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Support loop unrolling on width mismatches, bug 333

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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2
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@ -9,6 +9,8 @@ indicates the contributor was also the author of the fix; Thanks!
**** Support $bits(data_type), bug327. [Alex Solomatnikov]
**** Support loop unrolling on width mismatches, bug 333. [Joe Eiler]
**** Accelerate bit-selected inversions.
**** Add error on circular parameter definitions, bug329. [Alex Solomatnikov]

77
src/V3Const.cpp
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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)");

6
src/V3Number.cpp
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@ -555,6 +555,12 @@ bool V3Number::isNeqZero() const {
}
return false;
}
bool V3Number::isBitsZero(int msb, int lsb) const {
for (int i=lsb; i<=msb; i++) {
if (VL_UNLIKELY(!bitIs0(i))) return false;
}
return true;
}
bool V3Number::isEqOne() const {
if (m_value[0]!=1 || m_valueX[0]) return false;
for (int i=1; i<words(); i++) {

1
src/V3Number.h
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@ -138,6 +138,7 @@ public:
bool isAllZ() const { for(int i=0;i<width();i++) { if(!bitIsZ(i)){return false;} } return true; }
bool isEqZero() const;
bool isNeqZero() const;
bool isBitsZero(int msb, int lsb) const;
bool isEqOne() const;
bool isEqAllOnes(int optwidth=0) const;
bool isCaseEq(const V3Number& rhsp) const; // operator==

3
src/V3Unroll.cpp
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@ -187,8 +187,9 @@ private:
UINFO(8," In Numbers: for (v="<<valInit<<"; v<"<<valStop<<"; v=v+"<<valInc<<")\n");
//
if (!m_generate) {
UINFO(8, " ~Iters: "<<((valStop - valInit)/valInc)<<" c="<<unrollCount()<<endl);
int loops = ((valStop - valInit)/valInc);
if (loops < 0) { loops += (1ULL<<constStopp->width()); } // Will roll around
UINFO(8, " ~Iters: "<<loops<<" c="<<unrollCount()<<endl);
if (loops > unrollCount())
return cantUnroll(nodep, "too many iterations");

2
test_regress/t/t_mem_multidim.v
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@ -62,7 +62,7 @@ module t (/*AUTOARG*/
// We never read past bounds, or get unspecific results
// We also never read lowest indexes, as writing outside of range may corrupt them
if (index0>=0+1 && index0<=2 && index1>=1+1 && index1<=3 && index2>=2+1 && index2<=5) begin
if (index0>=0+1 && index0<=2 && index1>=1+1 /*&& index1<=3 CMPCONST*/ && index2>=2+1 && index2<=5) begin
narrow <= ({narrow[6:0], narrow[7]^narrow[0]}
^ {memn[index0][index1][index2]});
wread = memw[index0][index1][index2];

23
test_regress/t/t_unroll_signed.v
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@ -118,6 +118,29 @@ module t (/*AUTOARG*/
if (total != -28) $stop;
end
//===
10: begin
// mostly cover a small index
total = 0;
for (i3=0; i3<3'd7; i3=i3+3'd1) begin
total = total - {29'd0,i3} -1;
dly_to_insure_was_unrolled[i3[0]] <= 0;
end
if (total != -28) $stop;
end
//===
11: begin
// width violation on <, causes extend
total = 0;
for (i3=3'd0; i3<7; i3=i3+1) begin
total = total - {29'd0,i3} -1;
dly_to_insure_was_unrolled[i3[0]] <= 0;
end
if (total != -28) $stop;
end
//===
// width violation on <, causes extend signed
// Unsupported as yet
//===
19: begin
$write("*-* All Finished *-*\n");
$finish;