ASTNode ArrayTransformer::TransformTerm(const ASTNode& term)
{
assert(TransformMap != NULL);
const Kind k = term.GetKind();
if (!is_Term_kind(k))
FatalError("TransformTerm: Illegal kind: You have input a nonterm:", term,
k);
ASTNodeMap::const_iterator iter;
if ((iter = TransformMap->find(term)) != TransformMap->end())
return iter->second;
ASTNode result;
switch (k)
{
case SYMBOL:
case BVCONST:
{
result = term;
break;
}
case WRITE:
FatalError("TransformTerm: this kind is not supported", term);
break;
case READ:
result = TransformArrayRead(term);
break;
case ITE:
{
ASTNode cond = term[0];
ASTNode thn = term[1];
ASTNode els = term[2];
cond = TransformFormula(cond);
if (ASTTrue == cond)
result = TransformTerm(thn);
else if (ASTFalse == cond)
result = TransformTerm(els);
else
{
thn = TransformTerm(thn);
els = TransformTerm(els);
if (bm->UserFlags.optimize_flag)
result = simp->CreateSimplifiedTermITE(cond, thn, els);
else
result = nf->CreateTerm(ITE, thn.GetValueWidth(), cond, thn, els);
}
assert(result.GetIndexWidth() == term.GetIndexWidth());
break;
}
default:
{
const ASTVec& c = term.GetChildren();
ASTVec::const_iterator it = c.begin();
ASTVec::const_iterator itend = c.end();
const unsigned width = term.GetValueWidth();
const unsigned indexwidth = term.GetIndexWidth();
ASTVec o;
o.reserve(c.size());
for (; it != itend; it++)
{
o.push_back(TransformTerm(*it));
}
if (c != o)
{
result = nf->CreateArrayTerm(k, indexwidth, width, o);
}
else
result = term;
}
break;
}
if (term.Degree() > 0)
(*TransformMap)[term] = result;
if (term.GetValueWidth() != result.GetValueWidth())
FatalError("TransformTerm: "
"result and input terms are of different length",
result);
if (term.GetIndexWidth() != result.GetIndexWidth())
{
std::cerr << "TransformTerm: input term is : " << term << std::endl;
FatalError("TransformTerm: "
"result & input terms have different index length",
result);
}
return result;
}
/* This function transforms Array Reads, Read over Writes, Read over
* ITEs into flattened form.
*
* Transform1: Suppose there are two array reads in the input
* Read(A,i) and Read(A,j) over the same array. Then Read(A,i) is
* replaced with a symbolic constant, say v1, and Read(A,j) is
* replaced with the following ITE:
*
* ITE(i=j,v1,v2)
*
*/
ASTNode ArrayTransformer::TransformArrayRead(const ASTNode& term)
{
assert(TransformMap != NULL);
const unsigned int width = term.GetValueWidth();
if (READ != term.GetKind())
return term;
ASTNodeMap::const_iterator iter;
if ((iter = TransformMap->find(term)) != TransformMap->end())
return iter->second;
//'term' is of the form READ(arrName, readIndex)
const ASTNode& arrName = term[0];
const ASTNode& readIndex = TransformTerm(term[1]);
ASTNode result;
switch (arrName.GetKind())
{
case SYMBOL:
{
/* input is of the form: READ(A, readIndex)
*
* output is of the from: A1, if this is the first READ over A
*
* ITE(previous_readIndex=readIndex,A1,A2)
*
* .....
*/
{
ArrType::const_iterator it;
if ((it = arrayToIndexToRead.find(arrName)) != arrayToIndexToRead.end())
{
std::map<ASTNode, ArrayRead>::const_iterator it2;
if ((it2 = it->second.find(readIndex)) != it->second.end())
{
result = it2->second.ite;
break;
}
}
}
// Make up a new abstract variable. Build symbolic name
// corresponding to array read. The symbolic name has 2
// components: stringname, and a count
ASTNode CurrentSymbol =
bm->CreateFreshVariable(term.GetIndexWidth(), term.GetValueWidth(),
"array_" + std::string(arrName.GetName()));
result = CurrentSymbol;
if (!bm->UserFlags.ackermannisation)
{
// result is a variable here; it is an ite in the
// else-branch
}
else if (bm->UserFlags.isSet("old_ack", "0"))
{
/* oops.
* This version of ack. doesn't do what I thought it did. The STP 0.1
* version of Ack. produces simpler
* expressions. I've put that in the next block. Trevor's thesis
* measures AckITE using this implementation,
* rather than the next one like it should have!!!!
*/
// Full Array transform if we're not doing read refinement.
// list of array-read indices corresponding to arrName, seen while
// traversing the AST tree. we need this list to construct the ITEs
const arrTypeMap& new_read_Indices = arrayToIndexToRead[arrName];
arrTypeMap::const_iterator it2 = new_read_Indices.begin();
arrTypeMap::const_iterator it2end = new_read_Indices.end();
for (; it2 != it2end; it2++)
{
ASTNode cond = simp->CreateSimplifiedEQ(readIndex, it2->first);
if (ASTFalse == cond)
continue;
if (ASTTrue == cond)
{
result = it2->second.ite;
break;
}
result = simp->CreateSimplifiedTermITE(cond, it2->second.ite, result);
}
}
else
{
// Full Array transform if we're not doing read refinement.
// list of array-read indices corresponding to arrName, seen while
// traversing the AST tree. we need this list to construct the ITEs
vector<std::pair<ASTNode, ASTNode>> p = ack_pair[arrName];
vector<std::pair<ASTNode, ASTNode>>::const_reverse_iterator it2 =
p.rbegin();
vector<std::pair<ASTNode, ASTNode>>::const_reverse_iterator it2end =
p.rend();
for (; it2 != it2end; it2++)
{
ASTNode cond = simp->CreateSimplifiedEQ(readIndex, it2->first);
if (ASTFalse == cond)
continue;
if (ASTTrue == cond)
{
result = it2->second;
break;
}
result = simp->CreateSimplifiedTermITE(cond, it2->second, result);
}
ack_pair[arrName].push_back(make_pair(readIndex, CurrentSymbol));
}
assert(arrName.GetType() == ARRAY_TYPE);
arrayToIndexToRead[arrName].insert(
make_pair(readIndex, ArrayRead(result, CurrentSymbol)));
break;
}
case WRITE:
{
/* The input to this case is: READ((WRITE A i val) j)
*
* The output of this case is: ITE( (= i j) val (READ A j))
*/
/* 1. arrName or term[0] is infact a WRITE(A,i,val) expression
*
* 2. term[1] is the read-index j
*
* 3. arrName[0] is the new arrName i.e. A. A can be either a
SYMBOL or a nested WRITE. no other possibility
*
* 4. arrName[1] is the WRITE index i.e. i
*
* 5. arrName[2] is the WRITE value i.e. val (val can inturn
* be an array read)
*/
ASTNode writeIndex = TransformTerm(arrName[1]);
ASTNode writeVal = TransformTerm(arrName[2]);
if (ARRAY_TYPE != arrName[0].GetType())
FatalError("TransformArray: "
"An array write is being attempted on a non-array:",
term);
// if ((SYMBOL == arrName[0].GetKind()
//|| WRITE == arrName[0].GetKind()))
{
ASTNode cond = simp->CreateSimplifiedEQ(writeIndex, readIndex);
assert(BVTypeCheck(cond));
// If the condition is true, it saves iteratively transforming through
// all the (possibly nested) arrays.
if (ASTTrue == cond)
{
result = writeVal;
}
else
{
ASTNode readTerm = nf->CreateTerm(READ, width, arrName[0], readIndex);
assert(BVTypeCheck(readTerm));
// The simplifying node factory may have produced
// something that's not a READ.
ASTNode readPushedIn = TransformTerm(readTerm);
assert(BVTypeCheck(readPushedIn));
result = simp->CreateSimplifiedTermITE(cond, writeVal, readPushedIn);
}
}
// Trevor: I've removed this code because I don't see the advantage in working
// inside out. i.e. transforming read(write(ite(p,A,B),i,j),k), into
// read(ite(p,write(A,i,j),write(B,i,j),k). That is bringing up the ite.
// Without this code it will become: ite(i=k, j, read(ite(p,A,B),k))
#if 0
else if (ITE == arrName[0].GetKind())
{
// pull out the ite from the write // pushes the write
// through.
ASTNode writeTrue =
nf->CreateNode(WRITE, (arrName[0][1]), writeIndex, writeVal);
writeTrue.SetIndexWidth(writeIndex.GetValueWidth());
writeTrue.SetValueWidth(writeVal.GetValueWidth());
assert(ARRAY_TYPE == writeTrue.GetType());
ASTNode writeFalse =
nf->CreateNode(WRITE, (arrName[0][2]), writeIndex, writeVal);
writeFalse.SetIndexWidth(writeIndex.GetValueWidth());
writeFalse.SetValueWidth(writeVal.GetValueWidth());
assert(ARRAY_TYPE == writeFalse.GetType());
result = (writeTrue == writeFalse) ?
writeTrue : simp->CreateSimplifiedTermITE(TransformFormula(arrName[0][0]),
writeTrue, writeFalse);
result.SetIndexWidth(writeIndex.GetValueWidth());
result.SetValueWidth(writeVal.GetValueWidth());
assert(ARRAY_TYPE == result.GetType());
result =
nf->CreateTerm(READ, writeVal.GetValueWidth(),
result, readIndex);
BVTypeCheck(result);
result = TransformArrayRead(result);
}
else
FatalError("TransformArray: Write over bad type.");
#endif
break;
}
case ITE:
{
/* READ((ITE cond thn els) j)
*
* is transformed into
*
* (ITE cond (READ thn j) (READ els j))
*/
// pull out the ite from the read // pushes the read through.
//(ITE cond thn els)
ASTNode cond = arrName[0];
cond = TransformFormula(cond);
const ASTNode& thn = arrName[1];
const ASTNode& els = arrName[2];
//(READ thn j)
ASTNode thnRead = nf->CreateTerm(READ, width, thn, readIndex);
assert(BVTypeCheck(thnRead));
//(READ els j)
ASTNode elsRead = nf->CreateTerm(READ, width, els, readIndex);
assert(BVTypeCheck(elsRead));
/* We try to call TransformTerm only if necessary, because it
* introduces a new symbol for each read. The amount of work we
* need to do later is based on the square of the number of symbols.
*/
if (ASTTrue == cond)
{
result = TransformTerm(thnRead);
}
else if (ASTFalse == cond)
{
result = TransformTerm(elsRead);
}
else
{
thnRead = TransformTerm(thnRead);
elsRead = TransformTerm(elsRead);
//(ITE cond (READ thn j) (READ els j))
result = simp->CreateSimplifiedTermITE(cond, thnRead, elsRead);
}
break;
}
default:
FatalError("TransformArray: "
"The READ is NOT over SYMBOL/WRITE/ITE",
term);
break;
}
ASTNode ArrayTransformer::TransformTerm(const ASTNode& term)
{
assert(TransformMap != NULL);
const Kind k = term.GetKind();
if (!is_Term_kind(k))
FatalError("TransformTerm: Illegal kind: You have input a nonterm:",
term, k);
ASTNodeMap::const_iterator iter;
if ((iter = TransformMap->find(term)) != TransformMap->end())
return iter->second;
ASTNode result;
switch (k)
{
case SYMBOL:
case BVCONST:
{
result = term;
break;
}
case WRITE:
FatalError("TransformTerm: this kind is not supported", term);
break;
case READ:
result = TransformArrayRead(term);
break;
case ITE:
{
ASTNode cond = term[0];
ASTNode thn = term[1];
ASTNode els = term[2];
cond = TransformFormula(cond);
if (ASTTrue == cond)
result = TransformTerm(thn);
else if (ASTFalse == cond)
result = TransformTerm(els);
else
{
thn = TransformTerm(thn);
els = TransformTerm(els);
result = simp->CreateSimplifiedTermITE(cond, thn, els);
}
assert(result.GetIndexWidth() ==term.GetIndexWidth());
break;
}
default:
{
const ASTVec& c = term.GetChildren();
ASTVec::const_iterator it = c.begin();
ASTVec::const_iterator itend = c.end();
const unsigned width = term.GetValueWidth();
const unsigned indexwidth = term.GetIndexWidth();
ASTVec o;
o.reserve(c.size());
for (; it != itend; it++)
{
o.push_back(TransformTerm(*it));
}
if (c!=o)
{
result = nf->CreateArrayTerm(k,indexwidth, width, o);
}
else
result = term;
const Kind k = result.GetKind();
if (BVDIV == k
|| BVMOD == k
|| SBVDIV == k
|| SBVREM == k
|| SBVMOD == k)
{
// I had this as a reference, but that was wrong. Because
// "result" gets over-written in the next block, result[1], may
// get a reference count of zero, so be garbage collected.
const ASTNode bottom = result[1];
if (SBVDIV == result.GetKind()
|| SBVREM == result.GetKind()
|| SBVMOD == result.GetKind())
{
result = TranslateSignedDivModRem(result);
}
if (bm->UserFlags.division_by_zero_returns_one_flag)
{
// This is a difficult rule to introduce in other
// places because it's recursive. i.e. result is
// embedded unchanged inside the result.
unsigned inputValueWidth = result.GetValueWidth();
ASTNode zero = bm->CreateZeroConst(inputValueWidth);
ASTNode one = bm->CreateOneConst(inputValueWidth);
result =
nf->CreateTerm(ITE, inputValueWidth,
nf->CreateNode(EQ, zero, bottom),
one, result);
//return result;
if (bm->UserFlags.optimize_flag)
return simp->SimplifyTerm_TopLevel(result);
else
return result;
}
}
}
break;
}
if (term.Degree() > 0)
(*TransformMap)[term] = result;
if (term.GetValueWidth() != result.GetValueWidth())
FatalError("TransformTerm: "\
"result and input terms are of different length", result);
if (term.GetIndexWidth() != result.GetIndexWidth())
{
cerr << "TransformTerm: input term is : " << term << endl;
FatalError("TransformTerm: "\
"result & input terms have different index length", result);
}
return result;
} //End of TransformTerm