virtual void visit(AstNodeAssign* nodep, AstNUser*) {
// See if simple assignments to variables may be eliminated because that variable is never used.
// Similar code in V3Life
m_sideEffect = false;
nodep->rhsp()->iterateAndNext(*this);
checkAll(nodep);
// Has to be direct assignment without any EXTRACTing.
AstVarRef* varrefp = nodep->lhsp()->castVarRef();
if (varrefp && !m_sideEffect
&& varrefp->varScopep()) { // For simplicity, we only remove post-scoping
m_assignMap.insert(make_pair(varrefp->varScopep(), nodep));
checkAll(varrefp); // Must track reference to dtype()
} else { // Track like any other statement
nodep->lhsp()->iterateAndNext(*this);
}
checkAll(nodep);
}
bool forUnrollCheck(AstNode* nodep,
AstNode* initp, // Maybe under nodep (no nextp), or standalone (ignore nextp)
AstNode* precondsp, AstNode* condp,
AstNode* incp, // Maybe under nodep or in bodysp
AstNode* bodysp) {
// To keep the IF levels low, we return as each test fails.
UINFO(4, " FOR Check "<<nodep<<endl);
if (initp) UINFO(6, " Init "<<initp<<endl);
if (precondsp) UINFO(6, " Pcon "<<precondsp<<endl);
if (condp) UINFO(6, " Cond "<<condp<<endl);
if (incp) UINFO(6, " Inc "<<incp<<endl);
// Initial value check
AstAssign* initAssp = initp->castAssign();
if (!initAssp) return cantUnroll(nodep, "no initial assignment");
if (initp->nextp() && initp->nextp()!=nodep) nodep->v3fatalSrc("initial assignment shouldn't be a list");
if (!initAssp->lhsp()->castVarRef()) return cantUnroll(nodep, "no initial assignment to simple variable");
m_forVarp = initAssp->lhsp()->castVarRef()->varp();
m_forVscp = initAssp->lhsp()->castVarRef()->varScopep();
if (nodep->castGenFor() && !m_forVarp->isGenVar()) {
nodep->v3error("Non-genvar used in generate for: "<<m_forVarp->name()<<endl);
}
if (m_generate) V3Const::constifyParamsEdit(initAssp->rhsp()); // rhsp may change
AstConst* constInitp = initAssp->rhsp()->castConst();
if (!constInitp) return cantUnroll(nodep, "non-constant initializer");
//
// Condition check
if (condp->nextp()) nodep->v3fatalSrc("conditional shouldn't be a list");
//
// Assignment of next value check
AstAssign* incAssp = incp->castAssign();
if (!incAssp) return cantUnroll(nodep, "no increment assignment");
if (incAssp->nextp()) nodep->v3fatalSrc("increment shouldn't be a list");
AstNodeBiop* incInstrp = incAssp->rhsp()->castNodeBiop();
//
if (m_forVscp) { UINFO(8, " Loop Variable: "<<m_forVscp<<endl); }
else { UINFO(8, " Loop Variable: "<<m_forVarp<<endl); }
if (debug()>=9) nodep->dumpTree(cout,"- for: ");
//
// Extract the constant loop bounds
bool subtract = incInstrp->castSub();
{
if (!subtract && !incInstrp->castAdd()) return cantUnroll(nodep, "missing add/sub for incrementer");
AstVarRef* incVarrp = (subtract ? incInstrp->lhsp()->castVarRef()
: incInstrp->rhsp()->castVarRef());
if (!incVarrp) return cantUnroll(nodep, "missing variable in incrementer");
if (incVarrp->varp() != m_forVarp
|| incVarrp->varScopep() != m_forVscp) {
return cantUnroll(nodep, "different variables in incrementer");
}
}
//
// Adds have the # on the lhsp because V3Const pushes rhs consts over to the lhs
// Subtracts have it on the rhs, because you write i=i-1; i=1-i is non-sensible.
AstConst* preconstIncp = (subtract ? incInstrp->rhsp()->castConst()
: incInstrp->lhsp()->castConst());
if (m_generate) preconstIncp = V3Const::constifyParamsEdit(preconstIncp)->castConst();
AstConst* constIncp = (subtract ? incInstrp->rhsp()->castConst()
: incInstrp->lhsp()->castConst());
UINFO(8, " Inc expr ok: "<<constIncp<<endl);
if (!constIncp) return cantUnroll(nodep, "non-constant increment");
if (constIncp->isZero()) return cantUnroll(nodep, "zero increment"); // Or we could loop forever below...
bool lt = condp->castLt() || condp->castLtS();
bool lte = condp->castLte() || condp->castLteS();
bool gt = condp->castGt() || condp->castGtS();
bool gte = condp->castGte() || condp->castGteS();
if (!lt && !lte && !gt && !gte)
return cantUnroll(nodep, "condition not <= or <");
AstNodeBiop* condBip = condp->castNodeBiop();
if (!condBip->lhsp()->castVarRef())
return cantUnroll(nodep, "no variable on lhs of condition");
if (condBip->lhsp()->castVarRef()->varp() != m_forVarp
|| condBip->lhsp()->castVarRef()->varScopep() != m_forVscp)
return cantUnroll(nodep, "different variable in condition");
if (m_generate) V3Const::constifyParamsEdit(condBip->rhsp()); // rhsp may change
AstConst* constStopp = condBip->rhsp()->castConst();
if (!constStopp) return cantUnroll(nodep, "non-constant final value");
UINFO(8, " Stop expr ok: "<<constStopp<<endl);
//
if (constInitp->width()>32 || constInitp->num().isFourState()
|| constStopp->width()>32 || constStopp->num().isFourState()
|| constIncp->width()>32 || constIncp->num().isFourState())
return cantUnroll(nodep, "init/final/increment too large or four state");
vlsint32_t valInit = constInitp->num().toSInt();
vlsint32_t valStop = constStopp->num().toSInt();
if (lte) valStop++; if (gte) valStop--;
vlsint32_t valInc = constIncp->num().toSInt();
if (subtract) valInc = -valInc;
UINFO(8," In Numbers: for (v="<<valInit<<"; v<"<<valStop<<"; v=v+"<<valInc<<")\n");
//
if (!m_generate) {
int loops = ((valStop - valInit)/valInc);
if (loops < 0) { loops += (1ULL<<constStopp->width()); } // Will roll around
UINFO(8, " ~Iters: "<<loops<<" c="<<unrollCount()<<endl);
if (loops > unrollCount())
return cantUnroll(nodep, "too many iterations");
// Less than 10 statements in the body?
int bodySize = 0;
int bodyLimit = v3Global.opt.unrollStmts();
if (loops>0) bodyLimit = v3Global.opt.unrollStmts() / loops;
if (bodySizeOverRecurse(precondsp, bodySize/*ref*/, bodyLimit)
|| bodySizeOverRecurse(bodysp, bodySize/*ref*/, bodyLimit)
|| bodySizeOverRecurse(incp, bodySize/*ref*/, bodyLimit)) {
return cantUnroll(nodep, "too many statements");
}
}
//
// Now, make sure there's no assignment to this variable in the loop
m_varModeCheck = true;
m_varAssignHit = false;
m_ignoreIncp = incp;
precondsp->iterateAndNext(*this);
bodysp->iterateAndNext(*this);
incp->iterateAndNext(*this);
m_varModeCheck = false;
m_ignoreIncp = NULL;
if (m_varAssignHit) return cantUnroll(nodep, "genvar assigned *inside* loop");
//
// Finally, we can do it
forUnroller(nodep, initp, precondsp, condp, incp, bodysp,
constInitp->num(),
condBip, constStopp->num(),
incInstrp, constIncp->num()); nodep = NULL;
// Cleanup
return true;
}
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());
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());
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, nodep->rhsp()->width());
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);
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;
}