Merge pull request #831 from larsclausen/void-func-always-comb

Let void functions in always_comb block contribute to sensitivity list

ivtest/ivltests/always_comb_void_func.v

@@ -0,0 +1,51 @@
+// Check that variables referenced in a void function contribute to the
+// sensitivity list of a always_comb block.
+
+module top;
+  logic passed;
+  logic [7:0] value;
+  integer counter;
+
+  function automatic void count(bit what);
+    counter = 0;
+    for (integer i = 0; i < $bits(value); i++) begin
+      if (value[i] == what)
+        counter += 1;
+    end
+  endfunction
+
+  always_comb begin
+    count(1'b1);
+  end
+
+  initial begin
+    passed = 1'b1;
+
+    value = 8'b0000_0000;
+    #1;
+    if (counter !== 0) begin
+      $display("Expected 0, got %d", counter);
+      passed = 1'b0;
+    end
+
+    value = 8'b0011_1100;
+    #1;
+    if (counter !== 4) begin
+      $display("Expected 4, got %d", counter);
+      passed = 1'b0;
+    end
+
+    value = 8'b1011_1101;
+    #1;
+    if (counter !== 6) begin
+      $display("Expected 6, got %d", counter);
+      passed = 1'b0;
+    end
+
+    if (passed) begin
+      $display("PASSED");
+    end else begin
+      $display("FAILED");
+    end
+  end
+endmodule

ivtest/regress-sv.list

@@ -76,6 +76,7 @@ always_comb_fail4	CE,-g2005-sv		ivltests
 always_comb_no_sens	nornal,-g2005-sv	ivltests gold=always_comb_no_sens.gold
 always_comb_rfunc	nornal,-g2005-sv	ivltests
 always_comb_trig	normal,-g2005-sv	ivltests
+always_comb_void_func	normal,-g2005-sv	ivltests
 always_comb_warn	normal,-g2005-sv	ivltests gold=always_comb_warn.gold
 always_ff		normal,-g2005-sv	ivltests
 always_ff_fail		CE,-g2005-sv		ivltests

ivtest/regress-vlog95.list

@@ -69,6 +69,7 @@
 
 # Verilog 95 does not support automatic tasks or functions.
 always_comb_rfunc	CE			ivltests
+always_comb_void_func	CE			ivltests
 automatic_error11	CE			ivltests
 automatic_error12	CE			ivltests
 automatic_error13	CE			ivltests

net_nex_input.cc

@@ -255,6 +255,30 @@ NexusSet* NetETernary::nex_input(bool rem_out, bool always_sens, bool nested_fun
       return result;
 }
 
+// Get the contribution of a function call in a always_comb block
+static void func_always_sens(NetFuncDef *func, NexusSet *result,
+			     bool rem_out, bool nested_func)
+{
+	  // Avoid recursive function calls.
+	static set<NetFuncDef*> func_set;
+	if (!nested_func)
+	      func_set.clear();
+
+	if (!func_set.insert(func).second)
+	      return;
+
+	std::unique_ptr<NexusSet> tmp(func->proc()->nex_input(rem_out, true, true));
+	  // Remove the function inputs
+	std::unique_ptr<NexusSet> in(new NexusSet);
+	for (unsigned idx = 0; idx < func->port_count(); idx++) {
+	      NetNet *net = func->port(idx);
+	      assert(net->pin_count() == 1);
+	      in->add(net->pin(0).nexus(), 0, net->vector_width());
+	}
+	tmp->rem(*in);
+	result->add(*tmp);
+}
+
 NexusSet* NetEUFunc::nex_input(bool rem_out, bool always_sens, bool nested_func) const
 {
       NexusSet*result = new NexusSet;
@@ -265,31 +289,8 @@ NexusSet* NetEUFunc::nex_input(bool rem_out, bool always_sens, bool nested_func)
 	    delete tmp;
       }
 
-      if (always_sens) {
-	    NetFuncDef*func = func_->func_def();
-
-	      // Avoid recursive function calls.
-	    static set<NetFuncDef*> func_set;
-	    if (!nested_func)
-		  func_set.clear();
-
-	    if (!func_set.insert(func).second)
-		  return result;
-
-	    NexusSet*tmp = func->proc()->nex_input(rem_out, always_sens, true);
-	      // Remove the function inputs
-	    NexusSet*in = new NexusSet;
-	    for (unsigned idx = 0 ;  idx < func->port_count() ;  idx += 1) {
-		  NetNet*net = func->port(idx);
-		  assert(net->pin_count() == 1);
-		  in->add(net->pin(0).nexus(), 0, net->vector_width());
-	    }
-	    tmp->rem(*in);
-	    delete in;
-
-	    result->add(*tmp);
-	    delete tmp;
-      }
+      if (always_sens)
+	    func_always_sens(func_->func_def(), result, rem_out, nested_func);
 
       return result;
 }
@@ -613,9 +614,18 @@ NexusSet* NetSTask::nex_input(bool rem_out, bool always_sens, bool nested_func)
  * parameters to consider, because the compiler already removed them
  * and converted them to blocking assignments.
  */
-NexusSet* NetUTask::nex_input(bool, bool, bool) const
+NexusSet* NetUTask::nex_input(bool rem_out, bool always_sens, bool nested_func) const
 {
-      return new NexusSet;
+      NexusSet *result = new NexusSet;
+
+      /*
+       * Let the contents of void functions contribute to the sensitivity list
+       * of always_comb blocks
+       */
+      if (always_sens && task_->type() == NetScope::FUNC)
+	    func_always_sens(task_->func_def(), result, rem_out, nested_func);
+
+      return result;
 }
 
 NexusSet* NetWhile::nex_input(bool rem_out, bool always_sens, bool nested_func) const