Added $anyconst and $aconst

frontends/ast/genrtlil.cc

@@ -750,6 +750,19 @@ void AstNode::detectSignWidthWorker(int &width_hint, bool &sign_hint, bool *foun
 		width_hint = max(width_hint, this_width);
 		break;
 
+	case AST_FCALL:
+		if (str == "\\$anyconst" || str == "\\$aconst") {
+			if (GetSize(children) == 1) {
+				while (children[0]->simplify(true, false, false, 1, -1, false, true) == true) { }
+				if (children[0]->type != AST_CONSTANT)
+					log_error("System function %s called with non-const argument at %s:%d!\n",
+							RTLIL::unescape_id(str).c_str(), filename.c_str(), linenum);
+				width_hint = max(width_hint, int(children[0]->asInt(true)));
+			}
+			break;
+		}
+		/* fall through */
+
 	// everything should have been handled above -> print error if not.
 	default:
 		for (auto f : log_files)
@@ -1427,6 +1440,38 @@ RTLIL::SigSpec AstNode::genRTLIL(int width_hint, bool sign_hint)
 			delete always;
 		} break;
 
+	case AST_FCALL: {
+			if (str == "\\$anyconst" || str == "\\$aconst")
+			{
+				string myid = stringf("%s$%d", RTLIL::unescape_id(str).c_str(), autoidx++);
+				int width = width_hint;
+
+				if (GetSize(children) > 1)
+					log_error("System function %s got %d arguments, expected 1 or 0 at %s:%d.\n",
+							RTLIL::unescape_id(str).c_str(), GetSize(children), filename.c_str(), linenum);
+
+				if (GetSize(children) == 1) {
+					if (children[0]->type != AST_CONSTANT)
+						log_error("System function %s called with non-const argument at %s:%d!\n",
+								RTLIL::unescape_id(str).c_str(), filename.c_str(), linenum);
+					width = children[0]->asInt(true);
+				}
+
+				if (width <= 0)
+					log_error("Failed to detect width of %s at %s:%d!\n",
+							RTLIL::unescape_id(str).c_str(), filename.c_str(), linenum);
+
+				Cell *cell = current_module->addCell(myid, str.substr(1));
+				cell->parameters["\\WIDTH"] = width;
+
+				Wire *wire = current_module->addWire(myid + "_wire", width);
+				cell->setPort("\\Y", wire);
+
+				is_signed = sign_hint;
+				return SigSpec(wire);
+			}
+		} /* fall through */
+
 	// everything should have been handled above -> print error if not.
 	default:
 		for (auto f : log_files)

frontends/ast/simplify.cc

@@ -1655,6 +1655,10 @@ skip_dynamic_range_lvalue_expansion:;
 				goto apply_newNode;
 			}
 
+			// $anyconst and $aconst are mapped in AstNode::genRTLIL()
+			if (str == "\\$anyconst" || str == "\\$aconst")
+				return false;
+
 			if (str == "\\$clog2")
 			{
 				if (children.size() != 1)

frontends/verilog/verilog_parser.y

@@ -1219,7 +1219,7 @@ rvalue:
 		$$ = new AstNode(AST_IDENTIFIER, $2);
 		$$->str = *$1;
 		delete $1;
-		if ($2 == nullptr && $$->str == "\\$initstate")
+		if ($2 == nullptr && formal_mode && ($$->str == "\\$initstate" || $$->str == "\\$anyconst" || $$->str == "\\$aconst"))
 			$$->type = AST_FCALL;
 	} |
 	hierarchical_id non_opt_multirange {

kernel/celltypes.h

@@ -118,6 +118,8 @@ struct CellTypes
 		setup_type("$assume", {A, EN}, pool<RTLIL::IdString>(), true);
 		setup_type("$predict", {A, EN}, pool<RTLIL::IdString>(), true);
 		setup_type("$initstate", pool<RTLIL::IdString>(), {Y}, true);
+		setup_type("$anyconst", pool<RTLIL::IdString>(), {Y}, true);
+		setup_type("$aconst", pool<RTLIL::IdString>(), {Y}, true);
 		setup_type("$equiv", {A, B}, {Y}, true);
 	}
 

kernel/rtlil.cc

@@ -1030,6 +1030,12 @@ namespace {
 				return;
 			}
 
+			if (cell->type.in("$aconst", "$anyconst")) {
+				port("\\Y", param("\\WIDTH"));
+				check_expected();
+				return;
+			}
+
 			if (cell->type == "$equiv") {
 				port("\\A", 1);
 				port("\\B", 1);

manual/CHAPTER_CellLib.tex

@@ -421,7 +421,7 @@ pass. The combinatorial logic cells can be mapped to physical cells from a Liber
 using the {\tt abc} pass.
 
 \begin{fixme}
-Add information about {\tt \$assert}, {\tt \$assume}, {\tt \$predict}, {\tt \$equiv}, and {\tt \$initstate} cells.
+Add information about {\tt \$assert}, {\tt \$assume}, {\tt \$predict}, {\tt \$equiv}, {\tt \$initstate}, {\tt \$aconst}, and {\tt \$anyconst} cells.
 \end{fixme}
 
 \begin{fixme}

techlibs/common/simlib.v

@@ -1330,6 +1330,30 @@ endmodule
 
 // --------------------------------------------------------
 
+module \$aconst (Y);
+
+parameter WIDTH = 0;
+
+output [WIDTH-1:0] Y;
+
+assign Y = 'bx;
+
+endmodule
+
+// --------------------------------------------------------
+
+module \$anyconst (Y);
+
+parameter WIDTH = 0;
+
+output [WIDTH-1:0] Y;
+
+assign Y = 'bx;
+
+endmodule
+
+// --------------------------------------------------------
+
 module \$equiv (A, B, Y);
 
 input A, B;