286 lines
6.4 KiB
C++
286 lines
6.4 KiB
C++
/* Definitions for simple data type for real numbers.
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Copyright (C) 2002-2023 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 under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 3, or (at your option) any later
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version.
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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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 GCC_SREAL_H
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#define GCC_SREAL_H
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#define SREAL_PART_BITS 31
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#define UINT64_BITS 64
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#define SREAL_MIN_SIG ((int64_t) 1 << (SREAL_PART_BITS - 2))
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#define SREAL_MAX_SIG (((int64_t) 1 << (SREAL_PART_BITS - 1)) - 1)
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#define SREAL_MAX_EXP (INT_MAX / 4)
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#define SREAL_BITS SREAL_PART_BITS
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#define SREAL_SIGN(v) (v < 0 ? -1: 1)
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#define SREAL_ABS(v) (v < 0 ? -v: v)
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struct output_block;
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class lto_input_block;
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/* Structure for holding a simple real number. */
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class sreal
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{
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public:
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/* Construct an uninitialized sreal. */
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sreal () : m_sig (-1), m_exp (-1) {}
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/* Construct a sreal. */
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sreal (int64_t sig, int exp = 0)
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{
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normalize (sig, exp);
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}
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void dump (FILE *) const;
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int64_t to_int () const;
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double to_double () const;
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void stream_out (struct output_block *);
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static sreal stream_in (class lto_input_block *);
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sreal operator+ (const sreal &other) const;
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sreal operator- (const sreal &other) const;
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sreal operator* (const sreal &other) const;
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sreal operator/ (const sreal &other) const;
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bool operator< (const sreal &other) const
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{
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if (m_exp == other.m_exp)
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return m_sig < other.m_sig;
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else
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{
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bool negative = m_sig < 0;
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bool other_negative = other.m_sig < 0;
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if (negative != other_negative)
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return negative > other_negative;
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bool r = m_exp < other.m_exp;
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return negative ? !r : r;
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}
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}
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bool operator== (const sreal &other) const
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{
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return m_exp == other.m_exp && m_sig == other.m_sig;
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}
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sreal operator- () const
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{
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sreal tmp = *this;
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tmp.m_sig *= -1;
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return tmp;
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}
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sreal shift (int s) const
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{
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/* Zero needs no shifting. */
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if (!m_sig)
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return *this;
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gcc_checking_assert (s <= SREAL_MAX_EXP);
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gcc_checking_assert (s >= -SREAL_MAX_EXP);
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/* Overflows/drop to 0 could be handled gracefully, but hopefully we do not
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need to do so. */
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gcc_checking_assert (m_exp + s <= SREAL_MAX_EXP);
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gcc_checking_assert (m_exp + s >= -SREAL_MAX_EXP);
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sreal tmp = *this;
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tmp.m_exp += s;
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return tmp;
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}
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/* Global minimum sreal can hold. */
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inline static sreal min ()
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{
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sreal min;
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/* This never needs normalization. */
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min.m_sig = -SREAL_MAX_SIG;
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min.m_exp = SREAL_MAX_EXP;
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return min;
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}
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/* Global minimum sreal can hold. */
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inline static sreal max ()
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{
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sreal max;
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/* This never needs normalization. */
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max.m_sig = SREAL_MAX_SIG;
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max.m_exp = SREAL_MAX_EXP;
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return max;
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}
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private:
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inline void normalize (int64_t new_sig, signed int new_exp);
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inline void normalize_up (int64_t new_sig, signed int new_exp);
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inline void normalize_down (int64_t new_sig, signed int new_exp);
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void shift_right (int amount);
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static sreal signedless_plus (const sreal &a, const sreal &b, bool negative);
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static sreal signedless_minus (const sreal &a, const sreal &b, bool negative);
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int32_t m_sig; /* Significant. */
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signed int m_exp; /* Exponent. */
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};
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extern void debug (const sreal &ref);
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extern void debug (const sreal *ptr);
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inline sreal &operator+= (sreal &a, const sreal &b)
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{
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return a = a + b;
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}
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inline sreal &operator-= (sreal &a, const sreal &b)
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{
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return a = a - b;
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}
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inline sreal &operator/= (sreal &a, const sreal &b)
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{
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return a = a / b;
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}
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inline sreal &operator*= (sreal &a, const sreal &b)
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{
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return a = a * b;
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}
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inline bool operator!= (const sreal &a, const sreal &b)
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{
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return !(a == b);
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}
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inline bool operator> (const sreal &a, const sreal &b)
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{
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return !(a == b || a < b);
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}
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inline bool operator<= (const sreal &a, const sreal &b)
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{
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return a < b || a == b;
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}
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inline bool operator>= (const sreal &a, const sreal &b)
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{
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return a == b || a > b;
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}
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inline sreal operator<< (const sreal &a, int exp)
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{
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return a.shift (exp);
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}
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inline sreal operator>> (const sreal &a, int exp)
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{
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return a.shift (-exp);
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}
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/* Make significant to be >= SREAL_MIN_SIG.
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Make this separate method so inliner can handle hot path better. */
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inline void
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sreal::normalize_up (int64_t new_sig, signed int new_exp)
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{
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unsigned HOST_WIDE_INT sig = absu_hwi (new_sig);
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int shift = SREAL_PART_BITS - 2 - floor_log2 (sig);
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gcc_checking_assert (shift > 0);
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sig <<= shift;
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new_exp -= shift;
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gcc_checking_assert (sig <= SREAL_MAX_SIG && sig >= SREAL_MIN_SIG);
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/* Check underflow. */
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if (new_exp < -SREAL_MAX_EXP)
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{
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new_exp = -SREAL_MAX_EXP;
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sig = 0;
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}
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m_exp = new_exp;
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if (SREAL_SIGN (new_sig) == -1)
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m_sig = -sig;
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else
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m_sig = sig;
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}
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/* Make significant to be <= SREAL_MAX_SIG.
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Make this separate method so inliner can handle hot path better. */
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inline void
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sreal::normalize_down (int64_t new_sig, signed int new_exp)
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{
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int last_bit;
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unsigned HOST_WIDE_INT sig = absu_hwi (new_sig);
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int shift = floor_log2 (sig) - SREAL_PART_BITS + 2;
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gcc_checking_assert (shift > 0);
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last_bit = (sig >> (shift-1)) & 1;
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sig >>= shift;
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new_exp += shift;
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gcc_checking_assert (sig <= SREAL_MAX_SIG && sig >= SREAL_MIN_SIG);
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/* Round the number. */
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sig += last_bit;
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if (sig > SREAL_MAX_SIG)
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{
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sig >>= 1;
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new_exp++;
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}
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/* Check overflow. */
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if (new_exp > SREAL_MAX_EXP)
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{
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new_exp = SREAL_MAX_EXP;
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sig = SREAL_MAX_SIG;
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}
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m_exp = new_exp;
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if (SREAL_SIGN (new_sig) == -1)
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m_sig = -sig;
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else
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m_sig = sig;
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}
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/* Normalize *this; the hot path. */
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inline void
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sreal::normalize (int64_t new_sig, signed int new_exp)
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{
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unsigned HOST_WIDE_INT sig = absu_hwi (new_sig);
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if (sig == 0)
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{
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m_sig = 0;
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m_exp = -SREAL_MAX_EXP;
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}
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else if (sig > SREAL_MAX_SIG)
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normalize_down (new_sig, new_exp);
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else if (sig < SREAL_MIN_SIG)
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normalize_up (new_sig, new_exp);
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else
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{
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m_sig = new_sig;
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m_exp = new_exp;
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}
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}
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#endif
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