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#include "klee/util/ArrayExprVisitor.h"
#include "klee/Internal/Support/ErrorHandling.h"
#include <algorithm>
using namespace klee;
//------------------------------ HELPER FUNCTIONS ---------------------------//
bool ArrayExprHelper::isReadExprAtOffset(ref<Expr> e, const ReadExpr *base,
ref<Expr> offset) {
const ReadExpr *re = dyn_cast<ReadExpr>(e.get());
if (!re || (re->getWidth() != Expr::Int8))
return false;
return SubExpr::create(re->index, base->index) == offset;
}
ReadExpr *ArrayExprHelper::hasOrderedReads(const ConcatExpr &ce) {
const ReadExpr *base = dyn_cast<ReadExpr>(ce.getKid(0));
// right now, all Reads are byte reads but some
// transformations might change this
if (!base || base->getWidth() != Expr::Int8)
return NULL;
// Get stride expr in proper index width.
Expr::Width idxWidth = base->index->getWidth();
ref<Expr> strideExpr = ConstantExpr::alloc(-1, idxWidth);
ref<Expr> offset = ConstantExpr::create(0, idxWidth);
ref<Expr> e = ce.getKid(1);
// concat chains are unbalanced to the right
while (e->getKind() == Expr::Concat) {
offset = AddExpr::create(offset, strideExpr);
if (!isReadExprAtOffset(e->getKid(0), base, offset))
return NULL;
e = e->getKid(1);
}
offset = AddExpr::create(offset, strideExpr);
if (!isReadExprAtOffset(e, base, offset))
return NULL;
return cast<ReadExpr>(e.get());
}
//--------------------------- INDEX-BASED OPTIMIZATION-----------------------//
ExprVisitor::Action
ConstantArrayExprVisitor::visitConcat(const ConcatExpr &ce) {
ReadExpr *base = ArrayExprHelper::hasOrderedReads(ce);
if (base) {
// It is an interesting ReadExpr if it contains a concrete array
// that is read at a symbolic index
if (base->updates.root->isConstantArray() &&
!isa<ConstantExpr>(base->index)) {
for (const UpdateNode *un = base->updates.head; un; un = un->next) {
if (!isa<ConstantExpr>(un->index) || !isa<ConstantExpr>(un->value)) {
incompatible = true;
return Action::skipChildren();
}
}
IndexCompatibilityExprVisitor compatible;
compatible.visit(base->index);
if (compatible.isCompatible() &&
addedIndexes.find(base->index.get()->hash()) == addedIndexes.end()) {
if (arrays.find(base->updates.root) == arrays.end()) {
arrays.insert(
std::make_pair(base->updates.root, std::vector<ref<Expr> >()));
} else {
// Another possible index to resolve, currently unsupported
incompatible = true;
return Action::skipChildren();
}
arrays.find(base->updates.root)->second.push_back(base->index);
addedIndexes.insert(base->index.get()->hash());
} else if (compatible.hasInnerReads()) {
// This Read has an inner Read, we want to optimize the inner one
// to create a cascading effect during assignment evaluation
return Action::doChildren();
}
return Action::skipChildren();
}
}
return Action::doChildren();
}
ExprVisitor::Action ConstantArrayExprVisitor::visitRead(const ReadExpr &re) {
// It is an interesting ReadExpr if it contains a concrete array
// that is read at a symbolic index
if (re.updates.root->isConstantArray() && !isa<ConstantExpr>(re.index)) {
for (const UpdateNode *un = re.updates.head; un; un = un->next) {
if (!isa<ConstantExpr>(un->index) || !isa<ConstantExpr>(un->value)) {
incompatible = true;
return Action::skipChildren();
}
}
IndexCompatibilityExprVisitor compatible;
compatible.visit(re.index);
if (compatible.isCompatible() &&
addedIndexes.find(re.index.get()->hash()) == addedIndexes.end()) {
if (arrays.find(re.updates.root) == arrays.end()) {
arrays.insert(
std::make_pair(re.updates.root, std::vector<ref<Expr> >()));
} else {
// Another possible index to resolve, currently unsupported
incompatible = true;
return Action::skipChildren();
}
arrays.find(re.updates.root)->second.push_back(re.index);
addedIndexes.insert(re.index.get()->hash());
} else if (compatible.hasInnerReads()) {
// This Read has an inner Read, we want to optimize the inner one
// to create a cascading effect during assignment evaluation
return Action::doChildren();
}
return Action::skipChildren();
} else if (re.updates.root->isSymbolicArray()) {
incompatible = true;
}
return Action::doChildren();
}
ExprVisitor::Action
IndexCompatibilityExprVisitor::visitRead(const ReadExpr &re) {
if (re.updates.head) {
compatible = false;
return Action::skipChildren();
} else if (re.updates.root->isConstantArray() &&
!isa<ConstantExpr>(re.index)) {
compatible = false;
inner = true;
return Action::skipChildren();
}
return Action::doChildren();
}
ExprVisitor::Action IndexCompatibilityExprVisitor::visitURem(const URemExpr &) {
compatible = false;
return Action::skipChildren();
}
ExprVisitor::Action IndexCompatibilityExprVisitor::visitSRem(const SRemExpr &) {
compatible = false;
return Action::skipChildren();
}
ExprVisitor::Action IndexCompatibilityExprVisitor::visitOr(const OrExpr &) {
compatible = false;
return Action::skipChildren();
}
ExprVisitor::Action
IndexTransformationExprVisitor::visitConcat(const ConcatExpr &ce) {
if (ReadExpr *re = dyn_cast<ReadExpr>(ce.getKid(0))) {
if (re->updates.root->hash() == array->hash() && width < ce.getWidth()) {
if (width == Expr::InvalidWidth)
width = ce.getWidth();
}
} else if (ReadExpr *re = dyn_cast<ReadExpr>(ce.getKid(1))) {
if (re->updates.root->hash() == array->hash() && width < ce.getWidth()) {
if (width == Expr::InvalidWidth)
width = ce.getWidth();
}
}
return Action::doChildren();
}
ExprVisitor::Action IndexTransformationExprVisitor::visitMul(const MulExpr &e) {
if (isa<ConstantExpr>(e.getKid(0)))
mul = e.getKid(0);
else if (isa<ConstantExpr>(e.getKid(0)))
mul = e.getKid(1);
return Action::doChildren();
}
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