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The proc_prune pass is similar in nature to proc_rmdead pass: while proc_rmdead removes branches that never become active because another branch preempts it, proc_prune removes assignments that never become active because another assignment preempts them. Genrtlil contains logic similar to the proc_prune pass, but their purpose is different: genrtlil has to prune assignments to adapt the semantics of blocking assignments in HDLs (latest assignment wins) to semantics of assignments in RTLIL processes (assignment in the most specific case wins). On the other hand proc_prune is a general purpose RTLIL simplification that benefits all frontends, even those not using the Yosys AST library. The proc_prune pass is added to the proc script after proc_rmdead, since it gives better results with fewer branches.
103 lines
3.1 KiB
C++
103 lines
3.1 KiB
C++
/*
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* yosys -- Yosys Open SYnthesis Suite
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*
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* Copyright (C) 2012 Clifford Wolf <clifford@clifford.at>
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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*/
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#include "kernel/register.h"
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#include "kernel/log.h"
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#include <stdlib.h>
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#include <stdio.h>
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USING_YOSYS_NAMESPACE
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PRIVATE_NAMESPACE_BEGIN
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struct ProcPass : public Pass {
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ProcPass() : Pass("proc", "translate processes to netlists") { }
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void help() YS_OVERRIDE
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{
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// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
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log("\n");
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log(" proc [options] [selection]\n");
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log("\n");
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log("This pass calls all the other proc_* passes in the most common order.\n");
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log("\n");
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log(" proc_clean\n");
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log(" proc_rmdead\n");
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log(" proc_prune\n");
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log(" proc_init\n");
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log(" proc_arst\n");
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log(" proc_mux\n");
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log(" proc_dlatch\n");
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log(" proc_dff\n");
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log(" proc_clean\n");
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log("\n");
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log("This replaces the processes in the design with multiplexers,\n");
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log("flip-flops and latches.\n");
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log("\n");
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log("The following options are supported:\n");
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log("\n");
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log(" -global_arst [!]<netname>\n");
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log(" This option is passed through to proc_arst.\n");
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log("\n");
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log(" -ifx\n");
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log(" This option is passed through to proc_mux. proc_rmdead is not\n");
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log(" executed in -ifx mode.\n");
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log("\n");
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}
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void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
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{
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std::string global_arst;
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bool ifxmode = false;
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log_header(design, "Executing PROC pass (convert processes to netlists).\n");
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log_push();
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size_t argidx;
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for (argidx = 1; argidx < args.size(); argidx++)
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{
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if (args[argidx] == "-global_arst" && argidx+1 < args.size()) {
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global_arst = args[++argidx];
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continue;
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}
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if (args[argidx] == "-ifx") {
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ifxmode = true;
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continue;
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}
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break;
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}
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extra_args(args, argidx, design);
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Pass::call(design, "proc_clean");
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if (!ifxmode)
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Pass::call(design, "proc_rmdead");
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Pass::call(design, "proc_prune");
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Pass::call(design, "proc_init");
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if (global_arst.empty())
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Pass::call(design, "proc_arst");
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else
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Pass::call(design, "proc_arst -global_arst " + global_arst);
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Pass::call(design, ifxmode ? "proc_mux -ifx" : "proc_mux");
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Pass::call(design, "proc_dlatch");
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Pass::call(design, "proc_dff");
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Pass::call(design, "proc_clean");
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log_pop();
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}
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} ProcPass;
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PRIVATE_NAMESPACE_END
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