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https://github.com/verilator/verilator.git
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3c144ada53
This saves about 5% memory. V3AstUserAllocator is appropriate for most use cases, performance is marginally up as we are mostly D-cache bound on large designs.
1500 lines
66 KiB
C++
1500 lines
66 KiB
C++
// -*- mode: C++; c-file-style: "cc-mode" -*-
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//*************************************************************************
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// DESCRIPTION: Verilator: Gate optimizations, such as wire elimination
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//
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// Code available from: https://verilator.org
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//
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//*************************************************************************
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//
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// Copyright 2003-2023 by Wilson Snyder. This program is free software; you
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// can redistribute it and/or modify it under the terms of either the GNU
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// Lesser General Public License Version 3 or the Perl Artistic License
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// Version 2.0.
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// SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
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//
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//*************************************************************************
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// V3Gate's Transformations:
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//
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// Extract a graph of the *entire* netlist with cells expanded
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// Perform constant optimization across the graph
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// Create VARSCOPEs for any variables we can rip out
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//
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//*************************************************************************
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#include "V3PchAstNoMT.h" // VL_MT_DISABLED_CODE_UNIT
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#include "V3Gate.h"
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#include "V3AstUserAllocator.h"
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#include "V3Const.h"
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#include "V3DupFinder.h"
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#include "V3Graph.h"
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#include "V3Stats.h"
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#include <list>
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#include <unordered_map>
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#include <unordered_set>
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VL_DEFINE_DEBUG_FUNCTIONS;
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class GateDedupeVarVisitor;
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using GateVarRefList = std::list<AstNodeVarRef*>;
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constexpr int GATE_DEDUP_MAX_DEPTH = 20;
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//######################################################################
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class GateLogicVertex;
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class GateVarVertex;
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class GateGraphBaseVisitor VL_NOT_FINAL {
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public:
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V3Graph* const m_graphp; // Graph this class is visiting
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explicit GateGraphBaseVisitor(V3Graph* graphp)
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: m_graphp{graphp} {}
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virtual ~GateGraphBaseVisitor() = default;
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virtual VNUser visit(GateLogicVertex* vertexp, VNUser vu = VNUser{0}) = 0;
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virtual VNUser visit(GateVarVertex* vertexp, VNUser vu = VNUser{0}) = 0;
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};
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//######################################################################
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// Support classes
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class GateEitherVertex VL_NOT_FINAL : public V3GraphVertex {
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VL_RTTI_IMPL(GateEitherVertex, V3GraphVertex)
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AstScope* const m_scopep; // Scope vertex refers to
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bool m_reducible = true; // True if this node should be able to be eliminated
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bool m_dedupable = true; // True if this node should be able to be deduped
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bool m_consumed = false; // Output goes to something meaningful
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public:
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GateEitherVertex(V3Graph* graphp, AstScope* scopep)
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: V3GraphVertex{graphp}
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, m_scopep{scopep} {}
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~GateEitherVertex() override = default;
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// ACCESSORS
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string dotStyle() const override { return m_consumed ? "" : "dotted"; }
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AstScope* scopep() const VL_MT_STABLE { return m_scopep; }
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bool reducible() const { return m_reducible; }
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bool dedupable() const { return m_dedupable; }
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void setConsumed(const char* /*consumedReason*/) {
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m_consumed = true;
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// UINFO(0, "\t\tSetConsumed "<<consumedReason<<" "<<this<<endl);
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}
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bool consumed() const { return m_consumed; }
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void clearReducible(const char* /*nonReducibleReason*/) {
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m_reducible = false;
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// UINFO(0, " NR: "<<nonReducibleReason<<" "<<name()<<endl);
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}
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void clearDedupable(const char* /*nonDedupableReason*/) {
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m_dedupable = false;
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// UINFO(0, " ND: "<<nonDedupableReason<<" "<<name()<<endl);
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}
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void clearReducibleAndDedupable(const char* nonReducibleReason) {
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clearReducible(nonReducibleReason);
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clearDedupable(nonReducibleReason);
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}
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virtual VNUser accept(GateGraphBaseVisitor& v, VNUser vu = VNUser{0}) = 0;
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// Returns only the result from the LAST vertex iterated over
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VNUser iterateInEdges(GateGraphBaseVisitor& v, VNUser vu = VNUser{0}) {
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VNUser ret{0};
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for (V3GraphEdge* edgep = inBeginp(); edgep; edgep = edgep->inNextp()) {
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ret = static_cast<GateEitherVertex*>(edgep->fromp())->accept(v, vu);
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}
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return ret;
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}
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// Returns only the result from the LAST vertex iterated over
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// Note: This behaves differently than iterateInEdges() in that it will traverse
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// all edges that exist when it is initially called, whereas
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// iterateInEdges() will stop traversing edges if one is deleted
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VNUser iterateCurrentOutEdges(GateGraphBaseVisitor& v, VNUser vu = VNUser{0}) {
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VNUser ret{0};
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V3GraphEdge* next_edgep = nullptr;
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for (V3GraphEdge* edgep = outBeginp(); edgep; edgep = next_edgep) {
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// Need to find the next edge before visiting in case the edge is deleted
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next_edgep = edgep->outNextp();
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ret = static_cast<GateEitherVertex*>(edgep->top())->accept(v, vu);
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}
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return ret;
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}
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};
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class GateVarVertex final : public GateEitherVertex {
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VL_RTTI_IMPL(GateVarVertex, GateEitherVertex)
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AstVarScope* const m_varScp;
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bool m_isTop = false;
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bool m_isClock = false;
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AstNode* m_rstSyncNodep = nullptr; // Used as reset and not in SenItem, in clocked always
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AstNode* m_rstAsyncNodep = nullptr; // Used as reset and in SenItem, in clocked always
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public:
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GateVarVertex(V3Graph* graphp, AstScope* scopep, AstVarScope* varScp)
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: GateEitherVertex{graphp, scopep}
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, m_varScp{varScp} {}
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~GateVarVertex() override = default;
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// ACCESSORS
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AstVarScope* varScp() const VL_MT_STABLE { return m_varScp; }
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string name() const override VL_MT_STABLE {
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return (cvtToHex(m_varScp) + " " + varScp()->name());
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}
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string dotColor() const override { return "blue"; }
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bool isTop() const { return m_isTop; }
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void setIsTop() { m_isTop = true; }
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bool isClock() const { return m_isClock; }
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void setIsClock() {
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m_isClock = true;
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setConsumed("isclk");
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}
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AstNode* rstSyncNodep() const { return m_rstSyncNodep; }
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void rstSyncNodep(AstNode* nodep) { m_rstSyncNodep = nodep; }
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AstNode* rstAsyncNodep() const { return m_rstAsyncNodep; }
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void rstAsyncNodep(AstNode* nodep) { m_rstAsyncNodep = nodep; }
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// METHODS
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void propagateAttrClocksFrom(GateVarVertex* fromp) {
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// Propagate clock and general attribute onto this node
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varScp()->varp()->propagateAttrFrom(fromp->varScp()->varp());
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if (fromp->isClock()) {
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varScp()->varp()->usedClock(true);
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setIsClock();
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}
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}
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VNUser accept(GateGraphBaseVisitor& v, VNUser vu = VNUser{0}) override {
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return v.visit(this, vu);
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}
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};
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class GateLogicVertex final : public GateEitherVertex {
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VL_RTTI_IMPL(GateLogicVertex, GateEitherVertex)
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AstNode* const m_nodep;
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AstActive* const m_activep; // Under what active; nullptr is ok (under cfunc or such)
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const bool m_slow; // In slow block
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public:
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GateLogicVertex(V3Graph* graphp, AstScope* scopep, AstNode* nodep, AstActive* activep,
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bool slow)
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: GateEitherVertex{graphp, scopep}
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, m_nodep{nodep}
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, m_activep{activep}
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, m_slow{slow} {}
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~GateLogicVertex() override = default;
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// ACCESSORS
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string name() const override { return (cvtToHex(m_nodep) + "@" + scopep()->prettyName()); }
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string dotColor() const override { return "purple"; }
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FileLine* fileline() const override { return nodep()->fileline(); }
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AstNode* nodep() const { return m_nodep; }
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AstActive* activep() const { return m_activep; }
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bool slow() const { return m_slow; }
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VNUser accept(GateGraphBaseVisitor& v, VNUser vu = VNUser{0}) override {
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return v.visit(this, vu);
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}
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};
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// ######################################################################
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// Is this a simple expression with a single input and single output?
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class GateOkVisitor final : public VNVisitorConst {
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private:
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// RETURN STATE
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bool m_isSimple = true; // Set false when we know it isn't simple
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GateVarRefList m_rhsVarRefs; // VarRefs on rhs of assignment
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AstNode* m_substTreep = nullptr; // What to replace the variable with
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// STATE
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const bool
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m_buffersOnly; // Set when we only allow simple buffering, no equations (for clocks)
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const AstNodeVarRef* m_lhsVarRef
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= nullptr; // VarRef on lhs of assignment (what we're replacing)
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const bool m_dedupe; // Set when we use isGateDedupable instead of isGateOptimizable
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int m_ops = 0; // Operation count
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// METHODS
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void clearSimple(const char* because) {
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if (m_isSimple) {
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m_isSimple = false;
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UINFO(9, "Clear simple " << because << endl);
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}
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}
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// VISITORS
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void visit(AstNodeVarRef* nodep) override {
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++m_ops;
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iterateChildrenConst(nodep);
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// We only allow a LHS ref for the var being set, and a RHS ref for
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// something else being read.
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if (nodep->varScopep()->varp()->isSc()) {
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clearSimple("SystemC sig"); // Don't want to eliminate the VL_ASSIGN_SI's
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}
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if (nodep->access().isRW()) {
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clearSimple("R/W");
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} else if (nodep->access().isWriteOrRW()) {
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if (m_lhsVarRef) clearSimple(">1 lhs varRefs");
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m_lhsVarRef = nodep;
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} else {
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if (m_rhsVarRefs.size() > 1) {
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const AstNodeVarRef* const lastRefp = m_rhsVarRefs.back();
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if (m_buffersOnly) clearSimple(">1 rhs varRefs");
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if (!nodep->varScopep()->varp()->gateMultiInputOptimizable()
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// We didn't check multiInput on the first varref, so check it here
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|| !lastRefp->varScopep()->varp()->gateMultiInputOptimizable()) {
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clearSimple("!gateMultiInputOptimizable");
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}
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}
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m_rhsVarRefs.push_back(nodep);
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}
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}
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void visit(AstNodeAssign* nodep) override {
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m_substTreep = nodep->rhsp();
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if (!VN_IS(nodep->lhsp(), NodeVarRef)) {
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clearSimple("ASSIGN(non-VARREF)");
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} else if (nodep->isTimingControl()) {
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clearSimple("Timing control");
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} else {
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iterateChildrenConst(nodep);
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}
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// We don't push logic other then assignments/NOTs into SenItems
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// This avoids a mess in computing what exactly a POSEDGE is
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// V3Const cleans up any NOTs by flipping the edges for us
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if (m_buffersOnly
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&& !(
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VN_IS(nodep->rhsp(), VarRef)
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// Avoid making non-clocked logic into clocked,
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// as it slows down the verilator_sim_benchmark
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|| (VN_IS(nodep->rhsp(), Not) && VN_IS(VN_AS(nodep->rhsp(), Not)->lhsp(), VarRef)
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&& VN_AS(VN_AS(nodep->rhsp(), Not)->lhsp(), VarRef)->varp()->isUsedClock()))) {
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clearSimple("Not a buffer (goes to a clock)");
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}
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}
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//--------------------
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void visit(AstNode* nodep) override {
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// *** Special iterator
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if (!m_isSimple) return; // Fastpath
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if (++m_ops > v3Global.opt.gateStmts()) clearSimple("--gate-stmts exceeded");
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if (!(m_dedupe ? nodep->isGateDedupable() : nodep->isGateOptimizable()) //
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|| !nodep->isPure() || nodep->isBrancher()) {
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UINFO(5, "Non optimizable type: " << nodep << endl);
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clearSimple("Non optimizable type");
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} else {
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iterateChildrenConst(nodep);
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}
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}
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public:
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// CONSTRUCTORS
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GateOkVisitor(AstNode* nodep, bool buffersOnly, bool dedupe)
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: m_buffersOnly{buffersOnly}
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, m_dedupe{dedupe} {
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// Iterate
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iterateConst(nodep);
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// Check results
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if (!m_substTreep) clearSimple("No assignment found\n");
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for (GateVarRefList::const_iterator it = m_rhsVarRefs.begin(); it != m_rhsVarRefs.end();
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++it) {
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if (m_lhsVarRef && m_lhsVarRef->varScopep() == (*it)->varScopep()) {
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clearSimple("Circular logic\n"); // Oh my, we'll get an UNOPTFLAT much later
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}
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}
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if (debug() >= 9 && !m_isSimple) nodep->dumpTree("- gate!Ok: ");
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}
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~GateOkVisitor() override = default;
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// PUBLIC METHODS
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bool isSimple() const { return m_isSimple; }
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AstNode* substTree() const { return m_substTreep; }
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const GateVarRefList& rhsVarRefs() const { return m_rhsVarRefs; }
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};
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// ######################################################################
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// Replace refs to 'varscp' with 'substp' in 'consumerp'
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static void eliminate(AstNode* logicp,
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const std::unordered_map<AstVarScope*, AstNode*>& substitutions,
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GateDedupeVarVisitor* varVisp);
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// ######################################################################
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// Gate class functions
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class GateVisitor final : public VNVisitor {
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private:
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// NODE STATE
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// Entire netlist:
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// AstVarScope::user1p -> GateVarVertex* for usage var, 0=not set yet
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// {logic}Node::user1 -> map of substitutions, via m_substitutions
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// AstVarScope::user2 -> bool: Signal used in SenItem in *this* always statement
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// AstVar::user2 -> bool: Warned about SYNCASYNCNET
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// AstNodeVarRef::user2 -> bool: ConcatOffset visited
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const VNUser1InUse m_inuser1;
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const VNUser2InUse m_inuser2;
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// Variable substitutions to apply to a given logic block
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AstUser1Allocator<AstNode, std::unordered_map<AstVarScope*, AstNode*>> m_substitutions;
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// STATE
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V3Graph m_graph; // Scoreboard of var usages/dependencies
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GateLogicVertex* m_logicVertexp = nullptr; // Current statement being tracked, nullptr=ignored
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AstScope* m_scopep = nullptr; // Current scope being processed
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const AstNodeModule* m_modp = nullptr; // Current module
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AstActive* m_activep = nullptr; // Current active
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bool m_activeReducible = true; // Is activation block reducible?
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bool m_inSenItem = false; // Underneath AstSenItem; any varrefs are clocks
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bool m_inSlow = false; // Inside a slow structure
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std::vector<AstNode*> m_optimized; // Logic blocks optimized
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VDouble0 m_statSigs; // Statistic tracking
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VDouble0 m_statRefs; // Statistic tracking
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VDouble0 m_statDedupLogic; // Statistic tracking
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VDouble0 m_statAssignMerged; // Statistic tracking
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// METHODS
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void checkTimingControl(AstNode* nodep) {
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if (nodep->isTimingControl() && m_logicVertexp) {
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m_logicVertexp->clearReducibleAndDedupable("TimingControl");
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m_logicVertexp->setConsumed("TimingControl");
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}
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}
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void iterateNewStmt(AstNode* nodep, const char* nonReducibleReason,
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const char* consumeReason) {
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if (m_scopep) {
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UINFO(5, " STMT " << nodep << endl);
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// m_activep is null under AstCFunc's, that's ok.
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m_logicVertexp = new GateLogicVertex{&m_graph, m_scopep, nodep, m_activep, m_inSlow};
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if (nonReducibleReason) {
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m_logicVertexp->clearReducibleAndDedupable(nonReducibleReason);
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} else if (!m_activeReducible) {
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// Sequential logic is dedupable
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m_logicVertexp->clearReducible("Block Unreducible");
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}
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if (consumeReason) m_logicVertexp->setConsumed(consumeReason);
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if (VN_IS(nodep, SenItem)) m_logicVertexp->setConsumed("senItem");
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checkTimingControl(nodep);
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iterateChildren(nodep);
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m_logicVertexp = nullptr;
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}
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}
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GateVarVertex* makeVarVertex(AstVarScope* varscp) {
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GateVarVertex* vertexp = reinterpret_cast<GateVarVertex*>(varscp->user1p());
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if (!vertexp) {
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UINFO(6, "New vertex " << varscp << endl);
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vertexp = new GateVarVertex{&m_graph, m_scopep, varscp};
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varscp->user1p(vertexp);
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if (varscp->varp()->isSigPublic()) {
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// Public signals shouldn't be changed, pli code might be messing with them
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vertexp->clearReducibleAndDedupable("SigPublic");
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vertexp->setConsumed("SigPublic");
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}
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if (varscp->varp()->isIO() && varscp->scopep()->isTop()) {
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// We may need to convert to/from sysc/reg sigs
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vertexp->setIsTop();
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vertexp->clearReducibleAndDedupable("isTop");
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vertexp->setConsumed("isTop");
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}
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if (varscp->varp()->isUsedClock()) vertexp->setConsumed("clock");
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}
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return vertexp;
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}
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void optimizeElimVar(AstVarScope* varscp, AstNode* substp, AstNode* consumerp) {
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if (debug() >= 5) consumerp->dumpTree("- elimUsePre: ");
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if (!m_substitutions.tryGet(consumerp)) m_optimized.push_back(consumerp);
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m_substitutions(consumerp).emplace(varscp, substp->cloneTreePure(false));
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}
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void commitElimVar(AstNode* logicp) {
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if (auto* const substitutionsp = m_substitutions.tryGet(logicp)) {
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if (!substitutionsp->empty()) {
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eliminate(logicp, *substitutionsp, nullptr);
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AstNode* const foldedp = V3Const::constifyEdit(logicp);
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UASSERT_OBJ(foldedp == logicp, foldedp, "Should not remove whole logic");
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for (const auto& pair : *substitutionsp) pair.second->deleteTree();
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substitutionsp->clear();
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}
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}
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}
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void optimizeSignals(bool allowMultiIn);
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bool elimLogicOkOutputs(GateLogicVertex* consumeVertexp, const GateOkVisitor& okVisitor);
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void warnSignals();
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void consumedMark();
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void consumedMarkRecurse(GateEitherVertex* vertexp);
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void consumedMove();
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void dedupe();
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void mergeAssigns();
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void decomposeClkVectors();
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// VISITORS
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void visit(AstNetlist* nodep) override {
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iterateChildren(nodep);
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if (dumpGraphLevel() >= 3) m_graph.dumpDotFilePrefixed("gate_pre");
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warnSignals(); // Before loss of sync/async pointers
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// Decompose clock vectors -- need to do this before removing redundant edges
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decomposeClkVectors();
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m_graph.removeRedundantEdgesSum(&V3GraphEdge::followAlwaysTrue);
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if (dumpGraphLevel() >= 6) m_graph.dumpDotFilePrefixed("gate_simp");
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// Find gate interconnect and optimize
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m_graph.userClearVertices(); // vertex->user(): bool. Indicates we've set it as consumed
|
|
// Get rid of buffers first,
|
|
optimizeSignals(false);
|
|
// Then propagate more complicated equations
|
|
optimizeSignals(true);
|
|
// Commit substitutions on the optimized logic
|
|
for (AstNode* const logicp : m_optimized) commitElimVar(logicp);
|
|
// Remove redundant logic
|
|
if (v3Global.opt.fDedupe()) {
|
|
dedupe();
|
|
if (dumpGraphLevel() >= 6) m_graph.dumpDotFilePrefixed("gate_dedup");
|
|
}
|
|
if (v3Global.opt.fAssemble()) {
|
|
mergeAssigns();
|
|
if (dumpGraphLevel() >= 6) m_graph.dumpDotFilePrefixed("gate_assm");
|
|
}
|
|
// Consumption warnings
|
|
consumedMark();
|
|
if (dumpGraphLevel() >= 3) m_graph.dumpDotFilePrefixed("gate_opt");
|
|
// Rewrite assignments
|
|
consumedMove();
|
|
}
|
|
void visit(AstNodeModule* nodep) override {
|
|
VL_RESTORER(m_modp);
|
|
VL_RESTORER(m_activeReducible);
|
|
m_modp = nodep;
|
|
m_activeReducible = true;
|
|
iterateChildren(nodep);
|
|
}
|
|
void visit(AstScope* nodep) override {
|
|
UINFO(4, " SCOPE " << nodep << endl);
|
|
VL_RESTORER(m_scopep);
|
|
m_scopep = nodep;
|
|
m_logicVertexp = nullptr;
|
|
iterateChildren(nodep);
|
|
}
|
|
void visit(AstActive* nodep) override {
|
|
// Create required blocks and add to module
|
|
UINFO(4, " BLOCK " << nodep << endl);
|
|
VL_RESTORER(m_activep);
|
|
VL_RESTORER(m_activeReducible);
|
|
m_activeReducible = !(nodep->hasClocked()); // Seq logic outputs aren't reducible
|
|
m_activep = nodep;
|
|
AstNode::user2ClearTree();
|
|
iterateChildren(nodep);
|
|
AstNode::user2ClearTree();
|
|
}
|
|
void visit(AstNodeVarRef* nodep) override {
|
|
if (m_scopep) {
|
|
UASSERT_OBJ(m_logicVertexp, nodep, "Var ref not under a logic block");
|
|
AstVarScope* const varscp = nodep->varScopep();
|
|
UASSERT_OBJ(varscp, nodep, "Var didn't get varscoped in V3Scope.cpp");
|
|
GateVarVertex* const vvertexp = makeVarVertex(varscp);
|
|
UINFO(5, " VARREF to " << varscp << endl);
|
|
if (m_inSenItem) {
|
|
vvertexp->setIsClock();
|
|
// For SYNCASYNCNET
|
|
varscp->user2(true);
|
|
} else if (m_activep && m_activep->hasClocked() && nodep->access().isReadOnly()) {
|
|
if (varscp->user2()) {
|
|
if (!vvertexp->rstAsyncNodep()) vvertexp->rstAsyncNodep(nodep);
|
|
} else {
|
|
if (!vvertexp->rstSyncNodep()) vvertexp->rstSyncNodep(nodep);
|
|
}
|
|
}
|
|
// We use weight of one; if we ref the var more than once, when we simplify,
|
|
// the weight will increase
|
|
if (nodep->access().isWriteOrRW()) {
|
|
new V3GraphEdge{&m_graph, m_logicVertexp, vvertexp, 1};
|
|
}
|
|
if (nodep->access().isReadOrRW()) {
|
|
new V3GraphEdge{&m_graph, vvertexp, m_logicVertexp, 1};
|
|
}
|
|
}
|
|
}
|
|
void visit(AstAlwaysPublic* nodep) override {
|
|
VL_RESTORER(m_inSlow);
|
|
m_inSlow = true;
|
|
iterateNewStmt(nodep, "AlwaysPublic", nullptr);
|
|
}
|
|
void visit(AstCFunc* nodep) override {
|
|
iterateNewStmt(nodep, "User C Function", "User C Function");
|
|
}
|
|
void visit(AstClocking* nodep) override { iterateNewStmt(nodep, nullptr, nullptr); }
|
|
void visit(AstSenItem* nodep) override {
|
|
VL_RESTORER(m_inSenItem);
|
|
m_inSenItem = true;
|
|
if (m_logicVertexp) { // Already under logic; presumably a SenGate
|
|
iterateChildren(nodep);
|
|
} else { // Standalone item, probably right under a SenTree
|
|
iterateNewStmt(nodep, nullptr, nullptr);
|
|
}
|
|
}
|
|
void visit(AstNodeProcedure* nodep) override {
|
|
VL_RESTORER(m_inSlow);
|
|
m_inSlow = VN_IS(nodep, Initial) || VN_IS(nodep, Final);
|
|
iterateNewStmt(nodep, (nodep->isJustOneBodyStmt() ? nullptr : "Multiple Stmts"), nullptr);
|
|
}
|
|
void visit(AstAssignAlias* nodep) override { //
|
|
iterateNewStmt(nodep, nullptr, nullptr);
|
|
}
|
|
void visit(AstAssignW* nodep) override { //
|
|
iterateNewStmt(nodep, nullptr, nullptr);
|
|
}
|
|
void visit(AstCoverToggle* nodep) override {
|
|
iterateNewStmt(nodep, "CoverToggle", "CoverToggle");
|
|
}
|
|
void visit(AstTraceDecl* nodep) override {
|
|
VL_RESTORER(m_inSlow);
|
|
m_inSlow = true;
|
|
iterateNewStmt(nodep, "Tracing", "Tracing");
|
|
}
|
|
void visit(AstConcat* nodep) override {
|
|
UASSERT_OBJ(!(VN_IS(nodep->backp(), NodeAssign)
|
|
&& VN_AS(nodep->backp(), NodeAssign)->lhsp() == nodep),
|
|
nodep, "Concat on LHS of assignment; V3Const should have deleted it");
|
|
iterateChildren(nodep);
|
|
}
|
|
|
|
//--------------------
|
|
void visit(AstNode* nodep) override {
|
|
iterateChildren(nodep);
|
|
if (nodep->isOutputter() && m_logicVertexp) m_logicVertexp->setConsumed("outputter");
|
|
checkTimingControl(nodep);
|
|
}
|
|
|
|
public:
|
|
// CONSTRUCTORS
|
|
explicit GateVisitor(AstNode* nodep) { iterate(nodep); }
|
|
~GateVisitor() override {
|
|
V3Stats::addStat("Optimizations, Gate sigs deleted", m_statSigs);
|
|
V3Stats::addStat("Optimizations, Gate inputs replaced", m_statRefs);
|
|
V3Stats::addStat("Optimizations, Gate sigs deduped", m_statDedupLogic);
|
|
V3Stats::addStat("Optimizations, Gate assign merged", m_statAssignMerged);
|
|
}
|
|
};
|
|
|
|
//----------------------------------------------------------------------
|
|
|
|
void GateVisitor::optimizeSignals(bool allowMultiIn) {
|
|
for (V3GraphVertex* itp = m_graph.verticesBeginp(); itp; itp = itp->verticesNextp()) {
|
|
GateVarVertex* const vvertexp = itp->cast<GateVarVertex>();
|
|
|
|
// Consider "inlining" variables
|
|
if (!vvertexp) continue;
|
|
|
|
if (vvertexp->inEmpty()) { // Can't deal with no sources
|
|
vvertexp->clearReducibleAndDedupable("inEmpty");
|
|
} else if (!vvertexp->inSize1()) { // Can't deal with more than one src
|
|
vvertexp->clearReducibleAndDedupable("size!1");
|
|
}
|
|
|
|
// Reduce it?
|
|
if (!vvertexp->reducible()) continue;
|
|
|
|
// Grab the driving logic
|
|
GateLogicVertex* const logicVertexp
|
|
= static_cast<GateLogicVertex*>(vvertexp->inBeginp()->fromp());
|
|
if (!logicVertexp->reducible()) continue;
|
|
AstNode* const logicp = logicVertexp->nodep();
|
|
|
|
// Commit pending optimizations to driving logic, as we will re-analyze
|
|
commitElimVar(logicp);
|
|
|
|
// Can we eliminate?
|
|
const GateOkVisitor okVisitor{logicp, vvertexp->isClock(), false};
|
|
|
|
// Was it ok?
|
|
if (!okVisitor.isSimple()) continue;
|
|
|
|
// Does it read multiple source variables?
|
|
if (okVisitor.rhsVarRefs().size() > 1) {
|
|
if (!allowMultiIn) continue;
|
|
// Do it if not used, or used only once, ignoring traces
|
|
int n = 0;
|
|
for (V3GraphEdge* edgep = vvertexp->outBeginp(); edgep; edgep = edgep->outNextp()) {
|
|
const GateLogicVertex* const consumeVertexp
|
|
= static_cast<GateLogicVertex*>(edgep->top());
|
|
// Ignore tracing or other slow path junk, or if the destination is not used
|
|
if (!consumeVertexp->slow() && consumeVertexp->outBeginp()) n += edgep->weight();
|
|
if (n > 1) break;
|
|
}
|
|
|
|
if (n > 1) continue;
|
|
}
|
|
|
|
// Process it
|
|
AstNode* const substp = okVisitor.substTree();
|
|
if (debug() >= 5) logicp->dumpTree("- elimVar: ");
|
|
if (debug() >= 5) substp->dumpTree("- subst: ");
|
|
++m_statSigs;
|
|
bool removedAllUsages = true;
|
|
for (V3GraphEdge* edgep = vvertexp->outBeginp(); edgep;) {
|
|
GateLogicVertex* const consumeVertexp = static_cast<GateLogicVertex*>(edgep->top());
|
|
AstNode* const consumerp = consumeVertexp->nodep();
|
|
if (!elimLogicOkOutputs(consumeVertexp, okVisitor /*ref*/)) {
|
|
// Cannot optimize this replacement
|
|
removedAllUsages = false;
|
|
edgep = edgep->outNextp();
|
|
} else {
|
|
optimizeElimVar(vvertexp->varScp(), substp, consumerp);
|
|
// If the new replacement referred to a signal,
|
|
// Correct the graph to point to this new generating variable
|
|
const GateVarRefList& rhsVarRefs = okVisitor.rhsVarRefs();
|
|
for (AstNodeVarRef* const refp : rhsVarRefs) {
|
|
AstVarScope* const newvarscp = refp->varScopep();
|
|
GateVarVertex* const varvertexp = makeVarVertex(newvarscp);
|
|
new V3GraphEdge{&m_graph, varvertexp, consumeVertexp, 1};
|
|
// Propagate clock attribute onto generating node
|
|
varvertexp->propagateAttrClocksFrom(vvertexp);
|
|
}
|
|
// Remove the edge
|
|
VL_DO_DANGLING(edgep->unlinkDelete(), edgep);
|
|
++m_statRefs;
|
|
edgep = vvertexp->outBeginp();
|
|
}
|
|
}
|
|
|
|
if (removedAllUsages) {
|
|
// Remove input links
|
|
while (V3GraphEdge* const edgep = vvertexp->inBeginp()) {
|
|
VL_DO_DANGLING(edgep->unlinkDelete(), edgep);
|
|
}
|
|
// Mark the vertex so we don't mark it as being unconsumed in the next step
|
|
vvertexp->user(true);
|
|
logicVertexp->user(true);
|
|
}
|
|
}
|
|
}
|
|
|
|
bool GateVisitor::elimLogicOkOutputs(GateLogicVertex* consumeVertexp,
|
|
const GateOkVisitor& okVisitor) {
|
|
// Return true if can optimize
|
|
// Return false if the consuming logic has an output signal that the
|
|
// replacement logic has as an input
|
|
|
|
// Use map to find duplicates between two lists
|
|
std::unordered_set<AstVarScope*> varscopes;
|
|
// Replacement logic usually has shorter input list, so faster to build list based on it
|
|
const GateVarRefList& rhsVarRefs = okVisitor.rhsVarRefs();
|
|
for (GateVarRefList::const_iterator it = rhsVarRefs.begin(); it != rhsVarRefs.end(); ++it) {
|
|
AstVarScope* const vscp = (*it)->varScopep();
|
|
varscopes.insert(vscp);
|
|
}
|
|
for (V3GraphEdge* edgep = consumeVertexp->outBeginp(); edgep; edgep = edgep->outNextp()) {
|
|
const GateVarVertex* const consVVertexp = static_cast<GateVarVertex*>(edgep->top());
|
|
AstVarScope* const vscp = consVVertexp->varScp();
|
|
if (varscopes.find(vscp) != varscopes.end()) {
|
|
UINFO(9, " Block-unopt, insertion generates input vscp " << vscp << endl);
|
|
return false;
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
|
|
//----------------------------------------------------------------------
|
|
|
|
void GateVisitor::consumedMark() {
|
|
// Propagate consumed signals backwards to all producers into a consumed node
|
|
m_graph.userClearVertices();
|
|
for (V3GraphVertex* vertexp = m_graph.verticesBeginp(); vertexp;
|
|
vertexp = vertexp->verticesNextp()) {
|
|
GateEitherVertex* const evertexp = static_cast<GateEitherVertex*>(vertexp);
|
|
if (!evertexp->user() && evertexp->consumed()) consumedMarkRecurse(evertexp);
|
|
}
|
|
}
|
|
|
|
void GateVisitor::consumedMarkRecurse(GateEitherVertex* vertexp) {
|
|
if (vertexp->user()) return; // Already marked
|
|
vertexp->user(true);
|
|
if (!vertexp->consumed()) vertexp->setConsumed("propagated");
|
|
// Walk sources and mark them too
|
|
for (V3GraphEdge* edgep = vertexp->inBeginp(); edgep; edgep = edgep->inNextp()) {
|
|
GateEitherVertex* const eFromVertexp = static_cast<GateEitherVertex*>(edgep->fromp());
|
|
consumedMarkRecurse(eFromVertexp);
|
|
}
|
|
}
|
|
|
|
void GateVisitor::consumedMove() {
|
|
// Remove unused logic (logic that doesn't hit a combo block or a display statement)
|
|
// We need the "usually" block logic to do a better job at this
|
|
for (V3GraphVertex* vertexp = m_graph.verticesBeginp(); vertexp;
|
|
vertexp = vertexp->verticesNextp()) {
|
|
if (const GateVarVertex* const vvertexp = vertexp->cast<GateVarVertex>()) {
|
|
if (!vvertexp->consumed() && !vvertexp->user()) {
|
|
UINFO(8, "Unconsumed " << vvertexp->varScp() << endl);
|
|
}
|
|
} else {
|
|
const GateLogicVertex* const lvertexp = static_cast<GateLogicVertex*>(vertexp);
|
|
AstNode* const nodep = lvertexp->nodep();
|
|
const AstActive* const oldactp = lvertexp->activep(); // nullptr under cfunc
|
|
if (!lvertexp->consumed() && oldactp) {
|
|
// Eventually: Move the statement to a new active block
|
|
// with "tracing-on" sensitivity
|
|
UINFO(8, " Remove unconsumed " << nodep << endl);
|
|
nodep->unlinkFrBack();
|
|
VL_DO_DANGLING(pushDeletep(nodep), nodep);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
//----------------------------------------------------------------------
|
|
|
|
void GateVisitor::warnSignals() {
|
|
AstNode::user2ClearTree();
|
|
for (V3GraphVertex* itp = m_graph.verticesBeginp(); itp; itp = itp->verticesNextp()) {
|
|
if (const GateVarVertex* const vvertexp = itp->cast<GateVarVertex>()) {
|
|
const AstVarScope* const vscp = vvertexp->varScp();
|
|
const AstNode* const sp = vvertexp->rstSyncNodep();
|
|
const AstNode* const ap = vvertexp->rstAsyncNodep();
|
|
if (ap && sp && !vscp->varp()->user2()) {
|
|
// This is somewhat wrong, as marking one flop as ok for sync
|
|
// may mean a different flop now fails. However it's a pain to
|
|
// then report a warning in a new place - we should report them all at once.
|
|
// Instead we'll disable if any disabled
|
|
if (!vscp->fileline()->warnIsOff(V3ErrorCode::SYNCASYNCNET)
|
|
&& !ap->fileline()->warnIsOff(V3ErrorCode::SYNCASYNCNET)
|
|
&& !sp->fileline()->warnIsOff(V3ErrorCode::SYNCASYNCNET)) {
|
|
vscp->varp()->user2(true); // Warn only once per signal
|
|
vscp->v3warn(SYNCASYNCNET,
|
|
"Signal flopped as both synchronous and async: "
|
|
<< vscp->prettyNameQ() << '\n'
|
|
<< ap->warnOther() << "... Location of async usage\n"
|
|
<< ap->warnContextPrimary() << '\n'
|
|
<< sp->warnOther() << "... Location of sync usage\n"
|
|
<< sp->warnContextSecondary());
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
//######################################################################
|
|
// Auxiliary hash class for GateDedupeVarVisitor
|
|
|
|
class GateDedupeHash final : public V3DupFinderUserSame {
|
|
private:
|
|
// NODE STATE
|
|
// Ast*::user2p -> parent AstNodeAssign* for this rhsp
|
|
// AstNodeExpr::user3p -> see AuxAstNodeExpr via m_aux
|
|
// VNUser1InUse m_inuser1; (Allocated for use in GateVisitor)
|
|
// VNUser2InUse m_inuser2; (Allocated for use in GateVisitor)
|
|
const VNUser3InUse m_inuser3;
|
|
// VNUser4InUse m_inuser4; (Allocated for use in V3Hasher via V3DupFinder)
|
|
|
|
struct AuxAstNodeExpr final {
|
|
// AstActive* of assign, for isSame() in test for duplicate. Set to nullptr if this
|
|
// assign's tree was later replaced
|
|
AstActive* activep = nullptr;
|
|
// AstNodeExpr* of assign if condition, for isSame() in test for duplicate. Set to nullptr
|
|
// if this assign's tree was later replaced
|
|
AstNodeExpr* condp = nullptr;
|
|
};
|
|
|
|
AstUser3Allocator<AstNodeExpr, AuxAstNodeExpr> m_auxNodeExpr;
|
|
|
|
V3DupFinder m_dupFinder; // Duplicate finder for rhs of assigns
|
|
std::unordered_set<AstNode*> m_nodeDeleteds; // Any node in this hash was deleted
|
|
|
|
bool same(AstNode* node1p, AstNode* node2p) {
|
|
// Regarding the complexity of this function 'same':
|
|
// Applying this comparison function to a a set of n trees pairwise is O(n^2) in the
|
|
// number of comparisons (number of pairs). AstNode::sameTree itself, is O(sizeOfTree) in
|
|
// the worst case, which happens if the operands of sameTree are indeed identical copies,
|
|
// which means this line is O(n^2*sizeOfTree), iff you are comparing identical copies of
|
|
// the same tree. In practice the identity comparison over the pointers, and the short
|
|
// circuiting in sameTree means that for comparing the same tree instance to itself, or
|
|
// trees of different types/shapes is a lot closer to O(1), so this 'same' function is
|
|
// Omega(n^2) and O(n^2*sizeOfTree), and in practice as we are mostly comparing the same
|
|
// instance to itself or different trees, the complexity should be closer to the lower
|
|
// bound.
|
|
//
|
|
// Also if you see where this 'same' function is used within isSame, it's only ever
|
|
// comparing AstActive nodes, which are very likely not to compare equals (and for the
|
|
// purposes of V3Gate, we probably only care about them either being identical instances,
|
|
// or having the same sensitivities anyway, so if this becomes a problem, it can be
|
|
// improved which should also speed things up), and AstNodeExpr for if conditions, which
|
|
// are hopefully small, and to be safe they should probably be only considered same when
|
|
// identical instances (otherwise if writing the condition between 2 ifs don't really
|
|
// merge).
|
|
return node1p == node2p || (node1p && node1p->sameTree(node2p));
|
|
}
|
|
|
|
public:
|
|
GateDedupeHash() = default;
|
|
~GateDedupeHash() override {
|
|
if (v3Global.opt.debugCheck()) check();
|
|
}
|
|
|
|
// About to replace a node; any node we're tracking refers to oldp, change it to newp.
|
|
// This might be a variable on the lhs of the duplicate tree,
|
|
// or could be a rhs variable in a tree we're not replacing (or not yet anyways)
|
|
void hashReplace(AstNode* oldp, AstNode* newp) {
|
|
UINFO(9, "replacing " << (void*)oldp << " with " << (void*)newp << endl);
|
|
// We could update the activep and condp but the resulting node
|
|
// still has incorrect hash. We really need to remove all hash on
|
|
// the whole hash entry tree involving the replaced node and
|
|
// rehash. That's complicated and this is rare, so just remove it
|
|
// from consideration.
|
|
m_nodeDeleteds.insert(oldp);
|
|
}
|
|
bool isReplaced(AstNodeExpr* nodep) {
|
|
// Assignment may have been hashReplaced, if so consider non-match (effectively removed)
|
|
const auto& aux = m_auxNodeExpr(nodep);
|
|
AstActive* const activep = aux.activep;
|
|
AstNodeExpr* const condp = aux.condp;
|
|
return (activep && m_nodeDeleteds.count(activep))
|
|
|| (condp && m_nodeDeleteds.count(condp));
|
|
}
|
|
|
|
// Callback from V3DupFinder::findDuplicate
|
|
bool isSame(AstNode* node1p, AstNode* node2p) override {
|
|
AstNodeExpr* const expr1p = VN_AS(node1p, NodeExpr);
|
|
AstNodeExpr* const expr2p = VN_AS(node2p, NodeExpr);
|
|
|
|
// Assignment may have been hashReplaced, if so consider non-match (effectively removed)
|
|
if (isReplaced(expr1p) || isReplaced(expr2p)) {
|
|
// UINFO(9, "isSame hit on replaced "<<(void*)node1p<<" "<<(void*)node2p<<endl);
|
|
return false;
|
|
}
|
|
|
|
const auto& aux1 = m_auxNodeExpr(expr1p);
|
|
const auto& aux2 = m_auxNodeExpr(expr2p);
|
|
|
|
return same(aux1.activep, aux2.activep) && same(aux1.condp, aux2.condp)
|
|
&& node1p->user2p()->type() == node2p->user2p()->type();
|
|
}
|
|
|
|
const AstNodeAssign* hashAndFindDupe(AstNodeAssign* assignp, AstActive* extra1p,
|
|
AstNodeExpr* extra2p) {
|
|
// Legal for extra1p/2p to be nullptr, we'll compare with other assigns with extras also
|
|
// nullptr
|
|
AstNodeExpr* const rhsp = assignp->rhsp();
|
|
rhsp->user2p(assignp);
|
|
auto& aux = m_auxNodeExpr(rhsp);
|
|
aux.activep = extra1p;
|
|
aux.condp = extra2p;
|
|
|
|
const auto inserted = m_dupFinder.insert(rhsp);
|
|
const auto dupit = m_dupFinder.findDuplicate(rhsp, this);
|
|
// Even though rhsp was just inserted, V3DupFinder::findDuplicate doesn't
|
|
// return anything in the hash that has the same pointer (V3DupFinder::findDuplicate)
|
|
// So dupit is either a different, duplicate rhsp, or the end of the hash.
|
|
if (dupit != m_dupFinder.end()) {
|
|
m_dupFinder.erase(inserted);
|
|
return VN_AS(dupit->second->user2p(), NodeAssign);
|
|
}
|
|
// Retain new inserted information
|
|
return nullptr;
|
|
}
|
|
|
|
void check() {
|
|
for (const auto& itr : m_dupFinder) {
|
|
AstNodeExpr* const nodep = VN_AS(itr.second, NodeExpr);
|
|
const auto& aux = m_auxNodeExpr(nodep);
|
|
const AstActive* const activep = aux.activep;
|
|
const AstNodeExpr* const condVarp = aux.condp;
|
|
if (!isReplaced(nodep)) {
|
|
// This class won't break if activep isn't an active, or
|
|
// ifVar isn't a var, but this is checking the caller's construction.
|
|
UASSERT_OBJ(!activep || (!VN_DELETED(activep)), nodep,
|
|
"V3DupFinder check failed, lost active pointer");
|
|
UASSERT_OBJ(!condVarp || !VN_DELETED(condVarp), nodep,
|
|
"V3DupFinder check failed, lost if pointer");
|
|
}
|
|
}
|
|
}
|
|
};
|
|
|
|
//######################################################################
|
|
// Have we seen the rhs of this assign before?
|
|
|
|
class GateDedupeVarVisitor final : public VNVisitor {
|
|
// Given a node, it is visited to try to find the AstNodeAssign under
|
|
// it that can used for dedupe.
|
|
// Right now, only the following node trees are supported for dedupe.
|
|
// 1. AstNodeAssign
|
|
// 2. AstAlways -> AstNodeAssign
|
|
// (Note, the assign must also be the only node under the always)
|
|
// 3. AstAlways -> AstNodeIf -> AstNodeAssign
|
|
// (Note, the IF must be the only node under the always,
|
|
// and the assign must be the only node under the if, other than the ifcond)
|
|
// Any other ordering or node type, except for an AstComment, makes it not dedupable
|
|
// AstExprStmt in the subtree of a node also makes the node not dedupable.
|
|
private:
|
|
// STATE
|
|
GateDedupeHash m_ghash; // Hash used to find dupes of rhs of assign
|
|
AstNodeAssign* m_assignp = nullptr; // Assign found for dedupe
|
|
AstNodeExpr* m_ifCondp = nullptr; // IF condition that assign is under
|
|
bool m_always = false; // Assign is under an always
|
|
bool m_dedupable = true; // Determined the assign to be dedupable
|
|
|
|
// VISITORS
|
|
void visit(AstNodeAssign* assignp) override {
|
|
if (m_dedupable) {
|
|
// I think we could safely dedupe an always block with multiple
|
|
// non-blocking statements, but erring on side of caution here
|
|
if (!m_assignp) {
|
|
m_assignp = assignp;
|
|
m_dedupable = !assignp->exists([&](AstExprStmt*) { return true; });
|
|
} else {
|
|
m_dedupable = false;
|
|
}
|
|
}
|
|
}
|
|
void visit(AstAlways* alwaysp) override {
|
|
if (m_dedupable) {
|
|
if (!m_always) {
|
|
m_always = true;
|
|
iterateAndNextNull(alwaysp->stmtsp());
|
|
} else {
|
|
m_dedupable = false;
|
|
}
|
|
}
|
|
}
|
|
// Ugly support for latches of the specific form -
|
|
// always @(...)
|
|
// if (...)
|
|
// foo = ...; // or foo <= ...;
|
|
void visit(AstNodeIf* ifp) override {
|
|
if (m_dedupable) {
|
|
if (m_always && !m_ifCondp && !ifp->elsesp()) {
|
|
// we're under an always, this is the first IF, and there's no else
|
|
m_ifCondp = ifp->condp();
|
|
m_dedupable = !m_ifCondp->exists([&](AstExprStmt*) { return true; });
|
|
iterateAndNextNull(ifp->thensp());
|
|
} else {
|
|
m_dedupable = false;
|
|
}
|
|
}
|
|
}
|
|
|
|
void visit(AstComment*) override {} // NOP
|
|
//--------------------
|
|
void visit(AstNode*) override { //
|
|
m_dedupable = false;
|
|
}
|
|
|
|
public:
|
|
// CONSTRUCTORS
|
|
GateDedupeVarVisitor() = default;
|
|
~GateDedupeVarVisitor() override = default;
|
|
// PUBLIC METHODS
|
|
AstNodeVarRef* findDupe(AstNode* nodep, AstVarScope* consumerVarScopep, AstActive* activep) {
|
|
m_assignp = nullptr;
|
|
m_ifCondp = nullptr;
|
|
m_always = false;
|
|
m_dedupable = true;
|
|
iterate(nodep);
|
|
if (m_dedupable && m_assignp) {
|
|
const AstNode* const lhsp = m_assignp->lhsp();
|
|
// Possible todo, handle more complex lhs expressions
|
|
if (const AstNodeVarRef* const lhsVarRefp = VN_CAST(lhsp, NodeVarRef)) {
|
|
UASSERT_OBJ(lhsVarRefp->varScopep() == consumerVarScopep, consumerVarScopep,
|
|
"Consumer doesn't match lhs of assign");
|
|
if (const AstNodeAssign* const dup
|
|
= m_ghash.hashAndFindDupe(m_assignp, activep, m_ifCondp)) {
|
|
return static_cast<AstNodeVarRef*>(dup->lhsp());
|
|
}
|
|
}
|
|
}
|
|
return nullptr;
|
|
}
|
|
void hashReplace(AstNode* oldp, AstNode* newp) { m_ghash.hashReplace(oldp, newp); }
|
|
};
|
|
|
|
// ######################################################################
|
|
|
|
static void eliminate(AstNode* logicp,
|
|
const std::unordered_map<AstVarScope*, AstNode*>& substitutions,
|
|
GateDedupeVarVisitor* varVisp) {
|
|
|
|
// Recursion filter holding already replaced variables
|
|
std::unordered_set<const AstVarScope*> replaced(substitutions.size() * 2);
|
|
|
|
const std::function<void(AstNodeVarRef*)> visit = [&, varVisp](AstNodeVarRef* nodep) -> void {
|
|
// See if this variable has a substitution
|
|
AstVarScope* const vscp = nodep->varScopep();
|
|
const auto& it = substitutions.find(vscp);
|
|
if (it == substitutions.end()) return;
|
|
|
|
// Do not substitute circular logic
|
|
if (!replaced.insert(vscp).second) return;
|
|
|
|
AstNode* const substp = it->second;
|
|
|
|
// Substitute in the new tree
|
|
UASSERT_OBJ(nodep->access().isReadOnly(), nodep,
|
|
"Can't replace lvalue assignments with const var");
|
|
UASSERT_OBJ(!(VN_IS(substp, NodeVarRef) && nodep->isSame(substp)),
|
|
// Prevent an infinite loop...
|
|
substp, "Replacing node with itself; perhaps circular logic?");
|
|
// The replacement
|
|
AstNode* const newp = substp->cloneTreePure(false);
|
|
// Which fileline() to use? If replacing with logic, an error/warning is likely to want
|
|
// to point to the logic IE what we're replacing with. However, a VARREF should point
|
|
// to the original as it's otherwise confusing to throw warnings that point to a PIN
|
|
// rather than where the pin us used.
|
|
if (VN_IS(newp, VarRef)) newp->fileline(nodep->fileline());
|
|
// Make the newp an rvalue like nodep. This facilitates the hashing in dedupe.
|
|
if (AstNodeVarRef* const varrefp = VN_CAST(newp, NodeVarRef)) {
|
|
varrefp->access(VAccess::READ);
|
|
}
|
|
// Update hash?
|
|
if (varVisp) varVisp->hashReplace(nodep, newp);
|
|
// Replace the node
|
|
nodep->replaceWith(newp);
|
|
VL_DO_DANGLING(nodep->deleteTree(), nodep);
|
|
// Recursively substitute the new tree
|
|
newp->foreach(visit);
|
|
|
|
// Remove from recursion filter
|
|
replaced.erase(vscp);
|
|
};
|
|
|
|
logicp->foreach(visit);
|
|
}
|
|
|
|
// ######################################################################
|
|
// Recurse through the graph, looking for duplicate expressions on the rhs of an assign
|
|
|
|
class GateDedupeGraphVisitor final : public GateGraphBaseVisitor {
|
|
private:
|
|
// NODE STATE
|
|
// AstVarScope::user2p -> bool: already visited
|
|
// VNUser2InUse m_inuser2; (Allocated for use in GateVisitor)
|
|
VDouble0 m_numDeduped; // Statistic tracking
|
|
GateDedupeVarVisitor m_varVisitor; // Looks for a dupe of the logic
|
|
int m_depth = 0; // Iteration depth
|
|
|
|
VNUser visit(GateVarVertex* vvertexp, VNUser) override {
|
|
// Check that we haven't been here before
|
|
if (m_depth > GATE_DEDUP_MAX_DEPTH)
|
|
return VNUser{0}; // Break loops; before user2 set so hit this vertex later
|
|
if (vvertexp->varScp()->user2()) return VNUser{0};
|
|
vvertexp->varScp()->user2(true);
|
|
|
|
m_depth++;
|
|
if (vvertexp->inSize1()) {
|
|
AstNodeVarRef* const dupVarRefp = static_cast<AstNodeVarRef*>(
|
|
vvertexp->iterateInEdges(*this, VNUser{vvertexp}).toNodep());
|
|
if (dupVarRefp) { // visit(GateLogicVertex*...) returned match
|
|
const V3GraphEdge* edgep = vvertexp->inBeginp();
|
|
GateLogicVertex* const lvertexp = static_cast<GateLogicVertex*>(edgep->fromp());
|
|
UASSERT_OBJ(vvertexp->dedupable(), vvertexp->varScp(),
|
|
"GateLogicVertex* visit should have returned nullptr "
|
|
"if consumer var vertex is not dedupable.");
|
|
const GateOkVisitor okVisitor{lvertexp->nodep(), false, true};
|
|
if (okVisitor.isSimple()) {
|
|
const AstVarScope* const dupVarScopep = dupVarRefp->varScopep();
|
|
GateVarVertex* const dupVvertexp
|
|
= reinterpret_cast<GateVarVertex*>(dupVarScopep->user1p());
|
|
UINFO(4, "replacing " << vvertexp << " with " << dupVvertexp << endl);
|
|
++m_numDeduped;
|
|
// Replace all of this varvertex's consumers with dupVarRefp
|
|
for (V3GraphEdge* outedgep = vvertexp->outBeginp(); outedgep;) {
|
|
const GateLogicVertex* const consumeVertexp
|
|
= static_cast<GateLogicVertex*>(outedgep->top());
|
|
AstNode* const consumerp = consumeVertexp->nodep();
|
|
UINFO(9,
|
|
"elim src vtx" << lvertexp << " node " << lvertexp->nodep() << endl);
|
|
UINFO(9,
|
|
"elim cons vtx" << consumeVertexp << " node " << consumerp << endl);
|
|
UINFO(9, "elim var vtx " << vvertexp << " node " << vvertexp->varScp()
|
|
<< endl);
|
|
UINFO(9, "replace with " << dupVarRefp << endl);
|
|
if (lvertexp == consumeVertexp) {
|
|
UINFO(9, "skipping as self-recirculates\n");
|
|
} else {
|
|
eliminate(consumerp, {std::make_pair(vvertexp->varScp(), dupVarRefp)},
|
|
&m_varVisitor);
|
|
}
|
|
outedgep = outedgep->relinkFromp(dupVvertexp);
|
|
}
|
|
// Propagate attributes
|
|
dupVvertexp->propagateAttrClocksFrom(vvertexp);
|
|
// Remove inputs links
|
|
while (V3GraphEdge* const inedgep = vvertexp->inBeginp()) {
|
|
VL_DO_DANGLING(inedgep->unlinkDelete(), inedgep);
|
|
}
|
|
vvertexp->user(true);
|
|
lvertexp->user(true);
|
|
}
|
|
}
|
|
}
|
|
m_depth--;
|
|
return VNUser{0};
|
|
}
|
|
|
|
// Given iterated logic, starting at vu which was consumer's GateVarVertex
|
|
// Returns a varref that has the same logic input; or nullptr if none
|
|
VNUser visit(GateLogicVertex* lvertexp, VNUser vu) override {
|
|
lvertexp->iterateInEdges(*this);
|
|
|
|
const GateVarVertex* const consumerVvertexpp
|
|
= static_cast<GateVarVertex*>(vu.toGraphVertex());
|
|
if (lvertexp->dedupable() && consumerVvertexpp->dedupable()) {
|
|
AstNode* const nodep = lvertexp->nodep();
|
|
AstVarScope* const consumerVarScopep = consumerVvertexpp->varScp();
|
|
// TODO: Doing a simple pointer comparison of activep won't work
|
|
// optimally for statements under generated clocks. Statements under
|
|
// different generated clocks will never compare as equal, even if the
|
|
// generated clocks are deduped into one clock.
|
|
AstActive* const activep = lvertexp->activep();
|
|
return VNUser{m_varVisitor.findDupe(nodep, consumerVarScopep, activep)};
|
|
}
|
|
return VNUser{0};
|
|
}
|
|
|
|
public:
|
|
explicit GateDedupeGraphVisitor(V3Graph* graphp)
|
|
: GateGraphBaseVisitor{graphp} {}
|
|
void dedupeTree(GateVarVertex* vvertexp) { vvertexp->accept(*this); }
|
|
VDouble0 numDeduped() { return m_numDeduped; }
|
|
};
|
|
|
|
//----------------------------------------------------------------------
|
|
|
|
void GateVisitor::dedupe() {
|
|
AstNode::user2ClearTree();
|
|
GateDedupeGraphVisitor deduper{&m_graph};
|
|
// Traverse starting from each of the clocks
|
|
UINFO(9, "Gate dedupe() clocks:\n");
|
|
for (V3GraphVertex* itp = m_graph.verticesBeginp(); itp; itp = itp->verticesNextp()) {
|
|
if (GateVarVertex* const vvertexp = itp->cast<GateVarVertex>()) {
|
|
if (vvertexp->isClock()) deduper.dedupeTree(vvertexp);
|
|
}
|
|
}
|
|
// Traverse starting from each of the outputs
|
|
UINFO(9, "Gate dedupe() outputs:\n");
|
|
for (V3GraphVertex* itp = m_graph.verticesBeginp(); itp; itp = itp->verticesNextp()) {
|
|
if (GateVarVertex* const vvertexp = itp->cast<GateVarVertex>()) {
|
|
if (vvertexp->isTop() && vvertexp->varScp()->varp()->isWritable()) {
|
|
deduper.dedupeTree(vvertexp);
|
|
}
|
|
}
|
|
}
|
|
m_statDedupLogic += deduper.numDeduped();
|
|
}
|
|
|
|
//######################################################################
|
|
// Recurse through the graph, try to merge assigns
|
|
|
|
class GateMergeAssignsGraphVisitor final : public GateGraphBaseVisitor {
|
|
private:
|
|
// NODE STATE
|
|
AstNodeAssign* m_assignp = nullptr;
|
|
const AstActive* m_activep = nullptr;
|
|
GateLogicVertex* m_logicvp = nullptr;
|
|
VDouble0 m_numMergedAssigns; // Statistic tracking
|
|
|
|
// assemble two Sel into one if possible
|
|
AstSel* merge(AstSel* pre, AstSel* cur) {
|
|
const AstVarRef* const preVarRefp = VN_CAST(pre->fromp(), VarRef);
|
|
AstVarRef* const curVarRefp = VN_CAST(cur->fromp(), VarRef);
|
|
if (!preVarRefp || !curVarRefp || !curVarRefp->same(preVarRefp)) {
|
|
return nullptr; // not the same var
|
|
}
|
|
const AstConst* const pstart = VN_CAST(pre->lsbp(), Const);
|
|
const AstConst* const pwidth = VN_CAST(pre->widthp(), Const);
|
|
const AstConst* const cstart = VN_CAST(cur->lsbp(), Const);
|
|
const AstConst* const cwidth = VN_CAST(cur->widthp(), Const);
|
|
if (!pstart || !pwidth || !cstart || !cwidth) return nullptr; // too complicated
|
|
if (cur->lsbConst() + cur->widthConst() == pre->lsbConst()) {
|
|
return new AstSel{curVarRefp->fileline(), curVarRefp->cloneTree(false),
|
|
cur->lsbConst(), pre->widthConst() + cur->widthConst()};
|
|
} else {
|
|
return nullptr;
|
|
}
|
|
}
|
|
|
|
VNUser visit(GateVarVertex* vvertexp, VNUser) override {
|
|
for (V3GraphEdge* edgep = vvertexp->inBeginp(); edgep;) {
|
|
V3GraphEdge* oldedgep = edgep;
|
|
edgep = edgep->inNextp(); // for recursive since the edge could be deleted
|
|
if (GateLogicVertex* const lvertexp = oldedgep->fromp()->cast<GateLogicVertex>()) {
|
|
if (AstNodeAssign* const assignp = VN_CAST(lvertexp->nodep(), NodeAssign)) {
|
|
// if (lvertexp->outSize1() && VN_IS(assignp->lhsp(), Sel)) {
|
|
if (VN_IS(assignp->lhsp(), Sel) && lvertexp->outSize1()) {
|
|
UINFO(9, "assing to the nodep[" << VN_AS(assignp->lhsp(), Sel)->lsbConst()
|
|
<< "]" << endl);
|
|
// first assign with Sel-lhs
|
|
if (!m_activep) m_activep = lvertexp->activep();
|
|
if (!m_logicvp) m_logicvp = lvertexp;
|
|
if (!m_assignp) m_assignp = assignp;
|
|
|
|
// not under the same active
|
|
if (m_activep != lvertexp->activep()) {
|
|
m_activep = lvertexp->activep();
|
|
m_logicvp = lvertexp;
|
|
m_assignp = assignp;
|
|
continue;
|
|
}
|
|
|
|
AstSel* const preselp = VN_CAST(m_assignp->lhsp(), Sel);
|
|
AstSel* const curselp = VN_CAST(assignp->lhsp(), Sel);
|
|
if (!preselp || !curselp) continue;
|
|
|
|
if (AstSel* const newselp = merge(preselp, curselp)) {
|
|
UINFO(5, "assemble to new sel: " << newselp << endl);
|
|
// replace preSel with newSel
|
|
preselp->replaceWith(newselp);
|
|
VL_DO_DANGLING(preselp->deleteTree(), preselp);
|
|
// create new rhs for pre assignment
|
|
AstNode* const newrhsp
|
|
= new AstConcat{m_assignp->rhsp()->fileline(),
|
|
m_assignp->rhsp()->cloneTreePure(false),
|
|
assignp->rhsp()->cloneTreePure(false)};
|
|
AstNode* const oldrhsp = m_assignp->rhsp();
|
|
oldrhsp->replaceWith(newrhsp);
|
|
VL_DO_DANGLING(oldrhsp->deleteTree(), oldrhsp);
|
|
m_assignp->dtypeChgWidthSigned(m_assignp->width() + assignp->width(),
|
|
m_assignp->width() + assignp->width(),
|
|
VSigning::SIGNED);
|
|
// don't need to delete, will be handled
|
|
// assignp->unlinkFrBack(); VL_DO_DANGLING(assignp->deleteTree(),
|
|
// assignp);
|
|
|
|
// update the graph
|
|
{
|
|
// delete all inedges to lvertexp
|
|
if (!lvertexp->inEmpty()) {
|
|
for (V3GraphEdge* ledgep = lvertexp->inBeginp(); ledgep;) {
|
|
V3GraphEdge* oedgep = ledgep;
|
|
ledgep = ledgep->inNextp();
|
|
GateEitherVertex* const fromvp
|
|
= static_cast<GateEitherVertex*>(oedgep->fromp());
|
|
new V3GraphEdge{m_graphp, fromvp, m_logicvp, 1};
|
|
VL_DO_DANGLING(oedgep->unlinkDelete(), oedgep);
|
|
}
|
|
}
|
|
// delete all outedges to lvertexp, only one
|
|
VL_DO_DANGLING(oldedgep->unlinkDelete(), oldedgep);
|
|
}
|
|
++m_numMergedAssigns;
|
|
} else {
|
|
m_assignp = assignp;
|
|
m_logicvp = lvertexp;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
return VNUser{0};
|
|
}
|
|
VNUser visit(GateLogicVertex*, VNUser) override { //
|
|
return VNUser{0};
|
|
}
|
|
|
|
public:
|
|
explicit GateMergeAssignsGraphVisitor(V3Graph* graphp)
|
|
: GateGraphBaseVisitor{graphp} {}
|
|
void mergeAssignsTree(GateVarVertex* vvertexp) { vvertexp->accept(*this); }
|
|
VDouble0 numMergedAssigns() { return m_numMergedAssigns; }
|
|
};
|
|
|
|
//----------------------------------------------------------------------
|
|
|
|
void GateVisitor::mergeAssigns() {
|
|
UINFO(6, "mergeAssigns\n");
|
|
GateMergeAssignsGraphVisitor merger{&m_graph};
|
|
for (V3GraphVertex* itp = m_graph.verticesBeginp(); itp; itp = itp->verticesNextp()) {
|
|
if (GateVarVertex* const vvertexp = itp->cast<GateVarVertex>()) {
|
|
merger.mergeAssignsTree(vvertexp);
|
|
}
|
|
}
|
|
m_statAssignMerged += merger.numMergedAssigns();
|
|
}
|
|
|
|
//######################################################################
|
|
// Find a var's offset in a concatenation
|
|
|
|
class GateConcatVisitor final : public VNVisitorConst {
|
|
private:
|
|
// STATE
|
|
const AstVarScope* m_vscp = nullptr; // Varscope we're trying to find
|
|
int m_offset = 0; // Current offset of varscope
|
|
int m_found_offset = 0; // Found offset of varscope
|
|
bool m_found = false; // Offset found
|
|
|
|
// VISITORS
|
|
void visit(AstNodeVarRef* nodep) override {
|
|
UINFO(9, "CLK DECOMP Concat search var (off = " << m_offset << ") - " << nodep << endl);
|
|
if (nodep->varScopep() == m_vscp && !nodep->user2() && !m_found) {
|
|
// A concatenation may use the same var multiple times
|
|
// But the graph will initially have an edge per instance
|
|
nodep->user2(true);
|
|
m_found_offset = m_offset;
|
|
m_found = true;
|
|
UINFO(9, "CLK DECOMP Concat found var (off = " << m_offset << ") - " << nodep << endl);
|
|
}
|
|
m_offset += nodep->dtypep()->width();
|
|
}
|
|
void visit(AstConcat* nodep) override {
|
|
UINFO(9, "CLK DECOMP Concat search (off = " << m_offset << ") - " << nodep << endl);
|
|
iterateConst(nodep->rhsp());
|
|
iterateConst(nodep->lhsp());
|
|
}
|
|
//--------------------
|
|
void visit(AstNode* nodep) override { iterateChildrenConst(nodep); }
|
|
|
|
public:
|
|
// CONSTRUCTORS
|
|
GateConcatVisitor() = default;
|
|
~GateConcatVisitor() override = default;
|
|
// PUBLIC METHODS
|
|
bool concatOffset(AstConcat* concatp, AstVarScope* vscp, int& offsetr) {
|
|
m_vscp = vscp;
|
|
m_offset = 0;
|
|
m_found = false;
|
|
// Iterate
|
|
iterateConst(concatp);
|
|
UINFO(9, "CLK DECOMP Concat Offset (found = " << m_found << ") (" << m_found_offset
|
|
<< ") - " << concatp << " : " << vscp
|
|
<< endl);
|
|
offsetr = m_found_offset;
|
|
return m_found;
|
|
}
|
|
};
|
|
|
|
//######################################################################
|
|
// Recurse through the graph, looking for clock vectors to bypass
|
|
|
|
class GateClkDecompState final {
|
|
public:
|
|
const int m_offset;
|
|
AstVarScope* const m_last_vsp;
|
|
GateClkDecompState(int offset, AstVarScope* vsp)
|
|
: m_offset{offset}
|
|
, m_last_vsp{vsp} {}
|
|
virtual ~GateClkDecompState() = default;
|
|
};
|
|
|
|
class GateClkDecompGraphVisitor final : public GateGraphBaseVisitor {
|
|
private:
|
|
// NODE STATE
|
|
// AstVarScope::user2p -> bool: already visited
|
|
int m_seen_clk_vectors = 0;
|
|
AstVarScope* m_clk_vsp = nullptr;
|
|
GateVarVertex* m_clk_vvertexp = nullptr;
|
|
GateConcatVisitor m_concat_visitor;
|
|
int m_total_seen_clk_vectors = 0;
|
|
int m_total_decomposed_clk_vectors = 0;
|
|
|
|
VNUser visit(GateVarVertex* vvertexp, VNUser vu) override {
|
|
// Check that we haven't been here before
|
|
AstVarScope* const vsp = vvertexp->varScp();
|
|
if (vsp->user2SetOnce()) return VNUser{0};
|
|
UINFO(9, "CLK DECOMP Var - " << vvertexp << " : " << vsp << endl);
|
|
if (vsp->varp()->width() > 1) {
|
|
++m_seen_clk_vectors;
|
|
++m_total_seen_clk_vectors;
|
|
}
|
|
const GateClkDecompState* const currState = reinterpret_cast<GateClkDecompState*>(vu.c());
|
|
GateClkDecompState nextState{currState->m_offset, vsp};
|
|
vvertexp->iterateCurrentOutEdges(*this, VNUser{&nextState});
|
|
if (vsp->varp()->width() > 1) --m_seen_clk_vectors;
|
|
vsp->user2(false);
|
|
return VNUser{0}; // Unused
|
|
}
|
|
|
|
VNUser visit(GateLogicVertex* lvertexp, VNUser vu) override {
|
|
const GateClkDecompState* const currState = reinterpret_cast<GateClkDecompState*>(vu.c());
|
|
int clk_offset = currState->m_offset;
|
|
if (const AstAssignW* const assignp = VN_CAST(lvertexp->nodep(), AssignW)) {
|
|
UINFO(9, "CLK DECOMP Logic (off = " << clk_offset << ") - " << lvertexp << " : "
|
|
<< m_clk_vsp << endl);
|
|
// RHS
|
|
if (const AstSel* const rselp = VN_CAST(assignp->rhsp(), Sel)) {
|
|
if (VN_IS(rselp->lsbp(), Const) && VN_IS(rselp->widthp(), Const)) {
|
|
if (clk_offset < rselp->lsbConst() || clk_offset > rselp->msbConst()) {
|
|
UINFO(9, "CLK DECOMP Sel [ " << rselp->msbConst() << " : "
|
|
<< rselp->lsbConst() << " ] dropped clock ("
|
|
<< clk_offset << ")" << endl);
|
|
return VNUser{0};
|
|
}
|
|
clk_offset -= rselp->lsbConst();
|
|
} else {
|
|
return VNUser{0};
|
|
}
|
|
} else if (AstConcat* const catp = VN_CAST(assignp->rhsp(), Concat)) {
|
|
UINFO(9, "CLK DECOMP Concat searching - " << assignp->lhsp() << endl);
|
|
int concat_offset;
|
|
if (!m_concat_visitor.concatOffset(catp, currState->m_last_vsp,
|
|
concat_offset /*ref*/)) {
|
|
return VNUser{0};
|
|
}
|
|
clk_offset += concat_offset;
|
|
} else if (VN_IS(assignp->rhsp(), VarRef)) {
|
|
UINFO(9, "CLK DECOMP VarRef searching - " << assignp->lhsp() << endl);
|
|
} else {
|
|
return VNUser{0};
|
|
}
|
|
// LHS
|
|
if (const AstSel* const lselp = VN_CAST(assignp->lhsp(), Sel)) {
|
|
if (VN_IS(lselp->lsbp(), Const) && VN_IS(lselp->widthp(), Const)) {
|
|
clk_offset += lselp->lsbConst();
|
|
} else {
|
|
return VNUser{0};
|
|
}
|
|
} else if (const AstVarRef* const vrp = VN_CAST(assignp->lhsp(), VarRef)) {
|
|
if (vrp->dtypep()->width() == 1 && m_seen_clk_vectors) {
|
|
if (clk_offset != 0) {
|
|
UINFO(9, "Should only make it here with clk_offset = 0" << endl);
|
|
return VNUser{0};
|
|
}
|
|
UINFO(9, "CLK DECOMP Connecting - " << assignp->lhsp() << endl);
|
|
UINFO(9, " to - " << m_clk_vsp << endl);
|
|
AstNode* const rhsp = assignp->rhsp();
|
|
rhsp->replaceWith(new AstVarRef{rhsp->fileline(), m_clk_vsp, VAccess::READ});
|
|
while (V3GraphEdge* const edgep = lvertexp->inBeginp()) {
|
|
VL_DO_DANGLING(edgep->unlinkDelete(), edgep);
|
|
}
|
|
new V3GraphEdge{m_graphp, m_clk_vvertexp, lvertexp, 1};
|
|
m_total_decomposed_clk_vectors++;
|
|
}
|
|
} else {
|
|
return VNUser{0};
|
|
}
|
|
GateClkDecompState nextState{clk_offset, currState->m_last_vsp};
|
|
return lvertexp->iterateCurrentOutEdges(*this, VNUser{&nextState});
|
|
}
|
|
return VNUser{0};
|
|
}
|
|
|
|
public:
|
|
explicit GateClkDecompGraphVisitor(V3Graph* graphp)
|
|
: GateGraphBaseVisitor{graphp} {}
|
|
~GateClkDecompGraphVisitor() override {
|
|
V3Stats::addStat("Optimizations, Clocker seen vectors", m_total_seen_clk_vectors);
|
|
V3Stats::addStat("Optimizations, Clocker decomposed vectors",
|
|
m_total_decomposed_clk_vectors);
|
|
}
|
|
void clkDecomp(GateVarVertex* vvertexp) {
|
|
UINFO(9, "CLK DECOMP Starting Var - " << vvertexp << endl);
|
|
m_seen_clk_vectors = 0;
|
|
m_clk_vsp = vvertexp->varScp();
|
|
m_clk_vvertexp = vvertexp;
|
|
GateClkDecompState nextState{0, m_clk_vsp};
|
|
vvertexp->accept(*this, VNUser{&nextState});
|
|
}
|
|
};
|
|
|
|
void GateVisitor::decomposeClkVectors() {
|
|
UINFO(9, "Starting clock decomposition" << endl);
|
|
AstNode::user2ClearTree();
|
|
GateClkDecompGraphVisitor decomposer{&m_graph};
|
|
for (V3GraphVertex* itp = m_graph.verticesBeginp(); itp; itp = itp->verticesNextp()) {
|
|
if (GateVarVertex* const vertp = itp->cast<GateVarVertex>()) {
|
|
const AstVarScope* const vsp = vertp->varScp();
|
|
if (vsp->varp()->attrClocker() == VVarAttrClocker::CLOCKER_YES) {
|
|
if (vsp->varp()->width() > 1) {
|
|
UINFO(9, "Clocker > 1 bit, not decomposing: " << vsp << endl);
|
|
} else {
|
|
UINFO(9, "CLK DECOMP - " << vertp << " : " << vsp << endl);
|
|
decomposer.clkDecomp(vertp);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
//######################################################################
|
|
// Gate class functions
|
|
|
|
void V3Gate::gateAll(AstNetlist* nodep) {
|
|
UINFO(2, __FUNCTION__ << ": " << endl);
|
|
{ const GateVisitor visitor{nodep}; } // Destruct before checking
|
|
V3Global::dumpCheckGlobalTree("gate", 0, dumpTreeLevel() >= 3);
|
|
}
|