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Akash Levy 2025-03-05 07:54:26 -08:00
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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/yosys.h"
#include "kernel/sigtools.h"
USING_YOSYS_NAMESPACE
PRIVATE_NAMESPACE_BEGIN
bool did_something;
// scratchpad configurations for pmgen
int shiftadd_max_ratio;
// Helper function, removes LSB 0s
SigSpec remove_bottom_padding(SigSpec sig);
#include "passes/opt/peepopt_pm.h"
struct PeepoptPass : public Pass {
PeepoptPass() : Pass("peepopt", "collection of peephole optimizers") { }
void help() override
{
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
log("\n");
log(" peepopt [options] [selection]\n");
log("\n");
log("This pass applies a collection of peephole optimizers to the current design.\n");
log("\n");
log("This pass employs the following rules by default:\n");
log("\n");
log(" * muldiv - Replace (A*B)/B with A\n");
log("\n");
log(" * muldiv_c - Replace (A*B)/C with A*(B/C) when C is a const divisible by B.\n");
log("\n");
log(" * shiftmul - Replace A>>(B*C) with A'>>(B<<K) where C and K are constants\n");
log(" and A' is derived from A by appropriately inserting padding\n");
log(" into the signal. (right variant)\n");
log("\n");
log(" Analogously, replace A<<(B*C) with appropriate selection of\n");
log(" output bits from A<<(B<<K). (left variant)\n");
log("\n");
log(" * shiftadd - Replace A>>(B+D) with (A'>>D)>>(B) where D is constant and\n");
log(" A' is derived from A by padding or cutting inaccessible bits.\n");
log(" Scratchpad: 'peepopt.shiftadd.max_data_multiple' (default: 2)\n");
log(" limits the amount of padding to a multiple of the data, \n");
log(" to avoid high resource usage from large temporary MUX trees.\n");
log("\n");
log("If -formalclk is specified it instead employs the following rules:\n");
log("\n");
log(" * clockgateff - Replace latch based clock gating patterns with a flip-flop\n");
log(" based pattern to prevent combinational paths from the\n");
log(" output to the enable input after running clk2fflogic.\n");
log("\n");
log("If -withmuxadd is specified it adds the following rule:\n");
log("\n");
log(" * muxadd - Replace S?(A+B):A with A+(S?B:0)\n");
log("\n");
}
void execute(std::vector<std::string> args, RTLIL::Design *design) override
{
log_header(design, "Executing PEEPOPT pass (run peephole optimizers).\n");
bool formalclk = false;
bool withmuxadd = false;
size_t argidx;
for (argidx = 1; argidx < args.size(); argidx++)
{
if (args[argidx] == "-formalclk") {
formalclk = true;
continue;
}
if (args[argidx] == "-withmuxadd") {
withmuxadd = true;
continue;
}
break;
}
extra_args(args, argidx, design);
// limit the padding from shiftadd to a multiple of the input data
// during techmap it creates (#data + #padding) * log(shift) $_MUX_ cells
// 2x implies there is a constant shift larger than the input-data which should be extremely rare
shiftadd_max_ratio = design->scratchpad_get_int("peepopt.shiftadd.max_data_multiple", 2);
for (auto module : design->selected_modules())
{
did_something = true;
while (did_something)
{
did_something = false;
peepopt_pm pm(module);
pm.setup(module->selected_cells());
if (formalclk) {
pm.run_formal_clockgateff();
} else {
pm.run_shiftadd();
pm.run_shiftmul_right();
pm.run_shiftmul_left();
pm.run_muldiv();
pm.run_muldiv_c();
if (withmuxadd)
pm.run_muxadd();
}
}
}
}
} PeepoptPass;
SigSpec remove_bottom_padding(SigSpec sig)
{
int i = 0;
for (; i < sig.size() - 1 && sig[i] == State::S0; i++) {
}
return sig.extract(i, sig.size() - i);
}
PRIVATE_NAMESPACE_END