471 lines
13 KiB
C++
471 lines
13 KiB
C++
/* Operations with long integers.
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Copyright (C) 2006-2023 Free Software Foundation, Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by the
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Free Software Foundation; either version 3, or (at your option) any
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later version.
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GCC is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING3. If not see
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<http://www.gnu.org/licenses/>. */
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#ifndef DOUBLE_INT_H
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#define DOUBLE_INT_H
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/* A large integer is currently represented as a pair of HOST_WIDE_INTs.
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It therefore represents a number with precision of
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2 * HOST_BITS_PER_WIDE_INT bits (it is however possible that the
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internal representation will change, if numbers with greater precision
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are needed, so the users should not rely on it). The representation does
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not contain any information about signedness of the represented value, so
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it can be used to represent both signed and unsigned numbers. For
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operations where the results depend on signedness (division, comparisons),
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it must be specified separately. For each such operation, there are three
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versions of the function -- double_int_op, that takes an extra UNS argument
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giving the signedness of the values, and double_int_sop and double_int_uop
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that stand for its specializations for signed and unsigned values.
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You may also represent with numbers in smaller precision using double_int.
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You however need to use double_int_ext (that fills in the bits of the
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number over the prescribed precision with zeros or with the sign bit) before
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operations that do not perform arithmetics modulo 2^precision (comparisons,
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division), and possibly before storing the results, if you want to keep
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them in some canonical form). In general, the signedness of double_int_ext
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should match the signedness of the operation.
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??? The components of double_int differ in signedness mostly for
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historical reasons (they replace an older structure used to represent
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numbers with precision higher than HOST_WIDE_INT). It might be less
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confusing to have them both signed or both unsigned. */
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struct double_int
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{
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/* Normally, we would define constructors to create instances.
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Two things prevent us from doing so.
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First, defining a constructor makes the class non-POD in C++03,
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and we certainly want double_int to be a POD.
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Second, the GCC conding conventions prefer explicit conversion,
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and explicit conversion operators are not available until C++11. */
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static double_int from_uhwi (unsigned HOST_WIDE_INT cst);
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static double_int from_shwi (HOST_WIDE_INT cst);
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static double_int from_pair (HOST_WIDE_INT high, unsigned HOST_WIDE_INT low);
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/* Construct from a fuffer of length LEN. BUFFER will be read according
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to byte endianness and word endianness. */
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static double_int from_buffer (const unsigned char *buffer, int len);
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/* No copy assignment operator or destructor to keep the type a POD. */
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/* There are some special value-creation static member functions. */
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static double_int mask (unsigned prec);
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static double_int max_value (unsigned int prec, bool uns);
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static double_int min_value (unsigned int prec, bool uns);
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/* The following functions are mutating operations. */
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double_int &operator ++ (); // prefix
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double_int &operator -- (); // prefix
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double_int &operator *= (double_int);
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double_int &operator += (double_int);
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double_int &operator -= (double_int);
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double_int &operator &= (double_int);
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double_int &operator ^= (double_int);
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double_int &operator |= (double_int);
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/* The following functions are non-mutating operations. */
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/* Conversion functions. */
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HOST_WIDE_INT to_shwi () const;
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unsigned HOST_WIDE_INT to_uhwi () const;
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/* Conversion query functions. */
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bool fits_uhwi () const;
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bool fits_shwi () const;
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bool fits_hwi (bool uns) const;
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/* Attribute query functions. */
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int trailing_zeros () const;
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int popcount () const;
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/* Arithmetic query operations. */
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bool multiple_of (double_int, bool, double_int *) const;
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/* Arithmetic operation functions. */
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/* The following operations perform arithmetics modulo 2^precision, so you
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do not need to call .ext between them, even if you are representing
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numbers with precision less than HOST_BITS_PER_DOUBLE_INT bits. */
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double_int set_bit (unsigned) const;
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double_int mul_with_sign (double_int, bool unsigned_p, bool *overflow) const;
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double_int wide_mul_with_sign (double_int, bool unsigned_p,
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double_int *higher, bool *overflow) const;
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double_int add_with_sign (double_int, bool unsigned_p, bool *overflow) const;
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double_int sub_with_overflow (double_int, bool *overflow) const;
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double_int neg_with_overflow (bool *overflow) const;
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double_int operator * (double_int) const;
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double_int operator + (double_int) const;
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double_int operator - (double_int) const;
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double_int operator - () const;
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double_int operator ~ () const;
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double_int operator & (double_int) const;
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double_int operator | (double_int) const;
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double_int operator ^ (double_int) const;
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double_int and_not (double_int) const;
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double_int lshift (HOST_WIDE_INT count) const;
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double_int lshift (HOST_WIDE_INT count, unsigned int prec, bool arith) const;
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double_int rshift (HOST_WIDE_INT count) const;
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double_int rshift (HOST_WIDE_INT count, unsigned int prec, bool arith) const;
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double_int alshift (HOST_WIDE_INT count, unsigned int prec) const;
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double_int arshift (HOST_WIDE_INT count, unsigned int prec) const;
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double_int llshift (HOST_WIDE_INT count, unsigned int prec) const;
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double_int lrshift (HOST_WIDE_INT count, unsigned int prec) const;
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double_int lrotate (HOST_WIDE_INT count, unsigned int prec) const;
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double_int rrotate (HOST_WIDE_INT count, unsigned int prec) const;
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/* You must ensure that double_int::ext is called on the operands
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of the following operations, if the precision of the numbers
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is less than HOST_BITS_PER_DOUBLE_INT bits. */
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double_int div (double_int, bool, unsigned) const;
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double_int sdiv (double_int, unsigned) const;
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double_int udiv (double_int, unsigned) const;
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double_int mod (double_int, bool, unsigned) const;
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double_int smod (double_int, unsigned) const;
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double_int umod (double_int, unsigned) const;
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double_int divmod_with_overflow (double_int, bool, unsigned,
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double_int *, bool *) const;
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double_int divmod (double_int, bool, unsigned, double_int *) const;
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double_int sdivmod (double_int, unsigned, double_int *) const;
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double_int udivmod (double_int, unsigned, double_int *) const;
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/* Precision control functions. */
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double_int ext (unsigned prec, bool uns) const;
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double_int zext (unsigned prec) const;
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double_int sext (unsigned prec) const;
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/* Comparative functions. */
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bool is_zero () const;
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bool is_one () const;
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bool is_minus_one () const;
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bool is_negative () const;
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int cmp (double_int b, bool uns) const;
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int ucmp (double_int b) const;
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int scmp (double_int b) const;
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bool ult (double_int b) const;
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bool ule (double_int b) const;
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bool ugt (double_int b) const;
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bool slt (double_int b) const;
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bool sle (double_int b) const;
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bool sgt (double_int b) const;
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double_int max (double_int b, bool uns);
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double_int smax (double_int b);
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double_int umax (double_int b);
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double_int min (double_int b, bool uns);
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double_int smin (double_int b);
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double_int umin (double_int b);
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bool operator == (double_int cst2) const;
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bool operator != (double_int cst2) const;
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/* Please migrate away from using these member variables publicly. */
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unsigned HOST_WIDE_INT low;
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HOST_WIDE_INT high;
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};
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#define HOST_BITS_PER_DOUBLE_INT (2 * HOST_BITS_PER_WIDE_INT)
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/* Constructors and conversions. */
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/* Constructs double_int from integer CST. The bits over the precision of
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HOST_WIDE_INT are filled with the sign bit. */
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inline double_int
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double_int::from_shwi (HOST_WIDE_INT cst)
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{
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double_int r;
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r.low = (unsigned HOST_WIDE_INT) cst;
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r.high = cst < 0 ? -1 : 0;
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return r;
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}
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/* Some useful constants. */
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/* FIXME(crowl): Maybe remove after converting callers?
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The problem is that a named constant would not be as optimizable,
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while the functional syntax is more verbose. */
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#define double_int_minus_one (double_int::from_shwi (-1))
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#define double_int_zero (double_int::from_shwi (0))
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#define double_int_one (double_int::from_shwi (1))
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#define double_int_two (double_int::from_shwi (2))
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#define double_int_ten (double_int::from_shwi (10))
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/* Constructs double_int from unsigned integer CST. The bits over the
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precision of HOST_WIDE_INT are filled with zeros. */
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inline double_int
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double_int::from_uhwi (unsigned HOST_WIDE_INT cst)
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{
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double_int r;
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r.low = cst;
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r.high = 0;
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return r;
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}
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inline double_int
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double_int::from_pair (HOST_WIDE_INT high, unsigned HOST_WIDE_INT low)
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{
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double_int r;
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r.low = low;
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r.high = high;
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return r;
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}
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inline double_int &
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double_int::operator ++ ()
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{
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*this += double_int_one;
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return *this;
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}
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inline double_int &
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double_int::operator -- ()
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{
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*this -= double_int_one;
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return *this;
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}
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inline double_int &
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double_int::operator &= (double_int b)
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{
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*this = *this & b;
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return *this;
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}
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inline double_int &
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double_int::operator ^= (double_int b)
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{
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*this = *this ^ b;
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return *this;
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}
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inline double_int &
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double_int::operator |= (double_int b)
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{
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*this = *this | b;
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return *this;
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}
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/* Returns value of CST as a signed number. CST must satisfy
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double_int::fits_signed. */
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inline HOST_WIDE_INT
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double_int::to_shwi () const
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{
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return (HOST_WIDE_INT) low;
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}
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/* Returns value of CST as an unsigned number. CST must satisfy
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double_int::fits_unsigned. */
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inline unsigned HOST_WIDE_INT
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double_int::to_uhwi () const
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{
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return low;
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}
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/* Returns true if CST fits in unsigned HOST_WIDE_INT. */
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inline bool
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double_int::fits_uhwi () const
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{
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return high == 0;
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}
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/* Logical operations. */
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/* Returns ~A. */
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inline double_int
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double_int::operator ~ () const
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{
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double_int result;
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result.low = ~low;
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result.high = ~high;
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return result;
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}
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/* Returns A | B. */
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inline double_int
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double_int::operator | (double_int b) const
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{
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double_int result;
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result.low = low | b.low;
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result.high = high | b.high;
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return result;
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}
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/* Returns A & B. */
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inline double_int
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double_int::operator & (double_int b) const
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{
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double_int result;
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result.low = low & b.low;
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result.high = high & b.high;
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return result;
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}
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/* Returns A & ~B. */
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inline double_int
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double_int::and_not (double_int b) const
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{
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double_int result;
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result.low = low & ~b.low;
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result.high = high & ~b.high;
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return result;
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}
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/* Returns A ^ B. */
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inline double_int
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double_int::operator ^ (double_int b) const
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{
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double_int result;
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result.low = low ^ b.low;
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result.high = high ^ b.high;
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return result;
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}
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void dump_double_int (FILE *, double_int, bool);
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#define ALL_ONES HOST_WIDE_INT_M1U
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/* The operands of the following comparison functions must be processed
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with double_int_ext, if their precision is less than
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HOST_BITS_PER_DOUBLE_INT bits. */
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/* Returns true if CST is zero. */
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inline bool
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double_int::is_zero () const
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{
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return low == 0 && high == 0;
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}
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/* Returns true if CST is one. */
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inline bool
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double_int::is_one () const
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{
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return low == 1 && high == 0;
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}
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/* Returns true if CST is minus one. */
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inline bool
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double_int::is_minus_one () const
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{
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return low == ALL_ONES && high == -1;
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}
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/* Returns true if CST is negative. */
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inline bool
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double_int::is_negative () const
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{
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return high < 0;
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}
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/* Returns true if CST1 == CST2. */
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inline bool
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double_int::operator == (double_int cst2) const
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{
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return low == cst2.low && high == cst2.high;
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}
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/* Returns true if CST1 != CST2. */
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inline bool
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double_int::operator != (double_int cst2) const
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{
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return low != cst2.low || high != cst2.high;
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}
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/* Return number of set bits of CST. */
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inline int
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double_int::popcount () const
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{
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return popcount_hwi (high) + popcount_hwi (low);
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}
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#ifndef GENERATOR_FILE
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/* Conversion to and from GMP integer representations. */
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void mpz_set_double_int (mpz_t, double_int, bool);
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double_int mpz_get_double_int (const_tree, mpz_t, bool);
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#endif
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namespace wi
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{
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template <>
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struct int_traits <double_int>
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{
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static const enum precision_type precision_type = CONST_PRECISION;
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static const bool host_dependent_precision = true;
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static const unsigned int precision = HOST_BITS_PER_DOUBLE_INT;
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static unsigned int get_precision (const double_int &);
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static wi::storage_ref decompose (HOST_WIDE_INT *, unsigned int,
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const double_int &);
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};
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}
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inline unsigned int
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wi::int_traits <double_int>::get_precision (const double_int &)
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{
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return precision;
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}
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inline wi::storage_ref
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wi::int_traits <double_int>::decompose (HOST_WIDE_INT *scratch, unsigned int p,
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const double_int &x)
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{
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gcc_checking_assert (precision == p);
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scratch[0] = x.low;
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if ((x.high == 0 && scratch[0] >= 0) || (x.high == -1 && scratch[0] < 0))
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return wi::storage_ref (scratch, 1, precision);
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scratch[1] = x.high;
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return wi::storage_ref (scratch, 2, precision);
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}
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#endif /* DOUBLE_INT_H */
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