Exemplo n.º 1
0
bool
ion::ExtractLinearInequality(MTest *test, BranchDirection direction,
                             LinearSum *plhs, MDefinition **prhs, bool *plessEqual)
{
    if (!test->getOperand(0)->isCompare())
        return false;

    MCompare *compare = test->getOperand(0)->toCompare();

    MDefinition *lhs = compare->getOperand(0);
    MDefinition *rhs = compare->getOperand(1);

    if (compare->specialization() != MIRType_Int32)
        return false;

    JS_ASSERT(lhs->type() == MIRType_Int32);
    JS_ASSERT(rhs->type() == MIRType_Int32);

    JSOp jsop = compare->jsop();
    if (direction == FALSE_BRANCH)
        jsop = analyze::NegateCompareOp(jsop);

    LinearSum lsum = ExtractLinearSum(lhs);
    LinearSum rsum = ExtractLinearSum(rhs);

    if (!SafeSub(lsum.constant, rsum.constant, &lsum.constant))
        return false;

    // Normalize operations to use <= or >=.
    switch (jsop) {
      case JSOP_LE:
        *plessEqual = true;
        break;
      case JSOP_LT:
        /* x < y ==> x + 1 <= y */
        if (!SafeAdd(lsum.constant, 1, &lsum.constant))
            return false;
        *plessEqual = true;
        break;
      case JSOP_GE:
        *plessEqual = false;
        break;
      case JSOP_GT:
        /* x > y ==> x - 1 >= y */
        if (!SafeSub(lsum.constant, 1, &lsum.constant))
            return false;
        *plessEqual = false;
        break;
      default:
        return false;
    }

    *plhs = lsum;
    *prhs = rsum.term;

    return true;
}