gcc/wide-int-range.h

/* Support routines for range operations on wide ints.
   Copyright (C) 2018-2019 Free Software Foundation, Inc.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.

GCC is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */

#ifndef GCC_WIDE_INT_RANGE_H
#define GCC_WIDE_INT_RANGE_H

extern bool wide_int_range_cross_product (wide_int &res_lb, wide_int &res_ub,
					  enum tree_code code, signop sign,
					  const wide_int &, const wide_int &,
					  const wide_int &, const wide_int &,
					  bool overflow_undefined);
extern bool wide_int_range_mult_wrapping (wide_int &res_lb,
					  wide_int &res_ub,
					  signop sign,
					  unsigned prec,
					  const wide_int &min0_,
					  const wide_int &max0_,
					  const wide_int &min1_,
					  const wide_int &max1_);
extern bool wide_int_range_multiplicative_op (wide_int &res_lb,
					      wide_int &res_ub,
					      enum tree_code code,
					      signop sign,
					      unsigned prec,
					      const wide_int &vr0_lb,
					      const wide_int &vr0_ub,
					      const wide_int &vr1_lb,
					      const wide_int &vr1_ub,
					      bool overflow_undefined);
extern bool wide_int_range_lshift (wide_int &res_lb, wide_int &res_ub,
				   signop sign, unsigned prec,
				   const wide_int &, const wide_int &,
				   const wide_int &, const wide_int &,
				   bool overflow_undefined);
extern void wide_int_range_set_zero_nonzero_bits (signop,
						  const wide_int &lb,
						  const wide_int &ub,
						  wide_int &may_be_nonzero,
						  wide_int &must_be_nonzero);
extern bool wide_int_range_optimize_bit_op (wide_int &res_lb, wide_int &res_ub,
					    enum tree_code code,
					    signop sign,
					    const wide_int &vr0_lb,
					    const wide_int &vr0_ub,
					    const wide_int &vr1_lb,
					    const wide_int &vr1_ub);
extern bool wide_int_range_get_mask_and_bounds (wide_int &mask,
						wide_int &lower_bound,
						wide_int &upper_bound,
						const wide_int &vr0_min,
						const wide_int &vr0_max,
						const wide_int &vr1_min,
						const wide_int &vr1_max);
extern bool wide_int_range_bit_xor (wide_int &wmin, wide_int &wmax,
				    signop sign,
				    unsigned prec,
				    const wide_int &must_be_nonzero0,
				    const wide_int &may_be_nonzero0,
				    const wide_int &must_be_nonzero1,
				    const wide_int &may_be_nonzero1);
extern bool wide_int_range_bit_ior (wide_int &wmin, wide_int &wmax,
				    signop sign,
				    const wide_int &vr0_min,
				    const wide_int &vr0_max,
				    const wide_int &vr1_min,
				    const wide_int &vr1_max,
				    const wide_int &must_be_nonzero0,
				    const wide_int &may_be_nonzero0,
				    const wide_int &must_be_nonzero1,
				    const wide_int &may_be_nonzero1);
extern bool wide_int_range_bit_and (wide_int &wmin, wide_int &wmax,
				    signop sign,
				    unsigned prec,
				    const wide_int &vr0_min,
				    const wide_int &vr0_max,
				    const wide_int &vr1_min,
				    const wide_int &vr1_max,
				    const wide_int &must_be_nonzero0,
				    const wide_int &may_be_nonzero0,
				    const wide_int &must_be_nonzero1,
				    const wide_int &may_be_nonzero1);
extern void wide_int_range_trunc_mod (wide_int &wmin, wide_int &wmax,
				      signop sign,
				      unsigned prec,
				      const wide_int &vr0_min,
				      const wide_int &vr0_max,
				      const wide_int &vr1_min,
				      const wide_int &vr1_max);
extern bool wide_int_range_abs (wide_int &min, wide_int &max,
				signop sign, unsigned prec,
				const wide_int &vr0_min,
				const wide_int &vr0_max,
				bool overflow_undefined);
extern void wide_int_range_absu (wide_int &min, wide_int &max,
				 unsigned prec,
				 const wide_int &vr0_min,
				 const wide_int &vr0_max);
extern bool wide_int_range_convert (wide_int &min, wide_int &max,
				    signop inner_sign,
				    unsigned inner_prec,
				    signop outer_sign,
				    unsigned outer_prec,
				    const wide_int &vr0_min,
				    const wide_int &vr0_max);
extern bool wide_int_range_div (wide_int &wmin, wide_int &wmax,
				enum tree_code code,
				signop sign, unsigned prec,
				const wide_int &dividend_min,
				const wide_int &dividend_max,
				const wide_int &divisor_min,
				const wide_int &divisor_max,
				bool overflow_undefined,
				bool &extra_range_p,
				wide_int &extra_min, wide_int &extra_max);

/* Return TRUE if shifting by range [MIN, MAX] is undefined behavior,
   interpreting MIN and MAX according to SIGN.  */

inline bool
wide_int_range_shift_undefined_p (signop sign, unsigned prec,
				  const wide_int &min, const wide_int &max)
{
  /* ?? Note: The original comment said this only applied to
     RSHIFT_EXPR, but it was being applied to both left and right
     shifts.  */

  /* Shifting by any values outside [0..prec-1], gets undefined
     behavior from the shift operation.  We cannot even trust
     SHIFT_COUNT_TRUNCATED at this stage, because that applies to rtl
     shifts, and the operation at the tree level may be widened.  */
  return wi::lt_p (min, 0, sign) || wi::ge_p (max, prec, sign);
}

/* Calculate MIN/MAX_EXPR of two ranges and store the result in [MIN, MAX].  */

inline bool
wide_int_range_min_max (wide_int &min, wide_int &max,
			tree_code code,
			signop sign, unsigned prec,
			const wide_int &vr0_min, const wide_int &vr0_max,
			const wide_int &vr1_min, const wide_int &vr1_max)
{
  wi::overflow_type overflow;
  wide_int_binop (min, code, vr0_min, vr1_min, sign, &overflow);
  wide_int_binop (max, code, vr0_max, vr1_max, sign, &overflow);
  /* If the new range covers the entire domain, that's really no range
     at all.  */
  if (min == wi::min_value (prec, sign)
      && max == wi::max_value (prec, sign))
    return false;
  return true;
}

/* Return TRUE if 0 is within [WMIN, WMAX].  */

inline bool
wide_int_range_includes_zero_p (const wide_int &wmin, const wide_int &wmax,
				signop sign)
{
  return wi::le_p (wmin, 0, sign) && wi::ge_p (wmax, 0, sign);
}

/* Return TRUE if [WMIN, WMAX] is the singleton 0.  */

inline bool
wide_int_range_zero_p (const wide_int &wmin, const wide_int &wmax,
		       unsigned prec)
{
  return wmin == wmax && wi::eq_p (wmin, wi::zero (prec));
}

#endif /* GCC_WIDE_INT_RANGE_H */