fhdl/verilog: add option to display which comb blocks are run

This is a debug hack to help find combinatorial loops in designs.

diff --git a/migen/fhdl/verilog.py b/migen/fhdl/verilog.py
index 4552c0d30831bd2ef3718ed441420ae50da9a617..81a02ac5e9b269acf5f365906b394e505e0d9b87 100644 (file)
--- a/migen/fhdl/verilog.py
+++ b/migen/fhdl/verilog.py
@@ -132,7 +132,7 @@ def _printheader(f, ios, name, ns):
        r += "\n"
        return r
 
-def _printcomb(f, ns):
+def _printcomb(f, ns, display_run):
        r = ""
        if f.comb.l:
                # Generate a dummy event to get the simulator
@@ -147,7 +147,7 @@ def _printcomb(f, ns):
                
                groups = group_by_targets(f.comb)
                
-               for g in groups:
+               for n, g in enumerate(groups):
                        if len(g[1]) == 1 and isinstance(g[1][0], _Assign):
                                r += "assign " + _printnode(ns, _AT_BLOCKING, 0, g[1][0])
                        else:
@@ -157,6 +157,8 @@ def _printcomb(f, ns):
                                r += syn_on
                                
                                r += "always @(*) begin\n"
+                               if display_run:
+                                       r += "\t$display(\"Running comb block #" + str(n) + "\");\n"
                                for t in g[0]:
                                        r += "\t" + ns.get_name(t) + " <= " + str(t.reset) + ";\n"
                                r += _printnode(ns, _AT_NONBLOCKING, 1, _StatementList(g[1]))
@@ -237,7 +239,8 @@ def _printinit(f, ios, ns):
 def convert(f, ios=set(), name="top",
   clk_signal=None, rst_signal=None,
   return_ns=False,
-  memory_handler=verilog_mem_behavioral.handler):
+  memory_handler=verilog_mem_behavioral.handler,
+  display_run=False):
        if clk_signal is None:
                clk_signal = Signal(name_override="sys_clk")
                ios.add(clk_signal)
@@ -252,7 +255,7 @@ def convert(f, ios=set(), name="top",
 
        r = "/* Machine-generated using Migen */\n"
        r += _printheader(f, ios, name, ns)
-       r += _printcomb(f, ns)
+       r += _printcomb(f, ns, display_run)
        r += _printsync(f, ns, clk_signal, rst_signal)
        r += _printinstances(f, ns, clk_signal, rst_signal)
        r += _printmemories(f, ns, memory_handler, clk_signal)