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Optimize two-level shift and and/or trees.

This commit is contained in:
Wilson Snyder 2008-11-17 11:36:01 -05:00
parent c5d41ee2d9
commit 2e0f6e2b13
2 changed files with 76 additions and 0 deletions
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2
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@ -5,6 +5,8 @@ indicates the contributor was also the author of the fix; Thanks!
* Verilator 3.68***
*** Optimize two-level shift and and/or trees, +23% on one test.
**** Fix 'bad select range' warning missing some cases, bug43. [Lane Brooks]
* Verilator 3.681 2008/11/12

74
src/V3Const.cpp
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@ -161,6 +161,37 @@ private:
if (rnodep->width() != bnodep->width()) return false;
return rnodep->lhsp()->castConst();
}
static bool operandAndOrSame(AstNode* nodep) {
AstNodeBiop* np = nodep->castNodeBiop();
AstNodeBiop* lp = np->lhsp()->castNodeBiop();
AstNodeBiop* rp = np->rhsp()->castNodeBiop();
return (lp && rp
&& lp->width()==rp->width()
&& lp->type()==rp->type()
&& operandsSame(lp->lhsp(),rp->lhsp()));
}
static bool operandShiftSame(AstNode* nodep) {
AstNodeBiop* np = nodep->castNodeBiop();
{
AstShiftL* lp = np->lhsp()->castShiftL();
AstShiftL* rp = np->rhsp()->castShiftL();
if (lp && rp) {
return (lp->width() == rp->width()
&& lp->lhsp()->width() == rp->lhsp()->width()
&& operandsSame(lp->rhsp(), rp->rhsp()));
}
}
{
AstShiftR* lp = np->lhsp()->castShiftR();
AstShiftR* rp = np->rhsp()->castShiftR();
if (lp && rp) {
return (lp->width() == rp->width()
&& lp->lhsp()->width() == rp->lhsp()->width()
&& operandsSame(lp->rhsp(), rp->rhsp()));
}
}
return false;
}
bool operandHugeShiftL(AstNodeBiop* nodep) {
return (nodep->rhsp()->castConst()
&& nodep->rhsp()->castConst()->toUInt() >= (uint32_t)(nodep->width()));
@ -421,6 +452,42 @@ private:
rp->rhsp(rrp);
//nodep->dumpTree(cout, " repAsvRUp_new: ");
}
void replaceAndOr (AstNodeBiop* nodep) {
// Or(And(CONSTll,lr),And(CONSTrl==ll,rr)) -> And(CONSTll,Or(lr,rr))
// (Or/And may also be reversed)
AstNodeBiop* lp = nodep->lhsp()->unlinkFrBack()->castNodeBiop();
AstNode* llp = lp->lhsp()->unlinkFrBack();
AstNode* lrp = lp->rhsp()->unlinkFrBack();
AstNodeBiop* rp = nodep->rhsp()->unlinkFrBack()->castNodeBiop();
AstNode* rlp = rp->lhsp()->unlinkFrBack();
AstNode* rrp = rp->rhsp()->unlinkFrBack();
nodep->replaceWith(lp);
lp->lhsp(llp);
lp->rhsp(nodep);
nodep->lhsp(lrp);
nodep->rhsp(rrp);
rp->deleteTree();
rlp->deleteTree();
//nodep->dumpTree(cout, " repAndOr_new: ");
}
void replaceShiftSame (AstNodeBiop* nodep) {
// Or(Shift(ll,CONSTlr),Shift(rl,CONSTrr==lr)) -> Shift(Or(ll,rl),CONSTlr)
// (Or/And may also be reversed)
AstNodeBiop* lp = nodep->lhsp()->unlinkFrBack()->castNodeBiop();
AstNode* llp = lp->lhsp()->unlinkFrBack();
AstNode* lrp = lp->rhsp()->unlinkFrBack();
AstNodeBiop* rp = nodep->rhsp()->unlinkFrBack()->castNodeBiop();
AstNode* rlp = rp->lhsp()->unlinkFrBack();
AstNode* rrp = rp->rhsp()->unlinkFrBack();
nodep->replaceWith(lp);
lp->lhsp(nodep);
lp->rhsp(lrp);
nodep->lhsp(llp);
nodep->rhsp(rlp);
rp->deleteTree();
rrp->deleteTree();
//nodep->dumpTree(cout, " repShiftSame_new: ");
}
void replaceExtend (AstNode* nodep, AstNode* arg0p) {
// -> EXTEND(nodep)
// like a AstExtend{$rhsp}, but we need to set the width correctly from base node
@ -1374,6 +1441,13 @@ private:
// CONCAT({const},CONCAT({const},{c})) -> CONCAT((constifiedCONC{const|const},{c}))
TREEOPV("AstConcat{operandConcatMove(nodep)}", "moveConcat(nodep)");
TREEOPV("AstConcat{$lhsp.isZero, $rhsp}", "replaceExtend(nodep, nodep->rhsp())");
// Common two-level operations that can be simplified
TREEOP ("AstAnd {$lhsp.castOr, $rhsp.castOr, operandAndOrSame(nodep)}", "replaceAndOr(nodep)");
TREEOP ("AstOr {$lhsp.castAnd,$rhsp.castAnd,operandAndOrSame(nodep)}", "replaceAndOr(nodep)");
TREEOP ("AstAnd {operandShiftSame(nodep)}", "replaceShiftSame(nodep)");
TREEOP ("AstOr {operandShiftSame(nodep)}", "replaceShiftSame(nodep)");
TREEOP ("AstXor {operandShiftSame(nodep)}", "replaceShiftSame(nodep)");
TREEOP ("AstXnor{operandShiftSame(nodep)}", "replaceShiftSame(nodep)");
// Note can't simplify a extend{extends}, extends{extend}, as the sign bits end up in the wrong places
TREEOPV("AstExtend {$lhsp.castExtend}", "replaceExtend(nodep, nodep->lhsp()->castExtend()->lhsp())");
TREEOPV("AstExtendS{$lhsp.castExtendS}", "replaceExtend(nodep, nodep->lhsp()->castExtendS()->lhsp())");