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yosys/kernel/celledges.cc
George Rennie 4fbb2bc1f3 celledges: use capped shift width
2025-04-26 18:34:21 +02:00

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/*
* yosys -- Yosys Open SYnthesis Suite
*
* Copyright (C) 2012 Claire Xenia Wolf <claire@yosyshq.com>
*
* 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.
*
*/
#include "kernel/celledges.h"
USING_YOSYS_NAMESPACE
PRIVATE_NAMESPACE_BEGIN
void bitwise_unary_op(AbstractCellEdgesDatabase *db, RTLIL::Cell *cell)
{
bool is_signed = (cell->type != ID($buf)) && cell->getParam(ID::A_SIGNED).as_bool();
int a_width = GetSize(cell->getPort(ID::A));
int y_width = GetSize(cell->getPort(ID::Y));
for (int i = 0; i < y_width; i++)
{
if (i < a_width)
db->add_edge(cell, ID::A, i, ID::Y, i, -1);
else if (is_signed && a_width > 0)
db->add_edge(cell, ID::A, a_width-1, ID::Y, i, -1);
}
}
void bitwise_binary_op(AbstractCellEdgesDatabase *db, RTLIL::Cell *cell)
{
bool is_signed = cell->getParam(ID::A_SIGNED).as_bool();
int a_width = GetSize(cell->getPort(ID::A));
int b_width = GetSize(cell->getPort(ID::B));
int y_width = GetSize(cell->getPort(ID::Y));
if (cell->type == ID($and) && !is_signed) {
if (a_width > b_width)
a_width = b_width;
else
b_width = a_width;
}
for (int i = 0; i < y_width; i++)
{
if (i < a_width)
db->add_edge(cell, ID::A, i, ID::Y, i, -1);
else if (is_signed && a_width > 0)
db->add_edge(cell, ID::A, a_width-1, ID::Y, i, -1);
if (i < b_width)
db->add_edge(cell, ID::B, i, ID::Y, i, -1);
else if (is_signed && b_width > 0)
db->add_edge(cell, ID::B, b_width-1, ID::Y, i, -1);
}
}
void arith_neg_op(AbstractCellEdgesDatabase *db, RTLIL::Cell *cell)
{
bool is_signed = cell->getParam(ID::A_SIGNED).as_bool();
int a_width = GetSize(cell->getPort(ID::A));
int y_width = GetSize(cell->getPort(ID::Y));
if (is_signed && a_width == 1)
y_width = std::min(y_width, 1);
for (int i = 0; i < y_width; i++)
for (int k = 0; k <= i && k < a_width; k++)
db->add_edge(cell, ID::A, k, ID::Y, i, -1);
}
void arith_binary_op(AbstractCellEdgesDatabase *db, RTLIL::Cell *cell)
{
bool is_signed = cell->getParam(ID::A_SIGNED).as_bool();
int a_width = GetSize(cell->getPort(ID::A));
int b_width = GetSize(cell->getPort(ID::B));
int y_width = GetSize(cell->getPort(ID::Y));
if (!is_signed && cell->type != ID($sub)) {
int ab_width = std::max(a_width, b_width);
y_width = std::min(y_width, ab_width+1);
}
for (int i = 0; i < y_width; i++)
{
for (int k = 0; k <= i; k++)
{
if (k < a_width)
db->add_edge(cell, ID::A, k, ID::Y, i, -1);
if (k < b_width)
db->add_edge(cell, ID::B, k, ID::Y, i, -1);
}
}
}
void reduce_op(AbstractCellEdgesDatabase *db, RTLIL::Cell *cell)
{
int a_width = GetSize(cell->getPort(ID::A));
for (int i = 0; i < a_width; i++)
db->add_edge(cell, ID::A, i, ID::Y, 0, -1);
}
void compare_op(AbstractCellEdgesDatabase *db, RTLIL::Cell *cell)
{
int a_width = GetSize(cell->getPort(ID::A));
int b_width = GetSize(cell->getPort(ID::B));
for (int i = 0; i < a_width; i++)
db->add_edge(cell, ID::A, i, ID::Y, 0, -1);
for (int i = 0; i < b_width; i++)
db->add_edge(cell, ID::B, i, ID::Y, 0, -1);
}
void mux_op(AbstractCellEdgesDatabase *db, RTLIL::Cell *cell)
{
int a_width = GetSize(cell->getPort(ID::A));
int b_width = GetSize(cell->getPort(ID::B));
int s_width = GetSize(cell->getPort(ID::S));
for (int i = 0; i < a_width; i++)
{
db->add_edge(cell, ID::A, i, ID::Y, i, -1);
for (int k = i; k < b_width; k += a_width)
db->add_edge(cell, ID::B, k, ID::Y, i, -1);
for (int k = 0; k < s_width; k++)
db->add_edge(cell, ID::S, k, ID::Y, i, -1);
}
}
void bmux_op(AbstractCellEdgesDatabase *db, RTLIL::Cell *cell)
{
int width = GetSize(cell->getPort(ID::Y));
int a_width = GetSize(cell->getPort(ID::A));
int s_width = GetSize(cell->getPort(ID::S));
for (int i = 0; i < width; i++)
{
for (int k = i; k < a_width; k += width)
db->add_edge(cell, ID::A, k, ID::Y, i, -1);
for (int k = 0; k < s_width; k++)
db->add_edge(cell, ID::S, k, ID::Y, i, -1);
}
}
void demux_op(AbstractCellEdgesDatabase *db, RTLIL::Cell *cell)
{
int width = GetSize(cell->getPort(ID::Y));
int a_width = GetSize(cell->getPort(ID::A));
int s_width = GetSize(cell->getPort(ID::S));
for (int i = 0; i < width; i++)
{
db->add_edge(cell, ID::A, i % a_width, ID::Y, i, -1);
for (int k = 0; k < s_width; k++)
db->add_edge(cell, ID::S, k, ID::Y, i, -1);
}
}
void shift_op(AbstractCellEdgesDatabase *db, RTLIL::Cell *cell)
{
bool is_signed = cell->getParam(ID::A_SIGNED).as_bool();
bool is_b_signed = cell->getParam(ID::B_SIGNED).as_bool();
int a_width = GetSize(cell->getPort(ID::A));
int b_width = GetSize(cell->getPort(ID::B));
int y_width = GetSize(cell->getPort(ID::Y));
// Behavior of the different shift cells:
//
// $shl, $sshl -- shifts left by the amount on B port, B always unsigned
// $shr, $sshr -- ditto right
// $shift, $shiftx -- shifts right by the amount on B port, B optionally signed
//
// Sign extension (if A signed):
//
// $shl, $shr, $shift -- only sign-extends up to size of Y, then shifts in zeroes
// $sshl, $sshr -- fully sign-extends
// $shiftx -- no sign extension
//
// Because $shl, $sshl only shift left, and $shl sign-extens up to size of Y, they
// are effectively the same.
// the cap below makes sure we don't overflow in the arithmetic further down, though
// it makes the edge data invalid once a_width approaches the order of 2**30
// (that ever happening is considered improbable)
int b_width_capped = min(b_width, 30);
int b_high, b_low;
if (!is_b_signed) {
b_high = (1 << b_width_capped) - 1;
b_low = 0;
} else {
b_high = (1 << (b_width_capped - 1)) - 1;
b_low = -(1 << (b_width_capped - 1));
}
for (int i = 0; i < y_width; i++){
// highest position of Y that can change with the value of B
int b_range_upper = 0;
// 1 + highest position of A that can be moved to Y[i]
int a_range_upper;
// lowest position of A that can be moved to Y[i]
int a_range_lower;
if (cell->type.in(ID($shl), ID($sshl))) {
b_range_upper = a_width + b_high;
if (is_signed) b_range_upper -= 1;
a_range_lower = max(0, i - b_high);
a_range_upper = min(i+1, a_width);
} else if (cell->type.in(ID($shr), ID($sshr)) || (cell->type.in(ID($shift), ID($shiftx)) && !is_b_signed)) {
b_range_upper = a_width;
a_range_lower = min(i, a_width - 1);
a_range_upper = min(i+1 + b_high, a_width);
} else if (cell->type.in(ID($shift), ID($shiftx)) && is_b_signed) {
// can go both ways depending on sign of B
// 2's complement range is different depending on direction
b_range_upper = a_width - b_low;
a_range_lower = max(0, i + b_low);
if (is_signed)
a_range_lower = min(a_range_lower, a_width - 1);
a_range_upper = min(i+1 + b_high, a_width);
} else {
log_assert(false && "unreachable");
}
if (i < b_range_upper) {
for (int k = a_range_lower; k < a_range_upper; k++)
db->add_edge(cell, ID::A, k, ID::Y, i, -1);
} else {
// only influence is through sign extension
if (is_signed)
db->add_edge(cell, ID::A, a_width - 1, ID::Y, i, -1);
}
for (int k = 0; k < b_width_capped; k++) {
// left shifts
if (cell->type.in(ID($shl), ID($sshl))) {
if (a_width == 1 && is_signed) {
int skip = 1 << (k + 1);
int base = skip -1;
if (i % skip != base && i - a_width + 2 < 1 << b_width_capped)
db->add_edge(cell, ID::B, k, ID::Y, i, -1);
} else if (is_signed) {
if (i - a_width + 2 < 1 << b_width_capped)
db->add_edge(cell, ID::B, k, ID::Y, i, -1);
} else {
if (i - a_width + 1 < 1 << b_width_capped)
db->add_edge(cell, ID::B, k, ID::Y, i, -1);
}
// right shifts
} else if (cell->type.in(ID($shr), ID($sshr)) || (cell->type.in(ID($shift), ID($shiftx)) && !is_b_signed)) {
if (is_signed) {
bool shift_in_bulk = i < a_width - 1;
// can we jump into the zero-padding by toggling B[k]?
bool zpad_jump = (((y_width - i) & ((1 << (k + 1)) - 1)) != 0 \
&& (((y_width - i) & ~(1 << k)) < (1 << b_width_capped)));
if (shift_in_bulk || (cell->type.in(ID($shr), ID($shift), ID($shiftx)) && zpad_jump))
db->add_edge(cell, ID::B, k, ID::Y, i, -1);
} else {
if (i < a_width)
db->add_edge(cell, ID::B, k, ID::Y, i, -1);
}
// bidirectional shifts (positive B shifts right, negative left)
} else if (cell->type.in(ID($shift), ID($shiftx)) && is_b_signed) {
if (is_signed) {
if (k != b_width_capped - 1) {
bool r_shift_in_bulk = i < a_width - 1;
// assuming B is positive, can we jump into the upper zero-padding by toggling B[k]?
bool r_zpad_jump = (((y_width - i) & ((1 << (k + 1)) - 1)) != 0 \
&& (((y_width - i) & ~(1 << k)) <= b_high));
// assuming B is negative, can we influence Y[i] by toggling B[k]?
bool l = a_width - 2 - i >= b_low;
if (a_width == 1) {
// in case of a_width==1 we go into more detailed reasoning
l = l && (~(i - a_width) & ((1 << (k + 1)) - 1)) != 0;
}
if (r_shift_in_bulk || r_zpad_jump || l)
db->add_edge(cell, ID::B, k, ID::Y, i, -1);
} else {
if (y_width - i <= b_high || a_width - 2 - i >= b_low)
db->add_edge(cell, ID::B, k, ID::Y, i, -1);
}
} else {
if (a_width - 1 - i >= b_low)
db->add_edge(cell, ID::B, k, ID::Y, i, -1);
}
} else {
log_assert(false && "unreachable");
}
}
}
}
void packed_mem_op(AbstractCellEdgesDatabase *db, RTLIL::Cell *cell)
{
log_assert(cell->type == ID($mem_v2));
Const rd_clk_enable = cell->getParam(ID::RD_CLK_ENABLE);
int n_rd_ports = cell->getParam(ID::RD_PORTS).as_int();
int abits = cell->getParam(ID::ABITS).as_int();
int width = cell->getParam(ID::WIDTH).as_int();
for (int i = 0; i < n_rd_ports; i++) {
if (rd_clk_enable[i] != State::S0) {
for (int k = 0; k < width; k++)
db->add_edge(cell, ID::RD_ARST, i, ID::RD_DATA, i * width + k, -1);
continue;
}
for (int j = 0; j < abits; j++)
for (int k = 0; k < width; k++)
db->add_edge(cell, ID::RD_ADDR, i * abits + j,
ID::RD_DATA, i * width + k, -1);
}
}
void memrd_op(AbstractCellEdgesDatabase *db, RTLIL::Cell *cell)
{
log_assert(cell->type.in(ID($memrd), ID($memrd_v2)));
int abits = cell->getParam(ID::ABITS).as_int();
int width = cell->getParam(ID::WIDTH).as_int();
if (cell->getParam(ID::CLK_ENABLE).as_bool()) {
if (cell->type == ID($memrd_v2)) {
for (int k = 0; k < width; k++)
db->add_edge(cell, ID::ARST, 0, ID::DATA, k, -1);
}
return;
}
for (int j = 0; j < abits; j++)
for (int k = 0; k < width; k++)
db->add_edge(cell, ID::ADDR, j, ID::DATA, k, -1);
}
void mem_op(AbstractCellEdgesDatabase *db, RTLIL::Cell *cell)
{
if (cell->type == ID($mem_v2))
packed_mem_op(db, cell);
else if (cell->type.in(ID($memrd), ID($memrd_v2)))
memrd_op(db, cell);
else if (cell->type.in(ID($memwr), ID($memwr_v2), ID($meminit)))
return; /* no edges here */
else
log_abort();
}
void ff_op(AbstractCellEdgesDatabase *db, RTLIL::Cell *cell)
{
int width = cell->getPort(ID::Q).size();
if (cell->type.in(ID($dlatch), ID($adlatch), ID($dlatchsr))) {
for (int k = 0; k < width; k++) {
db->add_edge(cell, ID::D, k, ID::Q, k, -1);
db->add_edge(cell, ID::EN, 0, ID::Q, k, -1);
}
}
if (cell->hasPort(ID::CLR))
for (int k = 0; k < width; k++)
db->add_edge(cell, ID::CLR, 0, ID::Q, k, -1);
if (cell->hasPort(ID::SET))
for (int k = 0; k < width; k++)
db->add_edge(cell, ID::SET, 0, ID::Q, k, -1);
if (cell->hasPort(ID::ALOAD))
for (int k = 0; k < width; k++)
db->add_edge(cell, ID::ALOAD, 0, ID::Q, k, -1);
if (cell->hasPort(ID::AD))
for (int k = 0; k < width; k++)
db->add_edge(cell, ID::AD, k, ID::Q, k, -1);
if (cell->hasPort(ID::ARST))
for (int k = 0; k < width; k++)
db->add_edge(cell, ID::ARST, 0, ID::Q, k, -1);
}
PRIVATE_NAMESPACE_END
bool YOSYS_NAMESPACE_PREFIX AbstractCellEdgesDatabase::add_edges_from_cell(RTLIL::Cell *cell)
{
if (cell->type.in(ID($not), ID($pos), ID($buf))) {
bitwise_unary_op(this, cell);
return true;
}
if (cell->type.in(ID($and), ID($or), ID($xor), ID($xnor))) {
bitwise_binary_op(this, cell);
return true;
}
if (cell->type == ID($neg)) {
arith_neg_op(this, cell);
return true;
}
if (cell->type.in(ID($add), ID($sub))) {
arith_binary_op(this, cell);
return true;
}
if (cell->type.in(ID($reduce_and), ID($reduce_or), ID($reduce_xor), ID($reduce_xnor), ID($reduce_bool), ID($logic_not))) {
reduce_op(this, cell);
return true;
}
if (cell->type.in(ID($shl), ID($shr), ID($sshl), ID($sshr), ID($shift), ID($shiftx))) {
shift_op(this, cell);
return true;
}
if (cell->type.in(ID($lt), ID($le), ID($eq), ID($ne), ID($eqx), ID($nex), ID($ge), ID($gt))) {
compare_op(this, cell);
return true;
}
if (cell->type.in(ID($mux), ID($pmux))) {
mux_op(this, cell);
return true;
}
if (cell->type == ID($bmux)) {
bmux_op(this, cell);
return true;
}
if (cell->type == ID($demux)) {
demux_op(this, cell);
return true;
}
if (cell->type.in(ID($mem_v2), ID($memrd), ID($memrd_v2), ID($memwr), ID($memwr_v2), ID($meminit))) {
mem_op(this, cell);
return true;
}
if (RTLIL::builtin_ff_cell_types().count(cell->type)) {
ff_op(this, cell);
return true;
}
// FIXME: $mul $div $mod $divfloor $modfloor $slice $concat
// FIXME: $lut $sop $alu $lcu $macc $macc_v2 $fa
// FIXME: $mul $div $mod $divfloor $modfloor $pow $slice $concat $bweqx
// FIXME: $lut $sop $alu $lcu $macc $fa $logic_and $logic_or $bwmux
// FIXME: $_BUF_ $_NOT_ $_AND_ $_NAND_ $_OR_ $_NOR_ $_XOR_ $_XNOR_ $_ANDNOT_ $_ORNOT_
// FIXME: $_MUX_ $_NMUX_ $_MUX4_ $_MUX8_ $_MUX16_ $_AOI3_ $_OAI3_ $_AOI4_ $_OAI4_
// FIXME: $specify2 $specify3 $specrule ???
// FIXME: $equiv $set_tag $get_tag $overwrite_tag $original_tag
if (cell->type.in(ID($assert), ID($assume), ID($live), ID($fair), ID($cover), ID($initstate), ID($anyconst), ID($anyseq), ID($allconst), ID($allseq)))
return true; // no-op: these have either no inputs or no outputs
return false;
}
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