sv: fix some edge cases for unbased unsized literals

- Fix explicit size cast of unbased unsized literals
- Fix unbased unsized literal bound directly to port
- Output `is_unsized` flag in `dumpAst`

frontends/ast/ast.cc

@@ -317,6 +317,8 @@ void AstNode::dumpAst(FILE *f, std::string indent) const
 		fprintf(f, " reg");
 	if (is_signed)
 		fprintf(f, " signed");
+	if (is_unsized)
+		fprintf(f, " unsized");
 	if (basic_prep)
 		fprintf(f, " basic_prep");
 	if (lookahead)

frontends/ast/simplify.cc

@@ -915,6 +915,22 @@ bool AstNode::simplify(bool const_fold, bool at_zero, bool in_lvalue, int stage,
 			}
 	}
 
+	if (type == AST_ARGUMENT)
+	{
+		if (children.size() == 1 && children[0]->type == AST_CONSTANT)
+		{
+			// HACK: For port bindings using unbased unsized literals, mark them
+			// signed so they sign-extend. The hierarchy will still incorrectly
+			// generate a warning complaining about resizing the expression.
+			// This also doesn't handle the complex of something like a ternary
+			// expression bound to a port, where the actual size of the port is
+			// needed to resolve the expression correctly.
+			AstNode *arg = children[0];
+			if (arg->is_unsized)
+				arg->is_signed = true;
+		}
+	}
+
 	int backup_width_hint = width_hint;
 	bool backup_sign_hint = sign_hint;
 
@@ -3773,7 +3789,11 @@ replace_fcall_later:;
 		case AST_CAST_SIZE:
 			if (children.at(0)->type == AST_CONSTANT && children.at(1)->type == AST_CONSTANT) {
 				int width = children[0]->bitsAsConst().as_int();
-				RTLIL::Const val = children[1]->bitsAsConst(width);
+				RTLIL::Const val;
+				if (children[1]->is_unsized)
+					val = children[1]->bitsAsUnsizedConst(width);
+				else
+					val = children[1]->bitsAsConst(width);
 				newNode = mkconst_bits(val.bits, children[1]->is_signed);
 			}
 			break;

tests/verilog/unbased_unsized.sv

@@ -0,0 +1,40 @@
+module pass_through(
+    input [63:0] inp,
+    output [63:0] out
+);
+    assign out = inp;
+endmodule
+
+module top;
+    logic [63:0]
+        o01, o02, o03, o04,
+        o05, o06, o07, o08,
+        o09, o10, o11, o12,
+        o13, o14, o15, o16;
+    assign o01 = '0;
+    assign o02 = '1;
+    assign o03 = 'x;
+    assign o04 = 'z;
+    assign o05 = 3'('0);
+    assign o06 = 3'('1);
+    assign o07 = 3'('x);
+    assign o08 = 3'('z);
+    pass_through pt09('0, o09);
+    pass_through pt10('1, o10);
+    pass_through pt11('x, o11);
+    pass_through pt12('z, o12);
+    always @* begin
+        assert (o01 === {64 {1'b0}});
+        assert (o02 === {64 {1'b1}});
+        assert (o03 === {64 {1'bx}});
+        assert (o04 === {64 {1'bz}});
+        assert (o05 === {61'b0, 3'b000});
+        assert (o06 === {61'b0, 3'b111});
+        assert (o07 === {61'b0, 3'bxxx});
+        assert (o08 === {61'b0, 3'bzzz});
+        assert (o09 === {64 {1'b0}});
+        assert (o10 === {64 {1'b1}});
+        assert (o11 === {64 {1'bx}});
+        assert (o12 === {64 {1'bz}});
+    end
+endmodule

tests/verilog/unbased_unsized.ys

@@ -0,0 +1,7 @@
+read_verilog -sv unbased_unsized.sv
+hierarchy
+proc
+flatten
+opt -full
+select -module top
+sat -verify -seq 1 -tempinduct -prove-asserts -show-all