yosys/frontends/verilog/parser.y

/*
 *  yosys -- Yosys Open SYnthesis Suite
 *
 *  Copyright (C) 2012  Clifford Wolf <clifford@clifford.at>
 *  
 *  Permission to use, copy, modify, and/or distribute this software for any
 *  purpose with or without fee is hereby granted, provided that the above
 *  copyright notice and this permission notice appear in all copies.
 *  
 *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 *  ---
 *
 *  The Verilog frontend.
 *
 *  This frontend is using the AST frontend library (see frontends/ast/).
 *  Thus this frontend does not generate RTLIL code directly but creates an
 *  AST directly from the Verilog parse tree and then passes this AST to
 *  the AST frontend library.
 *
 *  ---
 *
 *  This is the actual bison parser for Verilog code. The AST ist created directly
 *  from the bison reduce functions here. Note that this code uses a few global
 *  variables to hold the state of the AST generator and therefore this parser is
 *  not reentrant.
 *
 */

%{
#include <list>
#include <assert.h>
#include "verilog_frontend.h"
#include "kernel/log.h"

using namespace AST;
using namespace VERILOG_FRONTEND;

namespace VERILOG_FRONTEND {
	int port_counter;
	std::map<std::string, int> port_stubs;
	std::map<std::string, AstNode*> attr_list, default_attr_list;
	std::map<std::string, AstNode*> *albuf;
	std::vector<AstNode*> ast_stack;
	struct AstNode *astbuf1, *astbuf2, *astbuf3;
	struct AstNode *current_function_or_task;
	struct AstNode *current_ast, *current_ast_mod;
	int current_function_or_task_port_id;
	std::vector<char> case_type_stack;
}

static void append_attr(AstNode *ast, std::map<std::string, AstNode*> *al)
{
	for (auto &it : *al) {
		if (ast->attributes.count(it.first) > 0)
			delete ast->attributes[it.first];
		ast->attributes[it.first] = it.second;
	}
	delete al;
}

static void append_attr_clone(AstNode *ast, std::map<std::string, AstNode*> *al)
{
	for (auto &it : *al) {
		if (ast->attributes.count(it.first) > 0)
			delete ast->attributes[it.first];
		ast->attributes[it.first] = it.second->clone();
	}
}

static void free_attr(std::map<std::string, AstNode*> *al)
{
	for (auto &it : *al)
		delete it.second;
	delete al;
}

%}

%name-prefix="frontend_verilog_yy"

%union {
	std::string *string;
	struct AstNode *ast;
	std::map<std::string, AstNode*> *al;
	bool boolean;
}

%token <string> TOK_STRING TOK_ID TOK_CONST TOK_PRIMITIVE
%token ATTR_BEGIN ATTR_END DEFATTR_BEGIN DEFATTR_END
%token TOK_MODULE TOK_ENDMODULE TOK_PARAMETER TOK_LOCALPARAM
%token TOK_INPUT TOK_OUTPUT TOK_INOUT TOK_WIRE TOK_REG
%token TOK_INTEGER TOK_SIGNED TOK_ASSIGN TOK_ALWAYS TOK_INITIAL
%token TOK_BEGIN TOK_END TOK_IF TOK_ELSE TOK_FOR
%token TOK_POSEDGE TOK_NEGEDGE TOK_OR
%token TOK_CASE TOK_CASEX TOK_CASEZ TOK_ENDCASE TOK_DEFAULT
%token TOK_FUNCTION TOK_ENDFUNCTION TOK_TASK TOK_ENDTASK
%token TOK_GENERATE TOK_ENDGENERATE TOK_GENVAR
%token TOK_SYNOPSYS_FULL_CASE TOK_SYNOPSYS_PARALLEL_CASE
%token TOK_SUPPLY0 TOK_SUPPLY1 TOK_TO_SIGNED TOK_TO_UNSIGNED

%type <ast> wire_type range expr basic_expr concat_list rvalue lvalue lvalue_concat_list
%type <string> opt_label tok_prim_wrapper
%type <boolean> opt_signed
%type <al> attr

// operator precedence from low to high
%left OP_LOR
%left OP_LAND
%left '|'
%left '^' OP_XNOR
%left '&'
%left OP_EQ OP_NE
%left '<' OP_LE OP_GE '>'
%left OP_SHL OP_SHR OP_SSHL OP_SSHR
%left '+' '-'
%left '*' '/' '%'
%left OP_POW
%right UNARY_OPS

%expect 2
%debug

%%

input:
	module input |
	defattr input |
	/* empty */ {
		for (auto &it : default_attr_list)
			delete it.second;
		default_attr_list.clear();
	};

attr:
	{
		for (auto &it : attr_list)
			delete it.second;
		attr_list.clear();
		for (auto &it : default_attr_list)
			attr_list[it.first] = it.second->clone();
	} attr_opt {
		std::map<std::string, AstNode*> *al = new std::map<std::string, AstNode*>;
		al->swap(attr_list);
		$$ = al;
	};

attr_opt:
	attr_opt ATTR_BEGIN opt_attr_list ATTR_END |
	/* empty */;

defattr:
	DEFATTR_BEGIN {
		for (auto &it : default_attr_list)
			delete it.second;
		default_attr_list.clear();
		for (auto &it : attr_list)
			delete it.second;
		attr_list.clear();
	} opt_attr_list {
		default_attr_list = attr_list;
		attr_list.clear();
	} DEFATTR_END;

opt_attr_list:
	attr_list | /* empty */;

attr_list:
	attr_assign |
	attr_list ',' attr_assign;

attr_assign:
	TOK_ID {
		if (attr_list.count(*$1) != 0)
			delete attr_list[*$1];
		attr_list[*$1] = AstNode::mkconst_int(0, false, 0);
		delete $1;
	} |
	TOK_ID '=' expr {
		if (attr_list.count(*$1) != 0)
			delete attr_list[*$1];
		attr_list[*$1] = $3;
		delete $1;
	};

module:
	attr TOK_MODULE TOK_ID {
		AstNode *mod = new AstNode(AST_MODULE);
		current_ast->children.push_back(mod);
		current_ast_mod = mod;
		ast_stack.push_back(mod);
		port_stubs.clear();
		port_counter = 0;
		mod->str = *$3;
		append_attr(mod, $1);
		delete $3;
	} module_para_opt module_args_opt ';' module_body TOK_ENDMODULE {
		if (port_stubs.size() != 0)
			frontend_verilog_yyerror("Missing details for module port `%s'.",
					port_stubs.begin()->first.c_str());
		ast_stack.pop_back();
		assert(ast_stack.size() == 0);
	};

module_para_opt:
	'#' '(' module_para_list ')' | /* empty */;

module_para_list:
	TOK_PARAMETER single_param_decl |
	TOK_PARAMETER single_param_decl ',' module_para_list |
	/* empty */;

module_args_opt:
	'(' ')' | /* empty */ | '(' module_args optional_comma ')';

module_args:
	module_arg | module_args ',' module_arg;

optional_comma:
	',' | /* empty */;

module_arg:
	TOK_ID range {
		if (port_stubs.count(*$1) != 0)
			frontend_verilog_yyerror("Duplicate module port `%s'.", $1->c_str());
		port_stubs[*$1] = ++port_counter;
		if ($2 != NULL)
			delete $2;
		delete $1;
	} |
	attr wire_type range TOK_ID {
		AstNode *node = $2;
		node->str = *$4;
		node->port_id = ++port_counter;
		if ($3 != NULL)
			node->children.push_back($3);
		if (!node->is_input && !node->is_output)
			frontend_verilog_yyerror("Module port `%s' is neither input nor output.", $4->c_str());
		if (node->is_reg && node->is_input && !node->is_output)
			frontend_verilog_yyerror("Input port `%s' is declared as register.", $4->c_str());
		ast_stack.back()->children.push_back(node);
		append_attr(node, $1);
		delete $4;
	};

wire_type:
	{
		astbuf3 = new AstNode(AST_WIRE);
	} wire_type_token_list {
		$$ = astbuf3;
	};

wire_type_token_list:
	wire_type_token | wire_type_token_list wire_type_token;

wire_type_token:
	TOK_INPUT {
		astbuf3->is_input = true;
	} |
	TOK_OUTPUT {
		astbuf3->is_output = true;
	} |
	TOK_INOUT {
		astbuf3->is_input = true;
		astbuf3->is_output = true;
	} |
	TOK_WIRE {
	} |
	TOK_REG {
		astbuf3->is_reg = true;
	} |
	TOK_INTEGER {
		astbuf3->is_reg = true;
		astbuf3->range_left = 31;
		astbuf3->range_right = 0;
	} |
	TOK_GENVAR {
		astbuf3->type = AST_GENVAR;
		astbuf3->is_reg = true;
		astbuf3->range_left = 31;
		astbuf3->range_right = 0;
	} |
	TOK_SIGNED {
		astbuf3->is_signed = true;
	};

range:
	'[' expr ':' expr ']' {
		$$ = new AstNode(AST_RANGE);
		$$->children.push_back($2);
		$$->children.push_back($4);
	} |
	'[' expr ']' {
		$$ = new AstNode(AST_RANGE);
		$$->children.push_back($2);
	} |
	/* empty */ {
		$$ = NULL;
	};

module_body:
	module_body module_body_stmt |
	/* empty */;

module_body_stmt:
	task_func_decl | param_decl | localparam_decl | wire_decl | assign_stmt | cell_stmt |
	always_stmt | TOK_GENERATE module_gen_body TOK_ENDGENERATE | defattr;

task_func_decl:
	TOK_TASK TOK_ID ';' {
		current_function_or_task = new AstNode(AST_TASK);
		current_function_or_task->str = *$2;
		ast_stack.back()->children.push_back(current_function_or_task);
		ast_stack.push_back(current_function_or_task);
		current_function_or_task_port_id = 1;
		delete $2;
	} task_func_body TOK_ENDTASK {
		current_function_or_task = NULL;
		ast_stack.pop_back();
	} |
	TOK_FUNCTION opt_signed range TOK_ID ';' {
		current_function_or_task = new AstNode(AST_FUNCTION);
		current_function_or_task->str = *$4;
		ast_stack.back()->children.push_back(current_function_or_task);
		ast_stack.push_back(current_function_or_task);
		AstNode *outreg = new AstNode(AST_WIRE);
		if ($3 != NULL)
			outreg->children.push_back($3);
		outreg->str = *$4;
		outreg->is_signed = $2;
		current_function_or_task->children.push_back(outreg);
		current_function_or_task_port_id = 1;
		delete $4;
	} task_func_body TOK_ENDFUNCTION {
		current_function_or_task = NULL;
		ast_stack.pop_back();
	};

opt_signed:
	TOK_SIGNED {
		$$ = true;
	} |
	/* empty */ {
		$$ = false;
	};

task_func_body:
	task_func_body wire_decl |
	task_func_body behavioral_stmt |
	/* empty */;

param_decl:
	TOK_PARAMETER param_decl_list ';';

param_decl_list:
	single_param_decl | param_decl_list ',' single_param_decl;

single_param_decl:
	range TOK_ID '=' expr {
		AstNode *node = new AstNode(AST_PARAMETER);
		node->str = *$2;
		node->children.push_back($4);
		if ($1 != NULL)
			node->children.push_back($1);
		ast_stack.back()->children.push_back(node);
		delete $2;
	};

localparam_decl:
	TOK_LOCALPARAM localparam_decl_list ';';

localparam_decl_list:
	single_localparam_decl | localparam_decl_list ',' single_localparam_decl;

single_localparam_decl:
	range TOK_ID '=' expr {
		AstNode *node = new AstNode(AST_LOCALPARAM);
		node->str = *$2;
		node->children.push_back($4);
		if ($1 != NULL)
			node->children.push_back($1);
		ast_stack.back()->children.push_back(node);
		delete $2;
	};

wire_decl:
	attr wire_type range {
		albuf = $1;
		astbuf1 = $2;
		astbuf2 = $3;
		if (astbuf1->range_left >= 0 && astbuf1->range_right >= 0) {
			if (astbuf2) {
				frontend_verilog_yyerror("Syntax error.");
			} else {
				astbuf2 = new AstNode(AST_RANGE);
				astbuf2->children.push_back(AstNode::mkconst_int(astbuf1->range_left, true));
				astbuf2->children.push_back(AstNode::mkconst_int(astbuf1->range_right, true));
			}
		}
		if (astbuf2 && astbuf2->children.size() != 2)
			frontend_verilog_yyerror("Syntax error.");
	} wire_name_list ';' {
		delete astbuf1;
		if (astbuf2 != NULL)
			delete astbuf2;
		free_attr(albuf);
	} |
	attr TOK_SUPPLY0 TOK_ID ';' {
		ast_stack.back()->children.push_back(new AstNode(AST_WIRE));
		ast_stack.back()->children.back()->str = *$3;
		append_attr(ast_stack.back()->children.back(), $1);
		ast_stack.back()->children.push_back(new AstNode(AST_ASSIGN, new AstNode(AST_IDENTIFIER), AstNode::mkconst_int(0, false, 1)));
		ast_stack.back()->children.back()->children[0]->str = *$3;
		delete $3;
	} |
	attr TOK_SUPPLY1 TOK_ID ';' {
		ast_stack.back()->children.push_back(new AstNode(AST_WIRE));
		ast_stack.back()->children.back()->str = *$3;
		append_attr(ast_stack.back()->children.back(), $1);
		ast_stack.back()->children.push_back(new AstNode(AST_ASSIGN, new AstNode(AST_IDENTIFIER), AstNode::mkconst_int(1, false, 1)));
		ast_stack.back()->children.back()->children[0]->str = *$3;
		delete $3;
	};

wire_name_list:
	wire_name_and_opt_assign | wire_name_list ',' wire_name_and_opt_assign;

wire_name_and_opt_assign:
	wire_name |
	wire_name '=' expr {
		if (!astbuf1->is_reg) {
			AstNode *wire = new AstNode(AST_IDENTIFIER);
			wire->str = ast_stack.back()->children.back()->str;
			ast_stack.back()->children.push_back(new AstNode(AST_ASSIGN, wire, $3));
		}
	};

wire_name:
	TOK_ID range {
		AstNode *node = astbuf1->clone();
		node->str = *$1;
		append_attr_clone(node, albuf);
		if (astbuf2 != NULL)
			node->children.push_back(astbuf2->clone());
		if ($2 != NULL) {
			if (node->is_input || node->is_output)
				frontend_verilog_yyerror("Syntax error.");
			if (!astbuf2) {
				AstNode *rng = new AstNode(AST_RANGE);
				rng->children.push_back(AstNode::mkconst_int(0, true));
				rng->children.push_back(AstNode::mkconst_int(0, true));
				node->children.push_back(rng);
			}
			node->type = AST_MEMORY;
			node->children.push_back($2);
		}
		if (current_function_or_task == NULL) {
			if (port_stubs.count(*$1) != 0) {
				if (!node->is_input && !node->is_output)
					frontend_verilog_yyerror("Module port `%s' is neither input nor output.", $1->c_str());
				if (node->is_reg && node->is_input && !node->is_output)
					frontend_verilog_yyerror("Input port `%s' is declared as register.", $1->c_str());
				node->port_id = port_stubs[*$1];
				port_stubs.erase(*$1);
			} else {
				if (node->is_input || node->is_output)
					frontend_verilog_yyerror("Module port `%s' is not declared in module header.", $1->c_str());
			}
			ast_stack.back()->children.push_back(node);
		} else {
			if (node->is_input || node->is_output)
				node->port_id = current_function_or_task_port_id++;
			current_function_or_task->children.push_back(node);
		}
		delete $1;
	};

assign_stmt:
	TOK_ASSIGN assign_expr_list ';';

assign_expr_list:
	assign_expr | assign_expr_list ',' assign_expr;

assign_expr:
	expr '=' expr {
		ast_stack.back()->children.push_back(new AstNode(AST_ASSIGN, $1, $3));
	};

cell_stmt:
	attr TOK_ID {
		astbuf1 = new AstNode(AST_CELL);
		append_attr(astbuf1, $1);
		astbuf1->children.push_back(new AstNode(AST_CELLTYPE));
		astbuf1->children[0]->str = *$2;
		delete $2;
	} cell_parameter_list_opt cell_list ';' {
		delete astbuf1;
	} |
	attr tok_prim_wrapper {
		astbuf1 = new AstNode(AST_PRIMITIVE);
		astbuf1->str = *$2;
		append_attr(astbuf1, $1);
		delete $2;
	} prim_list ';' {
		delete astbuf1;
	};

tok_prim_wrapper:
	TOK_PRIMITIVE {
		$$ = $1;
	} |
	TOK_OR {
		$$ = new std::string("or");
	};

cell_list:
	single_cell |
	cell_list ',' single_cell;

single_cell:
	TOK_ID {
		astbuf2 = astbuf1->clone();
		if (astbuf2->type != AST_PRIMITIVE)
			astbuf2->str = *$1;
		delete $1;
		ast_stack.back()->children.push_back(astbuf2);
	} '(' cell_port_list ')';

prim_list:
	single_prim |
	prim_list ',' single_prim;

single_prim:
	single_cell |
	/* no name */ {
		astbuf2 = astbuf1->clone();
		ast_stack.back()->children.push_back(astbuf2);
	} '(' cell_port_list ')';

cell_parameter_list_opt:
	'#' '(' cell_parameter_list ')' | /* empty */;

cell_parameter_list:
	/* empty */ | cell_parameter |
	cell_parameter ',' cell_parameter_list;

cell_parameter:
	expr {
		AstNode *node = new AstNode(AST_PARASET);
		astbuf1->children.push_back(node);
		node->children.push_back($1);
	} |
	'.' TOK_ID '(' expr ')' {
		AstNode *node = new AstNode(AST_PARASET);
		node->str = *$2;
		astbuf1->children.push_back(node);
		node->children.push_back($4);
		delete $2;
	};

cell_port_list:
	/* empty */ | cell_port |
	cell_port ',' cell_port_list |
	/* empty */ ',' {
		AstNode *node = new AstNode(AST_ARGUMENT);
		astbuf2->children.push_back(node);
	} cell_port_list;

cell_port:
	expr {
		AstNode *node = new AstNode(AST_ARGUMENT);
		astbuf2->children.push_back(node);
		node->children.push_back($1);
	} |
	'.' TOK_ID '(' expr ')' {
		AstNode *node = new AstNode(AST_ARGUMENT);
		node->str = *$2;
		astbuf2->children.push_back(node);
		node->children.push_back($4);
		delete $2;
	} |
	'.' TOK_ID '(' ')' {
		AstNode *node = new AstNode(AST_ARGUMENT);
		node->str = *$2;
		astbuf2->children.push_back(node);
		delete $2;
	};

always_stmt:
	attr TOK_ALWAYS {
		AstNode *node = new AstNode(AST_ALWAYS);
		append_attr(node, $1);
		ast_stack.back()->children.push_back(node);
		ast_stack.push_back(node);
	} always_cond {
		AstNode *block = new AstNode(AST_BLOCK);
		ast_stack.back()->children.push_back(block);
		ast_stack.push_back(block);
	} behavioral_stmt {
		ast_stack.pop_back();
		ast_stack.pop_back();
	} |
	attr TOK_INITIAL {
		AstNode *node = new AstNode(AST_ALWAYS);
		append_attr(node, $1);
		ast_stack.back()->children.push_back(node);
		ast_stack.push_back(node);
		AstNode *block = new AstNode(AST_BLOCK);
		ast_stack.back()->children.push_back(block);
		ast_stack.push_back(block);
	} behavioral_stmt {
		ast_stack.pop_back();
		ast_stack.pop_back();
	};

always_cond:
	'@' '(' always_events ')' |
	'@' '(' '*' ')' |
	'@' ATTR_BEGIN ')' |
	'@' '(' ATTR_END |
	'@' '*' |
	/* empty */;

always_events:
	always_event |
	always_events TOK_OR always_event |
	always_events ',' always_event;

always_event:
	TOK_POSEDGE expr {
		AstNode *node = new AstNode(AST_POSEDGE);
		ast_stack.back()->children.push_back(node);
		node->children.push_back($2);
	} |
	TOK_NEGEDGE expr {
		AstNode *node = new AstNode(AST_NEGEDGE);
		ast_stack.back()->children.push_back(node);
		node->children.push_back($2);
	} |
	expr {
		AstNode *node = new AstNode(AST_EDGE);
		ast_stack.back()->children.push_back(node);
		node->children.push_back($1);
	};

opt_label:
	':' TOK_ID {
		$$ = $2;
	} |
	/* empty */ {
		$$ = NULL;
	};

simple_behavioral_stmt:
	lvalue '=' expr {
		AstNode *node = new AstNode(AST_ASSIGN_EQ, $1, $3);
		ast_stack.back()->children.push_back(node);
	} |
	lvalue OP_LE expr {
		AstNode *node = new AstNode(AST_ASSIGN_LE, $1, $3);
		ast_stack.back()->children.push_back(node);
	};

// this production creates the obligatory if-else shift/reduce conflict
behavioral_stmt:
	defattr |
	simple_behavioral_stmt ';' |
	TOK_ID attr {
		AstNode *node = new AstNode(AST_TCALL);
		node->str = *$1;
		delete $1;
		ast_stack.back()->children.push_back(node);
		ast_stack.push_back(node);
		append_attr(node, $2);
	} opt_arg_list ';'{
		ast_stack.pop_back();
	} |
	attr TOK_BEGIN opt_label {
		AstNode *node = new AstNode(AST_BLOCK);
		ast_stack.back()->children.push_back(node);
		ast_stack.push_back(node);
		append_attr(node, $1);
	} behavioral_stmt_list TOK_END opt_label {
		if ($3 != NULL)
			delete $3;
		if ($7 != NULL)
			delete $7;
		ast_stack.pop_back();
	} |
	attr TOK_FOR '(' {
		AstNode *node = new AstNode(AST_FOR);
		ast_stack.back()->children.push_back(node);
		ast_stack.push_back(node);
		append_attr(node, $1);
	} simple_behavioral_stmt ';' expr {
		ast_stack.back()->children.push_back($7);
	} ';' simple_behavioral_stmt ')' {
		AstNode *block = new AstNode(AST_BLOCK);
		ast_stack.back()->children.push_back(block);
		ast_stack.push_back(block);
	} behavioral_stmt {
		ast_stack.pop_back();
		ast_stack.pop_back();
	} |
	attr TOK_IF '(' expr ')' {
		AstNode *node = new AstNode(AST_CASE);
		AstNode *block = new AstNode(AST_BLOCK);
		AstNode *cond = new AstNode(AST_COND, AstNode::mkconst_int(1, false, 1), block);
		ast_stack.back()->children.push_back(node);
		node->children.push_back(new AstNode(AST_REDUCE_BOOL, $4));
		node->children.push_back(cond);
		ast_stack.push_back(node);
		ast_stack.push_back(block);
		append_attr(node, $1);
	} behavioral_stmt optional_else {
		ast_stack.pop_back();
		ast_stack.pop_back();
	} |
	attr case_type '(' expr ')' {
		AstNode *node = new AstNode(AST_CASE, $4);
		ast_stack.back()->children.push_back(node);
		ast_stack.push_back(node);
		append_attr(node, $1);
	} opt_synopsys_attr case_body TOK_ENDCASE {
		case_type_stack.pop_back();
		ast_stack.pop_back();
	};

case_type:
	TOK_CASE { 
		case_type_stack.push_back(0);
	} |
	TOK_CASEX { 
		case_type_stack.push_back('x');
	} |
	TOK_CASEZ { 
		case_type_stack.push_back('z');
	};

opt_synopsys_attr:
	opt_synopsys_attr TOK_SYNOPSYS_FULL_CASE {
		if (ast_stack.back()->attributes.count("\\full_case") == 0)
			ast_stack.back()->attributes["\\full_case"] = AstNode::mkconst_int(0, false, 0);
	} |
	opt_synopsys_attr TOK_SYNOPSYS_PARALLEL_CASE {
		if (ast_stack.back()->attributes.count("\\parallel_case") == 0)
			ast_stack.back()->attributes["\\parallel_case"] = AstNode::mkconst_int(0, false, 0);
	} |
	/* empty */;

behavioral_stmt_opt:
	behavioral_stmt |
	';' ;

behavioral_stmt_list:
	behavioral_stmt_list behavioral_stmt |
	/* empty */;

optional_else:
	TOK_ELSE {
		AstNode *block = new AstNode(AST_BLOCK);
		AstNode *cond = new AstNode(AST_COND, new AstNode(AST_DEFAULT), block);
		ast_stack.pop_back();
		ast_stack.back()->children.push_back(cond);
		ast_stack.push_back(block);
	} behavioral_stmt |
	/* empty */;

case_body:
	case_body case_item |
	/* empty */;

case_item:
	{
		AstNode *node = new AstNode(AST_COND);
		ast_stack.back()->children.push_back(node);
		ast_stack.push_back(node);
	} case_select {
		AstNode *block = new AstNode(AST_BLOCK);
		ast_stack.back()->children.push_back(block);
		ast_stack.push_back(block);
		case_type_stack.push_back(0);
	} behavioral_stmt_opt {
		case_type_stack.pop_back();
		ast_stack.pop_back();
		ast_stack.pop_back();
	};

case_select:
	case_expr_list ':' |
	TOK_DEFAULT;

case_expr_list:
	TOK_DEFAULT {
		ast_stack.back()->children.push_back(new AstNode(AST_DEFAULT));
	} |
	expr {
		ast_stack.back()->children.push_back($1);
	} |
	case_expr_list ',' expr {
		ast_stack.back()->children.push_back($3);
	};

rvalue:
	TOK_ID '[' expr ']' '.' rvalue {
		$$ = new AstNode(AST_PREFIX, $3, $6);
		$$->str = *$1;
		delete $1;
	} |
	TOK_ID range {
		$$ = new AstNode(AST_IDENTIFIER, $2);
		$$->str = *$1;
		delete $1;
	};

lvalue:
	rvalue {
		$$ = $1;
	} |
	'{' lvalue_concat_list '}' {
		$$ = $2;
	};

lvalue_concat_list:
	expr {
		$$ = new AstNode(AST_CONCAT);
		$$->children.push_back($1);
	} |
	expr ',' lvalue_concat_list {
		$$ = $3;
		$$->children.push_back($1);
	};

opt_arg_list:
	'(' arg_list optional_comma ')' |
	/* empty */;

arg_list:
	arg_list2 |
	/* empty */;

arg_list2:
	single_arg |
	arg_list ',' single_arg;

single_arg:
	expr {
		ast_stack.back()->children.push_back($1);
	};

module_gen_body:
	module_gen_body gen_stmt |
	module_gen_body module_body_stmt |
	/* empty */;

// this production creates the obligatory if-else shift/reduce conflict
gen_stmt:
	TOK_FOR '(' {
		AstNode *node = new AstNode(AST_GENFOR);
		ast_stack.back()->children.push_back(node);
		ast_stack.push_back(node);
	} simple_behavioral_stmt ';' expr {
		ast_stack.back()->children.push_back($6);
	} ';' simple_behavioral_stmt ')' gen_stmt {
		ast_stack.pop_back();
	} |
	TOK_IF '(' expr ')' {
		AstNode *node = new AstNode(AST_GENIF);
		ast_stack.back()->children.push_back(node);
		ast_stack.push_back(node);
		ast_stack.back()->children.push_back($3);
	} gen_stmt opt_gen_else {
		ast_stack.pop_back();
	} |
	TOK_BEGIN opt_label {
		AstNode *node = new AstNode(AST_GENBLOCK);
		node->str = $2 ? *$2 : std::string();
		ast_stack.back()->children.push_back(node);
		ast_stack.push_back(node);
	} module_gen_body TOK_END opt_label {
		if ($2 != NULL)
			delete $2;
		if ($6 != NULL)
			delete $6;
		ast_stack.pop_back();
	};

opt_gen_else:
	TOK_ELSE gen_stmt | /* empty */;

expr:
	basic_expr {
		$$ = $1;
	} |
	basic_expr '?' attr expr ':' expr {
		$$ = new AstNode(AST_TERNARY);
		$$->children.push_back($1);
		$$->children.push_back($4);
		$$->children.push_back($6);
		append_attr($$, $3);
	};

basic_expr:
	rvalue {
		$$ = $1;
	} |
	TOK_CONST {
		$$ = const2ast(*$1, case_type_stack.size() == 0 ? 0 : case_type_stack.back());
		delete $1;
	} |
	TOK_STRING {
		std::string str = *$1;
		std::vector<RTLIL::State> data;
		data.reserve(str.size() * 8);
		for (size_t i = 0; i < str.size(); i++) {
			unsigned char ch = str[str.size() - i - 1];
			for (int j = 0; j < 8; j++) {
				data.push_back((ch & 1) ? RTLIL::S1 : RTLIL::S0);
				ch = ch >> 1;
			}
		}
		$$ = AstNode::mkconst_bits(data, false);
		$$->str = str;
		delete $1;
	} |
	TOK_ID attr {
		AstNode *node = new AstNode(AST_FCALL);
		node->str = *$1;
		delete $1;
		ast_stack.push_back(node);
		append_attr(node, $2);
	} '(' arg_list optional_comma ')' {
		$$ = ast_stack.back();
		ast_stack.pop_back();
	} |
	TOK_TO_SIGNED attr '(' expr ')' {
		$$ = new AstNode(AST_TO_SIGNED, $4);
		append_attr($$, $2);
	} |
	TOK_TO_UNSIGNED attr '(' expr ')' {
		$$ = new AstNode(AST_TO_UNSIGNED, $4);
		append_attr($$, $2);
	} |
	'(' expr ')' {
		$$ = $2;
	} |
	'{' concat_list '}' {
		$$ = $2;
	} |
	'{' expr '{' expr '}' '}' {
		$$ = new AstNode(AST_REPLICATE, $2, $4);
	} |
	'~' attr basic_expr %prec UNARY_OPS {
		$$ = new AstNode(AST_BIT_NOT, $3);
		append_attr($$, $2);
	} |
	basic_expr '&' attr basic_expr {
		$$ = new AstNode(AST_BIT_AND, $1, $4);
		append_attr($$, $3);
	} |
	basic_expr '|' attr basic_expr {
		$$ = new AstNode(AST_BIT_OR, $1, $4);
		append_attr($$, $3);
	} |
	basic_expr '^' attr basic_expr {
		$$ = new AstNode(AST_BIT_XOR, $1, $4);
		append_attr($$, $3);
	} |
	basic_expr OP_XNOR attr basic_expr {
		$$ = new AstNode(AST_BIT_XNOR, $1, $4);
		append_attr($$, $3);
	} |
	'&' attr basic_expr %prec UNARY_OPS {
		$$ = new AstNode(AST_REDUCE_AND, $3);
		append_attr($$, $2);
	} |
	'|' attr basic_expr %prec UNARY_OPS {
		$$ = new AstNode(AST_REDUCE_OR, $3);
		append_attr($$, $2);
	} |
	'^' attr basic_expr %prec UNARY_OPS {
		$$ = new AstNode(AST_REDUCE_XOR, $3);
		append_attr($$, $2);
	} |
	OP_XNOR attr basic_expr %prec UNARY_OPS {
		$$ = new AstNode(AST_REDUCE_XNOR, $3);
		append_attr($$, $2);
	} |
	basic_expr OP_SHL attr basic_expr {
		$$ = new AstNode(AST_SHIFT_LEFT, $1, $4);
		append_attr($$, $3);
	} |
	basic_expr OP_SHR attr basic_expr {
		$$ = new AstNode(AST_SHIFT_RIGHT, $1, $4);
		append_attr($$, $3);
	} |
	basic_expr OP_SSHL attr basic_expr {
		$$ = new AstNode(AST_SHIFT_SLEFT, $1, $4);
		append_attr($$, $3);
	} |
	basic_expr OP_SSHR attr basic_expr {
		$$ = new AstNode(AST_SHIFT_SRIGHT, $1, $4);
		append_attr($$, $3);
	} |
	basic_expr '<' attr basic_expr {
		$$ = new AstNode(AST_LT, $1, $4);
		append_attr($$, $3);
	} |
	basic_expr OP_LE attr basic_expr {
		$$ = new AstNode(AST_LE, $1, $4);
		append_attr($$, $3);
	} |
	basic_expr OP_EQ attr basic_expr {
		$$ = new AstNode(AST_EQ, $1, $4);
		append_attr($$, $3);
	} |
	basic_expr OP_NE attr basic_expr {
		$$ = new AstNode(AST_NE, $1, $4);
		append_attr($$, $3);
	} |
	basic_expr OP_GE attr basic_expr {
		$$ = new AstNode(AST_GE, $1, $4);
		append_attr($$, $3);
	} |
	basic_expr '>' attr basic_expr {
		$$ = new AstNode(AST_GT, $1, $4);
		append_attr($$, $3);
	} |
	basic_expr '+' attr basic_expr {
		$$ = new AstNode(AST_ADD, $1, $4);
		append_attr($$, $3);
	} |
	basic_expr '-' attr basic_expr {
		$$ = new AstNode(AST_SUB, $1, $4);
		append_attr($$, $3);
	} |
	basic_expr '*' attr basic_expr {
		$$ = new AstNode(AST_MUL, $1, $4);
		append_attr($$, $3);
	} |
	basic_expr '/' attr basic_expr {
		$$ = new AstNode(AST_DIV, $1, $4);
		append_attr($$, $3);
	} |
	basic_expr '%' attr basic_expr {
		$$ = new AstNode(AST_MOD, $1, $4);
		append_attr($$, $3);
	} |
	basic_expr OP_POW attr basic_expr {
		$$ = new AstNode(AST_POW, $1, $4);
		append_attr($$, $3);
	} |
	'+' attr basic_expr %prec UNARY_OPS {
		$$ = new AstNode(AST_POS, $3);
		append_attr($$, $2);
	} |
	'-' attr basic_expr %prec UNARY_OPS {
		$$ = new AstNode(AST_NEG, $3);
		append_attr($$, $2);
	} |
	basic_expr OP_LAND attr basic_expr {
		$$ = new AstNode(AST_LOGIC_AND, $1, $4);
		append_attr($$, $3);
	} |
	basic_expr OP_LOR attr basic_expr {
		$$ = new AstNode(AST_LOGIC_OR, $1, $4);
		append_attr($$, $3);
	} |
	'!' attr basic_expr %prec UNARY_OPS {
		$$ = new AstNode(AST_LOGIC_NOT, $3);
		append_attr($$, $2);
	};

concat_list:
	expr {
		$$ = new AstNode(AST_CONCAT, $1);
	} |
	expr ',' concat_list {
		$$ = $3;
		$$->children.push_back($1);
	};