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Support loop unrolling on width mismatches, bug 333

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This commit is contained in:
Wilson Snyder
2011-03-12 07:45:04 -05:00
parent 890dab0742
commit 2923893d34
7 changed files with 104 additions and 10 deletions
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src/V3Const.cpp
+69 -8
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@@ -290,13 +290,61 @@ private:
// SEL(EXTEND(any,width,...),(width-1),0) -> ...
// Since select's return unsigned, this is always an extend
AstExtend* extendp = nodep->fromp()->castExtend();
return (m_doV
&& extendp
&& nodep->lsbp()->castConst()
&& nodep->widthp()->castConst()
&& nodep->lsbConst()==0
&& (int)nodep->widthConst()==extendp->lhsp()->width()
);
if (!(m_doV
&& extendp
&& nodep->lsbp()->castConst()
&& nodep->widthp()->castConst()
&& nodep->lsbConst()==0
&& (int)nodep->widthConst()==extendp->lhsp()->width()
)) return false;
replaceWChild(nodep, extendp->lhsp()); nodep=NULL;
return true;
}
bool operandSelBiLower(AstSel* nodep) {
// SEL(ADD(a,b),(width-1),0) -> ADD(SEL(a),SEL(b))
// Add or any operation which doesn't care if we discard top bits
AstNodeBiop* bip = nodep->fromp()->castNodeBiop();
if (!(m_doV
&& bip
&& nodep->lsbp()->castConst()
&& nodep->widthp()->castConst()
&& nodep->lsbConst()==0
)) return false;
if (debug()>=9) nodep->dumpTree(cout,"SEL(BI)-in:");
AstNode* bilhsp = bip->lhsp()->unlinkFrBack();
AstNode* birhsp = bip->rhsp()->unlinkFrBack();
bip->lhsp(new AstSel(nodep->fileline(), bilhsp, 0, nodep->widthConst()));
bip->rhsp(new AstSel(nodep->fileline(), birhsp, 0, nodep->widthConst()));
if (debug()>=9) bip->dumpTree(cout,"SEL(BI)-ou:");
replaceWChild(nodep, bip); nodep=NULL;
return true;
}
bool operandBiExtendConst(AstNodeBiop* nodep) {
// Loop unrolling likes standalone compares
// EQ(EXTEND(xx{width3}), const{width32}) -> EQ(xx{3},const{3})
// Beware that the constant must have zero bits (+ 1 if signed) or compare
// would be incorrect
AstExtend* extendp = nodep->lhsp()->castExtend();
if (!extendp) return false;
AstNode* smallerp = extendp->lhsp();
int subsize = smallerp->width();
AstConst* constp = nodep->rhsp()->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);
constp->unlinkFrBack();
V3Number num (constp->fileline(), subsize);
num.opAssign(constp->num());
nodep->rhsp(new AstConst(constp->fileline(), num));
constp->deleteTree(); constp=NULL;
if (debug()>=9) nodep->dumpTree(cout,"BI(EXTEND)-ou:");
return true;
}
AstNode* afterComment(AstNode* nodep) {
@@ -1716,6 +1764,13 @@ private:
TREEOP ("AstShiftL{operandShiftShift(nodep)}", "replaceShiftShift(nodep)");
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");
// Identical operands on both sides
// AstLogAnd/AstLogOr already converted to AstAnd/AstOr for these rules
// AstAdd->ShiftL(#,1) but uncommon
@@ -1793,9 +1848,15 @@ private:
TREEOPV("AstReplicate{$lhsp, $rhsp.isOne, $lhsp->width()==nodep->width()}", "replaceWLhs(nodep)"); // {1{lhs}}->lhs
// Next rule because AUTOINST puts the width of bits in
// to pins, even when the widths are exactly the same across the hierarchy.
TREEOPV("AstSel{operandSelExtend(nodep)}", "replaceWChild(nodep, nodep->fromp()->castExtend()->lhsp())");
TREEOPV("AstSel{operandSelExtend(nodep)}", "DONE");
TREEOPV("AstSel{operandSelFull(nodep)}", "replaceWChild(nodep, nodep->fromp())");
TREEOPV("AstSel{$fromp.castSel}", "replaceSelSel(nodep)");
TREEOPV("AstSel{$fromp.castAdd, operandSelBiLower(nodep)}", "DONE");
TREEOPV("AstSel{$fromp.castAnd, operandSelBiLower(nodep)}", "DONE");
TREEOPV("AstSel{$fromp.castOr, operandSelBiLower(nodep)}", "DONE");
TREEOPV("AstSel{$fromp.castSub, operandSelBiLower(nodep)}", "DONE");
TREEOPV("AstSel{$fromp.castXnor,operandSelBiLower(nodep)}", "DONE");
TREEOPV("AstSel{$fromp.castXor, operandSelBiLower(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)");