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Internals: Minor tristate changes from branch. No functional change.

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This commit is contained in:
Wilson Snyder 2012-05-06 16:52:08 -04:00
parent 7b3eb22865
commit e97541dcbc
1 changed files with 43 additions and 36 deletions
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79
src/V3Tristate.cpp
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@ -120,6 +120,11 @@ class TristateVisitor : public TristateBaseVisitor {
V3Double0 m_statTriSigs; // stat tracking
// METHODS
string dbgState() {
string o;
if (m_alhs) o += "alhs ";
return o;
}
AstNode* getEnp(AstNode* nodep) {
// checks if user1p() is null, and if so, adds a constant output
// enable driver of all 1's. Otherwise returns the user1p() data.
@ -221,12 +226,14 @@ class TristateVisitor : public TristateBaseVisitor {
) {
VarMap::iterator it = m_lhsmap.find(varp);
if (it == m_lhsmap.end()) {
// set output enable to always be off on this assign statement so that this var is floating
UINFO(8," Adding driver to var "<<varp<<endl);
V3Number zeros (varp->fileline(), varp->width());
zeros.setAllBits0();
AstConst* constp = new AstConst(varp->fileline(), zeros);
AstVarRef* varrefp = new AstVarRef(varp->fileline(), varp, true);
nodep->addStmtp(new AstAssignW(varp->fileline(), varrefp, constp));
AstNode* newp = new AstAssignW(varp->fileline(), varrefp, constp);
nodep->addStmtp(newp);
visit(varrefp, NULL);
varrefp->user1p(new AstConst(varp->fileline(),zeros));//set output enable to always be off on this assign statement so that this var is floating
}
@ -261,7 +268,7 @@ class TristateVisitor : public TristateBaseVisitor {
}
m_statTriSigs++;
UINFO(8, " TRISTATE EXPANDING("<<needs_expanded<<"):" << invarp << endl);
UINFO(8, " TRISTATE EXPANDING:" << invarp << endl);
// If the lhs var is a port, then we need to create ports for
// the output (__out) and output enable (__en) signals. The
@ -283,7 +290,7 @@ class TristateVisitor : public TristateBaseVisitor {
envarp->varType2Out();
//
outvarp->user1p(envarp);
outvarp->user3p(invarp->user3p());
outvarp->user3p(invarp->user3p()); // AstPull* propagation
if (invarp->user3p()) UINFO(9, "propagate pull to "<<outvarp);
} else if (invarp->user1p()) {
envarp = invarp->user1p()->castNode()->castVar(); // From CASEEQ, foo === 1'bz
@ -303,7 +310,8 @@ class TristateVisitor : public TristateBaseVisitor {
AstVar* newlhsp = new AstVar(lhsp->fileline(),
AstVarType::MODULETEMP,
lhsp->name()+"__out"+cvtToStr(m_unique),
VFlagLogicPacked(), w);
VFlagBitPacked(), w); // 2-state ok; sep enable
UINFO(9," newout "<<newlhsp);
nodep->addStmtp(newlhsp);
refp->varp(newlhsp); // assign the new var to the varref
refp->name(newlhsp->name());
@ -312,12 +320,13 @@ class TristateVisitor : public TristateBaseVisitor {
AstVar* newenp = new AstVar(lhsp->fileline(),
AstVarType::MODULETEMP,
lhsp->name()+"__en"+cvtToStr(m_unique++),
VFlagLogicPacked(), w);
VFlagBitPacked(), w); // 2-state ok
nodep->addStmtp(newenp);
nodep->addStmtp(new AstAssignW(refp->fileline(),
new AstVarRef(refp->fileline(), newenp, true),
getEnp(refp)));
AstNode* enassp = new AstAssignW(refp->fileline(),
new AstVarRef(refp->fileline(), newenp, true),
getEnp(refp));
nodep->addStmtp(enassp);
// now append this driver to the driver logic.
AstNode* ref1p = new AstVarRef(nodep->fileline(), newlhsp,false);
@ -377,7 +386,7 @@ class TristateVisitor : public TristateBaseVisitor {
// VISITORS
virtual void visit(AstConst* nodep, AstNUser*) {
UINFO(9,(m_alhs?"alhs":"")<<" "<<nodep<<endl);
UINFO(9,dbgState()<<nodep<<endl);
// Detect any Z consts and convert them to 0's with an enable that is also 0.
if (m_alhs && nodep->user1p()) {
// A pin with 1'b0 or similar connection results in an assign with constant on LHS
@ -406,7 +415,7 @@ class TristateVisitor : public TristateBaseVisitor {
virtual void visit(AstCond* nodep, AstNUser*) {
if (m_alhs && nodep->user1p()) { nodep->v3error("Unsupported LHS tristate construct: "<<nodep->prettyTypeName()); return; }
nodep->iterateChildren(*this);
UINFO(9,(m_alhs?"alhs":"")<<" "<<nodep<<endl);
UINFO(9,dbgState()<<nodep<<endl);
// Generate the new output enable signal for this cond if either
// expression 1 or 2 have an output enable '__en' signal. If the
// condition has an enable, not sure what to do, so generate an
@ -417,22 +426,21 @@ class TristateVisitor : public TristateBaseVisitor {
}
AstNode* expr1p = nodep->expr1p();
AstNode* expr2p = nodep->expr2p();
if (!expr1p->user1p() && !expr2p->user1p()) {
return; // no tristates in either expression, so nothing to do
if (expr1p->user1p() || expr2p->user1p()) { // else no tristates
AstNode* en1p = getEnp(expr1p);
AstNode* en2p = getEnp(expr2p);
// The output enable of a cond is a cond of the output enable of the
// two expressions with the same conditional.
AstNode* enp = new AstCond(nodep->fileline(), condp->cloneTree(false), en1p, en2p);
nodep->user1p(enp);
expr1p->user1p(NULL);
expr2p->user1p(NULL);
}
AstNode* en1p = getEnp(expr1p);
AstNode* en2p = getEnp(expr2p);
// The output enable of a cond is a cond of the output enable of the
// two expressions with the same conditional.
AstNode* enp = new AstCond(nodep->fileline(), condp->cloneTree(false), en1p, en2p);
nodep->user1p(enp);
expr1p->user1p(NULL);
expr2p->user1p(NULL);
}
virtual void visit(AstSel* nodep, AstNUser*) {
if (m_alhs) {
UINFO(9,"alhs "<<nodep<<endl);
UINFO(9,dbgState()<<nodep<<endl);
if (nodep->user1p()) {
// Form a "deposit" instruction. Would be nicer if we made this a new AST type
AstNode* newp = newEnableDeposit(nodep, nodep->user1p()->castNode());
@ -442,7 +450,7 @@ class TristateVisitor : public TristateBaseVisitor {
nodep->iterateChildren(*this);
} else {
nodep->iterateChildren(*this);
UINFO(9," "<<nodep<<endl);
UINFO(9,dbgState()<<nodep<<endl);
if (nodep->fromp()->user1p() || nodep->lsbp()->user1p())
nodep->v3error("Unsupported RHS tristate construct: "<<nodep->prettyTypeName());
}
@ -450,7 +458,7 @@ class TristateVisitor : public TristateBaseVisitor {
virtual void visit(AstConcat* nodep, AstNUser*) {
if (m_alhs) {
UINFO(9,(m_alhs?"alhs":"")<<" "<<nodep<<endl);
UINFO(9,dbgState()<<nodep<<endl);
if (nodep->user1p()) {
// Each half of the concat gets a select of the enable expression
AstNode* enp = nodep->user1p()->castNode();
@ -467,26 +475,25 @@ class TristateVisitor : public TristateBaseVisitor {
nodep->iterateChildren(*this);
} else {
nodep->iterateChildren(*this);
UINFO(9,(m_alhs?"alhs":"")<<" "<<nodep<<endl);
UINFO(9,dbgState()<<nodep<<endl);
// Generate the new output enable signal, just as a concat identical to the data concat
AstNode* expr1p = nodep->lhsp();
AstNode* expr2p = nodep->rhsp();
if (!expr1p->user1p() && !expr2p->user1p()) {
return; // no tristates in either expression, so nothing to do
if (expr1p->user1p() || expr2p->user1p()) { // else no tristates
AstNode* en1p = getEnp(expr1p);
AstNode* en2p = getEnp(expr2p);
AstNode* enp = new AstConcat(nodep->fileline(), en1p, en2p);
nodep->user1p(enp);
expr1p->user1p(NULL);
expr2p->user1p(NULL);
}
AstNode* en1p = getEnp(expr1p);
AstNode* en2p = getEnp(expr2p);
AstNode* enp = new AstConcat(nodep->fileline(), en1p, en2p);
nodep->user1p(enp);
expr1p->user1p(NULL);
expr2p->user1p(NULL);
}
}
virtual void visit(AstBufIf1* nodep, AstNUser*) {
// For BufIf1, the enable is the LHS expression
nodep->iterateChildren(*this);
UINFO(9,(m_alhs?"alhs":"")<<" "<<nodep<<endl);
UINFO(9,dbgState()<<nodep<<endl);
if (debug()>=9) nodep->backp()->dumpTree(cout,"-bufif: ");
if (m_alhs) { nodep->v3error("Unsupported LHS tristate construct: "<<nodep->prettyTypeName()); return; }
AstNode* expr1p = nodep->lhsp()->unlinkFrBack();
@ -589,7 +596,7 @@ class TristateVisitor : public TristateBaseVisitor {
// Otherwise we'd need to attach an enable to every signal, then optimize then
// away later when we determine the signal has no tristate
nodep->iterateChildren(*this);
UINFO(9," "<<nodep<<endl);
UINFO(9,dbgState()<<nodep<<endl);
AstConst* constp = nodep->lhsp()->castConst(); // Constification always moves const to LHS
AstVarRef* varrefp = nodep->rhsp()->castVarRef(); // Input variable
if (constp && constp->user1p() && varrefp) {
@ -621,7 +628,7 @@ class TristateVisitor : public TristateBaseVisitor {
}
virtual void visit(AstPull* nodep, AstNUser*) {
UINFO(9," "<<nodep<<endl);
UINFO(9,dbgState()<<nodep<<endl);
// Replace any pullup/pulldowns with assignw logic and set the
// direction of the pull in the user2() data on the var. Given
// the complexity of merging tristate drivers at any level, the
@ -755,6 +762,7 @@ class TristateVisitor : public TristateBaseVisitor {
setPullDirection(refp->varp(), pullp);
}
}
// Don't need to visit the created assigns, as it was added at the end of the next links
// and normal iterateChild recursion will come back to them eventually.
}
@ -835,7 +843,6 @@ class TristateVisitor : public TristateBaseVisitor {
// Default: Just iterate
virtual void visit(AstNode* nodep, AstNUser*) {
nodep->iterateChildren(*this);
UINFO(9," "<<nodep<<endl);
checkUnhandled(nodep);
}