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Associative same variable elimination

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git-svn-id: file://localhost/svn/verilator/trunk/verilator@799 77ca24e4-aefa-0310-84f0-b9a241c72d87
This commit is contained in:
Wilson Snyder
2006-09-28 14:37:28 +00:00
parent 94f0809d33
commit 5c93520b27
9 changed files with 147 additions and 34 deletions
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src/V3Const.cpp
+19 -4
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@@ -70,6 +70,16 @@ private:
if (!rnodep->lhsp()->castConst()) return false;
return true;
}
bool operandAsvSame (AstNode* nodep) {
// BIASV(SAMEa, BIASV(SAMEb,...)) -> BIASV( BIASV(SAMEa,SAMEb), ...)
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 operandsSame(bnodep->lhsp(), rnodep->lhsp());
}
bool operandHugeShiftL(AstNodeBiop* nodep) {
return (nodep->rhsp()->castConst()
&& nodep->rhsp()->castConst()->asInt() >= (uint32_t)(nodep->width()));
@@ -284,8 +294,9 @@ private:
// Keep RHS, remove LHS
replaceWChild(nodep, nodep->rhsp());
}
void replaceAsvConst (AstNodeBiop* nodep) {
void replaceAsv (AstNodeBiop* nodep) {
// BIASV(CONSTa, BIASV(CONSTb, c)) -> BIASV( BIASV_CONSTED(a,b), c)
// BIASV(SAMEa, BIASV(SAMEb, c)) -> BIASV( BIASV(SAMEa,SAMEb), c)
//nodep->dumpTree(cout, " repAsvConst_old: ");
AstNode* ap = nodep->lhsp();
AstNodeBiop* rp = nodep->rhsp()->castNodeBiop();
@@ -299,7 +310,7 @@ private:
nodep->rhsp(cp);
rp->lhsp(ap);
rp->rhsp(bp);
replaceConst(rp);
if (rp->lhsp()->castConst() && rp->rhsp()->castConst()) replaceConst(rp);
//nodep->dumpTree(cout, " repAsvConst_new: ");
}
void replaceExtend (AstNode* nodep, AstNode* arg0p) {
@@ -1017,8 +1028,9 @@ private:
TREEOP("AstNodeCond{$condp.width1, $expr1p.width1, $expr1p.isZero, $expr2p}", "AstAnd{AstNot{$condp}, $expr2p}"); // a?0:b == ~a&b
TREEOP("AstNodeCond{!$condp.width1, operandBoolShift(nodep->condp())}", "replaceBoolShift(nodep->condp())");
// Prefer constants on left, since that often needs a shift, it lets constant red remove the shift
TREEOP("AstNodeBiCom{$lhsp, $rhsp.castConst}", "swapSides(nodep)");
TREEOP("AstNodeBiComAsv{operandAsvConst(nodep)}", "replaceAsvConst(nodep)");
TREEOP("AstNodeBiCom{!$lhsp.castConst, $rhsp.castConst}", "swapSides(nodep)");
TREEOP("AstNodeBiComAsv{operandAsvConst(nodep)}", "replaceAsv(nodep)");
TREEOP("AstNodeBiComAsv{operandAsvSame(nodep)}", "replaceAsv(nodep)");
// v--- *1* as These ops are always first, as we warn before replacing
TREEOP1("AstLt {$lhsp, $rhsp.isZero}", "replaceNumSigned(nodep,0)");
TREEOP1("AstGte {$lhsp, $rhsp.isZero}", "replaceNumSigned(nodep,1)");
@@ -1067,6 +1079,7 @@ private:
// AstLogAnd/AstLogOr already converted to AstAnd/AstOr for these rules
// AstAdd->ShiftL(#,1) but uncommon
TREEOP("AstAnd {operandsSame($lhsp,,$rhsp)}", "replaceWLhs(nodep)");
TREEOP("AstChangeXor{operandsSame($lhsp,,$rhsp)}", "replaceZero(nodep)");
TREEOP("AstDiv {operandsSame($lhsp,,$rhsp)}", "replaceNum(nodep,1)");
TREEOP("AstDivS {operandsSame($lhsp,,$rhsp)}", "replaceNum(nodep,1)");
TREEOP("AstOr {operandsSame($lhsp,,$rhsp)}", "replaceWLhs(nodep)");
@@ -1085,6 +1098,8 @@ private:
TREEOP("AstLteS {operandsSame($lhsp,,$rhsp)}", "replaceNum(nodep,1)");
TREEOP("AstNeq {operandsSame($lhsp,,$rhsp)}", "replaceZero(nodep)");
TREEOP("AstNeqCase{operandsSame($lhsp,,$rhsp)}", "replaceZero(nodep)");
TREEOP("AstLogAnd {operandsSame($lhsp,,$rhsp), $lhsp.width1}", "replaceWLhs(nodep)");
TREEOP("AstLogOr {operandsSame($lhsp,,$rhsp), $lhsp.width1}", "replaceWLhs(nodep)");
///=== Verilog operators
// Comparison against 1'b0/1'b1; must be careful about widths.
// These use Not, so must be Verilog only