verilator/src/V3Delayed.cpp
2016-01-06 20:36:41 -05:00

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// -*- mode: C++; c-file-style: "cc-mode" -*-
//*************************************************************************
// DESCRIPTION: Verilator: Add temporaries, such as for delayed nodes
//
// Code available from: http://www.veripool.org/verilator
//
//*************************************************************************
//
// Copyright 2003-2016 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.
//
// Verilator is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
//*************************************************************************
// V3Delayed's Transformations:
//
// Each module:
// Replace ASSIGNDLY var, exp
// With ASSIGNDLY newvar, exp
// At top of block: VAR newvar
// At bottom of block: ASSIGNW var newvar
// Need _x_dly = x at top of active if "x" is not always set
// For now we'll say it's set if at top of block (not under IF, etc)
// Need x = _x_dly at bottom of active if "x" is never referenced on LHS
// in the active, and above rule applies too. (If so, use x on LHS, not _x_dly.)
//
// If a signal is set in multiple always blocks, we need a dly read & set with
// multiple clock sensitivities. We have 3 options:
// 1. When detected, make a new ACTIVE and move earlier created delayed assignment there
// 2. Form unique ACTIVE for every multiple clocked assignment
// 3. Predetect signals from multiple always blocks and do #2 on them
// Since all 3 require a top activation cleanup, we do #2 which is easiest.
//
// ASSIGNDLY (BITSEL(ARRAYSEL (VARREF(v), bits), selbits), rhs)
// -> VAR __Vdlyvset_x
// VAR __Vdlyvval_x
// VAR __Vdlyvdim_x
// VAR __Vdlyvlsb_x
// ASSIGNW (__Vdlyvset_x,0)
// ...
// ASSIGNW (VARREF(__Vdlyvval_x), rhs)
// ASSIGNW (__Vdlyvdim_x, dimension_number)
// ASSIGNW (__Vdlyvset_x, 1)
// ...
// ASSIGNW (BITSEL(ARRAYSEL(VARREF(x), __Vdlyvdim_x), __Vdlyvlsb_x), __Vdlyvval_x)
//
//*************************************************************************
#include "config_build.h"
#include "verilatedos.h"
#include <cstdio>
#include <cstdarg>
#include <unistd.h>
#include <algorithm>
#include <map>
#include <deque>
#include "V3Global.h"
#include "V3Delayed.h"
#include "V3Ast.h"
#include "V3Stats.h"
//######################################################################
// Delayed state, as a visitor of each AstNode
class DelayedVisitor : public AstNVisitor {
private:
// NODE STATE
// Cleared each module:
// AstVarScope::user1p() -> AstVarScope*. Points to temp var created.
// AstVarScope::user2p() -> AstActive*. Points to activity block of signal (valid when AstVarScope::user1p is valid)
// AstVarScope::user4p() -> AstAlwaysPost*. Post block for this variable
// AstVarScope::user5() -> VarUsage. Tracks delayed vs non-delayed usage
// AstVar::user2() -> bool. Set true if already made warning
// AstVar::user4() -> int. Vector number, for assignment creation
// AstVarRef::user2() -> bool. Set true if already processed
// AstAlwaysPost::user2() -> ActActive*. Points to activity block of signal (valid when AstAlwaysPost::user4p is valid)
// AstAlwaysPost::user4() -> AstIf*. Last IF (__Vdlyvset__) created under this AlwaysPost
// Cleared each scope/active:
// AstAssignDly::user3() -> AstVarScope*. __Vdlyvset__ created for this assign
// AstAlwaysPost::user3() -> AstVarScope*. __Vdlyvset__ last referenced in IF
AstUser1InUse m_inuser1;
AstUser2InUse m_inuser2;
AstUser3InUse m_inuser3;
AstUser4InUse m_inuser4;
AstUser5InUse m_inuser5;
enum VarUsage { VU_NONE=0, VU_DLY=1, VU_NONDLY=2 };
// STATE
AstActive* m_activep; // Current activate
AstCFunc* m_cfuncp; // Current public C Function
AstAssignDly* m_nextDlyp; // Next delayed assignment in a list of assignments
bool m_inDly; // True in delayed assignments
bool m_inLoop; // True in for loops
bool m_inInitial; // True in intial blocks
typedef std::map<pair<AstNodeModule*,string>,AstVar*> VarMap;
VarMap m_modVarMap; // Table of new var names created under module
V3Double0 m_statSharedSet;// Statistic tracking
// METHODS
static int debug() {
static int level = -1;
if (VL_UNLIKELY(level < 0)) level = v3Global.opt.debugSrcLevel(__FILE__);
return level;
}
void markVarUsage(AstVarScope* nodep, uint32_t flags) {
//UINFO(4," MVU "<<flags<<" "<<nodep<<endl);
nodep->user5( nodep->user5() | flags );
if ((nodep->user5() & VU_DLY) && (nodep->user5() & VU_NONDLY)) {
nodep->v3warn(BLKANDNBLK,"Unsupported: Blocked and non-blocking assignments to same variable: "<<nodep->varp()->prettyName());
}
}
AstVarScope* createVarSc(AstVarScope* oldvarscp, string name, int width/*0==fromoldvar*/, AstNodeDType* newdtypep) {
// Because we've already scoped it, we may need to add both the AstVar and the AstVarScope
if (!oldvarscp->scopep()) oldvarscp->v3fatalSrc("Var unscoped");
AstVar* varp;
AstNodeModule* addmodp = oldvarscp->scopep()->modp();
// We need a new AstVar, but only one for all scopes, to match the new AstVarScope
VarMap::iterator it = m_modVarMap.find(make_pair(addmodp,name));
if (it != m_modVarMap.end()) {
// Created module's AstVar earlier under some other scope
varp = it->second;
} else {
if (newdtypep) {
varp = new AstVar (oldvarscp->fileline(), AstVarType::BLOCKTEMP, name, newdtypep);
} else if (width==0) {
varp = new AstVar (oldvarscp->fileline(), AstVarType::BLOCKTEMP, name, oldvarscp->varp());
varp->dtypeFrom(oldvarscp);
} else { // Used for vset and dimensions, so can zero init
varp = new AstVar (oldvarscp->fileline(), AstVarType::BLOCKTEMP, name, VFlagBitPacked(), width);
}
addmodp->addStmtp(varp);
m_modVarMap.insert(make_pair(make_pair(addmodp, name), varp));
}
AstVarScope* varscp = new AstVarScope (oldvarscp->fileline(), oldvarscp->scopep(), varp);
oldvarscp->scopep()->addVarp(varscp);
return varscp;
}
AstActive* createActivePost(AstVarRef* varrefp) {
AstActive* newactp = new AstActive (varrefp->fileline(), "sequentdly",
m_activep->sensesp());
m_activep->addNext(newactp);
return newactp;
}
void checkActivePost(AstVarRef* varrefp, AstActive* oldactivep) {
// Check for MULTIDRIVEN, and if so make new sentree that joins old & new sentree
if (!oldactivep) varrefp->v3fatalSrc("<= old dly assignment not put under sensitivity block");
if (oldactivep->sensesp() != m_activep->sensesp()) {
if (!varrefp->varp()->fileline()->warnIsOff(V3ErrorCode::MULTIDRIVEN)
&& !varrefp->varp()->user2()) {
varrefp->varp()->v3warn(MULTIDRIVEN,"Signal has multiple driving blocks: "<<varrefp->varp()->prettyName()<<endl
<<varrefp->warnMore()<<"... Location of first driving block"<<endl
<<oldactivep->warnMore()<<"... Location of other driving block");
varrefp->varp()->user2(true);
}
UINFO(4,"AssignDupDlyVar: "<<varrefp<<endl);
UINFO(4," Act: "<<m_activep<<endl);
UINFO(4," Act: "<<oldactivep<<endl);
// Make a new sensitivity list, which is the combination of both blocks
AstNodeSenItem* sena = m_activep->sensesp()->sensesp()->cloneTree(true);
AstNodeSenItem* senb = oldactivep->sensesp()->sensesp()->cloneTree(true);
AstSenTree* treep = new AstSenTree(m_activep->fileline(), sena);
if (senb) treep->addSensesp(senb);
if (AstSenTree* storep = oldactivep->sensesStorep()) {
storep->unlinkFrBack();
pushDeletep(storep);
}
oldactivep->sensesStorep(treep);
oldactivep->sensesp(treep);
}
}
AstNode* createDlyArray(AstAssignDly* nodep, AstNode* lhsp) {
// Create delayed assignment
// See top of this file for transformation
// Return the new LHS for the assignment, Null = unlink
// Find selects
AstNode* newlhsp = NULL; // NULL = unlink old assign
AstSel* bitselp = NULL;
AstArraySel* arrayselp = NULL;
if (lhsp->castSel()) {
bitselp = lhsp->castSel();
arrayselp = bitselp->fromp()->castArraySel();
} else {
arrayselp = lhsp->castArraySel();
}
if (!arrayselp) nodep->v3fatalSrc("No arraysel under bitsel?");
if (arrayselp->length()!=1) nodep->v3fatalSrc("ArraySel with length!=1 should have been removed in V3Slice");
UINFO(4,"AssignDlyArray: "<<nodep<<endl);
//
//=== Dimensions: __Vdlyvdim__
deque<AstNode*> dimvalp; // Assignment value for each dimension of assignment
AstNode* dimselp=arrayselp;
for (; dimselp->castArraySel(); dimselp=dimselp->castArraySel()->fromp()) {
AstNode* valp = dimselp->castArraySel()->bitp()->unlinkFrBack();
dimvalp.push_front(valp);
}
AstVarRef* varrefp = dimselp->castVarRef();
if (!varrefp) nodep->v3fatalSrc("No var underneath arraysels\n");
if (!varrefp->varScopep()) varrefp->v3fatalSrc("Var didn't get varscoped in V3Scope.cpp\n");
varrefp->unlinkFrBack();
AstVar* oldvarp = varrefp->varp();
int modVecNum = oldvarp->user4(); oldvarp->user4(modVecNum+1);
//
deque<AstNode*> dimreadps; // Read value for each dimension of assignment
for (unsigned dimension=0; dimension<dimvalp.size(); dimension++) {
AstNode* dimp = dimvalp[dimension];
if (dimp->castConst()) { // bit = const, can just use it
dimreadps.push_front(dimp);
} else {
string bitvarname = (string("__Vdlyvdim")+cvtToStr(dimension)
+"__"+oldvarp->shortName()+"__v"+cvtToStr(modVecNum));
AstVarScope* bitvscp = createVarSc(varrefp->varScopep(), bitvarname, dimp->width(), NULL);
AstAssign* bitassignp
= new AstAssign (nodep->fileline(),
new AstVarRef(nodep->fileline(), bitvscp, true),
dimp);
nodep->addNextHere(bitassignp);
dimreadps.push_front(new AstVarRef(nodep->fileline(), bitvscp, false));
}
}
//
//=== Bitselect: __Vdlyvlsb__
AstNode* bitreadp=NULL; // Code to read Vdlyvlsb
if (bitselp) {
AstNode* lsbvaluep = bitselp->lsbp()->unlinkFrBack();
if (bitselp->fromp()->castConst()) {// vlsb = constant, can just push constant into where we use it
bitreadp = lsbvaluep;
} else {
string bitvarname = (string("__Vdlyvlsb__")+oldvarp->shortName()+"__v"+cvtToStr(modVecNum));
AstVarScope* bitvscp = createVarSc(varrefp->varScopep(), bitvarname, lsbvaluep->width(), NULL);
AstAssign* bitassignp = new AstAssign (nodep->fileline(),
new AstVarRef(nodep->fileline(), bitvscp, true),
lsbvaluep);
nodep->addNextHere(bitassignp);
bitreadp = new AstVarRef(nodep->fileline(), bitvscp, false);
}
}
//
//=== Value: __Vdlyvval__
AstNode* valreadp; // Code to read Vdlyvval
if (nodep->rhsp()->castConst()) { // vval = constant, can just push constant into where we use it
valreadp = nodep->rhsp()->unlinkFrBack();
} else {
string valvarname = (string("__Vdlyvval__")+oldvarp->shortName()+"__v"+cvtToStr(modVecNum));
AstVarScope* valvscp = createVarSc(varrefp->varScopep(), valvarname, 0, nodep->rhsp()->dtypep());
newlhsp = new AstVarRef(nodep->fileline(), valvscp, true);
valreadp = new AstVarRef(nodep->fileline(), valvscp, false);
}
//
//=== Setting/not setting boolean: __Vdlyvset__
AstVarScope* setvscp;
AstAssignPre* setinitp = NULL;
if (nodep->user3p()) {
// Simplistic optimization. If the previous statement in same scope was also a =>,
// then we told this nodep->user3 we can use its Vdlyvset rather than making a new one.
// This is good for code like:
// for (i=0; i<5; i++) vector[i] <= something;
setvscp = nodep->user3p()->castNode()->castVarScope();
++m_statSharedSet;
} else { // Create new one
string setvarname = (string("__Vdlyvset__")+oldvarp->shortName()+"__v"+cvtToStr(modVecNum));
setvscp = createVarSc(varrefp->varScopep(), setvarname, 1, NULL);
setinitp = new AstAssignPre (nodep->fileline(),
new AstVarRef(nodep->fileline(), setvscp, true),
new AstConst(nodep->fileline(), 0));
AstAssign* setassignp
= new AstAssign (nodep->fileline(),
new AstVarRef(nodep->fileline(), setvscp, true),
new AstConst(nodep->fileline(),
V3Number(nodep->fileline(),1,true)));
nodep->addNextHere(setassignp);
}
if (m_nextDlyp) { // Tell next assigndly it can share the variable
m_nextDlyp->user3p(setvscp);
}
//
// Create ALWAYSPOST for delayed variable
// We add all logic to the same block if it's for the same memory
// This insures that multiple assignments to the same memory will result
// in correctly ordered code - the last assignment must be last.
// It also has the nice side effect of assisting cache locality.
AstNode* selectsp = varrefp;
for (int dimension=int(dimreadps.size())-1; dimension>=0; --dimension) {
selectsp = new AstArraySel(nodep->fileline(), selectsp, dimreadps[dimension]);
}
if (bitselp) {
selectsp = new AstSel(nodep->fileline(), selectsp, bitreadp,
bitselp->widthp()->cloneTree(false));
}
// Build "IF (changeit) ...
UINFO(9," For "<<setvscp<<endl);
UINFO(9," & "<<varrefp<<endl);
AstAlwaysPost* finalp = varrefp->varScopep()->user4p()->castNode()->castAlwaysPost();
if (finalp) {
AstActive* oldactivep = finalp->user2p()->castNode()->castActive();
checkActivePost(varrefp, oldactivep);
if (setinitp) oldactivep->addStmtsp(setinitp);
} else { // first time we've dealt with this memory
finalp = new AstAlwaysPost(nodep->fileline(), NULL/*sens*/, NULL/*body*/);
UINFO(9," Created "<<finalp<<endl);
AstActive* newactp = createActivePost(varrefp);
newactp->addStmtsp(finalp);
varrefp->varScopep()->user4p(finalp);
finalp->user2p(newactp);
if (setinitp) newactp->addStmtsp(setinitp);
}
AstIf* postLogicp;
if (finalp->user3p()->castNode() == setvscp) {
// Optimize as above; if sharing Vdlyvset *ON SAME VARIABLE*,
// we can share the IF statement too
postLogicp = finalp->user4p()->castNode()->castIf();
if (!postLogicp) nodep->v3fatalSrc("Delayed assignment misoptimized; prev var found w/o associated IF");
} else {
postLogicp = new AstIf (nodep->fileline(),
new AstVarRef(nodep->fileline(), setvscp, false),
NULL,
NULL);
UINFO(9," Created "<<postLogicp<<endl);
finalp->addBodysp(postLogicp);
finalp->user3p(setvscp); // Remember IF's vset variable
finalp->user4p(postLogicp); // and the associated IF, as we may be able to reuse it
}
postLogicp->addIfsp(new AstAssign(nodep->fileline(), selectsp, valreadp));
return newlhsp;
}
// VISITORS
virtual void visit(AstNetlist* nodep, AstNUser*) {
//VV***** We reset all userp() on the netlist
m_modVarMap.clear();
nodep->iterateChildren(*this);
}
virtual void visit(AstScope* nodep, AstNUser*) {
UINFO(4," MOD "<<nodep<<endl);
AstNode::user3ClearTree();
nodep->iterateChildren(*this);
}
virtual void visit(AstCFunc* nodep, AstNUser*) {
m_cfuncp = nodep;
nodep->iterateChildren(*this);
m_cfuncp = NULL;
}
virtual void visit(AstActive* nodep, AstNUser*) {
m_activep = nodep;
bool oldinit = m_inInitial;
m_inInitial = nodep->hasInitial();
AstNode::user3ClearTree(); // Two sets to same variable in different actives must use different vars.
nodep->iterateChildren(*this);
m_inInitial = oldinit;
}
virtual void visit(AstAssignDly* nodep, AstNUser*) {
m_inDly = true;
m_nextDlyp = nodep->nextp()->castAssignDly(); // Next assignment in same block, maybe NULL.
if (m_cfuncp) nodep->v3error("Unsupported: Delayed assignment inside public function/task");
if (nodep->lhsp()->castArraySel()
|| (nodep->lhsp()->castSel()
&& nodep->lhsp()->castSel()->fromp()->castArraySel())) {
AstNode* lhsp = nodep->lhsp()->unlinkFrBack();
AstNode* newlhsp = createDlyArray(nodep, lhsp);
if (m_inLoop) nodep->v3warn(E_BLKLOOPINIT,"Unsupported: Delayed assignment to array inside for loops (non-delayed is ok - see docs)");
if (newlhsp) {
nodep->lhsp(newlhsp);
} else {
nodep->unlinkFrBack()->deleteTree(); VL_DANGLING(nodep);
}
lhsp->deleteTree(); VL_DANGLING(lhsp);
}
else {
nodep->iterateChildren(*this);
}
m_inDly = false;
m_nextDlyp = NULL;
}
virtual void visit(AstVarRef* nodep, AstNUser*) {
if (!nodep->user2Inc()) { // Not done yet
if (m_inDly && nodep->lvalue()) {
UINFO(4,"AssignDlyVar: "<<nodep<<endl);
markVarUsage(nodep->varScopep(), VU_DLY);
if (!m_activep) nodep->v3fatalSrc("<= not under sensitivity block");
if (!m_activep->hasClocked()) nodep->v3error("Internal: Blocking <= assignment in non-clocked block, should have converted in V3Active");
AstVarScope* oldvscp = nodep->varScopep();
if (!oldvscp) nodep->v3fatalSrc("Var didn't get varscoped in V3Scope.cpp\n");
AstVarScope* dlyvscp = oldvscp->user1p()->castNode()->castVarScope();
if (dlyvscp) { // Multiple use of delayed variable
AstActive* oldactivep = dlyvscp->user2p()->castNode()->castActive();
checkActivePost(nodep, oldactivep);
}
if (!dlyvscp) { // First use of this delayed variable
string newvarname = (string("__Vdly__")+nodep->varp()->shortName());
dlyvscp = createVarSc(oldvscp, newvarname, 0, NULL);
AstNodeAssign* prep
= new AstAssignPre (nodep->fileline(),
new AstVarRef(nodep->fileline(), dlyvscp, true),
new AstVarRef(nodep->fileline(), oldvscp, false));
AstNodeAssign* postp
= new AstAssignPost (nodep->fileline(),
new AstVarRef(nodep->fileline(), oldvscp, true),
new AstVarRef(nodep->fileline(), dlyvscp, false));
postp->lhsp()->user2(true); // Don't detect this assignment
oldvscp->user1p(dlyvscp); // So we can find it later
// Make new ACTIVE with identical sensitivity tree
AstActive* newactp = createActivePost(nodep);
dlyvscp->user2p(newactp);
newactp->addStmtsp(prep); // Add to FRONT of statements
newactp->addStmtsp(postp);
}
AstVarRef* newrefp = new AstVarRef(nodep->fileline(), dlyvscp, true);
newrefp->user2(true); // No reason to do it again
nodep->replaceWith(newrefp); nodep->deleteTree(); VL_DANGLING(nodep);
}
else if (!m_inDly && nodep->lvalue()) {
//UINFO(9,"NBA "<<nodep<<endl);
if (!m_inInitial) {
UINFO(4,"AssignNDlyVar: "<<nodep<<endl);
markVarUsage(nodep->varScopep(), VU_NONDLY);
}
}
}
}
virtual void visit(AstNodeFor* nodep, AstNUser*) {
nodep->v3fatalSrc("For statements should have been converted to while statements in V3Begin\n");
}
virtual void visit(AstWhile* nodep, AstNUser*) {
bool oldloop = m_inLoop;
m_inLoop = true;
nodep->iterateChildren(*this);
m_inLoop = oldloop;
}
//--------------------
// Default: Just iterate
virtual void visit(AstNode* nodep, AstNUser*) {
nodep->iterateChildren(*this);
}
public:
// CONSTUCTORS
explicit DelayedVisitor(AstNetlist* nodep) {
m_inDly = false;
m_activep=NULL;
m_cfuncp=NULL;
m_nextDlyp=NULL;
m_inLoop = false;
m_inInitial = false;
nodep->accept(*this);
}
virtual ~DelayedVisitor() {
V3Stats::addStat("Optimizations, Delayed shared-sets", m_statSharedSet);
}
};
//######################################################################
// Delayed class functions
void V3Delayed::delayedAll(AstNetlist* nodep) {
UINFO(2,__FUNCTION__<<": "<<endl);
DelayedVisitor visitor (nodep);
V3Global::dumpCheckGlobalTree("delayed.tree", 0, v3Global.opt.dumpTreeLevel(__FILE__) >= 3);
}