revised mir-dataflow so bitvectors carry a phantom type for their index domain.

As some drive-by's:

 * moved bitwise operators into `mod bitslice`

 * factored out `fn gen` and `fn kill` methods on `BlockSets` type

 * removed outdated comment about `fn propagate_call_return`

Author: pnkfelix

src/librustc_borrowck/bitslice.rs

@@ -109,3 +109,32 @@ pub fn bits_to_string(words: &[Word], bits: usize) -> String {
     result.push(']');
     return result
 }
+
+#[inline]
+pub fn bitwise<Op:BitwiseOperator>(out_vec: &mut [usize],
+                                   in_vec: &[usize],
+                                   op: &Op) -> bool {
+    assert_eq!(out_vec.len(), in_vec.len());
+    let mut changed = false;
+    for (out_elt, in_elt) in out_vec.iter_mut().zip(in_vec) {
+        let old_val = *out_elt;
+        let new_val = op.join(old_val, *in_elt);
+        *out_elt = new_val;
+        changed |= old_val != new_val;
+    }
+    changed
+}
+
+pub trait BitwiseOperator {
+    /// Applies some bit-operation pointwise to each of the bits in the two inputs.
+    fn join(&self, pred1: usize, pred2: usize) -> usize;
+}
+
+pub struct Union;
+impl BitwiseOperator for Union {
+    fn join(&self, a: usize, b: usize) -> usize { a | b }
+}
+pub struct Subtract;
+impl BitwiseOperator for Subtract {
+    fn join(&self, a: usize, b: usize) -> usize { a & !b }
+}

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

@@ -54,8 +54,9 @@ struct Graph<'a, 'tcx, MWF:'a> where MWF: MirWithFlowState<'tcx>,
 
 pub fn print_borrowck_graph_to<'a, 'tcx, BD>(
     mbcx: &MirBorrowckCtxtPreDataflow<'a, 'tcx, BD>,
-    path: &Path) -> io::Result<()> where BD: BitDenotation,
-                                        BD::Bit: Debug, BD::Ctxt: HasMoveData<'tcx>
+    path: &Path)
+    -> io::Result<()>
+    where BD: BitDenotation, BD::Bit: Debug, BD::Ctxt: HasMoveData<'tcx>,
 {
     let g = Graph { mbcx: mbcx, phantom: PhantomData };
     let mut v = Vec::new();
@@ -180,7 +181,7 @@ impl<'a, 'tcx, MWF> dot::Labeller<'a> for Graph<'a, 'tcx, MWF>
                                         <td></td></tr>",
                        bg = BG_FLOWCONTENT,
                        face = FACE_MONOSPACE,
-                       entrybits=bits_to_string(entry, bits_per_block))
+                       entrybits=bits_to_string(entry.words(), bits_per_block))
             },
             |w| {
                 let ctxt = self.mbcx.analysis_ctxt();
@@ -197,7 +198,7 @@ impl<'a, 'tcx, MWF> dot::Labeller<'a> for Graph<'a, 'tcx, MWF>
                                            <td></td></tr>",
                            bg = BG_FLOWCONTENT,
                            face = FACE_MONOSPACE,
-                           genbits=bits_to_string(gen, bits_per_block))?;
+                           genbits=bits_to_string(gen.words(), bits_per_block))?;
                 }
 
                 {
@@ -209,7 +210,7 @@ impl<'a, 'tcx, MWF> dot::Labeller<'a> for Graph<'a, 'tcx, MWF>
                            bg = BG_FLOWCONTENT,
                            align = ALIGN_RIGHT,
                            face = FACE_MONOSPACE,
-                           killbits=bits_to_string(kill, bits_per_block))?;
+                           killbits=bits_to_string(kill.words(), bits_per_block))?;
                 }
 
                 // (chunked_present_right)