X-Git-Url: https://git.lizzy.rs/?a=blobdiff_plain;f=crates%2Fhir_ty%2Fsrc%2Fconsteval.rs;h=24296c6b7b354d568e508905ff0e20c1e323fa77;hb=b301b040f5781a9083348936369a01c37138756f;hp=ab1afce081f3c7059c3cb318d2c83767e76d29c3;hpb=25bf451c8426a68ecfdc3a1d1be1db9702dd41d8;p=rust.git

diff --git a/crates/hir_ty/src/consteval.rs b/crates/hir_ty/src/consteval.rs
index ab1afce081f..24296c6b7b3 100644
--- a/crates/hir_ty/src/consteval.rs
+++ b/crates/hir_ty/src/consteval.rs
@@ -1,14 +1,26 @@
 //! Constant evaluation details
 
-use std::convert::TryInto;
+use std::{collections::HashMap, convert::TryInto, fmt::Display};
 
+use chalk_ir::{BoundVar, DebruijnIndex, GenericArgData, IntTy, Scalar};
 use hir_def::{
-    builtin_type::BuiltinUint,
-    expr::{Expr, Literal},
+    expr::{ArithOp, BinaryOp, Expr, Literal, Pat},
+    path::ModPath,
+    resolver::{Resolver, ValueNs},
     type_ref::ConstScalar,
 };
+use hir_expand::name::Name;
+use la_arena::{Arena, Idx};
+use stdx::never;
 
-use crate::{Const, ConstData, ConstValue, Interner, TyKind};
+use crate::{
+    db::HirDatabase,
+    infer::{Expectation, InferenceContext},
+    lower::ParamLoweringMode,
+    to_placeholder_idx,
+    utils::Generics,
+    Const, ConstData, ConstValue, GenericArg, Interner, Ty, TyKind,
+};
 
 /// Extension trait for [`Const`]
 pub trait ConstExt {
@@ -18,7 +30,7 @@ pub trait ConstExt {
 
 impl ConstExt for Const {
     fn is_unknown(&self) -> bool {
-        match self.data(&Interner).value {
+        match self.data(Interner).value {
             // interned Unknown
             chalk_ir::ConstValue::Concrete(chalk_ir::ConcreteConst {
                 interned: ConstScalar::Unknown,
@@ -28,28 +40,361 @@ fn is_unknown(&self) -> bool {
             chalk_ir::ConstValue::Concrete(..) => false,
 
             _ => {
-                log::error!("is_unknown was called on a non-concrete constant value! {:?}", self);
+                tracing::error!(
+                    "is_unknown was called on a non-concrete constant value! {:?}",
+                    self
+                );
                 true
             }
         }
     }
 }
 
-// FIXME: support more than just evaluating literals
-pub fn eval_usize(expr: &Expr) -> Option<u64> {
+pub struct ConstEvalCtx<'a> {
+    pub exprs: &'a Arena<Expr>,
+    pub pats: &'a Arena<Pat>,
+    pub local_data: HashMap<Name, ComputedExpr>,
+    pub infer: &'a mut dyn FnMut(Idx<Expr>) -> Ty,
+}
+
+#[derive(Debug, Clone)]
+pub enum ConstEvalError {
+    NotSupported(&'static str),
+    TypeError,
+    IncompleteExpr,
+    Panic(String),
+}
+
+#[derive(Debug, Clone)]
+pub enum ComputedExpr {
+    Literal(Literal),
+    Tuple(Box<[ComputedExpr]>),
+}
+
+impl Display for ComputedExpr {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            ComputedExpr::Literal(l) => match l {
+                Literal::Int(x, _) => {
+                    if *x >= 16 {
+                        write!(f, "{} ({:#X})", x, x)
+                    } else {
+                        write!(f, "{}", x)
+                    }
+                }
+                Literal::Uint(x, _) => {
+                    if *x >= 16 {
+                        write!(f, "{} ({:#X})", x, x)
+                    } else {
+                        write!(f, "{}", x)
+                    }
+                }
+                Literal::Float(x, _) => write!(f, "{}", x),
+                Literal::Bool(x) => write!(f, "{}", x),
+                Literal::Char(x) => write!(f, "{:?}", x),
+                Literal::String(x) => write!(f, "{:?}", x),
+                Literal::ByteString(x) => write!(f, "{:?}", x),
+            },
+            ComputedExpr::Tuple(t) => {
+                write!(f, "(")?;
+                for x in &**t {
+                    write!(f, "{}, ", x)?;
+                }
+                write!(f, ")")
+            }
+        }
+    }
+}
+
+fn scalar_max(scalar: &Scalar) -> i128 {
+    match scalar {
+        Scalar::Bool => 1,
+        Scalar::Char => u32::MAX as i128,
+        Scalar::Int(x) => match x {
+            IntTy::Isize => isize::MAX as i128,
+            IntTy::I8 => i8::MAX as i128,
+            IntTy::I16 => i16::MAX as i128,
+            IntTy::I32 => i32::MAX as i128,
+            IntTy::I64 => i64::MAX as i128,
+            IntTy::I128 => i128::MAX as i128,
+        },
+        Scalar::Uint(x) => match x {
+            chalk_ir::UintTy::Usize => usize::MAX as i128,
+            chalk_ir::UintTy::U8 => u8::MAX as i128,
+            chalk_ir::UintTy::U16 => u16::MAX as i128,
+            chalk_ir::UintTy::U32 => u32::MAX as i128,
+            chalk_ir::UintTy::U64 => u64::MAX as i128,
+            chalk_ir::UintTy::U128 => i128::MAX as i128, // ignore too big u128 for now
+        },
+        Scalar::Float(_) => 0,
+    }
+}
+
+fn is_valid(scalar: &Scalar, value: i128) -> bool {
+    if value < 0 {
+        !matches!(scalar, Scalar::Uint(_)) && -scalar_max(scalar) - 1 <= value
+    } else {
+        value <= scalar_max(scalar)
+    }
+}
+
+pub fn eval_const(expr: &Expr, ctx: &mut ConstEvalCtx<'_>) -> Result<ComputedExpr, ConstEvalError> {
     match expr {
-        Expr::Literal(Literal::Uint(v, None | Some(BuiltinUint::Usize))) => (*v).try_into().ok(),
+        Expr::Literal(l) => Ok(ComputedExpr::Literal(l.clone())),
+        &Expr::UnaryOp { expr, op } => {
+            let ty = &(ctx.infer)(expr);
+            let ev = eval_const(&ctx.exprs[expr], ctx)?;
+            match op {
+                hir_def::expr::UnaryOp::Deref => Err(ConstEvalError::NotSupported("deref")),
+                hir_def::expr::UnaryOp::Not => {
+                    let v = match ev {
+                        ComputedExpr::Literal(Literal::Bool(b)) => {
+                            return Ok(ComputedExpr::Literal(Literal::Bool(!b)))
+                        }
+                        ComputedExpr::Literal(Literal::Int(v, _)) => v,
+                        ComputedExpr::Literal(Literal::Uint(v, _)) => v
+                            .try_into()
+                            .map_err(|_| ConstEvalError::NotSupported("too big u128"))?,
+                        _ => return Err(ConstEvalError::NotSupported("this kind of operator")),
+                    };
+                    let r = match ty.kind(Interner) {
+                        TyKind::Scalar(Scalar::Uint(x)) => match x {
+                            chalk_ir::UintTy::U8 => !(v as u8) as i128,
+                            chalk_ir::UintTy::U16 => !(v as u16) as i128,
+                            chalk_ir::UintTy::U32 => !(v as u32) as i128,
+                            chalk_ir::UintTy::U64 => !(v as u64) as i128,
+                            chalk_ir::UintTy::U128 => {
+                                return Err(ConstEvalError::NotSupported("negation of u128"))
+                            }
+                            chalk_ir::UintTy::Usize => !(v as usize) as i128,
+                        },
+                        TyKind::Scalar(Scalar::Int(x)) => match x {
+                            chalk_ir::IntTy::I8 => !(v as i8) as i128,
+                            chalk_ir::IntTy::I16 => !(v as i16) as i128,
+                            chalk_ir::IntTy::I32 => !(v as i32) as i128,
+                            chalk_ir::IntTy::I64 => !(v as i64) as i128,
+                            chalk_ir::IntTy::I128 => !v,
+                            chalk_ir::IntTy::Isize => !(v as isize) as i128,
+                        },
+                        _ => return Err(ConstEvalError::NotSupported("unreachable?")),
+                    };
+                    Ok(ComputedExpr::Literal(Literal::Int(r, None)))
+                }
+                hir_def::expr::UnaryOp::Neg => {
+                    let v = match ev {
+                        ComputedExpr::Literal(Literal::Int(v, _)) => v,
+                        ComputedExpr::Literal(Literal::Uint(v, _)) => v
+                            .try_into()
+                            .map_err(|_| ConstEvalError::NotSupported("too big u128"))?,
+                        _ => return Err(ConstEvalError::NotSupported("this kind of operator")),
+                    };
+                    Ok(ComputedExpr::Literal(Literal::Int(
+                        v.checked_neg().ok_or_else(|| {
+                            ConstEvalError::Panic("overflow in negation".to_string())
+                        })?,
+                        None,
+                    )))
+                }
+            }
+        }
+        &Expr::BinaryOp { lhs, rhs, op } => {
+            let ty = &(ctx.infer)(lhs);
+            let lhs = eval_const(&ctx.exprs[lhs], ctx)?;
+            let rhs = eval_const(&ctx.exprs[rhs], ctx)?;
+            let op = op.ok_or(ConstEvalError::IncompleteExpr)?;
+            let v1 = match lhs {
+                ComputedExpr::Literal(Literal::Int(v, _)) => v,
+                ComputedExpr::Literal(Literal::Uint(v, _)) => {
+                    v.try_into().map_err(|_| ConstEvalError::NotSupported("too big u128"))?
+                }
+                _ => return Err(ConstEvalError::NotSupported("this kind of operator")),
+            };
+            let v2 = match rhs {
+                ComputedExpr::Literal(Literal::Int(v, _)) => v,
+                ComputedExpr::Literal(Literal::Uint(v, _)) => {
+                    v.try_into().map_err(|_| ConstEvalError::NotSupported("too big u128"))?
+                }
+                _ => return Err(ConstEvalError::NotSupported("this kind of operator")),
+            };
+            match op {
+                BinaryOp::ArithOp(b) => {
+                    let panic_arith = ConstEvalError::Panic(
+                        "attempt to run invalid arithmetic operation".to_string(),
+                    );
+                    let r = match b {
+                        ArithOp::Add => v1.checked_add(v2).ok_or_else(|| panic_arith.clone())?,
+                        ArithOp::Mul => v1.checked_mul(v2).ok_or_else(|| panic_arith.clone())?,
+                        ArithOp::Sub => v1.checked_sub(v2).ok_or_else(|| panic_arith.clone())?,
+                        ArithOp::Div => v1.checked_div(v2).ok_or_else(|| panic_arith.clone())?,
+                        ArithOp::Rem => v1.checked_rem(v2).ok_or_else(|| panic_arith.clone())?,
+                        ArithOp::Shl => v1
+                            .checked_shl(v2.try_into().map_err(|_| panic_arith.clone())?)
+                            .ok_or_else(|| panic_arith.clone())?,
+                        ArithOp::Shr => v1
+                            .checked_shr(v2.try_into().map_err(|_| panic_arith.clone())?)
+                            .ok_or_else(|| panic_arith.clone())?,
+                        ArithOp::BitXor => v1 ^ v2,
+                        ArithOp::BitOr => v1 | v2,
+                        ArithOp::BitAnd => v1 & v2,
+                    };
+                    if let TyKind::Scalar(s) = ty.kind(Interner) {
+                        if !is_valid(s, r) {
+                            return Err(panic_arith);
+                        }
+                    }
+                    Ok(ComputedExpr::Literal(Literal::Int(r, None)))
+                }
+                BinaryOp::LogicOp(_) => Err(ConstEvalError::TypeError),
+                _ => Err(ConstEvalError::NotSupported("bin op on this operators")),
+            }
+        }
+        Expr::Block { statements, tail, .. } => {
+            let mut prev_values = HashMap::<Name, Option<ComputedExpr>>::default();
+            for statement in &**statements {
+                match *statement {
+                    hir_def::expr::Statement::Let { pat, initializer, .. } => {
+                        let pat = &ctx.pats[pat];
+                        let name = match pat {
+                            Pat::Bind { name, subpat, .. } if subpat.is_none() => name.clone(),
+                            _ => {
+                                return Err(ConstEvalError::NotSupported("complex patterns in let"))
+                            }
+                        };
+                        let value = match initializer {
+                            Some(x) => eval_const(&ctx.exprs[x], ctx)?,
+                            None => continue,
+                        };
+                        if !prev_values.contains_key(&name) {
+                            let prev = ctx.local_data.insert(name.clone(), value);
+                            prev_values.insert(name, prev);
+                        } else {
+                            ctx.local_data.insert(name, value);
+                        }
+                    }
+                    hir_def::expr::Statement::Expr { .. } => {
+                        return Err(ConstEvalError::NotSupported("this kind of statement"))
+                    }
+                }
+            }
+            let r = match tail {
+                &Some(x) => eval_const(&ctx.exprs[x], ctx),
+                None => Ok(ComputedExpr::Tuple(Box::new([]))),
+            };
+            // clean up local data, so caller will receive the exact map that passed to us
+            for (name, val) in prev_values {
+                match val {
+                    Some(x) => ctx.local_data.insert(name, x),
+                    None => ctx.local_data.remove(&name),
+                };
+            }
+            r
+        }
+        Expr::Path(p) => {
+            let name = p.mod_path().as_ident().ok_or(ConstEvalError::NotSupported("big paths"))?;
+            let r = ctx
+                .local_data
+                .get(name)
+                .ok_or(ConstEvalError::NotSupported("Non local name resolution"))?;
+            Ok(r.clone())
+        }
+        _ => Err(ConstEvalError::NotSupported("This kind of expression")),
+    }
+}
+
+pub fn eval_usize(expr: Idx<Expr>, mut ctx: ConstEvalCtx<'_>) -> Option<u64> {
+    let expr = &ctx.exprs[expr];
+    if let Ok(ce) = eval_const(expr, &mut ctx) {
+        match ce {
+            ComputedExpr::Literal(Literal::Int(x, _)) => return x.try_into().ok(),
+            ComputedExpr::Literal(Literal::Uint(x, _)) => return x.try_into().ok(),
+            _ => {}
+        }
+    }
+    None
+}
+
+pub(crate) fn path_to_const(
+    db: &dyn HirDatabase,
+    resolver: &Resolver,
+    path: &ModPath,
+    mode: ParamLoweringMode,
+    args_lazy: impl FnOnce() -> Generics,
+    debruijn: DebruijnIndex,
+) -> Option<Const> {
+    match resolver.resolve_path_in_value_ns_fully(db.upcast(), &path) {
+        Some(ValueNs::GenericParam(p)) => {
+            let ty = db.const_param_ty(p);
+            let args = args_lazy();
+            let value = match mode {
+                ParamLoweringMode::Placeholder => {
+                    ConstValue::Placeholder(to_placeholder_idx(db, p.into()))
+                }
+                ParamLoweringMode::Variable => match args.param_idx(p.into()) {
+                    Some(x) => ConstValue::BoundVar(BoundVar::new(debruijn, x)),
+                    None => {
+                        never!(
+                            "Generic list doesn't contain this param: {:?}, {}, {:?}",
+                            args,
+                            path,
+                            p
+                        );
+                        return None;
+                    }
+                },
+            };
+            Some(ConstData { ty, value }.intern(Interner))
+        }
         _ => None,
     }
 }
 
+pub fn unknown_const(ty: Ty) -> Const {
+    ConstData {
+        ty,
+        value: ConstValue::Concrete(chalk_ir::ConcreteConst { interned: ConstScalar::Unknown }),
+    }
+    .intern(Interner)
+}
+
+pub fn unknown_const_usize() -> Const {
+    unknown_const(TyKind::Scalar(chalk_ir::Scalar::Uint(chalk_ir::UintTy::Usize)).intern(Interner))
+}
+
+pub fn unknown_const_as_generic(ty: Ty) -> GenericArg {
+    GenericArgData::Const(unknown_const(ty)).intern(Interner)
+}
+
 /// Interns a possibly-unknown target usize
 pub fn usize_const(value: Option<u64>) -> Const {
     ConstData {
-        ty: TyKind::Scalar(chalk_ir::Scalar::Uint(chalk_ir::UintTy::Usize)).intern(&Interner),
+        ty: TyKind::Scalar(chalk_ir::Scalar::Uint(chalk_ir::UintTy::Usize)).intern(Interner),
         value: ConstValue::Concrete(chalk_ir::ConcreteConst {
             interned: value.map(ConstScalar::Usize).unwrap_or(ConstScalar::Unknown),
         }),
     }
-    .intern(&Interner)
+    .intern(Interner)
+}
+
+pub(crate) fn eval_to_const(
+    expr: Idx<Expr>,
+    mode: ParamLoweringMode,
+    ctx: &mut InferenceContext,
+    args: impl FnOnce() -> Generics,
+    debruijn: DebruijnIndex,
+) -> Const {
+    if let Expr::Path(p) = &ctx.body.exprs[expr] {
+        let db = ctx.db;
+        let resolver = &ctx.resolver;
+        if let Some(c) = path_to_const(db, resolver, p.mod_path(), mode, args, debruijn) {
+            return c;
+        }
+    }
+    let body = ctx.body.clone();
+    let ctx = ConstEvalCtx {
+        exprs: &body.exprs,
+        pats: &body.pats,
+        local_data: HashMap::default(),
+        infer: &mut |x| ctx.infer_expr(x, &Expectation::None),
+    };
+    usize_const(eval_usize(expr, ctx))
 }