annotate gcc/align.h @ 158:494b0b89df80 default tip

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author Shinji KONO <kono@ie.u-ryukyu.ac.jp>
date Mon, 25 May 2020 18:13:55 +0900
parents 1830386684a0
children
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1 /* Alignment-related classes.
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2 Copyright (C) 2018-2020 Free Software Foundation, Inc.
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3
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4 This file is part of GCC.
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5
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6 GCC is free software; you can redistribute it and/or modify it under
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7 the terms of the GNU General Public License as published by the Free
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8 Software Foundation; either version 3, or (at your option) any later
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9 version.
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10
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11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
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13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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14 for more details.
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15
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16 You should have received a copy of the GNU General Public License
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17 along with GCC; see the file COPYING3. If not see
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18 <http://www.gnu.org/licenses/>. */
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19
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20 /* Align flags tuple with alignment in log form and with a maximum skip. */
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21
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22 struct align_flags_tuple
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23 {
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24 /* Values of the -falign-* flags: how much to align labels in code.
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25 log is "align to 2^log" (so 0 means no alignment).
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26 maxskip is the maximum allowed amount of padding to insert. */
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27 int log;
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28 int maxskip;
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29
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30 /* Normalize filled values so that maxskip is not bigger than 1 << log. */
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31 void normalize ()
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32 {
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33 int n = (1 << log);
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34 if (maxskip > n)
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35 maxskip = n - 1;
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36 }
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37
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38 /* Return original value of an alignment flag. */
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39 int get_value ()
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40 {
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41 return maxskip + 1;
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42 }
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43 };
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44
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45 /* Alignment flags is structure used as value of -align-* options.
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46 It's used in target-dependant code. */
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47
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48 class align_flags
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49 {
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50 public:
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51 /* Default constructor. */
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52 align_flags (int log0 = 0, int maxskip0 = 0, int log1 = 0, int maxskip1 = 0)
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53 {
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54 levels[0].log = log0;
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55 levels[0].maxskip = maxskip0;
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56 levels[1].log = log1;
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57 levels[1].maxskip = maxskip1;
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58 normalize ();
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59 }
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60
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61 /* Normalize both components of align_flags. */
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62 void normalize ()
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63 {
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64 for (unsigned i = 0; i < 2; i++)
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65 levels[i].normalize ();
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66 }
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67
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68 /* Get alignment that is common bigger alignment of alignments F0 and F1. */
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69 static align_flags max (const align_flags f0, const align_flags f1)
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70 {
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71 int log0 = MAX (f0.levels[0].log, f1.levels[0].log);
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72 int maxskip0 = MAX (f0.levels[0].maxskip, f1.levels[0].maxskip);
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73 int log1 = MAX (f0.levels[1].log, f1.levels[1].log);
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74 int maxskip1 = MAX (f0.levels[1].maxskip, f1.levels[1].maxskip);
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75 return align_flags (log0, maxskip0, log1, maxskip1);
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76 }
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77
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78 align_flags_tuple levels[2];
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79 };
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80
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81 /* Define maximum supported code alignment. */
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82 #define MAX_CODE_ALIGN 16
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83 #define MAX_CODE_ALIGN_VALUE (1 << MAX_CODE_ALIGN)