Add AST_SELFSZ and improve handling of bit slices

Signed-off-by: Claire Wolf <claire@symbioticeda.com>

frontends/ast/ast.cc

@@ -94,6 +94,7 @@ std::string AST::type2str(AstNodeType type)
 	X(AST_TO_BITS)
 	X(AST_TO_SIGNED)
 	X(AST_TO_UNSIGNED)
+	X(AST_SELFSZ)
 	X(AST_CONCAT)
 	X(AST_REPLICATE)
 	X(AST_BIT_NOT)
@@ -617,6 +618,7 @@ void AstNode::dumpVlog(FILE *f, std::string indent) const
 	if (0) { case AST_POS:         txt = "+";  }
 	if (0) { case AST_NEG:         txt = "-";  }
 	if (0) { case AST_LOGIC_NOT:   txt = "!";  }
+	if (0) { case AST_SELFSZ:      txt = "@selfsz@";  }
 		fprintf(f, "%s(", txt.c_str());
 		children[0]->dumpVlog(f, "");
 		fprintf(f, ")");

frontends/ast/ast.h

@@ -75,6 +75,7 @@ namespace AST
 		AST_TO_BITS,
 		AST_TO_SIGNED,
 		AST_TO_UNSIGNED,
+		AST_SELFSZ,
 		AST_CONCAT,
 		AST_REPLICATE,
 		AST_BIT_NOT,

frontends/ast/genrtlil.cc

@@ -809,6 +809,11 @@ void AstNode::detectSignWidthWorker(int &width_hint, bool &sign_hint, bool *foun
 		sign_hint = false;
 		break;
 
+	case AST_SELFSZ:
+		sub_width_hint = 0;
+		children.at(0)->detectSignWidthWorker(sub_width_hint, sign_hint);
+		break;
+
 	case AST_CONCAT:
 		for (auto child : children) {
 			sub_width_hint = 0;
@@ -1267,7 +1272,8 @@ RTLIL::SigSpec AstNode::genRTLIL(int width_hint, bool sign_hint)
 
 	// just pass thru the signal. the parent will evaluate the is_signed property and interpret the SigSpec accordingly
 	case AST_TO_SIGNED:
-	case AST_TO_UNSIGNED: {
+	case AST_TO_UNSIGNED:
+	case AST_SELFSZ: {
 			RTLIL::SigSpec sig = children[0]->genRTLIL();
 			if (sig.size() < width_hint)
 				sig.extend_u0(width_hint, sign_hint);

frontends/ast/simplify.cc

@@ -608,6 +608,7 @@ bool AstNode::simplify(bool const_fold, bool at_zero, bool in_lvalue, int stage,
 	case AST_TO_BITS:
 	case AST_TO_SIGNED:
 	case AST_TO_UNSIGNED:
+	case AST_SELFSZ:
 	case AST_CONCAT:
 	case AST_REPLICATE:
 	case AST_REDUCE_AND:
@@ -1855,8 +1856,12 @@ bool AstNode::simplify(bool const_fold, bool at_zero, bool in_lvalue, int stage,
 
 			AstNode *shamt = shift_expr;
 
+			int shamt_width_hint = 0;
+			bool shamt_sign_hint = true;
+			shamt->detectSignWidth(shamt_width_hint, shamt_sign_hint);
+
 			int start_bit = children[0]->id2ast->range_right;
-			bool use_shift = shamt->is_signed;
+			bool use_shift = shamt_sign_hint;
 
 			if (start_bit != 0) {
 				shamt = new AstNode(AST_SUB, shamt, mkconst_int(start_bit, true));
@@ -3060,6 +3065,7 @@ replace_fcall_later:;
 				}
 			}
 			break;
+		if (0) { case AST_SELFSZ: const_func = RTLIL::const_pos; }
 		if (0) { case AST_POS: const_func = RTLIL::const_pos; }
 		if (0) { case AST_NEG: const_func = RTLIL::const_neg; }
 			if (children[0]->type == AST_CONSTANT) {
@@ -3068,10 +3074,10 @@ replace_fcall_later:;
 			} else
 			if (children[0]->isConst()) {
 				newNode = new AstNode(AST_REALVALUE);
-				if (type == AST_POS)
+				if (type == AST_NEG)
-					newNode->realvalue = +children[0]->asReal(sign_hint);
-				else
 					newNode->realvalue = -children[0]->asReal(sign_hint);
+				else
+					newNode->realvalue = +children[0]->asReal(sign_hint);
 			}
 			break;
 		case AST_TERNARY:

frontends/verilog/verilog_parser.y

@@ -645,13 +645,13 @@ non_opt_range:
 	} |
 	'[' expr TOK_POS_INDEXED expr ']' {
 		$$ = new AstNode(AST_RANGE);
-		AstNode *expr = new AstNode(AST_CONCAT, $2);
+		AstNode *expr = new AstNode(AST_SELFSZ, $2);
 		$$->children.push_back(new AstNode(AST_SUB, new AstNode(AST_ADD, expr->clone(), $4), AstNode::mkconst_int(1, true)));
 		$$->children.push_back(new AstNode(AST_ADD, expr, AstNode::mkconst_int(0, true)));
 	} |
 	'[' expr TOK_NEG_INDEXED expr ']' {
 		$$ = new AstNode(AST_RANGE);
-		AstNode *expr = new AstNode(AST_CONCAT, $2);
+		AstNode *expr = new AstNode(AST_SELFSZ, $2);
 		$$->children.push_back(new AstNode(AST_ADD, expr, AstNode::mkconst_int(0, true)));
 		$$->children.push_back(new AstNode(AST_SUB, new AstNode(AST_ADD, expr->clone(), AstNode::mkconst_int(1, true)), $4));
 	} |