github/verilator
1
0
Fork 1
mirror of https://github.com/verilator/verilator.git synced 2025-04-25 10:06:54 +00:00
Code Issues Packages Projects Releases Wiki Activity

V3Unknown: Don't modify tree if SEL out-of-bounds would be constant. Prep for next change.

Browse Source
This commit is contained in:
Wilson Snyder 2009-10-06 17:19:38 -04:00
parent 7c8d914711
commit 3eb155cf2a
1 changed files with 62 additions and 57 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

119
src/V3Unknown.cpp
View File

@ -66,6 +66,19 @@ private:
return level;
}
AstNode* constify(AstNode* nodep) {
// Put the new nodes under a temporary XOR operator we'll rip up in a moment.
// This way when we constify, if the expression
// is a constant it will still be under the XOR.
AstXor* newp = new AstXor (nodep->fileline(), nodep,
new AstConst (nodep->fileline(), 0)); // Just so it's a valid XOR
V3Const::constifyTree(newp->lhsp()); nodep=NULL; // Just the conditional
// Nodep may now be a changed object like a constant
nodep = newp->lhsp()->unlinkFrBack();
newp->deleteTree(); newp=NULL;
return nodep;
}
// VISITORS
virtual void visit(AstModule* nodep, AstNUser*) {
UINFO(4," MOD "<<nodep<<endl);
@ -249,7 +262,17 @@ private:
int maxlsb = maxmsb - nodep->widthMin() + 1;
if (debug()>=9) nodep->dumpTree(cout,"sel_old: ");
V3Number maxlsbnum (nodep->fileline(), nodep->lsbp()->width(), maxlsb);
if (!lvalue) {
// See if the condition is constant true
AstNode* condp = new AstLte (nodep->fileline(),
nodep->lsbp()->cloneTree(false),
new AstConst(nodep->fileline(), maxlsbnum));
condp = constify(condp);
if (condp->isOne()) {
// We don't need to add a conditional; we know the existing expression is ok
condp->deleteTree();
}
else if (!lvalue) {
// SEL(...) -> COND(LTE(bit<=maxlsb), ARRAYSEL(...), {width{1'bx}})
AstNRelinker replaceHandle;
nodep->unlinkFrBack(&replaceHandle);
@ -258,43 +281,29 @@ private:
// Put the new nodes under a temporary XOR operator we'll rip up in a moment.
// This way when we constify, if the expression
// is a constant it will still be under the XOR.
AstXor* newp = new AstXor (
nodep->fileline(),
new AstCondBound (nodep->fileline(),
new AstLte (nodep->fileline(),
nodep->lsbp()->cloneTree(false),
new AstConst(nodep->fileline(), maxlsbnum)),
nodep,
new AstConst(nodep->fileline(), xnum)),
new AstConst (nodep->fileline(), 0)); // Just so it's a valid XOR
AstNode* newp = new AstCondBound (nodep->fileline(),
condp,
nodep,
new AstConst(nodep->fileline(), xnum));
if (debug()>=9) newp->dumpTree(cout," _new: ");
V3Const::constifyTree(newp->lhsp()); // Just the conditional
if (debug()>=9) newp->dumpTree(cout," _con: ");
// Link in conditional, can blow away temp xor
AstNode* nnp = newp->lhsp()->unlinkFrBack();
replaceHandle.relink(nnp); nodep=NULL;
newp->deleteTree(); newp=NULL;
// Link in conditional
replaceHandle.relink(newp);
// Added X's, tristate them too
nnp->accept(*this);
newp->accept(*this);
}
else {
else { // lvalue
// SEL(...) -> SEL(COND(LTE(bit<=maxlsb), bit, 0))
AstNRelinker replaceHandle;
AstNode* lsbp = nodep->lsbp()->unlinkFrBack(&replaceHandle);
V3Number zeronum (nodep->fileline(), lsbp->width(), 0);
AstCondBound* newp = new AstCondBound
(lsbp->fileline(),
new AstLte (lsbp->fileline(),
lsbp->cloneTree(false),
new AstConst(lsbp->fileline(), maxlsbnum)),
lsbp,
new AstConst(lsbp->fileline(), zeronum));
AstNode* newp = new AstCondBound (lsbp->fileline(),
condp,
lsbp,
new AstConst(lsbp->fileline(), zeronum));
if (debug()>=9) newp->dumpTree(cout," _new: ");
replaceHandle.relink(newp);
// Added X's, tristate them too
if (debug()>=9) nodep->dumpTree(cout," _new: ");
V3Const::constifyTree(nodep);
if (debug()>=9) nodep->dumpTree(cout," _con: ");
nodep->iterateChildren(*this);
newp->accept(*this);
}
}
}
@ -319,7 +328,17 @@ private:
}
if (debug()>=9) nodep->dumpTree(cout,"arraysel_old: ");
V3Number widthnum (nodep->fileline(), nodep->bitp()->width(), maxmsb);
if (!lvalue
// See if the condition is constant true
AstNode* condp = new AstLte (nodep->fileline(),
nodep->bitp()->cloneTree(false),
new AstConst(nodep->fileline(), widthnum));
condp = constify(condp);
if (condp->isOne()) {
// We don't need to add a conditional; we know the existing expression is ok
condp->deleteTree();
}
else if (!lvalue
&& !nodep->backp()->castArraySel()) { // Too complicated and slow if mid-multidimension
// ARRAYSEL(...) -> COND(LT(bit<maxbit), ARRAYSEL(...), {width{1'bx}})
AstNRelinker replaceHandle;
@ -329,43 +348,29 @@ private:
// Put the new nodes under a temporary XOR operator we'll rip up in a moment.
// This way when we constify, if the expression
// is a constant it will still be under the XOR.
AstXor* newp = new AstXor (
nodep->fileline(),
new AstCondBound (nodep->fileline(),
new AstLte (nodep->fileline(),
nodep->bitp()->cloneTree(false),
new AstConst(nodep->fileline(), widthnum)),
nodep,
new AstConst(nodep->fileline(), xnum)),
new AstConst (nodep->fileline(), 0)); // Just so it's a valid XOR
AstNode* newp = new AstCondBound (nodep->fileline(),
condp,
nodep,
new AstConst(nodep->fileline(), xnum));
if (debug()>=9) newp->dumpTree(cout," _new: ");
V3Const::constifyTree(newp->lhsp()); // Just the conditional
if (debug()>=9) newp->dumpTree(cout," _con: ");
// Link in conditional, can blow away temp xor
AstNode* nnp = newp->lhsp()->unlinkFrBack();
replaceHandle.relink(nnp); nodep=NULL;
newp->deleteTree(); newp=NULL;
replaceHandle.relink(newp);
// Added X's, tristate them too
nnp->accept(*this);
newp->accept(*this);
}
else {
// ARRAYSEL(...) -> ARRAYSEL(COND(LT(bit<maxbit), bit, 0))
AstNRelinker replaceHandle;
AstNode* bitp = nodep->bitp()->unlinkFrBack(&replaceHandle);
V3Number zeronum (nodep->fileline(), bitp->width(), 0);
AstCondBound* newp = new AstCondBound
(bitp->fileline(),
new AstLte (bitp->fileline(),
bitp->cloneTree(false),
new AstConst(bitp->fileline(), widthnum)),
bitp,
new AstConst(bitp->fileline(), zeronum));
replaceHandle.relink(newp);
AstNode* newp = new AstCondBound (bitp->fileline(),
condp,
bitp,
new AstConst(bitp->fileline(), zeronum));
// Added X's, tristate them too
if (debug()>=9) nodep->dumpTree(cout," _new: ");
V3Const::constifyTree(nodep);
if (debug()>=9) nodep->dumpTree(cout," _con: ");
nodep->iterateChildren(*this);
if (debug()>=9) newp->dumpTree(cout," _new: ");
replaceHandle.relink(newp);
newp->accept(*this);
}
}
}