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Optimize constants up across sub expressions

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This commit is contained in:
Wilson Snyder 2008-11-17 10:40:58 -05:00
parent 5f70c1aa68
commit c5d41ee2d9
1 changed files with 55 additions and 0 deletions
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55
src/V3Const.cpp
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@ -132,6 +132,35 @@ private:
if (rnodep->width() != bnodep->width()) return false;
return operandsSame(bnodep->lhsp(), rnodep->lhsp());
}
bool operandAsvLUp (AstNode* nodep) {
// BIASV(BIASV(CONSTll,lr),r) -> BIASV(CONSTll,BIASV(lr,r))
//
// Example of how this is useful:
// BIASV(BIASV(CONSTa,b...),BIASV(CONSTc,d...)) // hits operandAsvUp
// BIASV(CONSTa,BIASV(b...,BIASV(CONSTc,d...))) // hits operandAsvUp
// BIASV(CONSTa,BIASV(CONSTc,BIASV(c...,d...))) // hits operandAsvConst
// BIASV(BIASV(CONSTa,CONSTc),BIASV(c...,d...))) // hits normal constant propagation
// BIASV(CONST_a_c,BIASV(c...,d...)))
//
// Idea for the future: All BiComAsvs could be lists, sorted by if they're constant
AstNodeBiComAsv* bnodep = nodep->castNodeBiComAsv();
if (!bnodep) return false;
AstNodeBiComAsv* lnodep = bnodep->lhsp()->castNodeBiComAsv();
if (!lnodep) return false;
if (lnodep->type() != bnodep->type()) return false;
if (lnodep->width() != bnodep->width()) return false;
return lnodep->lhsp()->castConst();
}
bool operandAsvRUp (AstNode* nodep) {
// BIASV(l,BIASV(CONSTrl,rr)) -> BIASV(CONSTrl,BIASV(l,rr))
AstNodeBiComAsv* bnodep = nodep->castNodeBiComAsv();
if (!bnodep) return false;
AstNodeBiComAsv* rnodep = bnodep->rhsp()->castNodeBiComAsv();
if (!rnodep) return false;
if (rnodep->type() != bnodep->type()) return false;
if (rnodep->width() != bnodep->width()) return false;
return rnodep->lhsp()->castConst();
}
bool operandHugeShiftL(AstNodeBiop* nodep) {
return (nodep->rhsp()->castConst()
&& nodep->rhsp()->castConst()->toUInt() >= (uint32_t)(nodep->width()));
@ -368,6 +397,30 @@ private:
if (rp->lhsp()->castConst() && rp->rhsp()->castConst()) replaceConst(rp);
//nodep->dumpTree(cout, " repAsvConst_new: ");
}
void replaceAsvLUp (AstNodeBiop* nodep) {
// BIASV(BIASV(CONSTll,lr),r) -> BIASV(CONSTll,BIASV(lr,r))
AstNodeBiop* lp = nodep->lhsp()->unlinkFrBack()->castNodeBiop();
AstNode* llp = lp->lhsp()->unlinkFrBack();
AstNode* lrp = lp->rhsp()->unlinkFrBack();
AstNode* rp = nodep->rhsp()->unlinkFrBack();
nodep->lhsp(llp);
nodep->rhsp(lp);
lp->lhsp(lrp);
lp->rhsp(rp);
//nodep->dumpTree(cout, " repAsvLUp_new: ");
}
void replaceAsvRUp (AstNodeBiop* nodep) {
// BIASV(l,BIASV(CONSTrl,rr)) -> BIASV(CONSTrl,BIASV(l,rr))
AstNode* lp = nodep->lhsp()->unlinkFrBack();
AstNodeBiop* rp = nodep->rhsp()->unlinkFrBack()->castNodeBiop();
AstNode* rlp = rp->lhsp()->unlinkFrBack();
AstNode* rrp = rp->rhsp()->unlinkFrBack();
nodep->lhsp(rlp);
nodep->rhsp(rp);
rp->lhsp(lp);
rp->rhsp(rrp);
//nodep->dumpTree(cout, " repAsvRUp_new: ");
}
void replaceExtend (AstNode* nodep, AstNode* arg0p) {
// -> EXTEND(nodep)
// like a AstExtend{$rhsp}, but we need to set the width correctly from base node
@ -1208,6 +1261,8 @@ private:
TREEOP("AstNodeBiCom{!$lhsp.castConst, $rhsp.castConst}", "swapSides(nodep)");
TREEOP("AstNodeBiComAsv{operandAsvConst(nodep)}", "replaceAsv(nodep)");
TREEOP("AstNodeBiComAsv{operandAsvSame(nodep)}", "replaceAsv(nodep)");
TREEOP("AstNodeBiComAsv{operandAsvLUp(nodep)}", "replaceAsvLUp(nodep)");
TREEOP("AstNodeBiComAsv{operandAsvRUp(nodep)}", "replaceAsvRUp(nodep)");
// v--- *1* as These ops are always first, as we warn before replacing
TREEOP1("AstLt {$lhsp, $rhsp.isZero}", "replaceNumSigned(nodep,0)");
TREEOP1("AstGte {$lhsp, $rhsp.isZero}", "replaceNumSigned(nodep,1)");