/*
 *  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.
 *
 *  ---
 *
 *  This is the AST frontend library.
 *
 *  The AST frontend library is not a frontend on it's own but provides a
 *  generic abstract syntax tree (AST) abstraction for HDL code and can be
 *  used by HDL frontends. See "ast.h" for an overview of the API and the
 *  Verilog frontend for an usage example.
 *
 */

#include "kernel/log.h"
#include "libs/sha1/sha1.h"
#include "frontends/verilog/verilog_frontend.h"
#include "ast.h"

#include <sstream>
#include <stdarg.h>
#include <stdlib.h>
#include <math.h>

YOSYS_NAMESPACE_BEGIN

using namespace AST;
using namespace AST_INTERNAL;

// convert the AST into a simpler AST that has all parameters substituted by their
// values, unrolled for-loops, expanded generate blocks, etc. when this function
// is done with an AST it can be converted into RTLIL using genRTLIL().
//
// this function also does all name resolving and sets the id2ast member of all
// nodes that link to a different node using names and lexical scoping.
bool AstNode::simplify(bool const_fold, bool at_zero, bool in_lvalue, int stage, int width_hint, bool sign_hint, bool in_param)
{
	static int recursion_counter = 0;
	static bool deep_recursion_warning = false;

	if (recursion_counter++ == 1000 && deep_recursion_warning) {
		log_warning("Deep recursion in AST simplifier.\nDoes this design contain insanely long expressions?\n");
		deep_recursion_warning = false;
	}

	AstNode *newNode = NULL;
	bool did_something = false;

#if 0
	log("-------------\n");
	log("AST simplify[%d] depth %d at %s:%d on %s %p:\n", stage, recursion_counter, filename.c_str(), linenum, type2str(type).c_str(), this);
	log("const_fold=%d, at_zero=%d, in_lvalue=%d, stage=%d, width_hint=%d, sign_hint=%d, in_param=%d\n",
			int(const_fold), int(at_zero), int(in_lvalue), int(stage), int(width_hint), int(sign_hint), int(in_param));
	// dumpAst(NULL, "> ");
#endif

	if (stage == 0)
	{
		log_assert(type == AST_MODULE || type == AST_INTERFACE);

		deep_recursion_warning = true;
		while (simplify(const_fold, at_zero, in_lvalue, 1, width_hint, sign_hint, in_param)) { }

		if (!flag_nomem2reg && !get_bool_attribute("\\nomem2reg"))
		{
			dict<AstNode*, pool<std::string>> mem2reg_places;
			dict<AstNode*, uint32_t> mem2reg_candidates, dummy_proc_flags;
			uint32_t flags = flag_mem2reg ? AstNode::MEM2REG_FL_ALL : 0;
			mem2reg_as_needed_pass1(mem2reg_places, mem2reg_candidates, dummy_proc_flags, flags);

			pool<AstNode*> mem2reg_set;
			for (auto &it : mem2reg_candidates)
			{
				AstNode *mem = it.first;
				uint32_t memflags = it.second;
				bool this_nomeminit = flag_nomeminit;
				log_assert((memflags & ~0x00ffff00) == 0);

				if (mem->get_bool_attribute("\\nomem2reg"))
					continue;

				if (mem->get_bool_attribute("\\nomeminit") || get_bool_attribute("\\nomeminit"))
					this_nomeminit = true;

				if (memflags & AstNode::MEM2REG_FL_FORCED)
					goto silent_activate;

				if (memflags & AstNode::MEM2REG_FL_EQ2)
					goto verbose_activate;

				if (memflags & AstNode::MEM2REG_FL_SET_ASYNC)
					goto verbose_activate;

				if ((memflags & AstNode::MEM2REG_FL_SET_INIT) && (memflags & AstNode::MEM2REG_FL_SET_ELSE) && this_nomeminit)
					goto verbose_activate;

				if (memflags & AstNode::MEM2REG_FL_CMPLX_LHS)
					goto verbose_activate;

				if ((memflags & AstNode::MEM2REG_FL_CONST_LHS) && !(memflags & AstNode::MEM2REG_FL_VAR_LHS))
					goto verbose_activate;

				// log("Note: Not replacing memory %s with list of registers (flags=0x%08lx).\n", mem->str.c_str(), long(memflags));
				continue;

			verbose_activate:
				if (mem2reg_set.count(mem) == 0) {
					std::string message = stringf("Replacing memory %s with list of registers.", mem->str.c_str());
					bool first_element = true;
					for (auto &place : mem2reg_places[it.first]) {
						message += stringf("%s%s", first_element ? " See " : ", ", place.c_str());
						first_element = false;
					}
					log_warning("%s\n", message.c_str());
				}

			silent_activate:
				// log("Note: Replacing memory %s with list of registers (flags=0x%08lx).\n", mem->str.c_str(), long(memflags));
				mem2reg_set.insert(mem);
			}

			for (auto node : mem2reg_set)
			{
				int mem_width, mem_size, addr_bits;
				node->meminfo(mem_width, mem_size, addr_bits);

				int data_range_left = node->children[0]->range_left;
				int data_range_right = node->children[0]->range_right;

				if (node->children[0]->range_swapped)
					std::swap(data_range_left, data_range_right);

				for (int i = 0; i < mem_size; i++) {
					AstNode *reg = new AstNode(AST_WIRE, new AstNode(AST_RANGE,
							mkconst_int(data_range_left, true), mkconst_int(data_range_right, true)));
					reg->str = stringf("%s[%d]", node->str.c_str(), i);
					reg->is_reg = true;
					reg->is_signed = node->is_signed;
					for (auto &it : node->attributes)
						if (it.first != ID(mem2reg))
							reg->attributes.emplace(it.first, it.second->clone());
					reg->filename = node->filename;
					reg->linenum = node->linenum;
					children.push_back(reg);
					while (reg->simplify(true, false, false, 1, -1, false, false)) { }
				}
			}

			AstNode *async_block = NULL;
			while (mem2reg_as_needed_pass2(mem2reg_set, this, NULL, async_block)) { }

			vector<AstNode*> delnodes;
			mem2reg_remove(mem2reg_set, delnodes);

			for (auto node : delnodes)
				delete node;
		}

		while (simplify(const_fold, at_zero, in_lvalue, 2, width_hint, sign_hint, in_param)) { }
		recursion_counter--;
		return false;
	}

	current_filename = filename;
	set_line_num(linenum);

	// we do not look inside a task or function
	// (but as soon as a task or function is instantiated we process the generated AST as usual)
	if (type == AST_FUNCTION || type == AST_TASK) {
		recursion_counter--;
		return false;
	}

	// deactivate all calls to non-synthesis system tasks
	// note that $display, $finish, and $stop are used for synthesis-time DRC so they're not in this list
	if ((type == AST_FCALL || type == AST_TCALL) && (str == "$strobe" || str == "$monitor" || str == "$time" ||
			str == "$dumpfile" || str == "$dumpvars" || str == "$dumpon" || str == "$dumpoff" || str == "$dumpall")) {
		log_file_warning(filename, linenum, "Ignoring call to system %s %s.\n", type == AST_FCALL ? "function" : "task", str.c_str());
		delete_children();
		str = std::string();
	}

	if ((type == AST_TCALL) && (str == "$display" || str == "$write") && (!current_always || current_always->type != AST_INITIAL)) {
		log_file_warning(filename, linenum, "System task `%s' outside initial block is unsupported.\n", str.c_str());
		delete_children();
		str = std::string();
	}

	// print messages if this a call to $display() or $write()
	// This code implements only a small subset of Verilog-2005 $display() format specifiers,
	// but should be good enough for most uses
	if ((type == AST_TCALL) && ((str == "$display") || (str == "$write")))
	{
		int nargs = GetSize(children);
		if (nargs < 1)
			log_file_error(filename, linenum, "System task `%s' got %d arguments, expected >= 1.\n",
					str.c_str(), int(children.size()));

		// First argument is the format string
		AstNode *node_string = children[0];
		while (node_string->simplify(true, false, false, stage, width_hint, sign_hint, false)) { }
		if (node_string->type != AST_CONSTANT)
			log_file_error(filename, linenum, "Failed to evaluate system task `%s' with non-constant 1st argument.\n", str.c_str());
		std::string sformat = node_string->bitsAsConst().decode_string();

		// Other arguments are placeholders. Process the string as we go through it
		std::string sout;
		int next_arg = 1;
		for (size_t i = 0; i < sformat.length(); i++)
		{
			// format specifier
			if (sformat[i] == '%')
			{
				// If there's no next character, that's a problem
				if (i+1 >= sformat.length())
					log_file_error(filename, linenum, "System task `%s' called with `%%' at end of string.\n", str.c_str());

				char cformat = sformat[++i];

				// %% is special, does not need a matching argument
				if (cformat == '%')
				{
					sout += '%';
					continue;
				}

				// Simplify the argument
				AstNode *node_arg = nullptr;

				// Everything from here on depends on the format specifier
				switch (cformat)
				{
					case 's':
					case 'S':
					case 'd':
					case 'D':
					case 'x':
					case 'X':
						if (next_arg >= GetSize(children))
							log_file_error(filename, linenum, "Missing argument for %%%c format specifier in system task `%s'.\n",
									cformat, str.c_str());

						node_arg = children[next_arg++];
						while (node_arg->simplify(true, false, false, stage, width_hint, sign_hint, false)) { }
						if (node_arg->type != AST_CONSTANT)
							log_file_error(filename, linenum, "Failed to evaluate system task `%s' with non-constant argument.\n", str.c_str());
						break;

					case 'm':
					case 'M':
						break;

					default:
						log_file_error(filename, linenum, "System task `%s' called with invalid/unsupported format specifier.\n", str.c_str());
						break;
				}

				switch (cformat)
				{
					case 's':
					case 'S':
						sout += node_arg->bitsAsConst().decode_string();
						break;

					case 'd':
					case 'D':
						{
							char tmp[128];
							snprintf(tmp, sizeof(tmp), "%d", node_arg->bitsAsConst().as_int());
							sout += tmp;
						}
						break;

					case 'x':
					case 'X':
						{
							char tmp[128];
							snprintf(tmp, sizeof(tmp), "%x", node_arg->bitsAsConst().as_int());
							sout += tmp;
						}
						break;

					case 'm':
					case 'M':
						sout += log_id(current_module->name);
						break;

					default:
						log_abort();
				}
			}

			// not a format specifier
			else
				sout += sformat[i];
		}

		// Finally, print the message (only include a \n for $display, not for $write)
		log("%s", sout.c_str());
		if (str == "$display")
			log("\n");
		delete_children();
		str = std::string();
	}

	// activate const folding if this is anything that must be evaluated statically (ranges, parameters, attributes, etc.)
	if (type == AST_WIRE || type == AST_PARAMETER || type == AST_LOCALPARAM || type == AST_DEFPARAM || type == AST_PARASET || type == AST_RANGE || type == AST_PREFIX)
		const_fold = true;
	if (type == AST_IDENTIFIER && current_scope.count(str) > 0 && (current_scope[str]->type == AST_PARAMETER || current_scope[str]->type == AST_LOCALPARAM))
		const_fold = true;

	// in certain cases a function must be evaluated constant. this is what in_param controls.
	if (type == AST_PARAMETER || type == AST_LOCALPARAM || type == AST_DEFPARAM || type == AST_PARASET || type == AST_PREFIX)
		in_param = true;

	std::map<std::string, AstNode*> backup_scope;

	// create name resolution entries for all objects with names
	// also merge multiple declarations for the same wire (e.g. "output foobar; reg foobar;")
	if (type == AST_MODULE) {
		current_scope.clear();
		std::map<std::string, AstNode*> this_wire_scope;
		for (size_t i = 0; i < children.size(); i++) {
			AstNode *node = children[i];
			if (node->type == AST_WIRE) {
				if (node->children.size() == 1 && node->children[0]->type == AST_RANGE) {
					for (auto c : node->children[0]->children) {
						if (!c->is_simple_const_expr()) {
							if (attributes.count("\\dynports"))
								delete attributes.at("\\dynports");
							attributes["\\dynports"] = AstNode::mkconst_int(1, true);
						}
					}
				}
				if (this_wire_scope.count(node->str) > 0) {
					AstNode *first_node = this_wire_scope[node->str];
					if (first_node->is_input && node->is_reg)
						goto wires_are_incompatible;
					if (!node->is_input && !node->is_output && node->is_reg && node->children.size() == 0)
						goto wires_are_compatible;
					if (first_node->children.size() == 0 && node->children.size() == 1 && node->children[0]->type == AST_RANGE) {
						AstNode *r = node->children[0];
						if (r->range_valid && r->range_left == 0 && r->range_right == 0) {
							delete r;
							node->children.pop_back();
						}
					}
					if (first_node->children.size() != node->children.size())
						goto wires_are_incompatible;
					for (size_t j = 0; j < node->children.size(); j++) {
						AstNode *n1 = first_node->children[j], *n2 = node->children[j];
						if (n1->type == AST_RANGE && n2->type == AST_RANGE && n1->range_valid && n2->range_valid) {
							if (n1->range_left != n2->range_left)
								goto wires_are_incompatible;
							if (n1->range_right != n2->range_right)
								goto wires_are_incompatible;
						} else if (*n1 != *n2)
							goto wires_are_incompatible;
					}
					if (first_node->range_left != node->range_left)
						goto wires_are_incompatible;
					if (first_node->range_right != node->range_right)
						goto wires_are_incompatible;
					if (first_node->port_id == 0 && (node->is_input || node->is_output))
						goto wires_are_incompatible;
				wires_are_compatible:
					if (node->is_input)
						first_node->is_input = true;
					if (node->is_output)
						first_node->is_output = true;
					if (node->is_reg)
						first_node->is_reg = true;
					if (node->is_logic)
						first_node->is_logic = true;
					if (node->is_signed)
						first_node->is_signed = true;
					for (auto &it : node->attributes) {
						if (first_node->attributes.count(it.first) > 0)
							delete first_node->attributes[it.first];
						first_node->attributes[it.first] = it.second->clone();
					}
					children.erase(children.begin()+(i--));
					did_something = true;
					delete node;
					continue;
				wires_are_incompatible:
					if (stage > 1)
						log_file_error(filename, linenum, "Incompatible re-declaration of wire %s.\n", node->str.c_str());
					continue;
				}
				this_wire_scope[node->str] = node;
			}
			if (node->type == AST_PARAMETER || node->type == AST_LOCALPARAM || node->type == AST_WIRE || node->type == AST_AUTOWIRE || node->type == AST_GENVAR ||
					node->type == AST_MEMORY || node->type == AST_FUNCTION || node->type == AST_TASK || node->type == AST_DPI_FUNCTION || node->type == AST_CELL) {
				backup_scope[node->str] = current_scope[node->str];
				current_scope[node->str] = node;
			}
		}
		for (size_t i = 0; i < children.size(); i++) {
			AstNode *node = children[i];
			if (node->type == AST_PARAMETER || node->type == AST_LOCALPARAM || node->type == AST_WIRE || node->type == AST_AUTOWIRE || node->type == AST_MEMORY)
				while (node->simplify(true, false, false, 1, -1, false, node->type == AST_PARAMETER || node->type == AST_LOCALPARAM))
					did_something = true;
		}
	}

	auto backup_current_block = current_block;
	auto backup_current_block_child = current_block_child;
	auto backup_current_top_block = current_top_block;
	auto backup_current_always = current_always;
	auto backup_current_always_clocked = current_always_clocked;

	if (type == AST_ALWAYS || type == AST_INITIAL)
	{
		if (current_always != nullptr)
			log_file_error(filename, linenum, "Invalid nesting of always blocks and/or initializations.\n");

		current_always = this;
		current_always_clocked = false;

		if (type == AST_ALWAYS)
			for (auto child : children) {
				if (child->type == AST_POSEDGE || child->type == AST_NEGEDGE)
					current_always_clocked = true;
				if (child->type == AST_EDGE && GetSize(child->children) == 1 &&
						child->children[0]->type == AST_IDENTIFIER && child->children[0]->str == "\\$global_clock")
					current_always_clocked = true;
			}
	}

	int backup_width_hint = width_hint;
	bool backup_sign_hint = sign_hint;

	bool detect_width_simple = false;
	bool child_0_is_self_determined = false;
	bool child_1_is_self_determined = false;
	bool child_2_is_self_determined = false;
	bool children_are_self_determined = false;
	bool reset_width_after_children = false;

	switch (type)
	{
	case AST_ASSIGN_EQ:
	case AST_ASSIGN_LE:
	case AST_ASSIGN:
		while (!children[0]->basic_prep && children[0]->simplify(false, false, true, stage, -1, false, in_param) == true)
			did_something = true;
		while (!children[1]->basic_prep && children[1]->simplify(false, false, false, stage, -1, false, in_param) == true)
			did_something = true;
		children[0]->detectSignWidth(backup_width_hint, backup_sign_hint);
		children[1]->detectSignWidth(width_hint, sign_hint);
		width_hint = max(width_hint, backup_width_hint);
		child_0_is_self_determined = true;
		// test only once, before optimizations and memory mappings but after assignment LHS was mapped to an identifier
		if (children[0]->id2ast && !children[0]->was_checked) {
			if ((type == AST_ASSIGN_LE || type == AST_ASSIGN_EQ) && children[0]->id2ast->is_logic)
				children[0]->id2ast->is_reg = true; // if logic type is used in a block asignment
			if ((type == AST_ASSIGN_LE || type == AST_ASSIGN_EQ) && !children[0]->id2ast->is_reg)
				log_warning("wire '%s' is assigned in a block at %s:%d.\n", children[0]->str.c_str(), filename.c_str(), linenum);
			if (type == AST_ASSIGN && children[0]->id2ast->is_reg) {
				bool is_rand_reg = false;
				if (children[1]->type == AST_FCALL) {
					if (children[1]->str == "\\$anyconst")
						is_rand_reg = true;
					if (children[1]->str == "\\$anyseq")
						is_rand_reg = true;
					if (children[1]->str == "\\$allconst")
						is_rand_reg = true;
					if (children[1]->str == "\\$allseq")
						is_rand_reg = true;
				}
				if (!is_rand_reg)
					log_warning("reg '%s' is assigned in a continuous assignment at %s:%d.\n", children[0]->str.c_str(), filename.c_str(), linenum);
			}
			children[0]->was_checked = true;
		}
		break;

	case AST_PARAMETER:
	case AST_LOCALPARAM:
		while (!children[0]->basic_prep && children[0]->simplify(false, false, false, stage, -1, false, true) == true)
			did_something = true;
		children[0]->detectSignWidth(width_hint, sign_hint);
		if (children.size() > 1 && children[1]->type == AST_RANGE) {
			while (!children[1]->basic_prep && children[1]->simplify(false, false, false, stage, -1, false, true) == true)
				did_something = true;
			if (!children[1]->range_valid)
				log_file_error(filename, linenum, "Non-constant width range on parameter decl.\n");
			width_hint = max(width_hint, children[1]->range_left - children[1]->range_right + 1);
		}
		break;

	case AST_TO_BITS:
	case AST_TO_SIGNED:
	case AST_TO_UNSIGNED:
	case AST_CONCAT:
	case AST_REPLICATE:
	case AST_REDUCE_AND:
	case AST_REDUCE_OR:
	case AST_REDUCE_XOR:
	case AST_REDUCE_XNOR:
	case AST_REDUCE_BOOL:
		detect_width_simple = true;
		children_are_self_determined = true;
		break;

	case AST_NEG:
	case AST_BIT_NOT:
	case AST_POS:
	case AST_BIT_AND:
	case AST_BIT_OR:
	case AST_BIT_XOR:
	case AST_BIT_XNOR:
	case AST_ADD:
	case AST_SUB:
	case AST_MUL:
	case AST_DIV:
	case AST_MOD:
		detect_width_simple = true;
		break;

	case AST_SHIFT_LEFT:
	case AST_SHIFT_RIGHT:
	case AST_SHIFT_SLEFT:
	case AST_SHIFT_SRIGHT:
	case AST_POW:
		detect_width_simple = true;
		child_1_is_self_determined = true;
		break;

	case AST_LT:
	case AST_LE:
	case AST_EQ:
	case AST_NE:
	case AST_EQX:
	case AST_NEX:
	case AST_GE:
	case AST_GT:
		width_hint = -1;
		sign_hint = true;
		for (auto child : children) {
			while (!child->basic_prep && child->simplify(false, false, in_lvalue, stage, -1, false, in_param) == true)
				did_something = true;
			child->detectSignWidthWorker(width_hint, sign_hint);
		}
		reset_width_after_children = true;
		break;

	case AST_LOGIC_AND:
	case AST_LOGIC_OR:
	case AST_LOGIC_NOT:
		detect_width_simple = true;
		children_are_self_determined = true;
		break;

	case AST_TERNARY:
		detect_width_simple = true;
		child_0_is_self_determined = true;
		break;

	case AST_MEMRD:
		detect_width_simple = true;
		children_are_self_determined = true;
		break;

	case AST_FCALL:
	case AST_TCALL:
		children_are_self_determined = true;
		break;

	default:
		width_hint = -1;
		sign_hint = false;
	}

	if (detect_width_simple && width_hint < 0) {
		if (type == AST_REPLICATE)
			while (children[0]->simplify(true, false, in_lvalue, stage, -1, false, true) == true)
				did_something = true;
		for (auto child : children)
			while (!child->basic_prep && child->simplify(false, false, in_lvalue, stage, -1, false, in_param) == true)
				did_something = true;
		detectSignWidth(width_hint, sign_hint);
	}

	if (type == AST_FCALL && str == "\\$past")
		detectSignWidth(width_hint, sign_hint);

	if (type == AST_TERNARY) {
		int width_hint_left, width_hint_right;
		bool sign_hint_left, sign_hint_right;
		bool found_real_left, found_real_right;
		children[1]->detectSignWidth(width_hint_left, sign_hint_left, &found_real_left);
		children[2]->detectSignWidth(width_hint_right, sign_hint_right, &found_real_right);
		if (found_real_left || found_real_right) {
			child_1_is_self_determined = true;
			child_2_is_self_determined = true;
		}
	}

	if (type == AST_CONDX && children.size() > 0 && children.at(0)->type == AST_CONSTANT) {
		for (auto &bit : children.at(0)->bits)
			if (bit == State::Sz || bit == State::Sx)
				bit = State::Sa;
	}

	if (type == AST_CONDZ && children.size() > 0 && children.at(0)->type == AST_CONSTANT) {
		for (auto &bit : children.at(0)->bits)
			if (bit == State::Sz)
				bit = State::Sa;
	}

	if (const_fold && type == AST_CASE)
	{
		while (children[0]->simplify(const_fold, at_zero, in_lvalue, stage, width_hint, sign_hint, in_param)) { }
		if (children[0]->type == AST_CONSTANT && children[0]->bits_only_01()) {
			std::vector<AstNode*> new_children;
			new_children.push_back(children[0]);
			for (int i = 1; i < GetSize(children); i++) {
				AstNode *child = children[i];
				log_assert(child->type == AST_COND || child->type == AST_CONDX || child->type == AST_CONDZ);
				for (auto v : child->children) {
					if (v->type == AST_DEFAULT)
						goto keep_const_cond;
					if (v->type == AST_BLOCK)
						continue;
					while (v->simplify(const_fold, at_zero, in_lvalue, stage, width_hint, sign_hint, in_param)) { }
					if (v->type == AST_CONSTANT && v->bits_only_01()) {
						if (v->bits == children[0]->bits) {
							while (i+1 < GetSize(children))
								delete children[++i];
							goto keep_const_cond;
						}
						continue;
					}
					goto keep_const_cond;
				}
				if (0)
			keep_const_cond:
					new_children.push_back(child);
				else
					delete child;
			}
			new_children.swap(children);
		}
	}

	// simplify all children first
	// (iterate by index as e.g. auto wires can add new children in the process)
	for (size_t i = 0; i < children.size(); i++) {
		bool did_something_here = true;
		bool backup_flag_autowire = flag_autowire;
		if ((type == AST_GENFOR || type == AST_FOR) && i >= 3)
			break;
		if ((type == AST_GENIF || type == AST_GENCASE) && i >= 1)
			break;
		if (type == AST_GENBLOCK)
			break;
		if (type == AST_BLOCK && !str.empty())
			break;
		if (type == AST_PREFIX && i >= 1)
			break;
		if (type == AST_DEFPARAM && i == 0)
			flag_autowire = true;
		while (did_something_here && i < children.size()) {
			bool const_fold_here = const_fold, in_lvalue_here = in_lvalue;
			int width_hint_here = width_hint;
			bool sign_hint_here = sign_hint;
			bool in_param_here = in_param;
			if (i == 0 && (type == AST_REPLICATE || type == AST_WIRE))
				const_fold_here = true, in_param_here = true;
			if (type == AST_PARAMETER || type == AST_LOCALPARAM)
				const_fold_here = true;
			if (i == 0 && (type == AST_ASSIGN || type == AST_ASSIGN_EQ || type == AST_ASSIGN_LE))
				in_lvalue_here = true;
			if (type == AST_BLOCK) {
				current_block = this;
				current_block_child = children[i];
			}
			if ((type == AST_ALWAYS || type == AST_INITIAL) && children[i]->type == AST_BLOCK)
				current_top_block = children[i];
			if (i == 0 && child_0_is_self_determined)
				width_hint_here = -1, sign_hint_here = false;
			if (i == 1 && child_1_is_self_determined)
				width_hint_here = -1, sign_hint_here = false;
			if (i == 2 && child_2_is_self_determined)
				width_hint_here = -1, sign_hint_here = false;
			if (children_are_self_determined)
				width_hint_here = -1, sign_hint_here = false;
			did_something_here = children[i]->simplify(const_fold_here, at_zero, in_lvalue_here, stage, width_hint_here, sign_hint_here, in_param_here);
			if (did_something_here)
				did_something = true;
		}
		if (stage == 2 && children[i]->type == AST_INITIAL && current_ast_mod != this) {
			current_ast_mod->children.push_back(children[i]);
			children.erase(children.begin() + (i--));
			did_something = true;
		}
		flag_autowire = backup_flag_autowire;
	}
	for (auto &attr : attributes) {
		while (attr.second->simplify(true, false, false, stage, -1, false, true))
			did_something = true;
	}

	if (reset_width_after_children) {
		width_hint = backup_width_hint;
		sign_hint = backup_sign_hint;
		if (width_hint < 0)
			detectSignWidth(width_hint, sign_hint);
	}

	current_block = backup_current_block;
	current_block_child = backup_current_block_child;
	current_top_block = backup_current_top_block;
	current_always = backup_current_always;
	current_always_clocked = backup_current_always_clocked;

	for (auto it = backup_scope.begin(); it != backup_scope.end(); it++) {
		if (it->second == NULL)
			current_scope.erase(it->first);
		else
			current_scope[it->first] = it->second;
	}

	current_filename = filename;
	set_line_num(linenum);

	if (type == AST_MODULE)
		current_scope.clear();

	// convert defparam nodes to cell parameters
	if (type == AST_DEFPARAM && !children.empty())
	{
		if (children[0]->type != AST_IDENTIFIER)
			log_file_error(filename, linenum, "Module name in defparam contains non-constant expressions!\n");

		string modname, paramname = children[0]->str;

		size_t pos = paramname.rfind('.');

		while (pos != 0 && pos != std::string::npos)
		{
			modname = paramname.substr(0, pos);

			if (current_scope.count(modname))
				break;

			pos = paramname.rfind('.', pos - 1);
		}

		if (pos == std::string::npos)
			log_file_error(filename, linenum, "Can't find object for defparam `%s`!\n", RTLIL::unescape_id(paramname).c_str());

		paramname = "\\" + paramname.substr(pos+1);

		if (current_scope.at(modname)->type != AST_CELL)
			log_file_error(filename, linenum, "Defparam argument `%s . %s` does not match a cell!\n",
					RTLIL::unescape_id(modname).c_str(), RTLIL::unescape_id(paramname).c_str());

		AstNode *paraset = new AstNode(AST_PARASET, children[1]->clone(), GetSize(children) > 2 ? children[2]->clone() : NULL);
		paraset->str = paramname;

		AstNode *cell = current_scope.at(modname);
		cell->children.insert(cell->children.begin() + 1, paraset);
		delete_children();
	}

	// resolve constant prefixes
	if (type == AST_PREFIX) {
		if (children[0]->type != AST_CONSTANT) {
			// dumpAst(NULL, ">   ");
			log_file_error(filename, linenum, "Index in generate block prefix syntax is not constant!\n");
		}
		if (children[1]->type == AST_PREFIX)
			children[1]->simplify(const_fold, at_zero, in_lvalue, stage, width_hint, sign_hint, in_param);
		log_assert(children[1]->type == AST_IDENTIFIER);
		newNode = children[1]->clone();
		const char *second_part = children[1]->str.c_str();
		if (second_part[0] == '\\')
			second_part++;
		newNode->str = stringf("%s[%d].%s", str.c_str(), children[0]->integer, second_part);
		goto apply_newNode;
	}

	// evaluate TO_BITS nodes
	if (type == AST_TO_BITS) {
		if (children[0]->type != AST_CONSTANT)
			log_file_error(filename, linenum, "Left operand of to_bits expression is not constant!\n");
		if (children[1]->type != AST_CONSTANT)
			log_file_error(filename, linenum, "Right operand of to_bits expression is not constant!\n");
		RTLIL::Const new_value = children[1]->bitsAsConst(children[0]->bitsAsConst().as_int(), children[1]->is_signed);
		newNode = mkconst_bits(new_value.bits, children[1]->is_signed);
		goto apply_newNode;
	}

	// annotate constant ranges
	if (type == AST_RANGE) {
		bool old_range_valid = range_valid;
		range_valid = false;
		range_swapped = false;
		range_left = -1;
		range_right = 0;
		log_assert(children.size() >= 1);
		if (children[0]->type == AST_CONSTANT) {
			range_valid = true;
			range_left = children[0]->integer;
			if (children.size() == 1)
				range_right = range_left;
		}
		if (children.size() >= 2) {
			if (children[1]->type == AST_CONSTANT)
				range_right = children[1]->integer;
			else
				range_valid = false;
		}
		if (old_range_valid != range_valid)
			did_something = true;
		if (range_valid && range_left >= 0 && range_right > range_left) {
			int tmp = range_right;
			range_right = range_left;
			range_left = tmp;
			range_swapped = true;
		}
	}

	// annotate wires with their ranges
	if (type == AST_WIRE) {
		if (children.size() > 0) {
			if (children[0]->range_valid) {
				if (!range_valid)
					did_something = true;
				range_valid = true;
				range_swapped = children[0]->range_swapped;
				range_left = children[0]->range_left;
				range_right = children[0]->range_right;
			}
		} else {
			if (!range_valid)
				did_something = true;
			range_valid = true;
			range_swapped = false;
			range_left = 0;
			range_right = 0;
		}
	}

	// resolve multiranges on memory decl
	if (type == AST_MEMORY && children.size() > 1 && children[1]->type == AST_MULTIRANGE)
	{
		int total_size = 1;
		multirange_dimensions.clear();
		for (auto range : children[1]->children) {
			if (!range->range_valid)
				log_file_error(filename, linenum, "Non-constant range on memory decl.\n");
			multirange_dimensions.push_back(min(range->range_left, range->range_right));
			multirange_dimensions.push_back(max(range->range_left, range->range_right) - min(range->range_left, range->range_right) + 1);
			total_size *= multirange_dimensions.back();
		}
		delete children[1];
		children[1] = new AstNode(AST_RANGE, AstNode::mkconst_int(0, true), AstNode::mkconst_int(total_size-1, true));
		did_something = true;
	}

	// resolve multiranges on memory access
	if (type == AST_IDENTIFIER && id2ast && id2ast->type == AST_MEMORY && children.size() > 0 && children[0]->type == AST_MULTIRANGE)
	{
		AstNode *index_expr = nullptr;

		for (int i = 0; 2*i < GetSize(id2ast->multirange_dimensions); i++)
		{
			if (GetSize(children[0]->children) < i)
				log_file_error(filename, linenum, "Insufficient number of array indices for %s.\n", log_id(str));

			AstNode *new_index_expr = children[0]->children[i]->children.at(0)->clone();

			if (id2ast->multirange_dimensions[2*i])
				new_index_expr = new AstNode(AST_SUB, new_index_expr, AstNode::mkconst_int(id2ast->multirange_dimensions[2*i], true));

			if (i == 0)
				index_expr = new_index_expr;
			else
				index_expr = new AstNode(AST_ADD, new AstNode(AST_MUL, index_expr, AstNode::mkconst_int(id2ast->multirange_dimensions[2*i+1], true)), new_index_expr);
		}

		for (int i = GetSize(id2ast->multirange_dimensions)/2; i < GetSize(children[0]->children); i++)
			children.push_back(children[0]->children[i]->clone());

		delete children[0];
		if (index_expr == nullptr)
			children.erase(children.begin());
		else
			children[0] = new AstNode(AST_RANGE, index_expr);

		did_something = true;
	}

	// trim/extend parameters
	if (type == AST_PARAMETER || type == AST_LOCALPARAM) {
		if (children.size() > 1 && children[1]->type == AST_RANGE) {
			if (!children[1]->range_valid)
				log_file_error(filename, linenum, "Non-constant width range on parameter decl.\n");
			int width = std::abs(children[1]->range_left - children[1]->range_right) + 1;
			if (children[0]->type == AST_REALVALUE) {
				RTLIL::Const constvalue = children[0]->realAsConst(width);
				log_file_warning(filename, linenum, "converting real value %e to binary %s.\n",
						children[0]->realvalue, log_signal(constvalue));
				delete children[0];
				children[0] = mkconst_bits(constvalue.bits, sign_hint);
				did_something = true;
			}
			if (children[0]->type == AST_CONSTANT) {
				if (width != int(children[0]->bits.size())) {
					RTLIL::SigSpec sig(children[0]->bits);
					sig.extend_u0(width, children[0]->is_signed);
					AstNode *old_child_0 = children[0];
					children[0] = mkconst_bits(sig.as_const().bits, is_signed);
					delete old_child_0;
				}
				children[0]->is_signed = is_signed;
			}
			range_valid = true;
			range_swapped = children[1]->range_swapped;
			range_left = children[1]->range_left;
			range_right = children[1]->range_right;
		} else
		if (children.size() > 1 && children[1]->type == AST_REALVALUE && children[0]->type == AST_CONSTANT) {
			double as_realvalue = children[0]->asReal(sign_hint);
			delete children[0];
			children[0] = new AstNode(AST_REALVALUE);
			children[0]->realvalue = as_realvalue;
			did_something = true;
		}
	}

	// annotate identifiers using scope resolution and create auto-wires as needed
	if (type == AST_IDENTIFIER) {
		if (current_scope.count(str) == 0) {
			for (auto node : current_ast_mod->children) {
				if ((node->type == AST_PARAMETER || node->type == AST_LOCALPARAM || node->type == AST_WIRE || node->type == AST_AUTOWIRE || node->type == AST_GENVAR ||
						node->type == AST_MEMORY || node->type == AST_FUNCTION || node->type == AST_TASK || node->type == AST_DPI_FUNCTION) && str == node->str) {
					current_scope[node->str] = node;
					break;
				}
			}
		}
		if (current_scope.count(str) == 0) {
			if (flag_autowire || str == "\\$global_clock") {
				AstNode *auto_wire = new AstNode(AST_AUTOWIRE);
				auto_wire->str = str;
				current_ast_mod->children.push_back(auto_wire);
				current_scope[str] = auto_wire;
				did_something = true;
			} else {
				log_file_error(filename, linenum, "Identifier `%s' is implicitly declared and `default_nettype is set to none.\n", str.c_str());
			}
		}
		if (id2ast != current_scope[str]) {
			id2ast = current_scope[str];
			did_something = true;
		}
	}

	// split memory access with bit select to individual statements
	if (type == AST_IDENTIFIER && children.size() == 2 && children[0]->type == AST_RANGE && children[1]->type == AST_RANGE && !in_lvalue)
	{
		if (id2ast == NULL || id2ast->type != AST_MEMORY || children[0]->children.size() != 1)
			log_file_error(filename, linenum, "Invalid bit-select on memory access!\n");

		int mem_width, mem_size, addr_bits;
		id2ast->meminfo(mem_width, mem_size, addr_bits);

		int data_range_left = id2ast->children[0]->range_left;
		int data_range_right = id2ast->children[0]->range_right;

		if (id2ast->children[0]->range_swapped)
			std::swap(data_range_left, data_range_right);

		std::stringstream sstr;
		sstr << "$mem2bits$" << str << "$" << filename << ":" << linenum << "$" << (autoidx++);
		std::string wire_id = sstr.str();

		AstNode *wire = new AstNode(AST_WIRE, new AstNode(AST_RANGE, mkconst_int(data_range_left, true), mkconst_int(data_range_right, true)));
		wire->str = wire_id;
		if (current_block)
			wire->attributes["\\nosync"] = AstNode::mkconst_int(1, false);
		current_ast_mod->children.push_back(wire);
		while (wire->simplify(true, false, false, 1, -1, false, false)) { }

		AstNode *data = clone();
		delete data->children[1];
		data->children.pop_back();

		AstNode *assign = new AstNode(AST_ASSIGN_EQ, new AstNode(AST_IDENTIFIER), data);
		assign->children[0]->str = wire_id;
		assign->children[0]->was_checked = true;

		if (current_block)
		{
			size_t assign_idx = 0;
			while (assign_idx < current_block->children.size() && current_block->children[assign_idx] != current_block_child)
				assign_idx++;
			log_assert(assign_idx < current_block->children.size());
			current_block->children.insert(current_block->children.begin()+assign_idx, assign);
			wire->is_reg = true;
		}
		else
		{
			AstNode *proc = new AstNode(AST_ALWAYS, new AstNode(AST_BLOCK));
			proc->children[0]->children.push_back(assign);
			current_ast_mod->children.push_back(proc);
		}

		newNode = new AstNode(AST_IDENTIFIER, children[1]->clone());
		newNode->str = wire_id;
		newNode->id2ast = wire;
		goto apply_newNode;
	}

	if (type == AST_WHILE)
		log_file_error(filename, linenum, "While loops are only allowed in constant functions!\n");

	if (type == AST_REPEAT)
	{
		AstNode *count = children[0];
		AstNode *body = children[1];

		// eval count expression
		while (count->simplify(true, false, false, stage, 32, true, false)) { }

		if (count->type != AST_CONSTANT)
			log_file_error(filename, linenum, "Repeat loops outside must have constant repeat counts!\n");

		// convert to a block with the body repeated n times
		type = AST_BLOCK;
		children.clear();
		for (int i = 0; i < count->bitsAsConst().as_int(); i++)
			children.insert(children.begin(), body->clone());

		delete count;
		delete body;
		did_something = true;
	}

	// unroll for loops and generate-for blocks
	if ((type == AST_GENFOR || type == AST_FOR) && children.size() != 0)
	{
		AstNode *init_ast = children[0];
		AstNode *while_ast = children[1];
		AstNode *next_ast = children[2];
		AstNode *body_ast = children[3];

		while (body_ast->type == AST_GENBLOCK && body_ast->str.empty() &&
				body_ast->children.size() == 1 && body_ast->children.at(0)->type == AST_GENBLOCK)
			body_ast = body_ast->children.at(0);

		if (init_ast->type != AST_ASSIGN_EQ)
			log_file_error(filename, linenum, "Unsupported 1st expression of generate for-loop!\n");
		if (next_ast->type != AST_ASSIGN_EQ)
			log_file_error(filename, linenum, "Unsupported 3rd expression of generate for-loop!\n");

		if (type == AST_GENFOR) {
			if (init_ast->children[0]->id2ast == NULL || init_ast->children[0]->id2ast->type != AST_GENVAR)
				log_file_error(filename, linenum, "Left hand side of 1st expression of generate for-loop is not a gen var!\n");
			if (next_ast->children[0]->id2ast == NULL || next_ast->children[0]->id2ast->type != AST_GENVAR)
				log_file_error(filename, linenum, "Left hand side of 3rd expression of generate for-loop is not a gen var!\n");
		} else {
			if (init_ast->children[0]->id2ast == NULL || init_ast->children[0]->id2ast->type != AST_WIRE)
				log_file_error(filename, linenum, "Left hand side of 1st expression of generate for-loop is not a register!\n");
			if (next_ast->children[0]->id2ast == NULL || next_ast->children[0]->id2ast->type != AST_WIRE)
				log_file_error(filename, linenum, "Left hand side of 3rd expression of generate for-loop is not a register!\n");
		}

		if (init_ast->children[0]->id2ast != next_ast->children[0]->id2ast)
			log_file_error(filename, linenum, "Incompatible left-hand sides in 1st and 3rd expression of generate for-loop!\n");

		// eval 1st expression
		AstNode *varbuf = init_ast->children[1]->clone();
		{
			int expr_width_hint = -1;
			bool expr_sign_hint = true;
			varbuf->detectSignWidth(expr_width_hint, expr_sign_hint);
			while (varbuf->simplify(true, false, false, stage, 32, true, false)) { }
		}

		if (varbuf->type != AST_CONSTANT)
			log_file_error(filename, linenum, "Right hand side of 1st expression of generate for-loop is not constant!\n");

		varbuf = new AstNode(AST_LOCALPARAM, varbuf);
		varbuf->str = init_ast->children[0]->str;

		AstNode *backup_scope_varbuf = current_scope[varbuf->str];
		current_scope[varbuf->str] = varbuf;

		size_t current_block_idx = 0;
		if (type == AST_FOR) {
			while (current_block_idx < current_block->children.size() &&
					current_block->children[current_block_idx] != current_block_child)
				current_block_idx++;
		}

		while (1)
		{
			// eval 2nd expression
			AstNode *buf = while_ast->clone();
			{
				int expr_width_hint = -1;
				bool expr_sign_hint = true;
				buf->detectSignWidth(expr_width_hint, expr_sign_hint);
				while (buf->simplify(true, false, false, stage, expr_width_hint, expr_sign_hint, false)) { }
			}

			if (buf->type != AST_CONSTANT)
				log_file_error(filename, linenum, "2nd expression of generate for-loop is not constant!\n");

			if (buf->integer == 0) {
				delete buf;
				break;
			}
			delete buf;

			// expand body
			int index = varbuf->children[0]->integer;
			if (body_ast->type == AST_GENBLOCK)
				buf = body_ast->clone();
			else
				buf = new AstNode(AST_GENBLOCK, body_ast->clone());
			if (buf->str.empty()) {
				std::stringstream sstr;
				sstr << "$genblock$" << filename << ":" << linenum << "$" << (autoidx++);
				buf->str = sstr.str();
			}
			std::map<std::string, std::string> name_map;
			std::stringstream sstr;
			sstr << buf->str << "[" << index << "].";
			buf->expand_genblock(varbuf->str, sstr.str(), name_map);

			if (type == AST_GENFOR) {
				for (size_t i = 0; i < buf->children.size(); i++) {
					buf->children[i]->simplify(false, false, false, stage, -1, false, false);
					current_ast_mod->children.push_back(buf->children[i]);
				}
			} else {
				for (size_t i = 0; i < buf->children.size(); i++)
					current_block->children.insert(current_block->children.begin() + current_block_idx++, buf->children[i]);
			}
			buf->children.clear();
			delete buf;

			// eval 3rd expression
			buf = next_ast->children[1]->clone();
			{
				int expr_width_hint = -1;
				bool expr_sign_hint = true;
				buf->detectSignWidth(expr_width_hint, expr_sign_hint);
				while (buf->simplify(true, false, false, stage, expr_width_hint, expr_sign_hint, true)) { }
			}

			if (buf->type != AST_CONSTANT)
				log_file_error(filename, linenum, "Right hand side of 3rd expression of generate for-loop is not constant!\n");

			delete varbuf->children[0];
			varbuf->children[0] = buf;
		}

		if (type == AST_FOR) {
			AstNode *buf = next_ast->clone();
			delete buf->children[1];
			buf->children[1] = varbuf->children[0]->clone();
			current_block->children.insert(current_block->children.begin() + current_block_idx++, buf);
		}

		current_scope[varbuf->str] = backup_scope_varbuf;
		delete varbuf;
		delete_children();
		did_something = true;
	}

	// check for local objects in unnamed block
	if (type == AST_BLOCK && str.empty())
	{
		for (size_t i = 0; i < children.size(); i++)
			if (children[i]->type == AST_WIRE || children[i]->type == AST_MEMORY || children[i]->type == AST_PARAMETER || children[i]->type == AST_LOCALPARAM)
				log_file_error(children[i]->filename, children[i]->linenum, "Local declaration in unnamed block is an unsupported SystemVerilog feature!\n");
	}

	// transform block with name
	if (type == AST_BLOCK && !str.empty())
	{
		std::map<std::string, std::string> name_map;
		expand_genblock(std::string(), str + ".", name_map);

		std::vector<AstNode*> new_children;
		for (size_t i = 0; i < children.size(); i++)
			if (children[i]->type == AST_WIRE || children[i]->type == AST_MEMORY || children[i]->type == AST_PARAMETER || children[i]->type == AST_LOCALPARAM) {
				children[i]->simplify(false, false, false, stage, -1, false, false);
				current_ast_mod->children.push_back(children[i]);
				current_scope[children[i]->str] = children[i];
			} else
				new_children.push_back(children[i]);

		children.swap(new_children);
		did_something = true;
		str.clear();
	}

	// simplify unconditional generate block
	if (type == AST_GENBLOCK && children.size() != 0)
	{
		if (!str.empty()) {
			std::map<std::string, std::string> name_map;
			expand_genblock(std::string(), str + ".", name_map);
		}

		for (size_t i = 0; i < children.size(); i++) {
			children[i]->simplify(false, false, false, stage, -1, false, false);
			current_ast_mod->children.push_back(children[i]);
		}

		children.clear();
		did_something = true;
	}

	// simplify generate-if blocks
	if (type == AST_GENIF && children.size() != 0)
	{
		AstNode *buf = children[0]->clone();
		while (buf->simplify(true, false, false, stage, width_hint, sign_hint, false)) { }
		if (buf->type != AST_CONSTANT) {
			// for (auto f : log_files)
			// 	dumpAst(f, "verilog-ast> ");
			log_file_error(filename, linenum, "Condition for generate if is not constant!\n");
		}
		if (buf->asBool() != 0) {
			delete buf;
			buf = children[1]->clone();
		} else {
			delete buf;
			buf = children.size() > 2 ? children[2]->clone() : NULL;
		}

		if (buf)
		{
			if (buf->type != AST_GENBLOCK)
				buf = new AstNode(AST_GENBLOCK, buf);

			if (!buf->str.empty()) {
				std::map<std::string, std::string> name_map;
				buf->expand_genblock(std::string(), buf->str + ".", name_map);
			}

			for (size_t i = 0; i < buf->children.size(); i++) {
				buf->children[i]->simplify(false, false, false, stage, -1, false, false);
				current_ast_mod->children.push_back(buf->children[i]);
			}

			buf->children.clear();
			delete buf;
		}

		delete_children();
		did_something = true;
	}

	// simplify generate-case blocks
	if (type == AST_GENCASE && children.size() != 0)
	{
		AstNode *buf = children[0]->clone();
		while (buf->simplify(true, false, false, stage, width_hint, sign_hint, false)) { }
		if (buf->type != AST_CONSTANT) {
			// for (auto f : log_files)
			// 	dumpAst(f, "verilog-ast> ");
			log_file_error(filename, linenum, "Condition for generate case is not constant!\n");
		}

		bool ref_signed = buf->is_signed;
		RTLIL::Const ref_value = buf->bitsAsConst();
		delete buf;

		AstNode *selected_case = NULL;
		for (size_t i = 1; i < children.size(); i++)
		{
			log_assert(children.at(i)->type == AST_COND || children.at(i)->type == AST_CONDX || children.at(i)->type == AST_CONDZ);

			AstNode *this_genblock = NULL;
			for (auto child : children.at(i)->children) {
				log_assert(this_genblock == NULL);
				if (child->type == AST_GENBLOCK)
					this_genblock = child;
			}

			for (auto child : children.at(i)->children)
			{
				if (child->type == AST_DEFAULT) {
					if (selected_case == NULL)
						selected_case = this_genblock;
					continue;
				}
				if (child->type == AST_GENBLOCK)
					continue;

				buf = child->clone();
				while (buf->simplify(true, false, false, stage, width_hint, sign_hint, false)) { }
				if (buf->type != AST_CONSTANT) {
					// for (auto f : log_files)
					// 	dumpAst(f, "verilog-ast> ");
					log_file_error(filename, linenum, "Expression in generate case is not constant!\n");
				}

				bool is_selected = RTLIL::const_eq(ref_value, buf->bitsAsConst(), ref_signed && buf->is_signed, ref_signed && buf->is_signed, 1).as_bool();
				delete buf;

				if (is_selected) {
					selected_case = this_genblock;
					i = children.size();
					break;
				}
			}
		}

		if (selected_case != NULL)
		{
			log_assert(selected_case->type == AST_GENBLOCK);
			buf = selected_case->clone();

			if (!buf->str.empty()) {
				std::map<std::string, std::string> name_map;
				buf->expand_genblock(std::string(), buf->str + ".", name_map);
			}

			for (size_t i = 0; i < buf->children.size(); i++) {
				buf->children[i]->simplify(false, false, false, stage, -1, false, false);
				current_ast_mod->children.push_back(buf->children[i]);
			}

			buf->children.clear();
			delete buf;
		}

		delete_children();
		did_something = true;
	}

	// unroll cell arrays
	if (type == AST_CELLARRAY)
	{
		if (!children.at(0)->range_valid)
			log_file_error(filename, linenum, "Non-constant array range on cell array.\n");

		newNode = new AstNode(AST_GENBLOCK);
		int num = max(children.at(0)->range_left, children.at(0)->range_right) - min(children.at(0)->range_left, children.at(0)->range_right) + 1;

		for (int i = 0; i < num; i++) {
			int idx = children.at(0)->range_left > children.at(0)->range_right ? children.at(0)->range_right + i : children.at(0)->range_right - i;
			AstNode *new_cell = children.at(1)->clone();
			newNode->children.push_back(new_cell);
			new_cell->str += stringf("[%d]", idx);
			if (new_cell->type == AST_PRIMITIVE) {
				log_file_error(filename, linenum, "Cell arrays of primitives are currently not supported.\n");
			} else {
				log_assert(new_cell->children.at(0)->type == AST_CELLTYPE);
				new_cell->children.at(0)->str = stringf("$array:%d:%d:%s", i, num, new_cell->children.at(0)->str.c_str());
			}
		}

		goto apply_newNode;
	}

	// replace primitives with assignments
	if (type == AST_PRIMITIVE)
	{
		if (children.size() < 2)
			log_file_error(filename, linenum, "Insufficient number of arguments for primitive `%s'!\n", str.c_str());

		std::vector<AstNode*> children_list;
		for (auto child : children) {
			log_assert(child->type == AST_ARGUMENT);
			log_assert(child->children.size() == 1);
			children_list.push_back(child->children[0]);
			child->children.clear();
			delete child;
		}
		children.clear();

		if (str == "bufif0" || str == "bufif1" || str == "notif0" || str == "notif1")
		{
			if (children_list.size() != 3)
				log_file_error(filename, linenum, "Invalid number of arguments for primitive `%s'!\n", str.c_str());

			std::vector<RTLIL::State> z_const(1, RTLIL::State::Sz);

			AstNode *mux_input = children_list.at(1);
			if (str == "notif0" || str == "notif1") {
				mux_input = new AstNode(AST_BIT_NOT, mux_input);
			}
			AstNode *node = new AstNode(AST_TERNARY, children_list.at(2));
			if (str == "bufif0") {
				node->children.push_back(AstNode::mkconst_bits(z_const, false));
				node->children.push_back(mux_input);
			} else {
				node->children.push_back(mux_input);
				node->children.push_back(AstNode::mkconst_bits(z_const, false));
			}

			str.clear();
			type = AST_ASSIGN;
			children.push_back(children_list.at(0));
			children.back()->was_checked = true;
			children.push_back(node);
			did_something = true;
		}
		else
		{
			AstNodeType op_type = AST_NONE;
			bool invert_results = false;

			if (str == "and")
				op_type = AST_BIT_AND;
			if (str == "nand")
				op_type = AST_BIT_AND, invert_results = true;
			if (str == "or")
				op_type = AST_BIT_OR;
			if (str == "nor")
				op_type = AST_BIT_OR, invert_results = true;
			if (str == "xor")
				op_type = AST_BIT_XOR;
			if (str == "xnor")
				op_type = AST_BIT_XOR, invert_results = true;
			if (str == "buf")
				op_type = AST_POS;
			if (str == "not")
				op_type = AST_POS, invert_results = true;
			log_assert(op_type != AST_NONE);

			AstNode *node = children_list[1];
			if (op_type != AST_POS)
				for (size_t i = 2; i < children_list.size(); i++)
					node = new AstNode(op_type, node, children_list[i]);
			if (invert_results)
				node = new AstNode(AST_BIT_NOT, node);

			str.clear();
			type = AST_ASSIGN;
			children.push_back(children_list[0]);
			children.back()->was_checked = true;
			children.push_back(node);
			did_something = true;
		}
	}

	// replace dynamic ranges in left-hand side expressions (e.g. "foo[bar] <= 1'b1;") with
	// a big case block that selects the correct single-bit assignment.
	if (type == AST_ASSIGN_EQ || type == AST_ASSIGN_LE) {
		if (children[0]->type != AST_IDENTIFIER || children[0]->children.size() == 0)
			goto skip_dynamic_range_lvalue_expansion;
		if (children[0]->children[0]->range_valid || did_something)
			goto skip_dynamic_range_lvalue_expansion;
		if (children[0]->id2ast == NULL || children[0]->id2ast->type != AST_WIRE)
			goto skip_dynamic_range_lvalue_expansion;
		if (!children[0]->id2ast->range_valid)
			goto skip_dynamic_range_lvalue_expansion;
		int source_width = children[0]->id2ast->range_left - children[0]->id2ast->range_right + 1;
		int result_width = 1;
		AstNode *shift_expr = NULL;
		AstNode *range = children[0]->children[0];
		if (range->children.size() == 1) {
			shift_expr = range->children[0]->clone();
		} else {
			shift_expr = range->children[1]->clone();
			AstNode *left_at_zero_ast = range->children[0]->clone();
			AstNode *right_at_zero_ast = range->children[1]->clone();
			while (left_at_zero_ast->simplify(true, true, false, stage, -1, false, false)) { }
			while (right_at_zero_ast->simplify(true, true, false, stage, -1, false, false)) { }
			if (left_at_zero_ast->type != AST_CONSTANT || right_at_zero_ast->type != AST_CONSTANT)
				log_file_error(filename, linenum, "Unsupported expression on dynamic range select on signal `%s'!\n", str.c_str());
			result_width = abs(int(left_at_zero_ast->integer - right_at_zero_ast->integer)) + 1;
		}
		did_something = true;
		newNode = new AstNode(AST_CASE, shift_expr);
		for (int i = 0; i <= source_width-result_width; i++) {
			int start_bit = children[0]->id2ast->range_right + i;
			AstNode *cond = new AstNode(AST_COND, mkconst_int(start_bit, true));
			AstNode *lvalue = children[0]->clone();
			lvalue->delete_children();
			lvalue->children.push_back(new AstNode(AST_RANGE,
					mkconst_int(start_bit+result_width-1, true), mkconst_int(start_bit, true)));
			cond->children.push_back(new AstNode(AST_BLOCK, new AstNode(type, lvalue, children[1]->clone())));
			newNode->children.push_back(cond);
		}
		goto apply_newNode;
	}
skip_dynamic_range_lvalue_expansion:;

	if (stage > 1 && (type == AST_ASSERT || type == AST_ASSUME || type == AST_LIVE || type == AST_FAIR || type == AST_COVER) && current_block != NULL)
	{
		std::stringstream sstr;
		sstr << "$formal$" << filename << ":" << linenum << "$" << (autoidx++);
		std::string id_check = sstr.str() + "_CHECK", id_en = sstr.str() + "_EN";

		AstNode *wire_check = new AstNode(AST_WIRE);
		wire_check->str = id_check;
		wire_check->was_checked = true;
		current_ast_mod->children.push_back(wire_check);
		current_scope[wire_check->str] = wire_check;
		while (wire_check->simplify(true, false, false, 1, -1, false, false)) { }

		AstNode *wire_en = new AstNode(AST_WIRE);
		wire_en->str = id_en;
		wire_en->was_checked = true;
		current_ast_mod->children.push_back(wire_en);
		if (current_always_clocked) {
			current_ast_mod->children.push_back(new AstNode(AST_INITIAL, new AstNode(AST_BLOCK, new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER), AstNode::mkconst_int(0, false, 1)))));
			current_ast_mod->children.back()->children[0]->children[0]->children[0]->str = id_en;
			current_ast_mod->children.back()->children[0]->children[0]->children[0]->was_checked = true;
		}
		current_scope[wire_en->str] = wire_en;
		while (wire_en->simplify(true, false, false, 1, -1, false, false)) { }

		std::vector<RTLIL::State> x_bit;
		x_bit.push_back(RTLIL::State::Sx);

		AstNode *assign_check = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER), mkconst_bits(x_bit, false));
		assign_check->children[0]->str = id_check;
		assign_check->children[0]->was_checked = true;

		AstNode *assign_en = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER), mkconst_int(0, false, 1));
		assign_en->children[0]->str = id_en;
		assign_en->children[0]->was_checked = true;

		AstNode *default_signals = new AstNode(AST_BLOCK);
		default_signals->children.push_back(assign_check);
		default_signals->children.push_back(assign_en);
		current_top_block->children.insert(current_top_block->children.begin(), default_signals);

		assign_check = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER), new AstNode(AST_REDUCE_BOOL, children[0]->clone()));
		assign_check->children[0]->str = id_check;
		assign_check->children[0]->was_checked = true;

		if (current_always == nullptr || current_always->type != AST_INITIAL) {
			assign_en = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER), mkconst_int(1, false, 1));
		} else {
			assign_en = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER), new AstNode(AST_FCALL));
			assign_en->children[1]->str = "\\$initstate";
		}
		assign_en->children[0]->str = id_en;
		assign_en->children[0]->was_checked = true;

		newNode = new AstNode(AST_BLOCK);
		newNode->children.push_back(assign_check);
		newNode->children.push_back(assign_en);

		AstNode *assertnode = new AstNode(type);
		assertnode->str = str;
		assertnode->children.push_back(new AstNode(AST_IDENTIFIER));
		assertnode->children.push_back(new AstNode(AST_IDENTIFIER));
		assertnode->children[0]->str = id_check;
		assertnode->children[1]->str = id_en;
		assertnode->attributes.swap(attributes);
		current_ast_mod->children.push_back(assertnode);

		goto apply_newNode;
	}

	if (stage > 1 && (type == AST_ASSERT || type == AST_ASSUME || type == AST_LIVE || type == AST_FAIR || type == AST_COVER) && children.size() == 1)
	{
		children.push_back(mkconst_int(1, false, 1));
		did_something = true;
	}

	// found right-hand side identifier for memory -> replace with memory read port
	if (stage > 1 && type == AST_IDENTIFIER && id2ast != NULL && id2ast->type == AST_MEMORY && !in_lvalue &&
			children.size() == 1 && children[0]->type == AST_RANGE && children[0]->children.size() == 1) {
		newNode = new AstNode(AST_MEMRD, children[0]->children[0]->clone());
		newNode->str = str;
		newNode->id2ast = id2ast;
		goto apply_newNode;
	}

	// assignment with nontrivial member in left-hand concat expression -> split assignment
	if ((type == AST_ASSIGN_EQ || type == AST_ASSIGN_LE) && children[0]->type == AST_CONCAT && width_hint > 0)
	{
		bool found_nontrivial_member = false;

		for (auto child : children[0]->children) {
			if (child->type == AST_IDENTIFIER && child->id2ast != NULL && child->id2ast->type == AST_MEMORY)
				found_nontrivial_member = true;
		}

		if (found_nontrivial_member)
		{
			newNode = new AstNode(AST_BLOCK);

			AstNode *wire_tmp = new AstNode(AST_WIRE, new AstNode(AST_RANGE, mkconst_int(width_hint-1, true), mkconst_int(0, true)));
			wire_tmp->str = stringf("$splitcmplxassign$%s:%d$%d", filename.c_str(), linenum, autoidx++);
			current_ast_mod->children.push_back(wire_tmp);
			current_scope[wire_tmp->str] = wire_tmp;
			wire_tmp->attributes["\\nosync"] = AstNode::mkconst_int(1, false);
			while (wire_tmp->simplify(true, false, false, 1, -1, false, false)) { }
			wire_tmp->is_logic = true;

			AstNode *wire_tmp_id = new AstNode(AST_IDENTIFIER);
			wire_tmp_id->str = wire_tmp->str;

			newNode->children.push_back(new AstNode(AST_ASSIGN_EQ, wire_tmp_id, children[1]->clone()));
			newNode->children.back()->was_checked = true;

			int cursor = 0;
			for (auto child : children[0]->children)
			{
				int child_width_hint = -1;
				bool child_sign_hint = true;
				child->detectSignWidth(child_width_hint, child_sign_hint);

				AstNode *rhs = wire_tmp_id->clone();
				rhs->children.push_back(new AstNode(AST_RANGE, AstNode::mkconst_int(cursor+child_width_hint-1, true), AstNode::mkconst_int(cursor, true)));
				newNode->children.push_back(new AstNode(type, child->clone(), rhs));

				cursor += child_width_hint;
			}

			goto apply_newNode;
		}
	}

	// assignment with memory in left-hand side expression -> replace with memory write port
	if (stage > 1 && (type == AST_ASSIGN_EQ || type == AST_ASSIGN_LE) && children[0]->type == AST_IDENTIFIER &&
			children[0]->id2ast && children[0]->id2ast->type == AST_MEMORY && children[0]->id2ast->children.size() >= 2 &&
			children[0]->id2ast->children[0]->range_valid && children[0]->id2ast->children[1]->range_valid &&
			(children[0]->children.size() == 1 || children[0]->children.size() == 2) && children[0]->children[0]->type == AST_RANGE)
	{
		std::stringstream sstr;
		sstr << "$memwr$" << children[0]->str << "$" << filename << ":" << linenum << "$" << (autoidx++);
		std::string id_addr = sstr.str() + "_ADDR", id_data = sstr.str() + "_DATA", id_en = sstr.str() + "_EN";

		int mem_width, mem_size, addr_bits;
		bool mem_signed = children[0]->id2ast->is_signed;
		children[0]->id2ast->meminfo(mem_width, mem_size, addr_bits);

		int data_range_left = children[0]->id2ast->children[0]->range_left;
		int data_range_right = children[0]->id2ast->children[0]->range_right;
		int mem_data_range_offset = std::min(data_range_left, data_range_right);

		int addr_width_hint = -1;
		bool addr_sign_hint = true;
		children[0]->children[0]->children[0]->detectSignWidthWorker(addr_width_hint, addr_sign_hint);
		addr_bits = std::max(addr_bits, addr_width_hint);

		AstNode *wire_addr = new AstNode(AST_WIRE, new AstNode(AST_RANGE, mkconst_int(addr_bits-1, true), mkconst_int(0, true)));
		wire_addr->str = id_addr;
		wire_addr->was_checked = true;
		current_ast_mod->children.push_back(wire_addr);
		current_scope[wire_addr->str] = wire_addr;
		while (wire_addr->simplify(true, false, false, 1, -1, false, false)) { }

		AstNode *wire_data = new AstNode(AST_WIRE, new AstNode(AST_RANGE, mkconst_int(mem_width-1, true), mkconst_int(0, true)));
		wire_data->str = id_data;
		wire_data->was_checked = true;
		wire_data->is_signed = mem_signed;
		current_ast_mod->children.push_back(wire_data);
		current_scope[wire_data->str] = wire_data;
		while (wire_data->simplify(true, false, false, 1, -1, false, false)) { }

		AstNode *wire_en = nullptr;
		if (current_always->type != AST_INITIAL) {
			wire_en = new AstNode(AST_WIRE, new AstNode(AST_RANGE, mkconst_int(mem_width-1, true), mkconst_int(0, true)));
			wire_en->str = id_en;
			wire_en->was_checked = true;
			current_ast_mod->children.push_back(wire_en);
			current_scope[wire_en->str] = wire_en;
			while (wire_en->simplify(true, false, false, 1, -1, false, false)) { }
		}

		std::vector<RTLIL::State> x_bits_addr, x_bits_data, set_bits_en;
		for (int i = 0; i < addr_bits; i++)
			x_bits_addr.push_back(RTLIL::State::Sx);
		for (int i = 0; i < mem_width; i++)
			x_bits_data.push_back(RTLIL::State::Sx);
		for (int i = 0; i < mem_width; i++)
			set_bits_en.push_back(RTLIL::State::S1);

		AstNode *assign_addr = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER), mkconst_bits(x_bits_addr, false));
		assign_addr->children[0]->str = id_addr;
		assign_addr->children[0]->was_checked = true;

		AstNode *assign_data = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER), mkconst_bits(x_bits_data, false));
		assign_data->children[0]->str = id_data;
		assign_data->children[0]->was_checked = true;

		AstNode *assign_en = nullptr;
		if (current_always->type != AST_INITIAL) {
			assign_en = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER), mkconst_int(0, false, mem_width));
			assign_en->children[0]->str = id_en;
			assign_en->children[0]->was_checked = true;
		}

		AstNode *default_signals = new AstNode(AST_BLOCK);
		default_signals->children.push_back(assign_addr);
		default_signals->children.push_back(assign_data);
		if (current_always->type != AST_INITIAL)
			default_signals->children.push_back(assign_en);
		current_top_block->children.insert(current_top_block->children.begin(), default_signals);

		assign_addr = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER), children[0]->children[0]->children[0]->clone());
		assign_addr->children[0]->str = id_addr;
		assign_addr->children[0]->was_checked = true;

		if (children[0]->children.size() == 2)
		{
			if (children[0]->children[1]->range_valid)
			{
				int offset = children[0]->children[1]->range_right;
				int width = children[0]->children[1]->range_left - offset + 1;
				offset -= mem_data_range_offset;

				std::vector<RTLIL::State> padding_x(offset, RTLIL::State::Sx);

				assign_data = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER),
						new AstNode(AST_CONCAT, mkconst_bits(padding_x, false), children[1]->clone()));
				assign_data->children[0]->str = id_data;
				assign_data->children[0]->was_checked = true;

				if (current_always->type != AST_INITIAL) {
					for (int i = 0; i < mem_width; i++)
						set_bits_en[i] = offset <= i && i < offset+width ? RTLIL::State::S1 : RTLIL::State::S0;
					assign_en = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER), mkconst_bits(set_bits_en, false));
					assign_en->children[0]->str = id_en;
					assign_en->children[0]->was_checked = true;
				}
			}
			else
			{
				AstNode *the_range = children[0]->children[1];
				AstNode *left_at_zero_ast = the_range->children[0]->clone();
				AstNode *right_at_zero_ast = the_range->children.size() >= 2 ? the_range->children[1]->clone() : left_at_zero_ast->clone();
				AstNode *offset_ast = right_at_zero_ast->clone();

				if (mem_data_range_offset)
					offset_ast = new AstNode(AST_SUB, offset_ast, mkconst_int(mem_data_range_offset, true));

				while (left_at_zero_ast->simplify(true, true, false, 1, -1, false, false)) { }
				while (right_at_zero_ast->simplify(true, true, false, 1, -1, false, false)) { }
				if (left_at_zero_ast->type != AST_CONSTANT || right_at_zero_ast->type != AST_CONSTANT)
					log_file_error(filename, linenum, "Unsupported expression on dynamic range select on signal `%s'!\n", str.c_str());
				int width = abs(int(left_at_zero_ast->integer - right_at_zero_ast->integer)) + 1;

				assign_data = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER),
						new AstNode(AST_SHIFT_LEFT, children[1]->clone(), offset_ast->clone()));
				assign_data->children[0]->str = id_data;
				assign_data->children[0]->was_checked = true;

				if (current_always->type != AST_INITIAL) {
					for (int i = 0; i < mem_width; i++)
						set_bits_en[i] = i < width ? RTLIL::State::S1 : RTLIL::State::S0;
					assign_en = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER),
							new AstNode(AST_SHIFT_LEFT, mkconst_bits(set_bits_en, false), offset_ast->clone()));
					assign_en->children[0]->str = id_en;
					assign_en->children[0]->was_checked = true;
				}

				delete left_at_zero_ast;
				delete right_at_zero_ast;
				delete offset_ast;
			}
		}
		else
		{
			assign_data = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER), children[1]->clone());
			assign_data->children[0]->str = id_data;
			assign_data->children[0]->was_checked = true;

			if (current_always->type != AST_INITIAL) {
				assign_en = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER), mkconst_bits(set_bits_en, false));
				assign_en->children[0]->str = id_en;
				assign_en->children[0]->was_checked = true;
			}
		}

		newNode = new AstNode(AST_BLOCK);
		newNode->children.push_back(assign_addr);
		newNode->children.push_back(assign_data);
		if (current_always->type != AST_INITIAL)
			newNode->children.push_back(assign_en);

		AstNode *wrnode = new AstNode(current_always->type == AST_INITIAL ? AST_MEMINIT : AST_MEMWR);
		wrnode->children.push_back(new AstNode(AST_IDENTIFIER));
		wrnode->children.push_back(new AstNode(AST_IDENTIFIER));
		if (current_always->type != AST_INITIAL)
			wrnode->children.push_back(new AstNode(AST_IDENTIFIER));
		else
			wrnode->children.push_back(AstNode::mkconst_int(1, false));
		wrnode->str = children[0]->str;
		wrnode->id2ast = children[0]->id2ast;
		wrnode->children[0]->str = id_addr;
		wrnode->children[1]->str = id_data;
		if (current_always->type != AST_INITIAL)
			wrnode->children[2]->str = id_en;
		current_ast_mod->children.push_back(wrnode);

		goto apply_newNode;
	}

	// replace function and task calls with the code from the function or task
	if ((type == AST_FCALL || type == AST_TCALL) && !str.empty())
	{
		if (type == AST_FCALL)
		{
			if (str == "\\$initstate")
			{
				int myidx = autoidx++;

				AstNode *wire = new AstNode(AST_WIRE);
				wire->str = stringf("$initstate$%d_wire", myidx);
				current_ast_mod->children.push_back(wire);
				while (wire->simplify(true, false, false, 1, -1, false, false)) { }

				AstNode *cell = new AstNode(AST_CELL, new AstNode(AST_CELLTYPE), new AstNode(AST_ARGUMENT, new AstNode(AST_IDENTIFIER)));
				cell->str = stringf("$initstate$%d", myidx);
				cell->children[0]->str = "$initstate";
				cell->children[1]->str = "\\Y";
				cell->children[1]->children[0]->str = wire->str;
				cell->children[1]->children[0]->id2ast = wire;
				current_ast_mod->children.push_back(cell);
				while (cell->simplify(true, false, false, 1, -1, false, false)) { }

				newNode = new AstNode(AST_IDENTIFIER);
				newNode->str = wire->str;
				newNode->id2ast = wire;
				goto apply_newNode;
			}

			if (str == "\\$past")
			{
				if (width_hint < 0)
					goto replace_fcall_later;

				int num_steps = 1;

				if (GetSize(children) != 1 && GetSize(children) != 2)
					log_file_error(filename, linenum, "System function %s got %d arguments, expected 1 or 2.\n",
							RTLIL::unescape_id(str).c_str(), int(children.size()));

				if (!current_always_clocked)
					log_file_error(filename, linenum, "System function %s is only allowed in clocked blocks.\n",
							RTLIL::unescape_id(str).c_str());

				if (GetSize(children) == 2)
				{
					AstNode *buf = children[1]->clone();
					while (buf->simplify(true, false, false, stage, -1, false, false)) { }
					if (buf->type != AST_CONSTANT)
						log_file_error(filename, linenum, "Failed to evaluate system function `%s' with non-constant value.\n", str.c_str());

					num_steps = buf->asInt(true);
					delete buf;
				}

				AstNode *block = nullptr;

				for (auto child : current_always->children)
					if (child->type == AST_BLOCK)
						block = child;

				log_assert(block != nullptr);

				if (num_steps == 0) {
					newNode = children[0]->clone();
					goto apply_newNode;
				}

				int myidx = autoidx++;
				AstNode *outreg = nullptr;

				for (int i = 0; i < num_steps; i++)
				{
					AstNode *reg = new AstNode(AST_WIRE, new AstNode(AST_RANGE,
							mkconst_int(width_hint-1, true), mkconst_int(0, true)));

					reg->str = stringf("$past$%s:%d$%d$%d", filename.c_str(), linenum, myidx, i);
					reg->is_reg = true;

					current_ast_mod->children.push_back(reg);

					while (reg->simplify(true, false, false, 1, -1, false, false)) { }

					AstNode *regid = new AstNode(AST_IDENTIFIER);
					regid->str = reg->str;
					regid->id2ast = reg;
					regid->was_checked = true;

					AstNode *rhs = nullptr;

					if (outreg == nullptr) {
						rhs = children.at(0)->clone();
					} else {
						rhs = new AstNode(AST_IDENTIFIER);
						rhs->str = outreg->str;
						rhs->id2ast = outreg;
					}

					block->children.push_back(new AstNode(AST_ASSIGN_LE, regid, rhs));
					outreg = reg;
				}

				newNode = new AstNode(AST_IDENTIFIER);
				newNode->str = outreg->str;
				newNode->id2ast = outreg;
				goto apply_newNode;
			}

			if (str == "\\$stable" || str == "\\$rose" || str == "\\$fell" || str == "\\$changed")
			{
				if (GetSize(children) != 1)
					log_file_error(filename, linenum, "System function %s got %d arguments, expected 1.\n",
							RTLIL::unescape_id(str).c_str(), int(children.size()));

				if (!current_always_clocked)
					log_file_error(filename, linenum, "System function %s is only allowed in clocked blocks.\n",
							RTLIL::unescape_id(str).c_str());

				AstNode *present = children.at(0)->clone();
				AstNode *past = clone();
				past->str = "\\$past";

				if (str == "\\$stable")
					newNode = new AstNode(AST_EQ, past, present);

				else if (str == "\\$changed")
					newNode = new AstNode(AST_NE, past, present);

				else if (str == "\\$rose")
					newNode = new AstNode(AST_LOGIC_AND,
							new AstNode(AST_LOGIC_NOT, new AstNode(AST_BIT_AND, past, mkconst_int(1,false))),
							new AstNode(AST_BIT_AND, present, mkconst_int(1,false)));

				else if (str == "\\$fell")
					newNode = new AstNode(AST_LOGIC_AND,
							new AstNode(AST_BIT_AND, past, mkconst_int(1,false)),
							new AstNode(AST_LOGIC_NOT, new AstNode(AST_BIT_AND, present, mkconst_int(1,false))));

				else
					log_abort();

				goto apply_newNode;
			}

			// $anyconst and $anyseq are mapped in AstNode::genRTLIL()
			if (str == "\\$anyconst" || str == "\\$anyseq" || str == "\\$allconst" || str == "\\$allseq") {
				recursion_counter--;
				return false;
			}

			if (str == "\\$clog2")
			{
				if (children.size() != 1)
					log_file_error(filename, linenum, "System function %s got %d arguments, expected 1.\n",
							RTLIL::unescape_id(str).c_str(), int(children.size()));

				AstNode *buf = children[0]->clone();
				while (buf->simplify(true, false, false, stage, width_hint, sign_hint, false)) { }
				if (buf->type != AST_CONSTANT)
					log_file_error(filename, linenum, "Failed to evaluate system function `%s' with non-constant value.\n", str.c_str());

				RTLIL::Const arg_value = buf->bitsAsConst();
				if (arg_value.as_bool())
					arg_value = const_sub(arg_value, 1, false, false, GetSize(arg_value));
				delete buf;

				uint32_t result = 0;
				for (size_t i = 0; i < arg_value.bits.size(); i++)
					if (arg_value.bits.at(i) == RTLIL::State::S1)
						result = i + 1;

				newNode = mkconst_int(result, true);
				goto apply_newNode;
			}

			if (str == "\\$size" || str == "\\$bits")
			{
				if (str == "\\$bits" && children.size() != 1)
					log_file_error(filename, linenum, "System function %s got %d arguments, expected 1.\n",
							RTLIL::unescape_id(str).c_str(), int(children.size()));

				if (str == "\\$size" && children.size() != 1 && children.size() != 2)
					log_file_error(filename, linenum, "System function %s got %d arguments, expected 1 or 2.\n",
							RTLIL::unescape_id(str).c_str(), int(children.size()));

				int dim = 1;
				if (str == "\\$size" && children.size() == 2) {
					AstNode *buf = children[1]->clone();
					// Evaluate constant expression
					while (buf->simplify(true, false, false, stage, width_hint, sign_hint, false)) { }
					dim = buf->asInt(false);
					delete buf;
				}
				AstNode *buf = children[0]->clone();
				int mem_depth = 1;
				AstNode *id_ast = NULL;

				// Is this needed?
				//while (buf->simplify(true, false, false, stage, width_hint, sign_hint, false)) { }
				buf->detectSignWidth(width_hint, sign_hint);

				if (buf->type == AST_IDENTIFIER) {
					id_ast = buf->id2ast;
					if (id_ast == NULL && current_scope.count(buf->str))
						id_ast = current_scope.at(buf->str);
					if (!id_ast)
						log_file_error(filename, linenum, "Failed to resolve identifier %s for width detection!\n", buf->str.c_str());
					if (id_ast->type == AST_MEMORY) {
						// We got here only if the argument is a memory
						// Otherwise $size() and $bits() return the expression width
						AstNode *mem_range = id_ast->children[1];
						if (str == "\\$bits") {
							if (mem_range->type == AST_RANGE) {
								if (!mem_range->range_valid)
									log_file_error(filename, linenum, "Failed to detect width of memory access `%s'!\n", buf->str.c_str());
								mem_depth = mem_range->range_left - mem_range->range_right + 1;
							} else
								log_file_error(filename, linenum, "Unknown memory depth AST type in `%s'!\n", buf->str.c_str());
						} else {
							// $size()
							if (mem_range->type == AST_RANGE) {
								if (!mem_range->range_valid)
									log_file_error(filename, linenum, "Failed to detect width of memory access `%s'!\n", buf->str.c_str());
								int dims;
								if (id_ast->multirange_dimensions.empty())
									dims = 1;
								else
									dims = GetSize(id_ast->multirange_dimensions)/2;
								if (dim == 1)
									width_hint = (dims > 1) ? id_ast->multirange_dimensions[1] : (mem_range->range_left - mem_range->range_right + 1);
								else if (dim <= dims) {
									width_hint = id_ast->multirange_dimensions[2*dim-1];
								} else if ((dim > dims+1) || (dim < 0))
									log_file_error(filename, linenum, "Dimension %d out of range in `%s', as it only has dimensions 1..%d!\n", dim, buf->str.c_str(), dims+1);
							} else
								log_file_error(filename, linenum, "Unknown memory depth AST type in `%s'!\n", buf->str.c_str());
						}
					}
				}
				delete buf;

				newNode = mkconst_int(width_hint * mem_depth, false);
				goto apply_newNode;
			}

			if (str == "\\$ln" || str == "\\$log10" || str == "\\$exp" || str == "\\$sqrt" || str == "\\$pow" ||
					str == "\\$floor" || str == "\\$ceil" || str == "\\$sin" || str == "\\$cos" || str == "\\$tan" ||
					str == "\\$asin" || str == "\\$acos" || str == "\\$atan" || str == "\\$atan2" || str == "\\$hypot" ||
					str == "\\$sinh" || str == "\\$cosh" || str == "\\$tanh" || str == "\\$asinh" || str == "\\$acosh" || str == "\\$atanh" ||
					str == "\\$rtoi" || str == "\\$itor")
			{
				bool func_with_two_arguments = str == "\\$pow" || str == "\\$atan2" || str == "\\$hypot";
				double x = 0, y = 0;

				if (func_with_two_arguments) {
					if (children.size() != 2)
						log_file_error(filename, linenum, "System function %s got %d arguments, expected 2.\n",
								RTLIL::unescape_id(str).c_str(), int(children.size()));
				} else {
					if (children.size() != 1)
						log_file_error(filename, linenum, "System function %s got %d arguments, expected 1.\n",
								RTLIL::unescape_id(str).c_str(), int(children.size()));
				}

				if (children.size() >= 1) {
					while (children[0]->simplify(true, false, false, stage, width_hint, sign_hint, false)) { }
					if (!children[0]->isConst())
						log_file_error(filename, linenum, "Failed to evaluate system function `%s' with non-constant argument.\n",
								RTLIL::unescape_id(str).c_str());
					int child_width_hint = width_hint;
					bool child_sign_hint = sign_hint;
					children[0]->detectSignWidth(child_width_hint, child_sign_hint);
					x = children[0]->asReal(child_sign_hint);
				}

				if (children.size() >= 2) {
					while (children[1]->simplify(true, false, false, stage, width_hint, sign_hint, false)) { }
					if (!children[1]->isConst())
						log_file_error(filename, linenum, "Failed to evaluate system function `%s' with non-constant argument.\n",
								RTLIL::unescape_id(str).c_str());
					int child_width_hint = width_hint;
					bool child_sign_hint = sign_hint;
					children[1]->detectSignWidth(child_width_hint, child_sign_hint);
					y = children[1]->asReal(child_sign_hint);
				}

				if (str == "\\$rtoi") {
					newNode = AstNode::mkconst_int(x, true);
				} else {
					newNode = new AstNode(AST_REALVALUE);
					if (str == "\\$ln")         newNode->realvalue = ::log(x);
					else if (str == "\\$log10") newNode->realvalue = ::log10(x);
					else if (str == "\\$exp")   newNode->realvalue = ::exp(x);
					else if (str == "\\$sqrt")  newNode->realvalue = ::sqrt(x);
					else if (str == "\\$pow")   newNode->realvalue = ::pow(x, y);
					else if (str == "\\$floor") newNode->realvalue = ::floor(x);
					else if (str == "\\$ceil")  newNode->realvalue = ::ceil(x);
					else if (str == "\\$sin")   newNode->realvalue = ::sin(x);
					else if (str == "\\$cos")   newNode->realvalue = ::cos(x);
					else if (str == "\\$tan")   newNode->realvalue = ::tan(x);
					else if (str == "\\$asin")  newNode->realvalue = ::asin(x);
					else if (str == "\\$acos")  newNode->realvalue = ::acos(x);
					else if (str == "\\$atan")  newNode->realvalue = ::atan(x);
					else if (str == "\\$atan2") newNode->realvalue = ::atan2(x, y);
					else if (str == "\\$hypot") newNode->realvalue = ::hypot(x, y);
					else if (str == "\\$sinh")  newNode->realvalue = ::sinh(x);
					else if (str == "\\$cosh")  newNode->realvalue = ::cosh(x);
					else if (str == "\\$tanh")  newNode->realvalue = ::tanh(x);
					else if (str == "\\$asinh") newNode->realvalue = ::asinh(x);
					else if (str == "\\$acosh") newNode->realvalue = ::acosh(x);
					else if (str == "\\$atanh") newNode->realvalue = ::atanh(x);
					else if (str == "\\$itor")  newNode->realvalue = x;
					else log_abort();
				}
				goto apply_newNode;
			}

			if (current_scope.count(str) != 0 && current_scope[str]->type == AST_DPI_FUNCTION)
			{
				AstNode *dpi_decl = current_scope[str];

				std::string rtype, fname;
				std::vector<std::string> argtypes;
				std::vector<AstNode*> args;

				rtype = RTLIL::unescape_id(dpi_decl->children.at(0)->str);
				fname = RTLIL::unescape_id(dpi_decl->children.at(1)->str);

				for (int i = 2; i < GetSize(dpi_decl->children); i++)
				{
					if (i-2 >= GetSize(children))
						log_file_error(filename, linenum, "Insufficient number of arguments in DPI function call.\n");

					argtypes.push_back(RTLIL::unescape_id(dpi_decl->children.at(i)->str));
					args.push_back(children.at(i-2)->clone());
					while (args.back()->simplify(true, false, false, stage, -1, false, true)) { }

					if (args.back()->type != AST_CONSTANT && args.back()->type != AST_REALVALUE)
						log_file_error(filename, linenum, "Failed to evaluate DPI function with non-constant argument.\n");
				}

				newNode = dpi_call(rtype, fname, argtypes, args);

				for (auto arg : args)
					delete arg;

				goto apply_newNode;
			}

			if (current_scope.count(str) == 0 || current_scope[str]->type != AST_FUNCTION)
				log_file_error(filename, linenum, "Can't resolve function name `%s'.\n", str.c_str());
		}

		if (type == AST_TCALL)
		{
			if (str == "$finish" || str == "$stop")
			{
				if (!current_always || current_always->type != AST_INITIAL)
					log_file_error(filename, linenum, "System task `%s' outside initial block is unsupported.\n", str.c_str());

				log_file_error(filename, linenum, "System task `%s' executed.\n", str.c_str());
			}

			if (str == "\\$readmemh" || str == "\\$readmemb")
			{
				if (GetSize(children) < 2 || GetSize(children) > 4)
					log_file_error(filename, linenum, "System function %s got %d arguments, expected 2-4.\n",
							RTLIL::unescape_id(str).c_str(), int(children.size()));

				AstNode *node_filename = children[0]->clone();
				while (node_filename->simplify(true, false, false, stage, width_hint, sign_hint, false)) { }
				if (node_filename->type != AST_CONSTANT)
					log_file_error(filename, linenum, "Failed to evaluate system function `%s' with non-constant 1st argument.\n", str.c_str());

				AstNode *node_memory = children[1]->clone();
				while (node_memory->simplify(true, false, false, stage, width_hint, sign_hint, false)) { }
				if (node_memory->type != AST_IDENTIFIER || node_memory->id2ast == nullptr || node_memory->id2ast->type != AST_MEMORY)
					log_file_error(filename, linenum, "Failed to evaluate system function `%s' with non-memory 2nd argument.\n", str.c_str());

				int start_addr = -1, finish_addr = -1;

				if (GetSize(children) > 2) {
					AstNode *node_addr = children[2]->clone();
					while (node_addr->simplify(true, false, false, stage, width_hint, sign_hint, false)) { }
					if (node_addr->type != AST_CONSTANT)
						log_file_error(filename, linenum, "Failed to evaluate system function `%s' with non-constant 3rd argument.\n", str.c_str());
					start_addr = int(node_addr->asInt(false));
				}

				if (GetSize(children) > 3) {
					AstNode *node_addr = children[3]->clone();
					while (node_addr->simplify(true, false, false, stage, width_hint, sign_hint, false)) { }
					if (node_addr->type != AST_CONSTANT)
						log_file_error(filename, linenum, "Failed to evaluate system function `%s' with non-constant 4th argument.\n", str.c_str());
					finish_addr = int(node_addr->asInt(false));
				}

				bool unconditional_init = false;
				if (current_always->type == AST_INITIAL) {
					pool<AstNode*> queue;
					log_assert(current_always->children[0]->type == AST_BLOCK);
					queue.insert(current_always->children[0]);
					while (!unconditional_init && !queue.empty()) {
						pool<AstNode*> next_queue;
						for (auto n : queue)
						for (auto c : n->children) {
							if (c == this)
								unconditional_init = true;
							next_queue.insert(c);
						}
						next_queue.swap(queue);
					}
				}

				newNode = readmem(str == "\\$readmemh", node_filename->bitsAsConst().decode_string(), node_memory->id2ast, start_addr, finish_addr, unconditional_init);
				delete node_filename;
				delete node_memory;
				goto apply_newNode;
			}

			if (current_scope.count(str) == 0 || current_scope[str]->type != AST_TASK)
				log_file_error(filename, linenum, "Can't resolve task name `%s'.\n", str.c_str());
		}

		AstNode *decl = current_scope[str];

		std::stringstream sstr;
		sstr << "$func$" << str << "$" << filename << ":" << linenum << "$" << (autoidx++) << "$";
		std::string prefix = sstr.str();

		bool recommend_const_eval = false;
		bool require_const_eval = in_param ? false : has_const_only_constructs(recommend_const_eval);
		if ((in_param || recommend_const_eval || require_const_eval) && !decl->attributes.count("\\via_celltype"))
		{
			bool all_args_const = true;
			for (auto child : children) {
				while (child->simplify(true, false, false, 1, -1, false, true)) { }
				if (child->type != AST_CONSTANT)
					all_args_const = false;
			}

			if (all_args_const) {
				AstNode *func_workspace = current_scope[str]->clone();
				newNode = func_workspace->eval_const_function(this);
				delete func_workspace;
				goto apply_newNode;
			}

			if (in_param)
				log_file_error(filename, linenum, "Non-constant function call in constant expression.\n");
			if (require_const_eval)
				log_file_error(filename, linenum, "Function %s can only be called with constant arguments.\n", str.c_str());
		}

		size_t arg_count = 0;
		std::map<std::string, std::string> replace_rules;
		vector<AstNode*> added_mod_children;
		dict<std::string, AstNode*> wire_cache;
		vector<AstNode*> new_stmts;
		vector<AstNode*> output_assignments;

		if (current_block == NULL)
		{
			log_assert(type == AST_FCALL);

			AstNode *wire = NULL;
			for (auto child : decl->children)
				if (child->type == AST_WIRE && child->str == str)
					wire = child->clone();
			log_assert(wire != NULL);

			wire->str = prefix + str;
			wire->port_id = 0;
			wire->is_input = false;
			wire->is_output = false;

			current_ast_mod->children.push_back(wire);
			while (wire->simplify(true, false, false, 1, -1, false, false)) { }

			AstNode *lvalue = new AstNode(AST_IDENTIFIER);
			lvalue->str = wire->str;

			AstNode *always = new AstNode(AST_ALWAYS, new AstNode(AST_BLOCK,
					new AstNode(AST_ASSIGN_EQ, lvalue, clone())));
			always->children[0]->children[0]->was_checked = true;

			current_ast_mod->children.push_back(always);

			goto replace_fcall_with_id;
		}

		if (decl->attributes.count("\\via_celltype"))
		{
			std::string celltype = decl->attributes.at("\\via_celltype")->asAttrConst().decode_string();
			std::string outport = str;

			if (celltype.find(' ') != std::string::npos) {
				int pos = celltype.find(' ');
				outport = RTLIL::escape_id(celltype.substr(pos+1));
				celltype = RTLIL::escape_id(celltype.substr(0, pos));
			} else
				celltype = RTLIL::escape_id(celltype);

			AstNode *cell = new AstNode(AST_CELL, new AstNode(AST_CELLTYPE));
			cell->str = prefix.substr(0, GetSize(prefix)-1);
			cell->children[0]->str = celltype;

			for (auto attr : decl->attributes)
				if (attr.first.str().rfind("\\via_celltype_defparam_", 0) == 0)
				{
					AstNode *cell_arg = new AstNode(AST_PARASET, attr.second->clone());
					cell_arg->str = RTLIL::escape_id(attr.first.substr(strlen("\\via_celltype_defparam_")));
					cell->children.push_back(cell_arg);
				}

			for (auto child : decl->children)
				if (child->type == AST_WIRE && (child->is_input || child->is_output || (type == AST_FCALL && child->str == str)))
				{
					AstNode *wire = child->clone();
					wire->str = prefix + wire->str;
					wire->port_id = 0;
					wire->is_input = false;
					wire->is_output = false;
					current_ast_mod->children.push_back(wire);
					while (wire->simplify(true, false, false, 1, -1, false, false)) { }

					AstNode *wire_id = new AstNode(AST_IDENTIFIER);
					wire_id->str = wire->str;

					if ((child->is_input || child->is_output) && arg_count < children.size())
					{
						AstNode *arg = children[arg_count++]->clone();
						AstNode *assign = child->is_input ?
								new AstNode(AST_ASSIGN_EQ, wire_id->clone(), arg) :
								new AstNode(AST_ASSIGN_EQ, arg, wire_id->clone());
						assign->children[0]->was_checked = true;

						for (auto it = current_block->children.begin(); it != current_block->children.end(); it++) {
							if (*it != current_block_child)
								continue;
							current_block->children.insert(it, assign);
							break;
						}
					}

					AstNode *cell_arg = new AstNode(AST_ARGUMENT, wire_id);
					cell_arg->str = child->str == str ? outport : child->str;
					cell->children.push_back(cell_arg);
				}

			current_ast_mod->children.push_back(cell);
			goto replace_fcall_with_id;
		}

		for (auto child : decl->children)
			if (child->type == AST_WIRE || child->type == AST_MEMORY || child->type == AST_PARAMETER || child->type == AST_LOCALPARAM)
			{
				AstNode *wire = nullptr;

				if (wire_cache.count(child->str))
				{
					wire = wire_cache.at(child->str);
					if (wire->children.empty()) {
						for (auto c : child->children)
							wire->children.push_back(c->clone());
					} else if (!child->children.empty()) {
						while (child->simplify(true, false, false, stage, -1, false, false)) { }
						if (GetSize(child->children) == GetSize(wire->children)) {
							for (int i = 0; i < GetSize(child->children); i++)
								if (*child->children.at(i) != *wire->children.at(i))
									goto tcall_incompatible_wires;
						} else {
					tcall_incompatible_wires:
							log_file_error(filename, linenum, "Incompatible re-declaration of wire %s.\n", child->str.c_str());
						}
					}
				}
				else
				{
					wire = child->clone();
					wire->str = prefix + wire->str;
					wire->port_id = 0;
					wire->is_input = false;
					wire->is_output = false;
					wire->is_reg = true;
					wire->attributes["\\nosync"] = AstNode::mkconst_int(1, false);
					wire_cache[child->str] = wire;

					current_ast_mod->children.push_back(wire);
					added_mod_children.push_back(wire);
				}

				if (child->type == AST_WIRE)
					while (wire->simplify(true, false, false, 1, -1, false, false)) { }

				replace_rules[child->str] = wire->str;
				current_scope[wire->str] = wire;

				if ((child->is_input || child->is_output) && arg_count < children.size())
				{
					AstNode *arg = children[arg_count++]->clone();
					AstNode *wire_id = new AstNode(AST_IDENTIFIER);
					wire_id->str = wire->str;
					AstNode *assign = child->is_input ?
							new AstNode(AST_ASSIGN_EQ, wire_id, arg) :
							new AstNode(AST_ASSIGN_EQ, arg, wire_id);
					assign->children[0]->was_checked = true;
					if (child->is_input)
						new_stmts.push_back(assign);
					else
						output_assignments.push_back(assign);
				}
			}

		for (auto child : added_mod_children) {
			child->replace_ids(prefix, replace_rules);
			while (child->simplify(true, false, false, 1, -1, false, false)) { }
		}

		for (auto child : decl->children)
			if (child->type != AST_WIRE && child->type != AST_MEMORY && child->type != AST_PARAMETER && child->type != AST_LOCALPARAM)
			{
				AstNode *stmt = child->clone();
				stmt->replace_ids(prefix, replace_rules);
				new_stmts.push_back(stmt);
			}

		new_stmts.insert(new_stmts.end(), output_assignments.begin(), output_assignments.end());

		for (auto it = current_block->children.begin(); ; it++) {
			log_assert(it != current_block->children.end());