gcc/align.h

   1 /* Alignment-related classes.
   2    Copyright (C) 2018-2021 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify it under
   7 the terms of the GNU General Public License as published by the Free
   8 Software Foundation; either version 3, or (at your option) any later
   9 version.
  10
  11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14 for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING3.  If not see
  18 <http://www.gnu.org/licenses/>.  */
  19
  20 /* Align flags tuple with alignment in log form and with a maximum skip.  */
  21
  22 struct align_flags_tuple
  23 {
  24   /* Values of the -falign-* flags: how much to align labels in code.
  25      log is "align to 2^log" (so 0 means no alignment).
  26      maxskip is the maximum allowed amount of padding to insert.  */
  27   int log;
  28   int maxskip;
  29
  30   /* Normalize filled values so that maxskip is not bigger than 1 << log.  */
  31   void normalize ()
  32   {
  33     int n = (1 << log);
  34     if (maxskip > n)
  35       maxskip = n - 1;
  36   }
  37
  38   /* Return original value of an alignment flag.  */
  39   int get_value ()
  40   {
  41     return maxskip + 1;
  42   }
  43 };
  44
  45 /* Alignment flags is structure used as value of -align-* options.
  46    It's used in target-dependant code.  */
  47
  48 class align_flags
  49 {
  50 public:
  51   /* Default constructor.  */
  52   align_flags (int log0 = 0, int maxskip0 = 0, int log1 = 0, int maxskip1 = 0)
  53   {
  54     levels[0].log = log0;
  55     levels[0].maxskip = maxskip0;
  56     levels[1].log = log1;
  57     levels[1].maxskip = maxskip1;
  58     normalize ();
  59   }
  60
  61   /* Normalize both components of align_flags.  */
  62   void normalize ()
  63   {
  64     for (unsigned i = 0; i < 2; i++)
  65       levels[i].normalize ();
  66   }
  67
  68   /* Get alignment that is common bigger alignment of alignments F0 and F1.  */
  69   static align_flags max (const align_flags f0, const align_flags f1)
  70     {
  71       int log0 = MAX (f0.levels[0].log, f1.levels[0].log);
  72       int maxskip0 = MAX (f0.levels[0].maxskip, f1.levels[0].maxskip);
  73       int log1 = MAX (f0.levels[1].log, f1.levels[1].log);
  74       int maxskip1 = MAX (f0.levels[1].maxskip, f1.levels[1].maxskip);
  75       return align_flags (log0, maxskip0, log1, maxskip1);
  76     }
  77
  78   align_flags_tuple levels[2];
  79 };
  80
  81 /* Define maximum supported code alignment.  */
  82 #define MAX_CODE_ALIGN 16
  83 #define MAX_CODE_ALIGN_VALUE (1 << MAX_CODE_ALIGN)