Improve paths() function, more tests, small update on trailing whites…

…pace when printing a net

pyrtl/analysis.py

@@ -407,8 +407,34 @@ def extract_area_delay_from_yosys_output(yosys_output):
     return area, delay
 
 
+class PathsResult(dict):
+    def print(self, file=sys.stdout):
+        """ Pretty print the result of calling paths()
+
+        :param f: the open file to print to (defaults to stdout)
+        :return: None
+        """
+        # All this work, to make sure it's determinstic
+        def path_sort_key(path):
+            dst_names = [net.dests[0].name if net.dests else '' for net in path]
+            return (len(path), dst_names)
+
+        for start in sorted(self.keys(), key=lambda w: w.name):
+            print("From %s" % start.name, file=file)
+            for end in sorted(self[start].keys(), key=lambda w: w.name):
+                print("  To %s" % end.name, file=file)
+                paths = self[start][end]
+                if len(paths) > 0:
+                    for i, paths in enumerate(sorted(paths, key=path_sort_key)):
+                        print("    Path %d" % i, file=file)
+                        for path in paths:
+                            print("      %s" % str(path), file=file)
+                else:
+                    print("    (No paths)", file=file)
+
+
 def paths(src=None, dst=None, dst_nets=None, block=None):
-    """ Get the list of paths from src to dst.
+    """ Get the list of all paths from src to dst.
 
     :param Union[WireVector, Iterable[WireVector]] src: source wire(s) from which to
         trace your paths; if None, will get paths from all Inputs
@@ -420,7 +446,8 @@ def paths(src=None, dst=None, dst_nets=None, block=None):
     :param Block block: block to use (defaults to working block)
     :return: a map of the form {src_wire: {dst_wire: [path]}} for each src_wire in src
         (or all inputs if src is None), dst_wire in dst (or all outputs if dst is None),
-        where path is a list of nets
+        where path is a list of nets. This map is also an instance of PathsResult,
+        so you can call `print()` on it to pretty print it.
 
     You can provide dst_nets (the result of calling pyrtl.net_connections()), if you plan
     on calling this function repeatedly on a block that hasn't changed, to speed things up.
@@ -434,6 +461,11 @@ def paths(src=None, dst=None, dst_nets=None, block=None):
     to a given dst wire.
 
     If src and dst are both single wires, you still need to access the result via paths[src][dst].
+
+    This also finds and returns the loop paths in the case of registers or memories that feed into
+    themselves, i.e. paths[src][src] is not necessarily empty.
+
+    It does not distinguish between loops that include synchronous vs asynchronous memories.
     """
     block = working_block(block)
 
@@ -472,17 +504,36 @@ def dfs(w, curr_path):
                 paths.append(curr_path)
             for dst_net in dst_nets.get(w, []):
                 # Avoid loops and the mem net (has no output wire)
-                if (dst_net not in curr_path) and (dst_net.op != '@'):
-                    dfs(dst_net.dests[0], curr_path + [dst_net])
+                if dst_net not in curr_path:
+                    if dst_net.op == '@':  # dests will be the read ports
+                        for read_net in dst_net.op_param[1].readport_nets:
+                            dfs(read_net.dests[0], curr_path + [dst_net, read_net])
+                    else:
+                        dfs(dst_net.dests[0], curr_path + [dst_net])
         dfs(src, [])
         return paths
 
     all_paths = collections.defaultdict(dict)
     for src_wire in src:
         for dst_wire in dst:
-            all_paths[src_wire][dst_wire] = paths_src_dst(src_wire, dst_wire)
-
-    return all_paths
+            paths = paths_src_dst(src_wire, dst_wire)
+            # Remove empty paths...
+            paths = list(filter(lambda x: len(x) > 0, paths))
+            # ...and those that are supersets of others (resulting from an inner loop).
+            if src_wire is not dst_wire:
+                paths = sorted(paths, key=lambda p: len(p), reverse=True)
+                keep = []
+                for i in range(len(paths)):
+                    # Check if there is a path in paths[i+1:] that is the suffix
+                    # of paths[i] (paths[i] is at least as large as each path in
+                    # paths[i+1:]). If so, paths[i] contains a loop since both start
+                    # at src_wire, so don't keep it.
+                    if not any(paths[i][-len(p):] == p for p in paths[i + 1:]):
+                        keep.append(paths[i])
+                paths = keep
+            all_paths[src_wire][dst_wire] = paths
+
+    return PathsResult(all_paths)
 
 
 def distance(src, dst, f, block=None):

pyrtl/core.py

@@ -123,7 +123,8 @@ def __str__(self):
 
         else:  # not in ipython
             if self.op in 'w~&|^n+-*<>=xcsr':
-                return "{} <-- {} -- {} {}".format(lhs, self.op, rhs, options)
+                options = ' ' + options if options else ''
+                return "{} <-- {} -- {}{}".format(lhs, self.op, rhs, options)
             elif self.op in 'm@':
                 memid, memblock = self.op_param
                 extrainfo = 'memid=' + str(memid)

tests/test_analysis.py

@@ -1,6 +1,7 @@
 from __future__ import print_function, unicode_literals, absolute_import
 
 import unittest
+import io
 import pyrtl
 
 
@@ -113,10 +114,50 @@ def setUp(self):
         pyrtl.reset_working_block()
 
 
+paths_print_output = """\
+From i
+  To o
+    Path 0
+      tmp5/3W <-- - -- i/2I, tmp4/2W
+      tmp6/3W <-- | -- tmp2/3W, tmp5/3W
+      o/3O <-- w -- tmp6/3W
+    Path 1
+      tmp1/3W <-- c -- tmp0/1W, i/2I
+      tmp2/3W <-- & -- tmp1/3W, j/3I
+      tmp6/3W <-- | -- tmp2/3W, tmp5/3W
+      o/3O <-- w -- tmp6/3W
+  To p
+    Path 0
+      tmp8/4W <-- c -- tmp7/2W, i/2I
+      tmp9/5W <-- - -- k/4I, tmp8/4W
+      p/5O <-- w -- tmp9/5W
+From j
+  To o
+    Path 0
+      tmp2/3W <-- & -- tmp1/3W, j/3I
+      tmp6/3W <-- | -- tmp2/3W, tmp5/3W
+      o/3O <-- w -- tmp6/3W
+  To p
+    (No paths)
+From k
+  To o
+    (No paths)
+  To p
+    Path 0
+      tmp9/5W <-- - -- k/4I, tmp8/4W
+      p/5O <-- w -- tmp9/5W
+"""
+
+
 class TestPaths(unittest.TestCase):
 
     def setUp(self):
         pyrtl.reset_working_block()
+        # To compare textual consistency, need to make
+        # sure we're starting at the same index for all
+        # automatically created names.
+        pyrtl.wire._reset_wire_indexers()
+        pyrtl.memory._reset_memory_indexer()
 
     def test_one_path_to_one_output(self):
         a = pyrtl.Input(4, 'a')
@@ -181,6 +222,83 @@ def test_subset_of_all_paths(self):
         self.assertNotIn(p, paths_from_k)  # Because p was not provided as target output
         self.assertEqual(len(paths_from_k[o]), 0)  # 0 paths from k to o
 
+    def test_paths_empty_src_and_dst_equal_with_no_other_logic(self):
+        i = pyrtl.Input(4, 'i')
+        paths = pyrtl.paths(i, i)
+        self.assertEqual(len(paths[i][i]), 0)
+
+    def test_paths_with_loop(self):
+        r = pyrtl.Register(1, 'r')
+        r.next <<= r & ~r
+        paths = pyrtl.paths(r, r)
+        self.assertEqual(len(paths[r][r]), 2)
+        p1, p2 = sorted(paths[r][r], key=lambda p: len(p), reverse=True)
+        self.assertEqual(len(p1), 3)
+        self.assertEqual(p1[0].op, '~')
+        self.assertEqual(p1[1].op, '&')
+        self.assertEqual(p1[2].op, 'r')
+        self.assertEqual(len(p2), 2)
+        self.assertEqual(p2[0].op, '&')
+        self.assertEqual(p2[1].op, 'r')
+
+    def test_paths_loop_and_input(self):
+        i = pyrtl.Input(1, 'i')
+        o = pyrtl.Output(1, 'o')
+        r = pyrtl.Register(1, 'r')
+        r.next <<= i & r
+        o <<= r
+        paths = pyrtl.paths(r, o)
+        self.assertEqual(len(paths[r][o]), 1)
+
+    def test_paths_loop_get_arbitrary_inner_wires(self):
+        w = pyrtl.WireVector(1, 'w')
+        y = w & pyrtl.Const(1)
+        w <<= ~y
+        paths = pyrtl.paths(w, y)
+        self.assertEqual(len(paths[w][y]), 1)
+        self.assertEqual(paths[w][y][0][0].op, '&')
+
+    def test_paths_no_path_exists(self):
+        i = pyrtl.Input(1, 'i')
+        o = pyrtl.Output(1, 'o')
+        o <<= ~i
+
+        w = pyrtl.WireVector(1, 'w')
+        y = w & pyrtl.Const(1)
+        w <<= ~y
+
+        paths = pyrtl.paths(w, o)
+        self.assertEqual(len(paths[w][o]), 0)
+
+    def test_paths_with_memory(self):
+        i = pyrtl.Input(4, 'i')
+        o = pyrtl.Output(8, 'o')
+        mem = pyrtl.MemBlock(8, 32, 'mem')
+        waddr = pyrtl.Input(32, 'waddr')
+        raddr = pyrtl.Input(32, 'raddr')
+        data = mem[raddr]
+        mem[waddr] <<= (i + ~data).truncate(8)
+        o <<= data
+
+        paths = pyrtl.paths(i, o)
+        path = paths[i][o][0]
+        self.assertEqual(path[0].op, 'c')
+        self.assertEqual(path[1].op, '+')
+        self.assertEqual(path[2].op, 's')
+        self.assertEqual(path[3].op, '@')
+        self.assertEqual(path[4].op, 'm')
+        self.assertEqual(path[5].op, 'w')
+
+        # TODO Once issue with _MemIndexed lookups is resolved,
+        #      these should be `data` instead of `data.wire`.
+        paths = pyrtl.paths(data.wire, data.wire)
+        path = paths[data.wire][data.wire][0]
+        self.assertEqual(path[0].op, '~')
+        self.assertEqual(path[1].op, '+')
+        self.assertEqual(path[2].op, 's')
+        self.assertEqual(path[3].op, '@')
+        self.assertEqual(path[4].op, 'm')
+
     def test_all_paths(self):
         a, b, c = pyrtl.input_list('a/2 b/4 c/1')
         o, p = pyrtl.output_list('o/4 p/2')
@@ -218,6 +336,17 @@ def test_all_paths(self):
         paths_c_to_p = paths[c][p]
         self.assertEqual(len(paths_c_to_p), 1)
 
+    def test_pretty_print(self):
+        i, j, k = pyrtl.input_list('i/2 j/3 k/4')
+        o, p = pyrtl.Output(name='o'), pyrtl.Output(name='p')
+        o <<= (i & j) | (i - 1)
+        p <<= k - i
+
+        paths = pyrtl.paths()
+        output = io.StringIO()
+        paths.print(file=output)
+        self.assertEqual(output.getvalue(), paths_print_output)
+
 
 class TestDistance(unittest.TestCase):