bug!("could not compute layout for {:?}: {:?}", param_env_ty.value, e) + }) + .size; + let cv = ConstValue::Scalar(Scalar::from_uint(bits, size)); + + Self::Val(cv, param_env_ty.value) + } + + #[inline] + pub fn from_bool(tcx: TyCtxt<'tcx>, v: bool) -> Self { + let cv = ConstValue::from_bool(v); + Self::Val(cv, tcx.types.bool) + } + + #[inline] + pub fn zero_sized(ty: Ty<'tcx>) -> Self { + let cv = ConstValue::ZeroSized; + Self::Val(cv, ty) + } + + pub fn from_usize(tcx: TyCtxt<'tcx>, n: u64) -> Self { + let ty = tcx.types.usize; + Self::from_bits(tcx, n as u128, ty::ParamEnv::empty().and(ty)) + } + + #[inline] + pub fn from_scalar(_tcx: TyCtxt<'tcx>, s: Scalar, ty: Ty<'tcx>) -> Self { + let val = ConstValue::Scalar(s); + Self::Val(val, ty) + } + + /// Literals are converted to `ConstantKindVal`, const generic parameters are eagerly + /// converted to a constant, everything else becomes `Unevaluated`. + #[instrument(skip(tcx), level = "debug", ret)] + pub fn from_anon_const( + tcx: TyCtxt<'tcx>, + def: LocalDefId, + param_env: ty::ParamEnv<'tcx>, + ) -> Self { + let body_id = match tcx.hir().get_by_def_id(def) { + hir::Node::AnonConst(ac) => ac.body, + _ => { + span_bug!(tcx.def_span(def), "from_anon_const can only process anonymous constants") + } + }; + + let expr = &tcx.hir().body(body_id).value; + debug!(?expr); + + // Unwrap a block, so that e.g. `{ P }` is recognised as a parameter. Const arguments + // currently have to be wrapped in curly brackets, so it's necessary to special-case. + let expr = match &expr.kind { + hir::ExprKind::Block(block, _) if block.stmts.is_empty() && block.expr.is_some() => { + block.expr.as_ref().unwrap() + } + _ => expr, + }; + debug!("expr.kind: {:?}", expr.kind); + + let ty = tcx.type_of(def).instantiate_identity(); + debug!(?ty); + + // FIXME(const_generics): We currently have to special case parameters because `min_const_generics` + // does not provide the parents generics to anonymous constants. We still allow generic const + // parameters by themselves however, e.g. `N`. These constants would cause an ICE if we were to + // ever try to substitute the generic parameters in their bodies. + // + // While this doesn't happen as these constants are always used as `ty::ConstKind::Param`, it does + // cause issues if we were to remove that special-case and try to evaluate the constant instead. + use hir::{def::DefKind::ConstParam, def::Res, ExprKind, Path, QPath}; + match expr.kind { + ExprKind::Path(QPath::Resolved(_, &Path { res: Res::Def(ConstParam, def_id), .. })) => { + // Find the name and index of the const parameter by indexing the generics of + // the parent item and construct a `ParamConst`. + let item_def_id = tcx.parent(def_id); + let generics = tcx.generics_of(item_def_id); + let index = generics.param_def_id_to_index[&def_id]; + let name = tcx.item_name(def_id); + let ty_const = ty::Const::new_param(tcx, ty::ParamConst::new(index, name), ty); + debug!(?ty_const); + + return Self::Ty(ty_const); + } + _ => {} + } + + let hir_id = tcx.hir().local_def_id_to_hir_id(def); + let parent_args = if let Some(parent_hir_id) = tcx.hir().opt_parent_id(hir_id) + && let Some(parent_did) = parent_hir_id.as_owner() + { + GenericArgs::identity_for_item(tcx, parent_did) + } else { + List::empty() + }; + debug!(?parent_args); + + let did = def.to_def_id(); + let child_args = GenericArgs::identity_for_item(tcx, did); + let args = tcx.mk_args_from_iter(parent_args.into_iter().chain(child_args.into_iter())); + debug!(?args); + + let span = tcx.def_span(def); + let uneval = UnevaluatedConst::new(did, args); + debug!(?span, ?param_env); + + match tcx.const_eval_resolve(param_env, uneval, Some(span)) { + Ok(val) => { + debug!("evaluated const value"); + Self::Val(val, ty) + } + Err(_) => { + debug!("error encountered during evaluation"); + // Error was handled in `const_eval_resolve`. Here we just create a + // new unevaluated const and error hard later in codegen + Self::Unevaluated( + UnevaluatedConst { + def: did, + args: GenericArgs::identity_for_item(tcx, did), + promoted: None, + }, + ty, + ) + } + } + } + + pub fn from_ty_const(c: ty::Const<'tcx>, tcx: TyCtxt<'tcx>) -> Self { + match c.kind() { + ty::ConstKind::Value(valtree) => { + // Make sure that if `c` is normalized, then the return value is normalized. + let const_val = tcx.valtree_to_const_val((c.ty(), valtree)); + Self::Val(const_val, c.ty()) + } + _ => Self::Ty(c), + } + } +} + +/// An unevaluated (potentially generic) constant used in MIR. +#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, TyEncodable, TyDecodable)] +#[derive(Hash, HashStable, TypeFoldable, TypeVisitable)] +pub struct UnevaluatedConst<'tcx> { + pub def: DefId, + pub args: GenericArgsRef<'tcx>, + pub promoted: Option<Promoted>, +} + +impl<'tcx> UnevaluatedConst<'tcx> { + #[inline] + pub fn shrink(self) -> ty::UnevaluatedConst<'tcx> { + assert_eq!(self.promoted, None); + ty::UnevaluatedConst { def: self.def, args: self.args } + } +} + +impl<'tcx> UnevaluatedConst<'tcx> { + #[inline] + pub fn new(def: DefId, args: GenericArgsRef<'tcx>) -> UnevaluatedConst<'tcx> { + UnevaluatedConst { def, args, promoted: Default::default() } + } + + #[inline] + pub fn from_instance(instance: ty::Instance<'tcx>) -> Self { + UnevaluatedConst::new(instance.def_id(), instance.args) + } +} + +impl<'tcx> Debug for Constant<'tcx> { + fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result { + write!(fmt, "{self}") + } +} + +impl<'tcx> Display for Constant<'tcx> { + fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result { + match self.ty().kind() { + ty::FnDef(..) => {} + _ => write!(fmt, "const ")?, + } + Display::fmt(&self.literal, fmt) + } +} + +impl<'tcx> Display for ConstantKind<'tcx> { + fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result { + match *self { + ConstantKind::Ty(c) => pretty_print_const(c, fmt, true), + ConstantKind::Val(val, ty) => pretty_print_const_value(val, ty, fmt), + // FIXME(valtrees): Correctly print mir constants. + ConstantKind::Unevaluated(..) => { + fmt.write_str("_")?; + Ok(()) + } + } + } +} diff --git a/compiler/rustc_middle/src/mir/mod.rs b/compiler/rustc_middle/src/mir/mod.rs index b8032733868..3a79e1d31b4 100644 --- a/compiler/rustc_middle/src/mir/mod.rs +++ b/compiler/rustc_middle/src/mir/mod.rs @@ -2,9 +2,7 @@ //! //! [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/mir/index.html -use crate::mir::interpret::{ - AllocRange, ConstAllocation, ConstValue, ErrorHandled, GlobalAlloc, Scalar, -}; +use crate::mir::interpret::{AllocRange, ErrorHandled, ConstAllocation, ConstValue, Scalar}; use crate::mir::visit::MirVisitable; use crate::ty::codec::{TyDecoder, TyEncoder}; use crate::ty::fold::{FallibleTypeFolder, TypeFoldable}; @@ -12,13 +10,13 @@ use crate::ty::print::with_no_trimmed_paths; use crate::ty::print::{FmtPrinter, Printer}; use crate::ty::visit::TypeVisitableExt; use crate::ty::{self, List, Ty, TyCtxt}; -use crate::ty::{AdtDef, InstanceDef, ScalarInt, UserTypeAnnotationIndex}; -use crate::ty::{GenericArg, GenericArgs, GenericArgsRef}; +use crate::ty::{AdtDef, InstanceDef, UserTypeAnnotationIndex}; +use crate::ty::{GenericArg, GenericArgsRef}; use rustc_data_structures::captures::Captures; use rustc_errors::{DiagnosticArgValue, DiagnosticMessage, ErrorGuaranteed, IntoDiagnosticArg}; use rustc_hir::def::{CtorKind, Namespace}; -use rustc_hir::def_id::{DefId, LocalDefId, CRATE_DEF_ID}; +use rustc_hir::def_id::{DefId, CRATE_DEF_ID}; use rustc_hir::{self, GeneratorKind, ImplicitSelfKind}; use rustc_hir::{self as hir, HirId}; use rustc_session::Session; @@ -39,7 +37,7 @@ use either::Either; use std::borrow::Cow; use std::cell::RefCell; use std::collections::hash_map::Entry; -use std::fmt::{self, Debug, Display, Formatter, Write}; +use std::fmt::{self, Debug, Formatter, Write}; use std::ops::{Index, IndexMut}; use std::{iter, mem}; @@ -47,6 +45,8 @@ pub use self::query::*; pub use basic_blocks::BasicBlocks; mod basic_blocks; +mod consts; +pub use consts::*; pub mod coverage; mod generic_graph; pub mod generic_graphviz; @@ -60,7 +60,7 @@ pub mod spanview; mod syntax; pub use syntax::*; pub mod tcx; -pub mod terminator; +mod terminator; pub use terminator::*; pub mod traversal; @@ -2300,377 +2300,6 @@ impl<'tcx> Debug for Rvalue<'tcx> { } } -/////////////////////////////////////////////////////////////////////////// -/// Constants -/// -/// Two constants are equal if they are the same constant. Note that -/// this does not necessarily mean that they are `==` in Rust. In -/// particular, one must be wary of `NaN`! - -#[derive(Clone, Copy, PartialEq, TyEncodable, TyDecodable, Hash, HashStable)] -#[derive(TypeFoldable, TypeVisitable)] -pub struct Constant<'tcx> { - pub span: Span, - - /// Optional user-given type: for something like - /// `collect::<Vec<_>>`, this would be present and would - /// indicate that `Vec<_>` was explicitly specified. - /// - /// Needed for NLL to impose user-given type constraints. - pub user_ty: Option<UserTypeAnnotationIndex>, - - pub literal: ConstantKind<'tcx>, -} - -#[derive(Clone, Copy, PartialEq, Eq, TyEncodable, TyDecodable, Hash, HashStable, Debug)] -#[derive(TypeFoldable, TypeVisitable)] -pub enum ConstantKind<'tcx> { - /// This constant came from the type system. - /// - /// Any way of turning `ty::Const` into `ConstValue` should go through `valtree_to_const_val`; - /// this ensures that we consistently produce "clean" values without data in the padding or - /// anything like that. - Ty(ty::Const<'tcx>), - - /// An unevaluated mir constant which is not part of the type system. - Unevaluated(UnevaluatedConst<'tcx>, Ty<'tcx>), - - /// This constant cannot go back into the type system, as it represents - /// something the type system cannot handle (e.g. pointers). - Val(interpret::ConstValue<'tcx>, Ty<'tcx>), -} - -impl<'tcx> Constant<'tcx> { - pub fn check_static_ptr(&self, tcx: TyCtxt<'_>) -> Option<DefId> { - match self.literal.try_to_scalar() { - Some(Scalar::Ptr(ptr, _size)) => match tcx.global_alloc(ptr.provenance) { - GlobalAlloc::Static(def_id) => { - assert!(!tcx.is_thread_local_static(def_id)); - Some(def_id) - } - _ => None, - }, - _ => None, - } - } - #[inline] - pub fn ty(&self) -> Ty<'tcx> { - self.literal.ty() - } -} - -impl<'tcx> ConstantKind<'tcx> { - #[inline(always)] - pub fn ty(&self) -> Ty<'tcx> { - match self { - ConstantKind::Ty(c) => c.ty(), - ConstantKind::Val(_, ty) | ConstantKind::Unevaluated(_, ty) => *ty, - } - } - - #[inline] - pub fn try_to_scalar(self) -> Option<Scalar> { - match self { - ConstantKind::Ty(c) => match c.kind() { - ty::ConstKind::Value(valtree) => match valtree { - ty::ValTree::Leaf(scalar_int) => Some(Scalar::Int(scalar_int)), - ty::ValTree::Branch(_) => None, - }, - _ => None, - }, - ConstantKind::Val(val, _) => val.try_to_scalar(), - ConstantKind::Unevaluated(..) => None, - } - } - - #[inline] - pub fn try_to_scalar_int(self) -> Option<ScalarInt> { - self.try_to_scalar()?.try_to_int().ok() - } - - #[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 eval( - self, - tcx: TyCtxt<'tcx>, - param_env: ty::ParamEnv<'tcx>, - span: Option<Span>, - ) -> Result<interpret::ConstValue<'tcx>, ErrorHandled> { - match self { - ConstantKind::Ty(c) => { - // We want to consistently have a "clean" value for type system constants (i.e., no - // data hidden in the padding), so we always go through a valtree here. - let val = c.eval(tcx, param_env, span)?; - Ok(tcx.valtree_to_const_val((self.ty(), val))) - } - ConstantKind::Unevaluated(uneval, _) => { - // FIXME: We might want to have a `try_eval`-like function on `Unevaluated` - tcx.const_eval_resolve(param_env, uneval, span) - } - ConstantKind::Val(val, _) => Ok(val), - } - } - - /// Normalizes the constant to a value or an error if possible. - #[inline] - pub fn normalize(self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> Self { - match self.eval(tcx, param_env, None) { - Ok(val) => Self::Val(val, self.ty()), - Err(ErrorHandled::Reported(guar, _span)) => { - Self::Ty(ty::Const::new_error(tcx, guar.into(), self.ty())) - } - Err(ErrorHandled::TooGeneric(_span)) => self, - } - } - - #[inline] - pub fn try_eval_scalar( - self, - tcx: TyCtxt<'tcx>, - param_env: ty::ParamEnv<'tcx>, - ) -> Option<Scalar> { - self.eval(tcx, param_env, None).ok()?.try_to_scalar() - } - - #[inline] - pub fn try_eval_scalar_int( - self, - tcx: TyCtxt<'tcx>, - param_env: ty::ParamEnv<'tcx>, - ) -> Option<ScalarInt> { - self.try_eval_scalar(tcx, param_env)?.try_to_int().ok() - } - - #[inline] - pub fn try_eval_bits( - &self, - tcx: TyCtxt<'tcx>, - param_env: ty::ParamEnv<'tcx>, - ty: Ty<'tcx>, - ) -> Option<u128> { - let int = self.try_eval_scalar_int(tcx, param_env)?; - assert_eq!(self.ty(), ty); - let size = tcx.layout_of(param_env.with_reveal_all_normalized(tcx).and(ty)).ok()?.size; - int.to_bits(size).ok() - } - - /// Panics if the value cannot be evaluated or doesn't contain a valid integer of the given type. - #[inline] - pub fn eval_bits(self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>, ty: Ty<'tcx>) -> u128 { - self.try_eval_bits(tcx, param_env, ty) - .unwrap_or_else(|| bug!("expected bits of {:#?}, got {:#?}", ty, self)) - } - - #[inline] - pub fn try_eval_target_usize( - self, - tcx: TyCtxt<'tcx>, - param_env: ty::ParamEnv<'tcx>, - ) -> Option<u64> { - self.try_eval_scalar_int(tcx, param_env)?.try_to_target_usize(tcx).ok() - } - - #[inline] - /// Panics if the value cannot be evaluated or doesn't contain a valid `usize`. - pub fn eval_target_usize(self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> u64 { - self.try_eval_target_usize(tcx, param_env) - .unwrap_or_else(|| bug!("expected usize, got {:#?}", self)) - } - - #[inline] - pub fn try_eval_bool(self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> Option<bool> { - self.try_eval_scalar_int(tcx, param_env)?.try_into().ok() - } - - #[inline] - pub fn from_value(val: ConstValue<'tcx>, ty: Ty<'tcx>) -> Self { - Self::Val(val, ty) - } - - pub fn from_bits( - tcx: TyCtxt<'tcx>, - bits: u128, - param_env_ty: ty::ParamEnvAnd<'tcx, Ty<'tcx>>, - ) -> Self { - let size = tcx - .layout_of(param_env_ty) - .unwrap_or_else(|e| { - bug!("could not compute layout for {:?}: {:?}", param_env_ty.value, e) - }) - .size; - let cv = ConstValue::Scalar(Scalar::from_uint(bits, size)); - - Self::Val(cv, param_env_ty.value) - } - - #[inline] - pub fn from_bool(tcx: TyCtxt<'tcx>, v: bool) -> Self { - let cv = ConstValue::from_bool(v); - Self::Val(cv, tcx.types.bool) - } - - #[inline] - pub fn zero_sized(ty: Ty<'tcx>) -> Self { - let cv = ConstValue::ZeroSized; - Self::Val(cv, ty) - } - - pub fn from_usize(tcx: TyCtxt<'tcx>, n: u64) -> Self { - let ty = tcx.types.usize; - Self::from_bits(tcx, n as u128, ty::ParamEnv::empty().and(ty)) - } - - #[inline] - pub fn from_scalar(_tcx: TyCtxt<'tcx>, s: Scalar, ty: Ty<'tcx>) -> Self { - let val = ConstValue::Scalar(s); - Self::Val(val, ty) - } - - /// Literals are converted to `ConstantKindVal`, const generic parameters are eagerly - /// converted to a constant, everything else becomes `Unevaluated`. - #[instrument(skip(tcx), level = "debug", ret)] - pub fn from_anon_const( - tcx: TyCtxt<'tcx>, - def: LocalDefId, - param_env: ty::ParamEnv<'tcx>, - ) -> Self { - let body_id = match tcx.hir().get_by_def_id(def) { - hir::Node::AnonConst(ac) => ac.body, - _ => { - span_bug!(tcx.def_span(def), "from_anon_const can only process anonymous constants") - } - }; - - let expr = &tcx.hir().body(body_id).value; - debug!(?expr); - - // Unwrap a block, so that e.g. `{ P }` is recognised as a parameter. Const arguments - // currently have to be wrapped in curly brackets, so it's necessary to special-case. - let expr = match &expr.kind { - hir::ExprKind::Block(block, _) if block.stmts.is_empty() && block.expr.is_some() => { - block.expr.as_ref().unwrap() - } - _ => expr, - }; - debug!("expr.kind: {:?}", expr.kind); - - let ty = tcx.type_of(def).instantiate_identity(); - debug!(?ty); - - // FIXME(const_generics): We currently have to special case parameters because `min_const_generics` - // does not provide the parents generics to anonymous constants. We still allow generic const - // parameters by themselves however, e.g. `N`. These constants would cause an ICE if we were to - // ever try to substitute the generic parameters in their bodies. - // - // While this doesn't happen as these constants are always used as `ty::ConstKind::Param`, it does - // cause issues if we were to remove that special-case and try to evaluate the constant instead. - use hir::{def::DefKind::ConstParam, def::Res, ExprKind, Path, QPath}; - match expr.kind { - ExprKind::Path(QPath::Resolved(_, &Path { res: Res::Def(ConstParam, def_id), .. })) => { - // Find the name and index of the const parameter by indexing the generics of - // the parent item and construct a `ParamConst`. - let item_def_id = tcx.parent(def_id); - let generics = tcx.generics_of(item_def_id); - let index = generics.param_def_id_to_index[&def_id]; - let name = tcx.item_name(def_id); - let ty_const = ty::Const::new_param(tcx, ty::ParamConst::new(index, name), ty); - debug!(?ty_const); - - return Self::Ty(ty_const); - } - _ => {} - } - - let hir_id = tcx.hir().local_def_id_to_hir_id(def); - let parent_args = if let Some(parent_hir_id) = tcx.hir().opt_parent_id(hir_id) - && let Some(parent_did) = parent_hir_id.as_owner() - { - GenericArgs::identity_for_item(tcx, parent_did) - } else { - List::empty() - }; - debug!(?parent_args); - - let did = def.to_def_id(); - let child_args = GenericArgs::identity_for_item(tcx, did); - let args = tcx.mk_args_from_iter(parent_args.into_iter().chain(child_args.into_iter())); - debug!(?args); - - let span = tcx.def_span(def); - let uneval = UnevaluatedConst::new(did, args); - debug!(?span, ?param_env); - - match tcx.const_eval_resolve(param_env, uneval, Some(span)) { - Ok(val) => { - debug!("evaluated const value"); - Self::Val(val, ty) - } - Err(_) => { - debug!("error encountered during evaluation"); - // Error was handled in `const_eval_resolve`. Here we just create a - // new unevaluated const and error hard later in codegen - Self::Unevaluated( - UnevaluatedConst { - def: did, - args: GenericArgs::identity_for_item(tcx, did), - promoted: None, - }, - ty, - ) - } - } - } - - pub fn from_ty_const(c: ty::Const<'tcx>, tcx: TyCtxt<'tcx>) -> Self { - match c.kind() { - ty::ConstKind::Value(valtree) => { - // Make sure that if `c` is normalized, then the return value is normalized. - let const_val = tcx.valtree_to_const_val((c.ty(), valtree)); - Self::Val(const_val, c.ty()) - } - _ => Self::Ty(c), - } - } -} - -/// An unevaluated (potentially generic) constant used in MIR. -#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, TyEncodable, TyDecodable)] -#[derive(Hash, HashStable, TypeFoldable, TypeVisitable)] -pub struct UnevaluatedConst<'tcx> { - pub def: DefId, - pub args: GenericArgsRef<'tcx>, - pub promoted: Option<Promoted>, -} - -impl<'tcx> UnevaluatedConst<'tcx> { - #[inline] - pub fn shrink(self) -> ty::UnevaluatedConst<'tcx> { - assert_eq!(self.promoted, None); - ty::UnevaluatedConst { def: self.def, args: self.args } - } -} - -impl<'tcx> UnevaluatedConst<'tcx> { - #[inline] - pub fn new(def: DefId, args: GenericArgsRef<'tcx>) -> UnevaluatedConst<'tcx> { - UnevaluatedConst { def, args, promoted: Default::default() } - } - - #[inline] - pub fn from_instance(instance: ty::Instance<'tcx>) -> Self { - UnevaluatedConst::new(instance.def_id(), instance.args) - } -} - /// A collection of projections into user types. /// /// They are projections because a binding can occur a part of a @@ -2830,36 +2459,6 @@ rustc_index::newtype_index! { pub struct Promoted {} } -impl<'tcx> Debug for Constant<'tcx> { - fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result { - write!(fmt, "{self}") - } -} - -impl<'tcx> Display for Constant<'tcx> { - fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result { - match self.ty().kind() { - ty::FnDef(..) => {} - _ => write!(fmt, "const ")?, - } - Display::fmt(&self.literal, fmt) - } -} - -impl<'tcx> Display for ConstantKind<'tcx> { - fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result { - match *self { - ConstantKind::Ty(c) => pretty_print_const(c, fmt, true), - ConstantKind::Val(val, ty) => pretty_print_const_value(val, ty, fmt), - // FIXME(valtrees): Correctly print mir constants. - ConstantKind::Unevaluated(..) => { - fmt.write_str("_")?; - Ok(()) - } - } - } -} - fn pretty_print_const<'tcx>( c: ty::Const<'tcx>, fmt: &mut Formatter<'_>, |