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Optimizer: Put constants on left side of compares to match other AstBiOps and extend optimizations. No runtime result change intended.

This commit is contained in:
Wilson Snyder 2014-03-09 17:12:52 -04:00
parent 45bbae80e7
commit dce4519995
4 changed files with 40 additions and 31 deletions
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32
src/V3Const.cpp
View File

@ -327,27 +327,27 @@ private:
}
bool operandBiExtendConst(AstNodeBiop* nodep) {
// Loop unrolling likes standalone compares
// EQ(EXTEND(xx{width3}), const{width32}) -> EQ(xx{3},const{3})
// Loop unrolling favors standalone compares
// EQ(const{width32}, EXTEND(xx{width3})) -> EQ(const{3}, xx{3})
// Beware that the constant must have zero bits (+ 1 if signed) or compare
// would be incorrect
AstExtend* extendp = nodep->lhsp()->castExtend();
AstExtend* extendp = nodep->rhsp()->castExtend();
if (!extendp) return false;
AstNode* smallerp = extendp->lhsp();
int subsize = smallerp->width();
AstConst* constp = nodep->rhsp()->castConst();
AstConst* constp = nodep->lhsp()->castConst();
if (!constp) return false;
if (!constp->num().isBitsZero(constp->width()-1, subsize)) return false;
//
if (debug()>=9) nodep->dumpTree(cout,"BI(EXTEND)-in:");
smallerp->unlinkFrBack();
extendp->unlinkFrBack()->deleteTree(); // aka nodep->lhsp.
nodep->lhsp(smallerp);
nodep->rhsp(smallerp);
constp->unlinkFrBack();
V3Number num (constp->fileline(), subsize);
num.opAssign(constp->num());
nodep->rhsp(new AstConst(constp->fileline(), num));
nodep->lhsp(new AstConst(constp->fileline(), num));
constp->deleteTree(); constp=NULL;
if (debug()>=9) nodep->dumpTree(cout,"BI(EXTEND)-ou:");
return true;
@ -1812,6 +1812,14 @@ private:
TREEOP ("AstNodeBiComAsv{operandAsvSame(nodep)}", "replaceAsv(nodep)");
TREEOP ("AstNodeBiComAsv{operandAsvLUp(nodep)}", "replaceAsvLUp(nodep)");
TREEOP ("AstNodeBiComAsv{operandAsvRUp(nodep)}", "replaceAsvRUp(nodep)");
TREEOP ("AstLt {!$lhsp.castConst,$rhsp.castConst}", "AstGt {$rhsp,$lhsp}");
TREEOP ("AstLtS {!$lhsp.castConst,$rhsp.castConst}", "AstGtS {$rhsp,$lhsp}");
TREEOP ("AstLte {!$lhsp.castConst,$rhsp.castConst}", "AstGte {$rhsp,$lhsp}");
TREEOP ("AstLteS {!$lhsp.castConst,$rhsp.castConst}", "AstGteS{$rhsp,$lhsp}");
TREEOP ("AstGt {!$lhsp.castConst,$rhsp.castConst}", "AstLt {$rhsp,$lhsp}");
TREEOP ("AstGtS {!$lhsp.castConst,$rhsp.castConst}", "AstLtS {$rhsp,$lhsp}");
TREEOP ("AstGte {!$lhsp.castConst,$rhsp.castConst}", "AstLte {$rhsp,$lhsp}");
TREEOP ("AstGteS {!$lhsp.castConst,$rhsp.castConst}", "AstLteS{$rhsp,$lhsp}");
// v--- *1* as These ops are always first, as we warn before replacing
TREEOP1("AstLt {$lhsp, $rhsp.isZero}", "replaceNumSigned(nodep,0)");
TREEOP1("AstGte {$lhsp, $rhsp.isZero}", "replaceNumSigned(nodep,1)");
@ -1861,12 +1869,12 @@ private:
TREEOP ("AstShiftR{operandShiftShift(nodep)}", "replaceShiftShift(nodep)");
TREEOP ("AstWordSel{operandWordOOB(nodep)}", "replaceZero(nodep)");
// Compress out EXTENDs to appease loop unroller
TREEOPV("AstEq {$lhsp.castExtend,operandBiExtendConst(nodep)}", "DONE");
TREEOPV("AstNeq {$lhsp.castExtend,operandBiExtendConst(nodep)}", "DONE");
TREEOPV("AstGt {$lhsp.castExtend,operandBiExtendConst(nodep)}", "DONE");
TREEOPV("AstGte {$lhsp.castExtend,operandBiExtendConst(nodep)}", "DONE");
TREEOPV("AstLt {$lhsp.castExtend,operandBiExtendConst(nodep)}", "DONE");
TREEOPV("AstLte {$lhsp.castExtend,operandBiExtendConst(nodep)}", "DONE");
TREEOPV("AstEq {$rhsp.castExtend,operandBiExtendConst(nodep)}", "DONE");
TREEOPV("AstNeq {$rhsp.castExtend,operandBiExtendConst(nodep)}", "DONE");
TREEOPV("AstGt {$rhsp.castExtend,operandBiExtendConst(nodep)}", "DONE");
TREEOPV("AstGte {$rhsp.castExtend,operandBiExtendConst(nodep)}", "DONE");
TREEOPV("AstLt {$rhsp.castExtend,operandBiExtendConst(nodep)}", "DONE");
TREEOPV("AstLte {$rhsp.castExtend,operandBiExtendConst(nodep)}", "DONE");
// Identical operands on both sides
// AstLogAnd/AstLogOr already converted to AstAnd/AstOr for these rules
// AstAdd->ShiftL(#,1) but uncommon

6
src/V3Premit.cpp
View File

@ -225,9 +225,9 @@ private:
constwidthp->dtypeFrom (nodep->rhsp()); // unsigned
AstCond* newp =
new AstCond (nodep->fileline(),
new AstLte (nodep->fileline(),
nodep->rhsp()->cloneTree(false),
constwidthp),
new AstGte (nodep->fileline(),
constwidthp,
nodep->rhsp()->cloneTree(false)),
nodep,
constzerop);
replaceHandle.relink(newp);

12
src/V3Unknown.cpp
View File

@ -342,9 +342,9 @@ private:
V3Number maxlsbnum (nodep->fileline(), nodep->lsbp()->width(), maxlsb);
// See if the condition is constant true
AstNode* condp = new AstLte (nodep->fileline(),
nodep->lsbp()->cloneTree(false),
new AstConst(nodep->fileline(), maxlsbnum));
AstNode* condp = new AstGte (nodep->fileline(),
new AstConst(nodep->fileline(), maxlsbnum),
nodep->lsbp()->cloneTree(false));
// Note below has null backp(); the Edit function knows how to deal with that.
condp = V3Const::constifyEdit(condp);
if (condp->isOne()) {
@ -400,9 +400,9 @@ private:
V3Number widthnum (nodep->fileline(), nodep->bitp()->width(), declElements-1);
// See if the condition is constant true
AstNode* condp = new AstLte (nodep->fileline(),
nodep->bitp()->cloneTree(false),
new AstConst(nodep->fileline(), widthnum));
AstNode* condp = new AstGte (nodep->fileline(),
new AstConst(nodep->fileline(), widthnum),
nodep->bitp()->cloneTree(false));
// Note below has null backp(); the Edit function knows how to deal with that.
condp = V3Const::constifyEdit(condp);
if (condp->isOne()) {

21
src/V3Unroll.cpp
View File

@ -73,6 +73,7 @@ private:
nodep->v3error("Unsupported: Can't unroll generate for; "<<reason);
}
UINFO(3," Can't Unroll: "<<reason<<" :"<<nodep<<endl);
//if (debug()>=9) nodep->dumpTree(cout,"-cant-");
V3Stats::addStatSum(string("Unrolling gave up, ")+reason, 1);
return false;
}
@ -158,20 +159,20 @@ private:
if (!constIncp) return cantUnroll(nodep, "non-constant increment");
if (constIncp->isZero()) return cantUnroll(nodep, "zero increment"); // Or we could loop forever below...
bool lt = condp->castLt() || condp->castLtS();
bool lt = condp->castLt() || condp->castLtS();
bool lte = condp->castLte() || condp->castLteS();
bool gt = condp->castGt() || condp->castGtS();
bool gt = condp->castGt() || condp->castGtS();
bool gte = condp->castGte() || condp->castGteS();
if (!lt && !lte && !gt && !gte)
return cantUnroll(nodep, "condition not <= or <");
AstNodeBiop* condBip = condp->castNodeBiop();
if (!condBip->lhsp()->castVarRef())
return cantUnroll(nodep, "no variable on lhs of condition");
if (condBip->lhsp()->castVarRef()->varp() != m_forVarp
|| condBip->lhsp()->castVarRef()->varScopep() != m_forVscp)
if (!condBip->rhsp()->castVarRef())
return cantUnroll(nodep, "no variable on rhs of condition");
if (condBip->rhsp()->castVarRef()->varp() != m_forVarp
|| condBip->rhsp()->castVarRef()->varScopep() != m_forVscp)
return cantUnroll(nodep, "different variable in condition");
if (m_generate) V3Const::constifyParamsEdit(condBip->rhsp()); // rhsp may change
AstConst* constStopp = condBip->rhsp()->castConst();
if (m_generate) V3Const::constifyParamsEdit(condBip->lhsp()); // rhsp may change
AstConst* constStopp = condBip->lhsp()->castConst();
if (!constStopp) return cantUnroll(nodep, "non-constant final value");
UINFO(8, " Stop expr ok: "<<constStopp<<endl);
//
@ -181,7 +182,7 @@ private:
return cantUnroll(nodep, "init/final/increment too large or four state");
vlsint32_t valInit = constInitp->num().toSInt();
vlsint32_t valStop = constStopp->num().toSInt();
if (lte) valStop++; if (gte) valStop--;
if (gte) valStop++; if (lte) valStop--; // 23 >= a, handle as if 24 > a
vlsint32_t valInc = constIncp->num().toSInt();
if (subtract) valInc = -valInc;
UINFO(8," In Numbers: for (v="<<valInit<<"; v<"<<valStop<<"; v=v+"<<valInc<<")\n");
@ -269,7 +270,7 @@ private:
UINFO(8," Looping "<<loopValue<<endl);
// if loopValue<valStop
V3Number contin (nodep->fileline(), 1);
cmpInstrp->numberOperate(contin, loopValue, numStop);
cmpInstrp->numberOperate(contin, numStop, loopValue);
if (contin.isEqZero()) {
break; // Done with the loop
} else {