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/*
* Copyright (c) 2000-2011 Stephen Williams (steve@icarus.com)
*
* This source code is free software; you can redistribute it
* and/or modify it in source code form under the terms of the GNU
* General Public License as published by the Free Software
* Foundation; either version 2 of the License, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
# include "config.h"
# include "PExpr.h"
# include "netlist.h"
# include "netmisc.h"
# include "compiler.h"
# include <cstdlib>
# include <iostream>
# include <climits>
# include "ivl_assert.h"
/*
* These methods generate a NetAssign_ object for the l-value of the
* assignment. This is common code for the = and <= statements.
*
* What gets generated depends on the structure of the l-value. If the
* l-value is a simple name (i.e., foo <= <value>) then the NetAssign_
* is created the width of the foo reg and connected to all the
* bits.
*
* If there is a part select (i.e., foo[3:1] <= <value>) the NetAssign_
* is made only as wide as it needs to be (3 bits in this example) and
* connected to the correct bits of foo. A constant bit select is a
* special case of the part select.
*
* If the bit-select is non-constant (i.e., foo[<expr>] = <value>) the
* NetAssign_ is made wide enough to connect to all the bits of foo,
* then the mux expression is elaborated and attached to the
* NetAssign_ node as a b_mux value. The target must interpret the
* presence of a bmux value as taking a single bit and assigning it to
* the bit selected by the bmux expression.
*
* If the l-value expression is non-trivial, but can be fully
* evaluated at compile time (meaning any bit selects are constant)
* then elaboration will make a single NetAssign_ that connects to a
* synthetic reg that in turn connects to all the proper pins of the
* l-value.
*
* This last case can turn up in statements like: {a, b[1]} = c;
* rather than create a NetAssign_ for each item in the concatenation,
* elaboration makes a single NetAssign_ and connects it up properly.
*/
/*
* The default interpretation of an l-value to a procedural assignment
* is to try to make a net elaboration, and see if the result is
* suitable for assignment.
*/
NetAssign_* PExpr::elaborate_lval(Design*, NetScope*, bool) const
{
NetNet*ll = 0;
if (ll == 0) {
cerr << get_fileline() << ": Assignment l-value too complex."
<< endl;
return 0;
}
NetAssign_*lv = new NetAssign_(ll);
return lv;
}
/*
* Concatenation expressions can appear as l-values. Handle them here.
*
* If adjacent l-values in the concatenation are not bit selects, then
* merge them into a single NetAssign_ object. This can happen is code
* like ``{ ...a, b, ...}''. As long as "a" and "b" do not have bit
* selects (or the bit selects are constant) we can merge the
* NetAssign_ objects.
*
* Be careful to get the bit order right. In the expression ``{a, b}''
* a is the MSB and b the LSB. Connect the LSB to the low pins of the
* NetAssign_ object.
*/
NetAssign_* PEConcat::elaborate_lval(Design*des,
NetScope*scope,
bool is_force) const
{
if (repeat_) {
cerr << get_fileline() << ": error: Repeat concatenations make "
"no sense in l-value expressions. I refuse." << endl;
des->errors += 1;
return 0;
}
NetAssign_*res = 0;
for (unsigned idx = 0 ; idx < parms_.size() ; idx += 1) {
if (parms_[idx] == 0) {
cerr << get_fileline() << ": error: Empty expressions "
<< "not allowed in concatenations." << endl;
des->errors += 1;
continue;
}
NetAssign_*tmp = parms_[idx]->elaborate_lval(des, scope, is_force);
if (tmp->expr_type() == IVL_VT_REAL) {
cerr << parms_[idx]->get_fileline() << ": error: "
<< "concatenation operand can not be real: "
<< *parms_[idx] << endl;
des->errors += 1;
continue;
}
/* If the l-value doesn't elaborate, the error was
already detected and printed. We just skip it and let
the compiler catch more errors. */
if (tmp == 0) continue;
/* Link the new l-value to the previous one. */
NetAssign_*last = tmp;
while (last->more)
last = last->more;
last->more = res;
res = tmp;
}
return res;
}
/*
* Handle the ident as an l-value. This includes bit and part selects
* of that ident.
*/
NetAssign_* PEIdent::elaborate_lval(Design*des,
NetScope*scope,
bool is_force) const
{
NetNet* reg = 0;
const NetExpr*par = 0;
NetEvent* eve = 0;
symbol_search(this, des, scope, path_, reg, par, eve);
if (reg == 0) {
cerr << get_fileline() << ": error: Could not find variable ``"
<< path_ << "'' in ``" << scope_path(scope) <<
"''" << endl;
des->errors += 1;
return 0;
}
ivl_assert(*this, reg);
const name_component_t&name_tail = path_.back();
index_component_t::ctype_t use_sel = index_component_t::SEL_NONE;
if (!name_tail.index.empty())
use_sel = name_tail.index.back().sel;
// This is the special case that the l-value is an entire
// memory. This is, in fact, an error.
if (reg->array_dimensions() > 0 && name_tail.index.empty()) {
cerr << get_fileline() << ": error: Cannot assign to array "
<< path_ << ". Did you forget a word index?" << endl;
des->errors += 1;
return 0;
}
/* Get the signal referenced by the identifier, and make sure
it is a register. Wires are not allows in this context,
unless this is the l-value of a force. */
if ((reg->type() != NetNet::REG) && !is_force) {
cerr << get_fileline() << ": error: " << path_ <<
" is not a valid l-value in " << scope_path(scope) <<
"." << endl;
cerr << reg->get_fileline() << ": : " << path_ <<
" is declared here as " << reg->type() << "." << endl;
des->errors += 1;
return 0;
}
if (reg->array_dimensions() > 0)
return elaborate_lval_net_word_(des, scope, reg);
// This must be after the array word elaboration above!
if (reg->get_scalar() &&
use_sel != index_component_t::SEL_NONE) {
cerr << get_fileline() << ": error: can not select part of ";
if (reg->data_type() == IVL_VT_REAL) cerr << "real: ";
else cerr << "scalar: ";
cerr << reg->name() << endl;
des->errors += 1;
return 0;
}
if (use_sel == index_component_t::SEL_PART) {
NetAssign_*lv = new NetAssign_(reg);
elaborate_lval_net_part_(des, scope, lv);
return lv;
}
if (use_sel == index_component_t::SEL_IDX_UP ||
use_sel == index_component_t::SEL_IDX_DO) {
NetAssign_*lv = new NetAssign_(reg);
elaborate_lval_net_idx_(des, scope, lv, use_sel);
return lv;
}
if (use_sel == index_component_t::SEL_BIT) {
NetAssign_*lv = new NetAssign_(reg);
elaborate_lval_net_bit_(des, scope, lv);
return lv;
}
ivl_assert(*this, use_sel == index_component_t::SEL_NONE);
/* No select expressions. */
NetAssign_*lv = new NetAssign_(reg);
return lv;
}
NetAssign_* PEIdent::elaborate_lval_net_word_(Design*des,
NetScope*scope,
NetNet*reg) const
{
const name_component_t&name_tail = path_.back();
ivl_assert(*this, !name_tail.index.empty());
const index_component_t&index_head = name_tail.index.front();
if (index_head.sel == index_component_t::SEL_PART) {
cerr << get_fileline() << ": error: cannot perform a part "
<< "select on array " << reg->name() << "." << endl;
des->errors += 1;
return 0;
}
ivl_assert(*this, index_head.sel == index_component_t::SEL_BIT);
ivl_assert(*this, index_head.msb != 0);
ivl_assert(*this, index_head.lsb == 0);
NetExpr*word = elab_and_eval(des, scope, index_head.msb, -1);
// If there is a non-zero base to the memory, then build an
// expression to calculate the canonical address.
if (long base = reg->array_first()) {
word = normalize_variable_array_base(word, base,
reg->array_count());
eval_expr(word);
}
NetAssign_*lv = new NetAssign_(reg);
lv->set_word(word);
if (debug_elaborate)
cerr << get_fileline() << ": debug: Set array word=" << *word << endl;
// Test for the case that the index is a constant, and is out
// of bounds. The "word" expression is the word index already
// converted to canonical address, so this just needs to check
// that the address is not too big.
if (NetEConst*word_const = dynamic_cast<NetEConst*>(word)) {
verinum word_val = word_const->value();
long index = word_val.as_long();
if (index < 0 || index >= (long) reg->array_count()) {
cerr << get_fileline() << ": warning: Constant array index "
<< (index + reg->array_first())
<< " is out of range for array "
<< reg->name() << "." << endl;
}
}
/* An array word may also have part selects applied to them. */
index_component_t::ctype_t use_sel = index_component_t::SEL_NONE;
if (name_tail.index.size() > 1)
use_sel = name_tail.index.back().sel;
if (reg->get_scalar() &&
use_sel != index_component_t::SEL_NONE) {
cerr << get_fileline() << ": error: can not select part of ";
if (reg->data_type() == IVL_VT_REAL) cerr << "real";
else cerr << "scalar";
cerr << " array word: " << reg->name()
<< "[" << *word << "]" << endl;
des->errors += 1;
return 0;
}
if (use_sel == index_component_t::SEL_BIT)
elaborate_lval_net_bit_(des, scope, lv);
if (use_sel == index_component_t::SEL_PART)
elaborate_lval_net_part_(des, scope, lv);
if (use_sel == index_component_t::SEL_IDX_UP ||
use_sel == index_component_t::SEL_IDX_DO)
elaborate_lval_net_idx_(des, scope, lv, use_sel);
return lv;
}
bool PEIdent::elaborate_lval_net_bit_(Design*des,
NetScope*scope,
NetAssign_*lv) const
{
const name_component_t&name_tail = path_.back();
const index_component_t&index_tail = name_tail.index.back();
ivl_assert(*this, index_tail.msb != 0);
ivl_assert(*this, index_tail.lsb == 0);
NetNet*reg = lv->sig();
// Bit selects have a single select expression. Evaluate the
// constant value and treat it as a part select with a bit
// width of 1.
NetExpr*mux = elab_and_eval(des, scope, index_tail.msb, -1);
long lsb = 0;
if (NetEConst*index_con = dynamic_cast<NetEConst*> (mux)) {
lsb = index_con->value().as_long();
mux = 0;
}
if (mux) {
// Non-constant bit mux. Correct the mux for the range
// of the vector, then set the l-value part select expression.
mux = normalize_variable_base(mux, reg->msb(), reg->lsb(), 1, true);
lv->set_part(mux, 1);
} else if (lsb == reg->msb() && lsb == reg->lsb()) {
// Constant bit mux that happens to select the only bit
// of the l-value. Don't bother with any select at all.
} else {
// Constant bit select that does something useful.
long loff = reg->sb_to_idx(lsb);
if (loff < 0 || loff >= (long)reg->vector_width()) {
cerr << get_fileline() << ": error: bit select "
<< reg->name() << "[" <<lsb<<"]"
<< " is out of range." << endl;
des->errors += 1;
return 0;
}
lv->set_part(new NetEConst(verinum(loff)), 1);
}
return true;
}
bool PEIdent::elaborate_lval_net_part_(Design*des,
NetScope*scope,
NetAssign_*lv) const
{
// The range expressions of a part select must be
// constant. The calculate_parts_ function calculates the
// values into msb and lsb.
long msb, lsb;
bool parts_defined_flag;
bool flag = calculate_parts_(des, scope, msb, lsb, parts_defined_flag);
if (!flag)
return false;
ivl_assert(*this, parts_defined_flag);
NetNet*reg = lv->sig();
assert(reg);
if (msb == reg->msb() && lsb == reg->lsb()) {
/* Part select covers the entire vector. Simplest case. */
} else {
/* Get the canonical offsets into the vector. */
long loff = reg->sb_to_idx(lsb);
long moff = reg->sb_to_idx(msb);
long wid = moff - loff + 1;
if (moff < loff) {
cerr << get_fileline() << ": error: part select "
<< reg->name() << "[" << msb<<":"<<lsb<<"]"
<< " is reversed." << endl;
des->errors += 1;
return false;
}
/* If the part select extends beyond the extremes of the
variable, then report an error. Note that loff is
converted to normalized form so is relative the
variable pins. */
if (loff < 0 || moff >= (signed)reg->vector_width()) {
cerr << get_fileline() << ": warning: Part select "
<< reg->name() << "[" << msb<<":"<<lsb<<"]"
<< " is out of range." << endl;
}
lv->set_part(new NetEConst(verinum(loff)), wid);
}
return true;
}
bool PEIdent::elaborate_lval_net_idx_(Design*des,
NetScope*scope,
NetAssign_*lv,
index_component_t::ctype_t use_sel) const
{
const name_component_t&name_tail = path_.back();;
ivl_assert(*this, !name_tail.index.empty());
const index_component_t&index_tail = name_tail.index.back();
ivl_assert(*this, index_tail.msb != 0);
ivl_assert(*this, index_tail.lsb != 0);
NetNet*reg = lv->sig();
assert(reg);
if (reg->type() != NetNet::REG) {
cerr << get_fileline() << ": error: " << path_ <<
" is not a reg/integer/time in " << scope_path(scope) <<
"." << endl;
cerr << reg->get_fileline() << ": : " << path_ <<
" is declared here as " << reg->type() << "." << endl;
des->errors += 1;
return false;
}
unsigned long wid;
calculate_up_do_width_(des, scope, wid);
NetExpr*base = elab_and_eval(des, scope, index_tail.msb, -1);
ivl_select_type_t sel_type = IVL_SEL_OTHER;
// Handle the special case that the base is constant. For this
// case we can reduce the expression.
if (NetEConst*base_c = dynamic_cast<NetEConst*> (base)) {
// For the undefined case just let the constant pass and
// we will handle it in the code generator.
if (base_c->value().is_defined()) {
long lsv = base_c->value().as_long();
long offset = 0;
if (((reg->msb() < reg->lsb()) &&
use_sel == index_component_t::SEL_IDX_UP) ||
((reg->msb() > reg->lsb()) &&
use_sel == index_component_t::SEL_IDX_DO)) {
offset = -wid + 1;
}
delete base;
long rel_base = reg->sb_to_idx(lsv) + offset;
/* If we cover the entire lvalue just skip the select. */
if (rel_base == 0 && wid == reg->vector_width()) return true;
base = new NetEConst(verinum(rel_base));
if (warn_ob_select) {
if (rel_base < 0) {
cerr << get_fileline() << ": warning: " << reg->name();
if (reg->array_dimensions() > 0) cerr << "[]";
cerr << "[" << lsv;
if (use_sel == index_component_t::SEL_IDX_UP) {
cerr << "+:";
} else {
cerr << "-:";
}
cerr << wid << "] is selecting before vector." << endl;
}
if (rel_base + wid > reg->vector_width()) {
cerr << get_fileline() << ": warning: " << reg->name();
if (reg->array_dimensions() > 0) cerr << "[]";
cerr << "[" << lsv;
if (use_sel == index_component_t::SEL_IDX_UP) {
cerr << "+:";
} else {
cerr << "-:";
}
cerr << wid << "] is selecting after vector." << endl;
}
}
} else {
if (warn_ob_select) {
cerr << get_fileline() << ": warning: " << reg->name();
if (reg->array_dimensions() > 0) cerr << "[]";
cerr << "['bx";
if (use_sel == index_component_t::SEL_IDX_UP) {
cerr << "+:";
} else {
cerr << "-:";
}
cerr << wid << "] is always outside vector." << endl;
}
}
} else {
/* Correct the mux for the range of the vector. */
if (use_sel == index_component_t::SEL_IDX_UP) {
base = normalize_variable_base(base, reg->msb(), reg->lsb(),
wid, true);
sel_type = IVL_SEL_IDX_UP;
} else {
// This is assumed to be a SEL_IDX_DO.
base = normalize_variable_base(base, reg->msb(), reg->lsb(),
wid, false);
sel_type = IVL_SEL_IDX_DOWN;
}
}
if (debug_elaborate)
cerr << get_fileline() << ": debug: Set part select width="
<< wid << ", base=" << *base << endl;
lv->set_part(base, wid, sel_type);
return true;
}
NetAssign_* PENumber::elaborate_lval(Design*des, NetScope*, bool) const
{
cerr << get_fileline() << ": error: Constant values not allowed "
<< "in l-value expressions." << endl;
des->errors += 1;
return 0;
}
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