verilator/src/V3OptionParser.cpp
Geza Lore 47bce4157d
Introduce DFG based combinational logic optimizer (#3527)
Added a new data-flow graph (DFG) based combinational logic optimizer.
The capabilities of this covers a combination of V3Const and V3Gate, but
is also more capable of transforming combinational logic into simplified
forms and more.

This entail adding a new internal representation, `DfgGraph`, and
appropriate `astToDfg` and `dfgToAst` conversion functions. The graph
represents some of the combinational equations (~continuous assignments)
in a module, and for the duration of the DFG passes, it takes over the
role of AstModule. A bulk of the Dfg vertices represent expressions.
These vertex classes, and the corresponding conversions to/from AST are
mostly auto-generated by astgen, together with a DfgVVisitor that can be
used for dynamic dispatch based on vertex (operation) types.

The resulting combinational logic graph (a `DfgGraph`) is then optimized
in various ways. Currently we perform common sub-expression elimination,
variable inlining, and some specific peephole optimizations, but there
is scope for more optimizations in the future using the same
representation. The optimizer is run directly before and after inlining.
The pre inline pass can operate on smaller graphs and hence converges
faster, but still has a chance of substantially reducing the size of the
logic on some designs, making inlining both faster and less memory
intensive. The post inline pass can then optimize across the inlined
module boundaries. No optimization is performed across a module
boundary.

For debugging purposes, each peephole optimization can be disabled
individually via the -fno-dfg-peepnole-<OPT> option, where <OPT> is one
of the optimizations listed in V3DfgPeephole.h, for example
-fno-dfg-peephole-remove-not-not.

The peephole patterns currently implemented were mostly picked based on
the design that inspired this work, and on that design the optimizations
yields ~30% single threaded speedup, and ~50% speedup on 4 threads. As
you can imagine not having to haul around redundant combinational
networks in the rest of the compilation pipeline also helps with memory
consumption, and up to 30% peak memory usage of Verilator was observed
on the same design.

Gains on other arbitrary designs are smaller (and can be improved by
analyzing those designs). For example OpenTitan gains between 1-15%
speedup depending on build type.
2022-09-23 16:46:22 +01:00

266 lines
11 KiB
C++

// -*- mode: C++; c-file-style: "cc-mode" -*-
//*************************************************************************
// DESCRIPTION: Verilator: Command line option parser
//
// Code available from: https://verilator.org
//
//*************************************************************************
//
// Copyright 2003-2022 by Wilson Snyder. This program is free software; you
// can redistribute it and/or modify it under the terms of either the GNU
// Lesser General Public License Version 3 or the Perl Artistic License
// Version 2.0.
// SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
//
//*************************************************************************
#ifndef V3OPTION_PARSER_NO_VOPTION_BOOL
#include "V3Global.h"
#include "V3Options.h"
#endif
#include "V3Error.h"
#include "V3OptionParser.h"
#include "V3String.h"
//######################################################################
// V3OptionParser::Impl
struct V3OptionParser::Impl {
// TYPES
// Setting for isOnOffAllowed() and isPartialMatchAllowed()
enum class en : uint8_t {
NONE, // "-opt"
FONOFF, // "-fopt" and "-fno-opt"
ONOFF, // "-opt" and "-no-opt"
VALUE // "-opt val"
};
// Base class of actual action classes
template <en MODE, bool ALLOW_PARTIAL_MATCH = false>
class ActionBase VL_NOT_FINAL : public ActionIfs {
bool m_undocumented = false; // This option is not documented
public:
bool isValueNeeded() const override final { return MODE == en::VALUE; }
bool isFOnOffAllowed() const override final { return MODE == en::FONOFF; }
bool isOnOffAllowed() const override final { return MODE == en::ONOFF; }
bool isPartialMatchAllowed() const override final { return ALLOW_PARTIAL_MATCH; }
bool isUndocumented() const override { return m_undocumented; }
void undocumented() override { m_undocumented = true; }
};
// Actual action classes
template <typename T>
class ActionSet; // "-opt" for bool-ish, "-opt val" for int and string
template <typename BOOL>
class ActionFOnOff; // "-fopt" and "-fno-opt" for bool-ish
template <typename BOOL>
class ActionOnOff; // "-opt" and "-no-opt" for bool-ish
class ActionCbCall; // Callback without argument for "-opt"
class ActionCbFOnOff; // Callback for "-fopt" and "-fno-opt"
class ActionCbOnOff; // Callback for "-opt" and "-no-opt"
template <class T>
class ActionCbVal; // Callback for "-opt val"
class ActionCbPartialMatch; // Callback "-O3" for "-O"
class ActionCbPartialMatchVal; // Callback "-debugi-V3Options 3" for "-debugi-"
// MEMBERS
std::map<const string, std::unique_ptr<ActionIfs>> m_options; // All actions for option
bool m_isFinalized{false}; // Becomes after finalize() is called
VSpellCheck m_spellCheck; // Suggests closest option when not found
};
//######################################################################
// Action classes in V3OptionParser::Impl
#define V3OPTION_PARSER_DEF_ACT_CLASS(className, type, body, enType) \
template <> \
class V3OptionParser::Impl::className<type> final : public ActionBase<enType> { \
type* const m_valp; /* Pointer to a option variable*/ \
\
public: \
explicit className(type* valp) \
: m_valp(valp) {} \
void exec(const char* optp, const char* argp) override { body; } \
}
V3OPTION_PARSER_DEF_ACT_CLASS(ActionSet, bool, *m_valp = true, en::NONE);
#ifndef V3OPTION_PARSER_NO_VOPTION_BOOL
V3OPTION_PARSER_DEF_ACT_CLASS(ActionSet, VOptionBool, m_valp->setTrueOrFalse(true), en::NONE);
#endif
V3OPTION_PARSER_DEF_ACT_CLASS(ActionSet, int, *m_valp = std::atoi(argp), en::VALUE);
V3OPTION_PARSER_DEF_ACT_CLASS(ActionSet, string, *m_valp = argp, en::VALUE);
V3OPTION_PARSER_DEF_ACT_CLASS(ActionFOnOff, bool, *m_valp = !hasPrefixFNo(optp), en::FONOFF);
V3OPTION_PARSER_DEF_ACT_CLASS(ActionOnOff, bool, *m_valp = !hasPrefixNo(optp), en::ONOFF);
#ifndef V3OPTION_PARSER_NO_VOPTION_BOOL
V3OPTION_PARSER_DEF_ACT_CLASS(ActionOnOff, VOptionBool, m_valp->setTrueOrFalse(!hasPrefixNo(optp)),
en::ONOFF);
#endif
#undef V3OPTION_PARSER_DEF_ACT_CLASS
#define V3OPTION_PARSER_DEF_ACT_CB_CLASS(className, funcType, body, ...) \
class V3OptionParser::Impl::className final : public ActionBase<__VA_ARGS__> { \
std::function<funcType> m_cb; /* Callback function */ \
\
public: \
using CbType = std::function<funcType>; \
explicit className(CbType cb) \
: m_cb(std::move(cb)) {} \
void exec(const char* optp, const char* argp) override { body; } \
}
V3OPTION_PARSER_DEF_ACT_CB_CLASS(ActionCbCall, void(void), m_cb(), en::NONE);
V3OPTION_PARSER_DEF_ACT_CB_CLASS(ActionCbFOnOff, void(bool), m_cb(!hasPrefixFNo(optp)),
en::FONOFF);
V3OPTION_PARSER_DEF_ACT_CB_CLASS(ActionCbOnOff, void(bool), m_cb(!hasPrefixNo(optp)), en::ONOFF);
template <>
V3OPTION_PARSER_DEF_ACT_CB_CLASS(ActionCbVal<int>, void(int), m_cb(std::atoi(argp)), en::VALUE);
template <>
V3OPTION_PARSER_DEF_ACT_CB_CLASS(ActionCbVal<const char*>, void(const char*), m_cb(argp),
en::VALUE);
V3OPTION_PARSER_DEF_ACT_CB_CLASS(ActionCbPartialMatch, void(const char*), m_cb(optp), en::NONE,
true);
V3OPTION_PARSER_DEF_ACT_CB_CLASS(ActionCbPartialMatchVal, void(const char*, const char*),
m_cb(optp, argp), en::VALUE, true);
#undef V3OPTION_PARSER_DEF_ACT_CB_CLASS
//######################################################################
// Member functions of V3OptionParser
V3OptionParser::ActionIfs* V3OptionParser::find(const char* optp) {
const auto it = m_pimpl->m_options.find(optp);
if (it != m_pimpl->m_options.end()) return it->second.get(); // Exact match
for (auto&& act : m_pimpl->m_options) {
if (act.second->isFOnOffAllowed()) { // Find starts with "-fno"
if (const char* const nop
= VString::startsWith(optp, "-fno-") ? (optp + std::strlen("-fno-")) : nullptr) {
if (act.first.substr(std::strlen("-f"), std::string::npos)
== nop) { // [-f]opt = [-fno-]opt
return act.second.get();
}
}
}
if (act.second->isOnOffAllowed()) { // Find starts with "-no"
if (const char* const nop
= VString::startsWith(optp, "-no") ? (optp + std::strlen("-no")) : nullptr) {
if (act.first == nop || act.first == (std::string{"-"} + nop)) {
return act.second.get();
}
}
} else if (act.second->isPartialMatchAllowed()) {
if (VString::startsWith(optp, act.first)) return act.second.get();
}
}
return nullptr;
}
template <class ACT, class ARG>
V3OptionParser::ActionIfs& V3OptionParser::add(const std::string& opt, ARG arg) {
UASSERT(!m_pimpl->m_isFinalized, "Cannot add after finalize() is called");
std::unique_ptr<ACT> act{new ACT{std::move(arg)}};
UASSERT(opt.size() >= 2, opt << " is too short");
UASSERT(opt[0] == '-' || opt[0] == '+', opt << " does not start with either '-' or '+'");
UASSERT(!(opt[0] == '-' && opt[1] == '-'), "Option must have single '-', but " << opt);
const auto insertedResult = m_pimpl->m_options.emplace(opt, std::move(act));
UASSERT(insertedResult.second, opt << " is already registered");
return *insertedResult.first->second;
}
bool V3OptionParser::hasPrefixFNo(const char* strp) {
UASSERT(strp[0] == '-', strp << " does not start with '-'");
if (strp[1] == '-') ++strp;
return VString::startsWith(strp, "-fno");
}
bool V3OptionParser::hasPrefixNo(const char* strp) {
UASSERT(strp[0] == '-', strp << " does not start with '-'");
if (strp[1] == '-') ++strp;
return VString::startsWith(strp, "-no");
}
int V3OptionParser::parse(int idx, int argc, char* argv[]) {
UASSERT(m_pimpl->m_isFinalized, "finalize() must be called before parse()");
const char* optp = argv[idx];
if (optp[0] == '-' && optp[1] == '-') ++optp;
ActionIfs* const actp = find(optp);
if (!actp) return 0;
if (!actp->isValueNeeded()) {
actp->exec(optp, nullptr);
return 1;
} else if (idx + 1 < argc) {
actp->exec(optp, argv[idx + 1]);
return 2;
}
return 0;
}
string V3OptionParser::getSuggestion(const char* str) const {
return m_pimpl->m_spellCheck.bestCandidateMsg(str);
}
void V3OptionParser::addSuggestionCandidate(const string& s) {
m_pimpl->m_spellCheck.pushCandidate(s);
}
void V3OptionParser::finalize() {
UASSERT(!m_pimpl->m_isFinalized, "finalize() must not be called twice");
for (auto&& opt : m_pimpl->m_options) {
if (opt.second->isUndocumented()) continue;
m_pimpl->m_spellCheck.pushCandidate(opt.first);
if (opt.second->isFOnOffAllowed()) {
m_pimpl->m_spellCheck.pushCandidate(
"-fno-" + opt.first.substr(std::strlen("-f"), std::string::npos));
}
if (opt.second->isOnOffAllowed()) m_pimpl->m_spellCheck.pushCandidate("-no" + opt.first);
}
m_pimpl->m_isFinalized = true;
}
V3OptionParser::V3OptionParser()
: m_pimpl{new Impl{}} {}
V3OptionParser::~V3OptionParser() = default;
//######################################################################
// Member functions of V3OptionParser::AppendHelper
#define V3OPTION_PARSER_DEF_OP(actKind, argType, actType) \
V3OptionParser::ActionIfs& V3OptionParser::AppendHelper::operator()( \
const char* optp, actKind, argType arg) const { \
return m_parser.add<Impl::actType>(optp, arg); \
}
V3OPTION_PARSER_DEF_OP(Set, bool*, ActionSet<bool>)
#ifndef V3OPTION_PARSER_NO_VOPTION_BOOL
V3OPTION_PARSER_DEF_OP(Set, VOptionBool*, ActionSet<VOptionBool>)
#endif
V3OPTION_PARSER_DEF_OP(Set, int*, ActionSet<int>)
V3OPTION_PARSER_DEF_OP(Set, string*, ActionSet<string>)
V3OPTION_PARSER_DEF_OP(FOnOff, bool*, ActionFOnOff<bool>)
V3OPTION_PARSER_DEF_OP(OnOff, bool*, ActionOnOff<bool>)
#ifndef V3OPTION_PARSER_NO_VOPTION_BOOL
V3OPTION_PARSER_DEF_OP(OnOff, VOptionBool*, ActionOnOff<VOptionBool>)
#endif
V3OPTION_PARSER_DEF_OP(CbCall, Impl::ActionCbCall::CbType, ActionCbCall)
V3OPTION_PARSER_DEF_OP(CbFOnOff, Impl::ActionCbFOnOff::CbType, ActionCbFOnOff)
V3OPTION_PARSER_DEF_OP(CbOnOff, Impl::ActionCbOnOff::CbType, ActionCbOnOff)
V3OPTION_PARSER_DEF_OP(CbVal, Impl::ActionCbVal<int>::CbType, ActionCbVal<int>)
V3OPTION_PARSER_DEF_OP(CbVal, Impl::ActionCbVal<const char*>::CbType, ActionCbVal<const char*>)
#undef V3OPTION_PARSER_DEF_OP
V3OptionParser::ActionIfs&
V3OptionParser::AppendHelper::operator()(const char* optp, CbPartialMatch,
Impl::ActionCbPartialMatch::CbType cb) const {
const size_t prefixLen = std::strlen(optp);
const auto wrap = [prefixLen, cb](const char* optp) { cb(optp + prefixLen); };
return m_parser.add<Impl::ActionCbPartialMatch>(optp, std::move(wrap));
}
V3OptionParser::ActionIfs&
V3OptionParser::AppendHelper::operator()(const char* optp, CbPartialMatchVal,
Impl::ActionCbPartialMatchVal::CbType cb) const {
const size_t prefixLen = std::strlen(optp);
const auto wrap
= [prefixLen, cb](const char* optp, const char* argp) { cb(optp + prefixLen, argp); };
return m_parser.add<Impl::ActionCbPartialMatchVal>(optp, std::move(wrap));
}