Home | History | Annotate | Line # | Download | only in gcc
align.h revision 1.1.1.2 
      1 /* Alignment-related classes.
      2    Copyright (C) 2018-2020 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)
     84