tests/unit-tests/StrengthReduction_Test.cpp

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#include "stp/cpp_interface.h"
#include "stp/Parser/parser.h"
#include "stp/Simplifier/StrengthReduction.h"
#include <gtest/gtest.h>
#include <stdio.h>


  const std::string start_input = R"(
  (set-logic QF_BV)
  (set-info :smt-lib-version 2.0)
  (set-info :category "check")
  (set-info :status sat)

  (declare-fun v0 () (_ BitVec 20))
  (declare-fun v1 () (_ BitVec 20))
  (declare-fun v2 () (_ BitVec 20))
  (declare-fun v3 () (_ BitVec 20))
  (declare-fun v4 () (_ BitVec 20))

  (declare-fun x0 () (_ BitVec 1))

  (declare-fun a () Bool)
  (declare-fun b () Bool)
  (declare-fun c () Bool)

  (push 1)
  )";

struct Context
{
   stp::STPMgr mgr;
   SimplifyingNodeFactory snf;
   stp::Cpp_interface interface;
   stp::StrengthReduction sr;
   stp::NodeDomainAnalysis nda;

   Context() :
   snf (*(mgr.hashingNodeFactory), mgr),
   interface(mgr, &snf),
   sr(&snf, &mgr.UserFlags),
   nda(&mgr)
   { 
    mgr.defaultNodeFactory = &snf;
    interface.startup();
    stp::GlobalParserBM = &mgr;
    stp::GlobalParserInterface = &interface;
   }
   
   bool present(const Kind k, const ASTNode& n)
   {
      if (n.GetKind() == k)
        return true;

      for (const auto& c: n)
        if (present(k,c))
          return true;

      return false;
   }

   ASTNode process(std::string input)
   {
      stp::SMT2ScanString((start_input + input).c_str());
      stp::SMT2Parse();
      // TODO assert it was parsed properly.
      smt2lex_destroy();
      ASTNode n = mgr.CreateNode(stp::AND, mgr.GetAsserts());
      std::cerr << "Pre Strength reduction " << n;
      n = sr.topLevel(n, nda);
      std::cerr << "Post Strengthen reduction"<< n;
      return n;
    }
};

// signed comparison converted to unsigned.
TEST(StrengthReduction_Test , __LINE__)
{
  const std::string input = R"(
    (
      assert 
            (bvsgt 
                  ((_ zero_extend 1) v0)  
                  ((_ zero_extend 1) v1) 
            )
    )
    
    )";

  Context c;
  ASTNode n = c.process(input);
  ASSERT_TRUE(c.present(stp::BVGT, n));
}

// signed division converted to unsigned.
TEST(StrengthReduction_Test , __LINE__)
{
  const std::string input = R"(
    (
      assert 
            ( = 
              (bvsdiv 
                    (bvudiv v0 (_ bv3 20))  
                    (bvudiv v1 (_ bv3 20))  
              )
            v2
            )
    )
    
    )";

  Context c;
  ASTNode n = c.process(input);
  ASSERT_FALSE(c.present(stp::SBVDIV, n));
  ASSERT_TRUE(c.present(stp::BVDIV, n));
}

// Signed division is removed
TEST(StrengthReduction_Test , __LINE__)
{
  const std::string input = R"(
    (
      assert 
            ( = 
              (bvsdiv
                    (concat  (_ bv1 1 ) v0)  
                    (concat  (_ bv1 1 ) v1)  
              )
            (concat  (_ bv1 1 ) v2)  
            )
    )
    )";

  Context c;
  ASTNode n = c.process(input);
  ASSERT_FALSE(c.present(stp::SBVDIV, n));
  ASSERT_TRUE(c.present(stp::BVDIV, n));
}


// plus to OR.
TEST(StrengthReduction_Test , __LINE__)
{
  const std::string input = R"(
    (
      assert 
            ( = 
              (bvadd
                    (concat v0 (_ bv0 20))  
                    (concat (_ bv0 20) v1 )  
              )
            (concat v2 v3)
            )
    )
    
    )";

  Context c;
  ASTNode n = c.process(input);
  ASSERT_FALSE(c.present(stp::BVPLUS, n));
}

// Signed shift is converted to normal shift.
TEST(StrengthReduction_Test , __LINE__)
{
  const std::string input = R"(
    (
      assert 
            ( = 
              (bvashr
                    (bvudiv v0 (_ bv3 20))  
                    v1
              )
            v2
            )
    )
    )";

  Context c;
  ASTNode n = c.process(input);
  ASSERT_TRUE(c.present(stp::BVRIGHTSHIFT, n));
}