introduce the type-safe IdxVec and use it instead of loose indexes

Author: arielb1

src/librustc/mir/repr.rs

@@ -11,6 +11,7 @@
 use graphviz::IntoCow;
 use middle::const_val::ConstVal;
 use rustc_const_math::{ConstUsize, ConstInt, ConstMathErr};
+use rustc_data_structures::indexed_vec::{IdxVec, Idx};
 use hir::def_id::DefId;
 use ty::subst::Substs;
 use ty::{self, AdtDef, ClosureSubsts, FnOutput, Region, Ty};
@@ -25,37 +26,61 @@ use std::ops::{Index, IndexMut};
 use syntax::ast::{self, Name};
 use syntax::codemap::Span;
 
+macro_rules! newtype_index {
+    ($name:ident, $debug_name:expr) => (
+        #[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord,
+         RustcEncodable, RustcDecodable)]
+        pub struct $name(u32);
+
+        impl Idx for $name {
+            fn new(value: usize) -> Self {
+                assert!(value < (u32::MAX) as usize);
+                $name(value as u32)
+            }
+            fn index(self) -> usize {
+                self.0 as usize
+            }
+        }
+
+        impl Debug for $name {
+            fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
+                write!(fmt, "{}{}", $debug_name, self.0)
+            }
+        }
+    )
+}
+
 /// Lowered representation of a single function.
 #[derive(Clone, RustcEncodable, RustcDecodable)]
 pub struct Mir<'tcx> {
     /// List of basic blocks. References to basic block use a newtyped index type `BasicBlock`
     /// that indexes into this vector.
-    pub basic_blocks: Vec<BasicBlockData<'tcx>>,
+    pub basic_blocks: IdxVec<BasicBlock, BasicBlockData<'tcx>>,
 
     /// List of lexical scopes; these are referenced by statements and
     /// used (eventually) for debuginfo. Indexed by a `ScopeId`.
-    pub scopes: Vec<ScopeData>,
+    pub scopes: IdxVec<ScopeId, ScopeData>,
 
     /// Rvalues promoted from this function, such as borrows of constants.
     /// Each of them is the Mir of a constant with the fn's type parameters
     /// in scope, but no vars or args and a separate set of temps.
-    pub promoted: Vec<Mir<'tcx>>,
+    pub promoted: IdxVec<Promoted, Mir<'tcx>>,
 
     /// Return type of the function.
     pub return_ty: FnOutput<'tcx>,
 
     /// Variables: these are stack slots corresponding to user variables. They may be
     /// assigned many times.
-    pub var_decls: Vec<VarDecl<'tcx>>,
+    pub var_decls: IdxVec<Var, VarDecl<'tcx>>,
 
     /// Args: these are stack slots corresponding to the input arguments.
-    pub arg_decls: Vec<ArgDecl<'tcx>>,
+    pub arg_decls: IdxVec<Arg, ArgDecl<'tcx>>,
 
     /// Temp declarations: stack slots that for temporaries created by
     /// the compiler. These are assigned once, but they are not SSA
     /// values in that it is possible to borrow them and mutate them
     /// through the resulting reference.
-    pub temp_decls: Vec<TempDecl<'tcx>>,
+    pub temp_decls: IdxVec<Temp, TempDecl<'tcx>>,
 
     /// Names and capture modes of all the closure upvars, assuming
     /// the first argument is either the closure or a reference to it.
@@ -76,11 +101,11 @@ impl<'tcx> Mir<'tcx> {
     }
 
     pub fn basic_block_data(&self, bb: BasicBlock) -> &BasicBlockData<'tcx> {
-        &self.basic_blocks[bb.index()]
+        &self.basic_blocks[bb]
     }
 
     pub fn basic_block_data_mut(&mut self, bb: BasicBlock) -> &mut BasicBlockData<'tcx> {
-        &mut self.basic_blocks[bb.index()]
+        &mut self.basic_blocks[bb]
     }
 }
 
@@ -222,31 +247,7 @@ pub struct UpvarDecl {
 ///////////////////////////////////////////////////////////////////////////
 // BasicBlock
 
-/// The index of a particular basic block. The index is into the `basic_blocks`
-/// list of the `Mir`.
-///
-/// (We use a `u32` internally just to save memory.)
-#[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord,
-         RustcEncodable, RustcDecodable)]
-pub struct BasicBlock(u32);
-
-impl BasicBlock {
-    pub fn new(index: usize) -> BasicBlock {
-        assert!(index < (u32::MAX as usize));
-        BasicBlock(index as u32)
-    }
-
-    /// Extract the index.
-    pub fn index(self) -> usize {
-        self.0 as usize
-    }
-}
-
-impl Debug for BasicBlock {
-    fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
-        write!(fmt, "bb{}", self.0)
-    }
-}
+newtype_index!(BasicBlock, "bb");
 
 ///////////////////////////////////////////////////////////////////////////
 // BasicBlockData and Terminator
@@ -609,19 +610,23 @@ impl<'tcx> Debug for Statement<'tcx> {
 ///////////////////////////////////////////////////////////////////////////
 // Lvalues
 
+newtype_index!(Var, "var");
+newtype_index!(Temp, "tmp");
+newtype_index!(Arg, "arg");
+
 /// A path to a value; something that can be evaluated without
 /// changing or disturbing program state.
 #[derive(Clone, PartialEq, RustcEncodable, RustcDecodable)]
 pub enum Lvalue<'tcx> {
     /// local variable declared by the user
-    Var(u32),
+    Var(Var),
 
     /// temporary introduced during lowering into MIR
-    Temp(u32),
+    Temp(Temp),
 
     /// formal parameter of the function; note that these are NOT the
     /// bindings that the user declares, which are vars
-    Arg(u32),
+    Arg(Arg),
 
     /// static or static mut variable
     Static(DefId),
@@ -681,20 +686,7 @@ pub type LvalueProjection<'tcx> = Projection<'tcx, Lvalue<'tcx>, Operand<'tcx>>;
 /// and the index is an operand.
 pub type LvalueElem<'tcx> = ProjectionElem<'tcx, Operand<'tcx>>;
 
-/// Index into the list of fields found in a `VariantDef`
-#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
-pub struct Field(u32);
-
-impl Field {
-    pub fn new(value: usize) -> Field {
-        assert!(value < (u32::MAX) as usize);
-        Field(value as u32)
-    }
-
-    pub fn index(self) -> usize {
-        self.0 as usize
-    }
-}
+newtype_index!(Field, "field");
 
 impl<'tcx> Lvalue<'tcx> {
     pub fn field(self, f: Field, ty: Ty<'tcx>) -> Lvalue<'tcx> {
@@ -722,12 +714,9 @@ impl<'tcx> Debug for Lvalue<'tcx> {
         use self::Lvalue::*;
 
         match *self {
-            Var(id) =>
-                write!(fmt, "var{:?}", id),
-            Arg(id) =>
-                write!(fmt, "arg{:?}", id),
-            Temp(id) =>
-                write!(fmt, "tmp{:?}", id),
+            Var(id) => write!(fmt, "{:?}", id),
+            Arg(id) => write!(fmt, "{:?}", id),
+            Temp(id) => write!(fmt, "{:?}", id),
             Static(def_id) =>
                 write!(fmt, "{}", ty::tls::with(|tcx| tcx.item_path_str(def_id))),
             ReturnPointer =>
@@ -754,35 +743,8 @@ impl<'tcx> Debug for Lvalue<'tcx> {
 ///////////////////////////////////////////////////////////////////////////
 // Scopes
 
-impl Index<ScopeId> for Vec<ScopeData> {
-    type Output = ScopeData;
-
-    #[inline]
-    fn index(&self, index: ScopeId) -> &ScopeData {
-        &self[index.index()]
-    }
-}
-
-impl IndexMut<ScopeId> for Vec<ScopeData> {
-    #[inline]
-    fn index_mut(&mut self, index: ScopeId) -> &mut ScopeData {
-        &mut self[index.index()]
-    }
-}
-
-#[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, RustcEncodable, RustcDecodable)]
-pub struct ScopeId(u32);
-
-impl ScopeId {
-    pub fn new(index: usize) -> ScopeId {
-        assert!(index < (u32::MAX as usize));
-        ScopeId(index as u32)
-    }
-
-    pub fn index(self) -> usize {
-        self.0 as usize
-    }
-}
+newtype_index!(ScopeId, "scope");
+pub const TOPMOST_SCOPE : ScopeId = ScopeId(0);
 
 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
 pub struct ScopeData {
@@ -1067,6 +1029,8 @@ impl<'tcx> Debug for TypedConstVal<'tcx> {
     }
 }
 
+newtype_index!(Promoted, "promoted");
+
 #[derive(Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
 pub enum Literal<'tcx> {
     Item {
@@ -1078,7 +1042,7 @@ pub enum Literal<'tcx> {
     },
     Promoted {
         // Index into the `promoted` vector of `Mir`.
-        index: usize
+        index: Promoted
     },
 }
 
@@ -1102,7 +1066,7 @@ impl<'tcx> Debug for Literal<'tcx> {
                 fmt_const_val(fmt, value)
             }
             Promoted { index } => {
-                write!(fmt, "promoted{}", index)
+                write!(fmt, "{:?}", index)
             }
         }
     }

src/librustc/mir/tcx.rs

@@ -140,11 +140,11 @@ impl<'a, 'gcx, 'tcx> Mir<'tcx> {
     {
         match *lvalue {
             Lvalue::Var(index) =>
-                LvalueTy::Ty { ty: self.var_decls[index as usize].ty },
+                LvalueTy::Ty { ty: self.var_decls[index].ty },
             Lvalue::Temp(index) =>
-                LvalueTy::Ty { ty: self.temp_decls[index as usize].ty },
+                LvalueTy::Ty { ty: self.temp_decls[index].ty },
             Lvalue::Arg(index) =>
-                LvalueTy::Ty { ty: self.arg_decls[index as usize].ty },
+                LvalueTy::Ty { ty: self.arg_decls[index].ty },
             Lvalue::Static(def_id) =>
                 LvalueTy::Ty { ty: tcx.lookup_item_type(def_id).ty },
             Lvalue::ReturnPointer =>

src/librustc/mir/visit.rs

@@ -15,6 +15,7 @@ use ty::{ClosureSubsts, FnOutput, Region, Ty};
 use mir::repr::*;
 use rustc_const_math::ConstUsize;
 use rustc_data_structures::tuple_slice::TupleSlice;
+use rustc_data_structures::indexed_vec::Idx;
 use syntax::codemap::Span;
 
 // # The MIR Visitor

src/librustc_borrowck/Cargo.toml

@@ -14,4 +14,5 @@ log = { path = "../liblog" }
 syntax = { path = "../libsyntax" }
 graphviz = { path = "../libgraphviz" }
 rustc = { path = "../librustc" }
+rustc_data_structures = { path = "../librustc_data_structures" }
 rustc_mir = { path = "../librustc_mir" }

src/librustc_borrowck/borrowck/mir/dataflow/graphviz.rs

@@ -12,6 +12,7 @@
 
 use syntax::ast::NodeId;
 use rustc::mir::repr::{BasicBlock, Mir};
+use rustc_data_structures::indexed_vec::Idx;
 
 use dot;
 use dot::IntoCow;
@@ -27,7 +28,7 @@ use std::path::Path;
 use super::super::MoveDataParamEnv;
 use super::super::MirBorrowckCtxtPreDataflow;
 use bitslice::bits_to_string;
-use indexed_set::{Idx, IdxSet};
+use indexed_set::{IdxSet};
 use super::{BitDenotation, DataflowState};
 
 impl<O: BitDenotation> DataflowState<O> {

src/librustc_borrowck/borrowck/mir/dataflow/impls.rs

@@ -10,6 +10,7 @@
 
 use rustc::ty::TyCtxt;
 use rustc::mir::repr::{self, Mir};
+use rustc_data_structures::indexed_vec::Idx;
 
 use super::super::gather_moves::{Location};
 use super::super::gather_moves::{MoveOutIndex, MovePathIndex};
@@ -23,7 +24,7 @@ use super::{BitDenotation, BlockSets, DataflowOperator};
 
 use bitslice::BitSlice; // adds set_bit/get_bit to &[usize] bitvector rep.
 use bitslice::{BitwiseOperator};
-use indexed_set::{Idx, IdxSet};
+use indexed_set::{IdxSet};
 
 // Dataflow analyses are built upon some interpretation of the
 // bitvectors attached to each basic block, represented via a
@@ -451,7 +452,7 @@ impl<'a, 'tcx> BitDenotation for MovingOutStatements<'a, 'tcx> {
                                      move_data,
                                      move_path_index,
                                      |mpi| for moi in &path_map[mpi] {
-                                         assert!(moi.idx() < bits_per_block);
+                                         assert!(moi.index() < bits_per_block);
                                          sets.kill_set.add(&moi);
                                      });
             }
@@ -472,7 +473,7 @@ impl<'a, 'tcx> BitDenotation for MovingOutStatements<'a, 'tcx> {
                term, loc, &loc_map[loc]);
         let bits_per_block = self.bits_per_block(ctxt);
         for move_index in &loc_map[loc] {
-            assert!(move_index.idx() < bits_per_block);
+            assert!(move_index.index() < bits_per_block);
             zero_to_one(sets.gen_set.words_mut(), *move_index);
         }
     }
@@ -493,14 +494,14 @@ impl<'a, 'tcx> BitDenotation for MovingOutStatements<'a, 'tcx> {
                              move_data,
                              move_path_index,
                              |mpi| for moi in &path_map[mpi] {
-                                 assert!(moi.idx() < bits_per_block);
+                                 assert!(moi.index() < bits_per_block);
                                  in_out.remove(&moi);
                              });
     }
 }
 
 fn zero_to_one(bitvec: &mut [usize], move_index: MoveOutIndex) {
-    let retval = bitvec.set_bit(move_index.idx());
+    let retval = bitvec.set_bit(move_index.index());
     assert!(retval);
 }
 

src/librustc_borrowck/borrowck/mir/dataflow/mod.rs

@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+use rustc_data_structures::indexed_vec::Idx;
+
 use rustc::ty::TyCtxt;
 use rustc::mir::repr::{self, Mir};
 
@@ -21,7 +23,7 @@ use super::MirBorrowckCtxtPreDataflow;
 use super::MoveDataParamEnv;
 
 use bitslice::{bitwise, BitwiseOperator};
-use indexed_set::{Idx, IdxSet, IdxSetBuf};
+use indexed_set::{IdxSet, IdxSetBuf};
 
 pub use self::sanity_check::sanity_check_via_rustc_peek;
 pub use self::impls::{MaybeInitializedLvals, MaybeUninitializedLvals};

src/librustc_borrowck/borrowck/mir/dataflow/sanity_check.rs

@@ -14,6 +14,7 @@ use syntax::codemap::Span;
 
 use rustc::ty::{self, TyCtxt};
 use rustc::mir::repr::{self, Mir};
+use rustc_data_structures::indexed_vec::Idx;
 
 use super::super::gather_moves::{MovePathIndex};
 use super::super::MoveDataParamEnv;

src/librustc_borrowck/borrowck/mir/elaborate_drops.rs

@@ -22,6 +22,7 @@ use rustc::mir::transform::{Pass, MirPass, MirSource};
 use rustc::middle::const_val::ConstVal;
 use rustc::middle::lang_items;
 use rustc::util::nodemap::FnvHashMap;
+use rustc_data_structures::indexed_vec::Idx;
 use rustc_mir::pretty;
 use syntax::codemap::Span;
 
@@ -118,7 +119,7 @@ struct ElaborateDropsCtxt<'a, 'tcx: 'a> {
     env: &'a MoveDataParamEnv<'tcx>,
     flow_inits: DataflowResults<MaybeInitializedLvals<'a, 'tcx>>,
     flow_uninits:  DataflowResults<MaybeUninitializedLvals<'a, 'tcx>>,
-    drop_flags: FnvHashMap<MovePathIndex, u32>,
+    drop_flags: FnvHashMap<MovePathIndex, Temp>,
     patch: MirPatch<'tcx>,
 }