ExprPPrinter.cpp

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//===-- ExprPPrinter.cpp -   ----------------------------------------------===//
//
//                     The KLEE Symbolic Virtual Machine
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
 
#include "klee/Expr/ExprPPrinter.h"
 
#include "klee/Expr/Constraints.h"
#include "klee/Support/OptionCategories.h"
#include "klee/Support/PrintContext.h"
 
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/raw_ostream.h"
 
#include <map>
#include <vector>
 
using namespace klee;
 
namespace {
 
llvm::cl::opt<bool> PCWidthAsArg(
    "pc-width-as-arg", llvm::cl::init(true),
    llvm::cl::desc(
        "Print the width as a separate argument, as opposed to a prefix "
        "to the operation (default=true)"),
    llvm::cl::cat(klee::ExprCat));
 
llvm::cl::opt<bool>
    PCAllWidths("pc-all-widths", llvm::cl::init(false),
                llvm::cl::desc("Print the width of all operations, including "
                               "booleans (default=false)"),
                llvm::cl::cat(klee::ExprCat));
 
llvm::cl::opt<bool>
    PCPrefixWidth("pc-prefix-width", llvm::cl::init(true),
                  llvm::cl::desc("Print width with 'w' prefix (default=true)"),
                  llvm::cl::cat(klee::ExprCat));
 
llvm::cl::opt<bool>
    PCMultibyteReads("pc-multibyte-reads", llvm::cl::init(true),
                     llvm::cl::desc("Print ReadLSB and ReadMSB expressions "
                                    "when possible (default=true)"),
                     llvm::cl::cat(klee::ExprCat));
 
llvm::cl::opt<bool> PCAllConstWidths(
    "pc-all-const-widths", llvm::cl::init(false),
    llvm::cl::desc(
        "Always print the width of constant expressions (default=false)"),
    llvm::cl::cat(klee::ExprCat));
 
} // namespace
 
class PPrinter : public ExprPPrinter {
public:
  std::set<const Array*> usedArrays;
private:
  std::map<ref<Expr>, unsigned> bindings;
  std::map<const UpdateNode*, unsigned> updateBindings;
  std::set< ref<Expr> > couldPrint, shouldPrint;
  std::set<const UpdateNode*> couldPrintUpdates, shouldPrintUpdates;
  llvm::raw_ostream &os;
  unsigned counter;
  unsigned updateCounter;
  bool hasScan;
  bool forceNoLineBreaks;
  std::string newline;
 
  bool shouldPrintWidth(ref<Expr> e) {
    if (PCAllWidths)
      return true;
    return e->getWidth() != Expr::Bool;
  }
 
  bool isVerySimple(const ref<Expr> &e) { 
    return isa<ConstantExpr>(e) || bindings.find(e)!=bindings.end();
  }
 
  bool isVerySimpleUpdate(const UpdateNode *un) {
    return !un || updateBindings.find(un)!=updateBindings.end();
  }
 
 
  // document me!
  bool isSimple(const ref<Expr> &e) { 
    if (isVerySimple(e)) {
      return true;
    } else if (const ReadExpr *re = dyn_cast<ReadExpr>(e)) {
      return isVerySimple(re->index) &&
             isVerySimpleUpdate(re->updates.head.get());
    } else {
      Expr *ep = e.get();
      for (unsigned i=0; i<ep->getNumKids(); i++)
        if (!isVerySimple(ep->getKid(i)))
          return false;
      return true;
    }
  }
 
  bool hasSimpleKids(const Expr *ep) {
      for (unsigned i=0; i<ep->getNumKids(); i++)
        if (!isSimple(ep->getKid(i)))
          return false;
      return true;
  }
  
  void scanUpdate(const UpdateNode *un) {
    // FIXME: This needs to be non-recursive.
    if (un) {
      if (couldPrintUpdates.insert(un).second) {
        scanUpdate(un->next.get());
        scan1(un->index);
        scan1(un->value);
      } else {
        shouldPrintUpdates.insert(un);
      }
    }
  }
 
  void scan1(const ref<Expr> &e) {
    if (!isa<ConstantExpr>(e)) {
      if (couldPrint.insert(e).second) {
        Expr *ep = e.get();
        for (unsigned i=0; i<ep->getNumKids(); i++)
          scan1(ep->getKid(i));
        if (const ReadExpr *re = dyn_cast<ReadExpr>(e)) {
          usedArrays.insert(re->updates.root);
          scanUpdate(re->updates.head.get());
        }
      } else {
        shouldPrint.insert(e);
      }
    }
  }
 
  void printUpdateList(const UpdateList &updates, PrintContext &PC) {
    auto head = updates.head;
 
    // Special case empty list.
    if (!head) {
      // FIXME: We need to do something (assert, mangle, etc.) so that printing
      // distinct arrays with the same name doesn't fail.
      PC << updates.root->name;
      return;
    }
 
    // FIXME: Explain this breaking policy.
    bool openedList = false, nextShouldBreak = false;
    unsigned outerIndent = PC.pos;
    unsigned middleIndent = 0;
    for (auto un = head; un; un = un->next) {
      // We are done if we hit the cache.
      std::map<const UpdateNode *, unsigned>::iterator it =
          updateBindings.find(un.get());
      if (it!=updateBindings.end()) {
        if (openedList)
          PC << "] @ ";
        PC << "U" << it->second;
        return;
      } else if (!hasScan || shouldPrintUpdates.count(un.get())) {
        if (openedList)
          PC << "] @";
        if (un != head)
          PC.breakLine(outerIndent);
        PC << "U" << updateCounter << ":";
        updateBindings.insert(std::make_pair(un.get(), updateCounter++));
        openedList = nextShouldBreak = false;
     }
    
      if (!openedList) {
        openedList = 1;
        PC << '[';
        middleIndent = PC.pos;
      } else {
        PC << ',';
        printSeparator(PC, !nextShouldBreak, middleIndent);
      }
      //PC << "(=";
      //unsigned innerIndent = PC.pos;
      print(un->index, PC);
      //printSeparator(PC, isSimple(un->index), innerIndent);
      PC << "=";
      print(un->value, PC);
      //PC << ')';
      
      nextShouldBreak = !(isa<ConstantExpr>(un->index) && 
                          isa<ConstantExpr>(un->value));
    }
 
    if (openedList)
      PC << ']';
 
    PC << " @ " << updates.root->name;
  }
 
  void printWidth(PrintContext &PC, ref<Expr> e) {
    if (!shouldPrintWidth(e))
      return;
 
    if (PCWidthAsArg) {
      PC << ' ';
      if (PCPrefixWidth)
        PC << 'w';
    }
 
    PC << e->getWidth();
  }
 
  
  bool isReadExprAtOffset(ref<Expr> e, const ReadExpr *base, ref<Expr> offset) {
    const ReadExpr *re = dyn_cast<ReadExpr>(e.get());
      
    // right now, all Reads are byte reads but some
    // transformations might change this
    if (!re || (re->getWidth() != Expr::Int8))
      return false;
      
    // Check if the index follows the stride. 
    // FIXME: How aggressive should this be simplified. The
    // canonicalizing builder is probably the right choice, but this
    // is yet another area where we would really prefer it to be
    // global or else use static methods.
    return SubExpr::create(re->index, base->index) == offset;
  }
  
  
  const ReadExpr* hasOrderedReads(ref<Expr> e, int stride) {
    assert(e->getKind() == Expr::Concat);
    assert(stride == 1 || stride == -1);
    
    const ReadExpr *base = dyn_cast<ReadExpr>(e->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(stride, idxWidth);
    ref<Expr> offset = ConstantExpr::create(0, idxWidth);
    
    e = e->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;
    
    if (stride == -1)
      return cast<ReadExpr>(e.get());
    else return base;
  }
 
#if 0
  bool hasAllByteReads(const Expr *ep) {
    switch (ep->kind) {
      Expr::Read: {
        // right now, all Reads are byte reads but some
        // transformations might change this
        return ep->getWidth() == Expr::Int8;
      }
      Expr::Concat: {
        for (unsigned i=0; i<ep->getNumKids(); ++i) {
          if (!hashAllByteReads(ep->getKid(i)))
            return false;
        }
      }
    default: return false;
    }
  }
#endif
 
  void printRead(const ReadExpr *re, PrintContext &PC, unsigned indent) {
    print(re->index, PC);
    printSeparator(PC, isVerySimple(re->index), indent);
    printUpdateList(re->updates, PC);
  }
 
  void printExtract(const ExtractExpr *ee, PrintContext &PC, unsigned indent) {
    PC << ee->offset << ' ';
    print(ee->expr, PC);
  }
 
  void printExpr(const Expr *ep, PrintContext &PC, unsigned indent, bool printConstWidth=false) {
    bool simple = hasSimpleKids(ep);
    
    print(ep->getKid(0), PC);
    for (unsigned i=1; i<ep->getNumKids(); i++) {
      printSeparator(PC, simple, indent);
      print(ep->getKid(i), PC, printConstWidth);
    }
  }
 
public:
  PPrinter(llvm::raw_ostream &_os) : os(_os), newline("\n") {
    reset();
  }
 
  void setNewline(const std::string &_newline) {
    newline = _newline;
  }
 
  void setForceNoLineBreaks(bool _forceNoLineBreaks) {
    forceNoLineBreaks = _forceNoLineBreaks;
  }
 
  void reset() {
    counter = 0;
    updateCounter = 0;
    hasScan = false;
    forceNoLineBreaks = false;
    bindings.clear();
    updateBindings.clear();
    couldPrint.clear();
    shouldPrint.clear();
    couldPrintUpdates.clear();
    shouldPrintUpdates.clear();
  }
 
  void scan(const ref<Expr> &e) {
    hasScan = true;
    scan1(e);
  }
 
  void print(const ref<Expr> &e, unsigned level=0) {
    PrintContext PC(os);
    PC.pos = level;
    print(e, PC);
  }
 
  void printConst(const ref<ConstantExpr> &e, PrintContext &PC, 
                  bool printWidth) {
    if (e->getWidth() == Expr::Bool)
      PC << (e->isTrue() ? "true" : "false");
    else {
      if (PCAllConstWidths)
        printWidth = true;
    
      if (printWidth)
        PC << "(w" << e->getWidth() << " ";
 
      if (e->getWidth() <= 64) {
        PC << e->getZExtValue();
      } else {
        std::string S;
        e->toString(S);
        PC << S;
      }
 
      if (printWidth)
        PC << ")";
    }    
  }
 
  void print(const ref<Expr> &e, PrintContext &PC, bool printConstWidth=false) {
    if (ConstantExpr *CE = dyn_cast<ConstantExpr>(e))
      printConst(CE, PC, printConstWidth);
    else {
      std::map<ref<Expr>, unsigned>::iterator it = bindings.find(e);
      if (it!=bindings.end()) {
        PC << 'N' << it->second;
      } else {
        if (!hasScan || shouldPrint.count(e)) {
          PC << 'N' << counter << ':';
          bindings.insert(std::make_pair(e, counter++));
        }
 
        // Detect multibyte reads.
        // FIXME: Hrm. One problem with doing this is that we are
        // masking the sharing of the indices which aren't
        // visible. Need to think if this matters... probably not
        // because if they are offset reads then its either constant,
        // or they are (base + offset) and base will get printed with
        // a declaration.
        if (PCMultibyteReads && e->getKind() == Expr::Concat) {
          const ReadExpr *base = hasOrderedReads(e, -1);
          const bool isLSB = (base != nullptr);
          if (!isLSB)
            base = hasOrderedReads(e, 1);
          if (base) {
            PC << "(Read" << (isLSB ? "LSB" : "MSB");
            printWidth(PC, e);
            PC << ' ';
            printRead(base, PC, PC.pos);
            PC << ')';
            return;
          }
        }
 
        PC << '(' << e->getKind();
        printWidth(PC, e);
        PC << ' ';
 
        // Indent at first argument and dispatch to appropriate print
        // routine for exprs which require special handling.
        unsigned indent = PC.pos;
        if (const ReadExpr *re = dyn_cast<ReadExpr>(e)) {
          printRead(re, PC, indent);
        } else if (const ExtractExpr *ee = dyn_cast<ExtractExpr>(e)) {
          printExtract(ee, PC, indent);
        } else if (e->getKind() == Expr::Concat || e->getKind() == Expr::SExt)
          printExpr(e.get(), PC, indent, true);
        else
          printExpr(e.get(), PC, indent);       
        PC << ")";
      }
    }
  }
 
  /* Public utility functions */
 
  void printSeparator(PrintContext &PC, bool simple, unsigned indent) {
    if (simple || forceNoLineBreaks) {
      PC << ' ';
    } else {
      PC.breakLine(indent);
    }
  }
};
 
ExprPPrinter *klee::ExprPPrinter::create(llvm::raw_ostream &os) {
  return new PPrinter(os);
}
 
void ExprPPrinter::printOne(llvm::raw_ostream &os,
                            const char *message, 
                            const ref<Expr> &e) {
  PPrinter p(os);
  p.scan(e);
 
  // FIXME: Need to figure out what to do here. Probably print as a
  // "forward declaration" with whatever syntax we pick for that.
  PrintContext PC(os);
  PC << message << ": ";
  p.print(e, PC);
  PC.breakLine();
}
 
void ExprPPrinter::printSingleExpr(llvm::raw_ostream &os, const ref<Expr> &e) {
  PPrinter p(os);
  p.scan(e);
 
  // FIXME: Need to figure out what to do here. Probably print as a
  // "forward declaration" with whatever syntax we pick for that.
  PrintContext PC(os);
  p.print(e, PC);
}
 
void ExprPPrinter::printConstraints(llvm::raw_ostream &os,
                                    const ConstraintSet &constraints) {
  printQuery(os, constraints, ConstantExpr::alloc(false, Expr::Bool));
}
 
namespace {
 
struct ArrayPtrsByName {
  bool operator()(const Array *a1, const Array *a2) const {
    return a1->name < a2->name;
  }
};
}
 
void ExprPPrinter::printQuery(llvm::raw_ostream &os,
                              const ConstraintSet &constraints,
                              const ref<Expr> &q,
                              const ref<Expr> *evalExprsBegin,
                              const ref<Expr> *evalExprsEnd,
                              const Array * const *evalArraysBegin,
                              const Array * const *evalArraysEnd,
                              bool printArrayDecls) {
  PPrinter p(os);
 
  for (const auto &constraint : constraints)
    p.scan(constraint);
  p.scan(q);
 
  for (const ref<Expr> *it = evalExprsBegin; it != evalExprsEnd; ++it)
    p.scan(*it);
 
  PrintContext PC(os);
  
  // Print array declarations.
  if (printArrayDecls) {
    for (const Array * const* it = evalArraysBegin; it != evalArraysEnd; ++it)
      p.usedArrays.insert(*it);
    std::vector<const Array *> sortedArray(p.usedArrays.begin(),
                                           p.usedArrays.end());
    std::sort(sortedArray.begin(), sortedArray.end(), ArrayPtrsByName());
    for (std::vector<const Array *>::iterator it = sortedArray.begin(),
                                              ie = sortedArray.end();
         it != ie; ++it) {
      const Array *A = *it;
      PC << "array " << A->name << "[" << A->size << "]"
         << " : w" << A->domain << " -> w" << A->range << " = ";
      if (A->isSymbolicArray()) {
        PC << "symbolic";
      } else {
        PC << "[";
        for (unsigned i = 0, e = A->size; i != e; ++i) {
          if (i)
            PC << " ";
          PC << A->constantValues[i];
        }
        PC << "]";
      }
      PC.breakLine();
    }
  }
 
  PC << "(query [";
  
  // Ident at constraint list;
  unsigned indent = PC.pos;
  for (auto it = constraints.begin(), ie = constraints.end(); it != ie;) {
    p.print(*it, PC);
    ++it;
    if (it != ie)
      PC.breakLine(indent);
  }
  PC << ']';
 
  p.printSeparator(PC, constraints.empty(), indent-1);
  p.print(q, PC);
 
  // Print expressions to obtain values for, if any.
  if (evalExprsBegin != evalExprsEnd) {
    p.printSeparator(PC, q->isFalse(), indent-1);
    PC << '[';
    for (const ref<Expr> *it = evalExprsBegin; it != evalExprsEnd; ++it) {
      p.print(*it, PC, /*printConstWidth*/true);
      if (it + 1 != evalExprsEnd)
        PC.breakLine(indent);
    }
    PC << ']';
  }
 
  // Print arrays to obtain values for, if any.
  if (evalArraysBegin != evalArraysEnd) {
    if (evalExprsBegin == evalExprsEnd)
      PC << " []";
 
    PC.breakLine(indent - 1);
    PC << '[';
    for (const Array * const* it = evalArraysBegin; it != evalArraysEnd; ++it) {
      PC << (*it)->name;
      if (it + 1 != evalArraysEnd)
        PC.breakLine(indent);
    }
    PC << ']';
  }
 
  PC << ')';
  PC.breakLine();
}