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verilator/src/V3Active.cpp

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// -*- mode: C++; c-file-style: "cc-mode" -*-
//*************************************************************************
// DESCRIPTION: Verilator: Break always into sensitivity active domains
//
// Code available from: https://verilator.org
//
//*************************************************************************
//
// Copyright 2003-2020 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
//
//*************************************************************************
// V3Active's Transformations:
//
// Note this can be called multiple times.
// Create a IACTIVE(initial), SACTIVE(combo)
// ALWAYS: Remove any-edges from sense list
// If no POS/NEG in senselist, Fold into SACTIVE(combo)
// Else fold into SACTIVE(sequent).
// OPTIMIZE: When support async clocks, fold into that active if possible
// INITIAL: Move into IACTIVE
// WIRE: Move into SACTIVE(combo)
//
//*************************************************************************
#include "config_build.h"
#include "verilatedos.h"
#include "V3Global.h"
#include "V3Active.h"
#include "V3Ast.h"
#include "V3EmitCBase.h"
#include "V3Const.h"
#include "V3SenTree.h" // for SenTreeSet
#include VL_INCLUDE_UNORDERED_MAP
//***** See below for main transformation engine
//######################################################################
// Collect existing active names
class ActiveBaseVisitor : public AstNVisitor {
protected:
VL_DEBUG_FUNC; // Declare debug()
};
class ActiveNamer : public ActiveBaseVisitor {
private:
// STATE
AstScope* m_scopep; // Current scope to add statement to
AstActive* m_iActivep; // For current scope, the IActive we're building
AstActive* m_cActivep; // For current scope, the SActive(combo) we're building
SenTreeSet m_activeSens; // Sen lists for each active we've made
typedef vl_unordered_map<AstSenTree*, AstActive*> ActiveMap;
ActiveMap m_activeMap; // Map sentree to active, for folding.
// METHODS
void addActive(AstActive* nodep) {
UASSERT_OBJ(m_scopep, nodep, "NULL scope");
m_scopep->addActivep(nodep);
}
// VISITORS
virtual void visit(AstScope* nodep) VL_OVERRIDE {
m_scopep = nodep;
m_iActivep = NULL;
m_cActivep = NULL;
m_activeSens.clear();
m_activeMap.clear();
iterateChildren(nodep);
// Don't clear scopep, the namer persists beyond this visit
}
virtual void visit(AstSenTree* nodep) VL_OVERRIDE {
// Simplify sensitivity list
VL_DO_DANGLING(V3Const::constifyExpensiveEdit(nodep), nodep);
}
//--------------------
virtual void visit(AstNodeStmt*) VL_OVERRIDE {} // Accelerate
virtual void visit(AstNode* nodep) VL_OVERRIDE { iterateChildren(nodep); }
public:
// METHODS
AstScope* scopep() { return m_scopep; }
AstActive* getCActive(FileLine* fl) {
if (!m_cActivep) {
m_cActivep = new AstActive(
fl, "combo", new AstSenTree(fl, new AstSenItem(fl, AstSenItem::Combo())));
m_cActivep->sensesStorep(m_cActivep->sensesp());
addActive(m_cActivep);
}
return m_cActivep;
}
AstActive* getIActive(FileLine* fl) {
if (!m_iActivep) {
m_iActivep = new AstActive(
fl, "initial", new AstSenTree(fl, new AstSenItem(fl, AstSenItem::Initial())));
m_iActivep->sensesStorep(m_iActivep->sensesp());
addActive(m_iActivep);
}
return m_iActivep;
}
AstActive* getActive(FileLine* fl, AstSenTree* sensesp) {
// Return a sentree in this scope that matches given sense list.
AstActive* activep = NULL;
AstSenTree* activeSenp = m_activeSens.find(sensesp);
if (activeSenp) {
ActiveMap::iterator it = m_activeMap.find(activeSenp);
UASSERT(it != m_activeMap.end(), "Corrupt active map");
activep = it->second;
}
// Not found, form a new one
if (!activep) {
AstSenTree* newsenp = sensesp->cloneTree(false);
activep = new AstActive(fl, "sequent", newsenp);
activep->sensesStorep(activep->sensesp());
UINFO(8, " New ACTIVE " << activep << endl);
// Form the sensitivity list
addActive(activep);
m_activeMap[newsenp] = activep;
m_activeSens.add(newsenp);
// Note actives may have also been added above in the Active visitor
}
return activep;
}
public:
// CONSTRUCTORS
ActiveNamer() {
m_scopep = NULL;
m_iActivep = NULL;
m_cActivep = NULL;
}
virtual ~ActiveNamer() {}
void main(AstScope* nodep) { iterate(nodep); }
};
//######################################################################
// Active AssignDly replacement functions
class ActiveDlyVisitor : public ActiveBaseVisitor {
public:
enum CheckType { CT_SEQ, CT_COMBO, CT_INITIAL, CT_LATCH };
private:
CheckType m_check; // Combo logic or other
AstNode* m_alwaysp; // Always we're under
AstNode* m_assignp; // In assign
// VISITORS
virtual void visit(AstAssignDly* nodep) VL_OVERRIDE {
if (m_check != CT_SEQ) {
// Convert to a non-delayed assignment
UINFO(5, " ASSIGNDLY " << nodep << endl);
if (m_check == CT_INITIAL) {
nodep->v3warn(INITIALDLY, "Delayed assignments (<=) in initial or final block\n"
<< nodep->warnMore()
<< "... Suggest blocking assignments (=)");
} else if (m_check == CT_LATCH) {
// Suppress. Shouldn't matter that the interior of the latch races
} else {
nodep->v3warn(COMBDLY, "Delayed assignments (<=) in non-clocked"
" (non flop or latch) block\n"
<< nodep->warnMore()
<< "... Suggest blocking assignments (=)");
}
AstNode* newp = new AstAssign(nodep->fileline(), nodep->lhsp()->unlinkFrBack(),
nodep->rhsp()->unlinkFrBack());
nodep->replaceWith(newp);
VL_DO_DANGLING(nodep->deleteTree(), nodep);
}
}
virtual void visit(AstAssign* nodep) VL_OVERRIDE {
if (m_check == CT_SEQ) {
AstNode* las = m_assignp;
m_assignp = nodep;
iterateAndNextNull(nodep->lhsp());
m_assignp = las;
}
}
virtual void visit(AstVarRef* nodep) VL_OVERRIDE {
AstVar* varp = nodep->varp();
if (m_check == CT_SEQ && m_assignp && !varp->isUsedLoopIdx() // Ignore loop indices
&& !varp->isTemp()) {
// Allow turning off warnings on the always, or the variable also
if (!m_alwaysp->fileline()->warnIsOff(V3ErrorCode::BLKSEQ)
&& !m_assignp->fileline()->warnIsOff(V3ErrorCode::BLKSEQ)
&& !varp->fileline()->warnIsOff(V3ErrorCode::BLKSEQ)) {
m_assignp->v3warn(BLKSEQ,
"Blocking assignments (=) in sequential (flop or latch) block\n"
<< m_assignp->warnMore()
<< "... Suggest delayed assignments (<=)");
m_alwaysp->fileline()->modifyWarnOff(
V3ErrorCode::BLKSEQ, true); // Complain just once for the entire always
varp->fileline()->modifyWarnOff(V3ErrorCode::BLKSEQ, true);
}
}
}
//--------------------
virtual void visit(AstNode* nodep) VL_OVERRIDE { iterateChildren(nodep); }
public:
// CONSTRUCTORS
ActiveDlyVisitor(AstNode* nodep, CheckType check) {
m_alwaysp = nodep;
m_check = check;
m_assignp = NULL;
iterate(nodep);
}
virtual ~ActiveDlyVisitor() {}
};
//######################################################################
// Active class functions
class ActiveVisitor : public ActiveBaseVisitor {
private:
// NODE STATE
// Each call to V3Const::constify
// AstNode::user4() Used by V3Const::constify, called below
// STATE
ActiveNamer m_namer; // Tracking of active names
AstCFunc* m_scopeFinalp; // Final function for this scope
bool m_itemCombo; // Found a SenItem combo
bool m_itemSequent; // Found a SenItem sequential
// VISITORS
virtual void visit(AstScope* nodep) VL_OVERRIDE {
// Create required actives and add to scope
UINFO(4, " SCOPE " << nodep << endl);
// Clear last scope's names, and collect this scope's existing names
m_namer.main(nodep);
m_scopeFinalp = NULL;
iterateChildren(nodep);
}
virtual void visit(AstActive* nodep) VL_OVERRIDE {
// Actives are being formed, so we can ignore any already made
}
virtual void visit(AstInitial* nodep) VL_OVERRIDE {
// Relink to IACTIVE, unless already under it
UINFO(4, " INITIAL " << nodep << endl);
ActiveDlyVisitor dlyvisitor(nodep, ActiveDlyVisitor::CT_INITIAL);
AstActive* wantactivep = m_namer.getIActive(nodep->fileline());
nodep->unlinkFrBack();
wantactivep->addStmtsp(nodep);
}
virtual void visit(AstAssignAlias* nodep) VL_OVERRIDE {
// Relink to CACTIVE, unless already under it
UINFO(4, " ASSIGNW " << nodep << endl);
AstActive* wantactivep = m_namer.getCActive(nodep->fileline());
nodep->unlinkFrBack();
wantactivep->addStmtsp(nodep);
}
virtual void visit(AstAssignW* nodep) VL_OVERRIDE {
// Relink to CACTIVE, unless already under it
UINFO(4, " ASSIGNW " << nodep << endl);
AstActive* wantactivep = m_namer.getCActive(nodep->fileline());
nodep->unlinkFrBack();
wantactivep->addStmtsp(nodep);
}
virtual void visit(AstCoverToggle* nodep) VL_OVERRIDE {
// Relink to CACTIVE, unless already under it
UINFO(4, " COVERTOGGLE " << nodep << endl);
AstActive* wantactivep = m_namer.getCActive(nodep->fileline());
nodep->unlinkFrBack();
wantactivep->addStmtsp(nodep);
}
virtual void visit(AstFinal* nodep) VL_OVERRIDE {
// Relink to CFUNC for the final
UINFO(4, " FINAL " << nodep << endl);
if (!nodep->bodysp()) { // Empty, Kill it.
VL_DO_DANGLING(nodep->unlinkFrBack()->deleteTree(), nodep);
return;
}
ActiveDlyVisitor dlyvisitor(nodep, ActiveDlyVisitor::CT_INITIAL);
if (!m_scopeFinalp) {
m_scopeFinalp = new AstCFunc(
nodep->fileline(), "_final_" + m_namer.scopep()->nameDotless(), m_namer.scopep());
m_scopeFinalp->argTypes(EmitCBaseVisitor::symClassVar());
m_scopeFinalp->addInitsp(
new AstCStmt(nodep->fileline(), EmitCBaseVisitor::symTopAssign() + "\n"));
m_scopeFinalp->dontCombine(true);
m_scopeFinalp->formCallTree(true);
m_scopeFinalp->slow(true);
m_namer.scopep()->addActivep(m_scopeFinalp);
}
nodep->unlinkFrBack();
m_scopeFinalp->addStmtsp(new AstComment(nodep->fileline(), nodep->typeName(), true));
m_scopeFinalp->addStmtsp(nodep->bodysp()->unlinkFrBackWithNext());
VL_DO_DANGLING(nodep->deleteTree(), nodep);
}
// METHODS
void visitAlways(AstNode* nodep, AstSenTree* oldsensesp, VAlwaysKwd kwd) {
// Move always to appropriate ACTIVE based on its sense list
if (oldsensesp && oldsensesp->sensesp() && VN_IS(oldsensesp->sensesp(), SenItem)
&& VN_CAST(oldsensesp->sensesp(), SenItem)->isNever()) {
// Never executing. Kill it.
UASSERT_OBJ(!oldsensesp->sensesp()->nextp(), nodep,
"Never senitem should be alone, else the never should be eliminated.");
VL_DO_DANGLING(nodep->unlinkFrBack()->deleteTree(), nodep);
return;
}
// Read sensitivities
m_itemCombo = false;
m_itemSequent = false;
iterateAndNextNull(oldsensesp);
bool combo = m_itemCombo;
bool sequent = m_itemSequent;
if (!combo && !sequent) combo = true; // If no list, Verilog 2000: always @ (*)
if (combo && sequent) {
nodep->v3warn(E_UNSUPPORTED, "Unsupported: Mixed edge (pos/negedge) and activity "
"(no edge) sensitive activity list");
sequent = false;
}
AstActive* wantactivep = NULL;
if (combo && !sequent) {
// Combo: Relink to ACTIVE(combo)
wantactivep = m_namer.getCActive(nodep->fileline());
} else {
// Sequential: Build a ACTIVE(name)
// OPTIMIZE: We could substitute a constant for things in the sense list, for example
// always (posedge RESET) { if (RESET).... } we know RESET is true.
// Summarize a long list of combo inputs as just "combo"
#ifndef __COVERITY__ // Else dead code on next line.
if (combo) {
oldsensesp->addSensesp(new AstSenItem(nodep->fileline(), AstSenItem::Combo()));
}
#endif
wantactivep = m_namer.getActive(nodep->fileline(), oldsensesp);
}
// Delete sensitivity list
if (oldsensesp) {
VL_DO_DANGLING(oldsensesp->unlinkFrBackWithNext()->deleteTree(), oldsensesp);
}
// Move node to new active
nodep->unlinkFrBack();
wantactivep->addStmtsp(nodep);
// Warn and/or convert any delayed assignments
if (combo && !sequent) {
if (kwd == VAlwaysKwd::ALWAYS_LATCH) {
ActiveDlyVisitor dlyvisitor(nodep, ActiveDlyVisitor::CT_LATCH);
} else {
ActiveDlyVisitor dlyvisitor(nodep, ActiveDlyVisitor::CT_COMBO);
}
} else if (!combo && sequent) {
ActiveDlyVisitor dlyvisitor(nodep, ActiveDlyVisitor::CT_SEQ);
}
}
virtual void visit(AstAlways* nodep) VL_OVERRIDE {
// Move always to appropriate ACTIVE based on its sense list
UINFO(4, " ALW " << nodep << endl);
// if (debug() >= 9) nodep->dumpTree(cout, " Alw: ");
if (!nodep->bodysp()) {
// Empty always. Kill it.
VL_DO_DANGLING(nodep->unlinkFrBack()->deleteTree(), nodep);
return;
}
visitAlways(nodep, nodep->sensesp(), nodep->keyword());
}
virtual void visit(AstAlwaysPublic* nodep) VL_OVERRIDE {
// Move always to appropriate ACTIVE based on its sense list
UINFO(4, " ALWPub " << nodep << endl);
// if (debug() >= 9) nodep->dumpTree(cout, " Alw: ");
visitAlways(nodep, nodep->sensesp(), VAlwaysKwd::ALWAYS);
}
virtual void visit(AstSenItem* nodep) VL_OVERRIDE {
if (nodep->varrefp()) {
if (AstBasicDType* basicp = nodep->varrefp()->dtypep()->basicp()) {
if (basicp->isEventValue()) {
// Events need to be treated as active high so we only activate on event being
// 1
UINFO(8, "Demote event to HIGHEDGE " << nodep << endl);
nodep->edgeType(VEdgeType::ET_HIGHEDGE);
}
}
}
if (nodep->edgeType() == VEdgeType::ET_ANYEDGE) {
m_itemCombo = true;
// Delete the sensitivity
// We'll add it as a generic COMBO SenItem in a moment.
VL_DO_DANGLING(nodep->unlinkFrBack()->deleteTree(), nodep);
} else if (nodep->varrefp()) {
// V3LinkResolve should have cleaned most of these up
if (!nodep->varrefp()->width1()) {
nodep->v3warn(E_UNSUPPORTED,
"Unsupported: Non-single bit wide signal pos/negedge sensitivity: "
<< nodep->varrefp()->prettyNameQ());
}
m_itemSequent = true;
nodep->varrefp()->varp()->usedClock(true);
}
}
//--------------------
virtual void visit(AstNodeMath*) VL_OVERRIDE {} // Accelerate
virtual void visit(AstVarScope*) VL_OVERRIDE {} // Accelerate
virtual void visit(AstNode* nodep) VL_OVERRIDE { iterateChildren(nodep); }
public:
// CONSTRUCTORS
explicit ActiveVisitor(AstNetlist* nodep)
: m_scopeFinalp(NULL)
, m_itemCombo(false)
, m_itemSequent(false) {
iterate(nodep);
}
virtual ~ActiveVisitor() {}
};
//######################################################################
// Active class functions
void V3Active::activeAll(AstNetlist* nodep) {
UINFO(2, __FUNCTION__ << ": " << endl);
{ ActiveVisitor visitor(nodep); } // Destruct before checking
V3Global::dumpCheckGlobalTree("active", 0, v3Global.opt.dumpTreeLevel(__FILE__) >= 3);
}
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