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Optimize concat/replicate+replicate.

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This commit is contained in:
Wilson Snyder
2017-09-21 21:05:42 -04:00
parent 48d3ce46d8
commit 47e13cfdf4
3 changed files with 70 additions and 17 deletions
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src/V3Const.cpp
+55 -8
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@@ -1393,22 +1393,67 @@ private:
}
nodep->deleteTree(); VL_DANGLING(nodep);
}
void replaceSelReplicate(AstSel* nodep) {
// SEL(REPLICATE(a,b),1,bit) => SEL(a,1,bit)
bool operandSelReplicate(AstSel* nodep) {
// SEL(REPLICATE(from,rep),lsb,width) => SEL(from,0,width) as long as SEL's width <= b's width
AstReplicate* repp = nodep->fromp()->castReplicate();
AstNode* fromp = repp->lhsp()->unlinkFrBack();
AstConst* lsbp = nodep->lsbp()->castConst();
AstNode* widthp = nodep->widthp()->unlinkFrBack();
AstNode* fromp = repp->lhsp();
AstConst* lsbp = nodep->lsbp()->castConst(); if (!lsbp) return false;
AstNode* widthp = nodep->widthp(); if (!widthp->castConst()) return false;
if (!fromp->width()) nodep->v3fatalSrc("Not widthed");
if ((lsbp->toUInt() / fromp->width())
!= ((lsbp->toUInt()+nodep->width()-1) / fromp->width())) return false;
//
fromp->unlinkFrBack();
widthp->unlinkFrBack();
AstSel* newp = new AstSel(nodep->fileline(),
fromp,
new AstConst(lsbp->fileline(), lsbp->toUInt() % fromp->width()),
widthp);
newp->dtypeFrom(nodep);
nodep->replaceWith(newp); nodep->deleteTree(); VL_DANGLING(nodep);
return true;
}
bool operandRepRep(AstReplicate* nodep) {
// REPLICATE(REPLICATE2(from2,cnt2),cnt1) => REPLICATE(from2,(cnt1+cnt2))
AstReplicate* rep2p = nodep->lhsp()->castReplicate();
AstNode* from2p = rep2p->lhsp();
AstConst* cnt1p = nodep->rhsp()->castConst(); if (!cnt1p) return false;
AstConst* cnt2p = rep2p->rhsp()->castConst(); if (!cnt2p) return false;
//
from2p->unlinkFrBack();
cnt1p->unlinkFrBack();
cnt2p->unlinkFrBack();
AstReplicate* newp = new AstReplicate(nodep->fileline(),
from2p, cnt1p->toUInt()*cnt2p->toUInt());
newp->dtypeFrom(nodep);
nodep->replaceWith(newp); nodep->deleteTree(); VL_DANGLING(nodep);
return true;
}
bool operandConcatSame(AstConcat* nodep) {
// CONCAT(fromp,fromp) -> REPLICATE(fromp,1+1)
// CONCAT(REP(fromp,cnt1),fromp) -> REPLICATE(fromp,cnt1+1)
// CONCAT(fromp,REP(fromp,cnt1)) -> REPLICATE(fromp,1+cnt1)
// CONCAT(REP(fromp,cnt1),REP(fromp,cnt2)) -> REPLICATE(fromp,cnt1+cnt2)
AstNode* from1p = nodep->lhsp(); uint32_t cnt1 = 1;
AstNode* from2p = nodep->rhsp(); uint32_t cnt2 = 1;
if (from1p->castReplicate()) {
AstConst* cnt1p = from1p->castReplicate()->rhsp()->castConst(); if (!cnt1p) return false;
from1p = from1p->castReplicate()->lhsp();
cnt1 = cnt1p->toUInt();
}
if (from2p->castReplicate()) {
AstConst* cnt2p = from2p->castReplicate()->rhsp()->castConst(); if (!cnt2p) return false;
from2p = from2p->castReplicate()->lhsp();
cnt2 = cnt2p->toUInt();
}
if (!operandsSame(from1p,from2p)) return false;
//
from1p->unlinkFrBack();
AstReplicate* newp = new AstReplicate(nodep->fileline(), from1p, cnt1+cnt2);
newp->dtypeFrom(nodep);
nodep->replaceWith(newp); nodep->deleteTree(); VL_DANGLING(nodep);
return true;
}
void replaceSelIntoBiop(AstSel* nodep) {
// SEL(BUFIF1(a,b),1,bit) => BUFIF1(SEL(a,1,bit),SEL(b,1,bit))
AstNodeBiop* fromp = nodep->fromp()->unlinkFrBack()->castNodeBiop();
@@ -2268,6 +2313,8 @@ private:
TREEOPV("AstExtendS{$lhsp.castExtendS}", "replaceExtend(nodep, nodep->lhsp()->castExtendS()->lhsp())");
TREEOPV("AstReplicate{$lhsp, $rhsp.isOne, $lhsp->width()==nodep->width()}", "replaceWLhs(nodep)"); // {1{lhs}}->lhs
TREEOPV("AstReplicateN{$lhsp, $rhsp.isOne, $lhsp->width()==nodep->width()}", "replaceWLhs(nodep)"); // {1{lhs}}->lhs
TREEOPV("AstReplicate{$lhsp.castReplicate, operandRepRep(nodep)}", "DONE"); // {2{3{lhs}}}->{6{lhs}}
TREEOPV("AstConcat{operandConcatSame(nodep)}", "DONE"); // {a,a}->{2{a}}, {a,2{a}}->{3{a}, etc
// Next rule because AUTOINST puts the width of bits in
// to pins, even when the widths are exactly the same across the hierarchy.
TREEOPV("AstSel{operandSelExtend(nodep)}", "DONE");
@@ -2282,7 +2329,7 @@ private:
TREEOPV("AstSel{$fromp.castShiftR, operandSelShiftLower(nodep)}", "DONE");
TREEOPC("AstSel{$fromp.castConst, $lsbp.castConst, $widthp.castConst, }", "replaceConst(nodep)");
TREEOPV("AstSel{$fromp.castConcat, $lsbp.castConst, $widthp.castConst, }", "replaceSelConcat(nodep)");
TREEOPV("AstSel{$fromp.castReplicate, $lsbp.castConst, $widthp.isOne, }", "replaceSelReplicate(nodep)");
TREEOPV("AstSel{$fromp.castReplicate, $lsbp.castConst, $widthp.castConst, operandSelReplicate(nodep) }", "DONE");
// V3Tristate requires selects below BufIf1.
// Also do additional operators that are bit-independent, but only definite
// win if bit select is a constant (otherwise we may need to compute bit index several times)