gcc/go/go-backend.c

   1 /* go-backend.c -- Go frontend interface to gcc backend.
   2    Copyright (C) 2010, 2011 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 #include "config.h"
  21 #include "system.h"
  22 #include "coretypes.h"
  23 #include "tm.h"
  24 #include "rtl.h"
  25 #include "tree.h"
  26 #include "tm_p.h"
  27 #include "target.h"
  28
  29 #include "go-c.h"
  30
  31 /* This file holds all the cases where the Go frontend needs
  32    information from gcc's backend.  */
  33
  34 /* Return the alignment in bytes of a value of type T.  */
  35
  36 unsigned int
  37 go_type_alignment (tree t)
  38 {
  39   return TYPE_ALIGN_UNIT (t);
  40 }
  41
  42 /* Return the alignment in bytes of a struct field of type T.  */
  43
  44 unsigned int
  45 go_field_alignment (tree t)
  46 {
  47   unsigned int v;
  48
  49   v = TYPE_ALIGN (t);
  50
  51 #ifdef BIGGEST_FIELD_ALIGNMENT
  52   if (v > BIGGEST_FIELD_ALIGNMENT)
  53     v = BIGGEST_FIELD_ALIGNMENT;
  54 #endif
  55
  56 #ifdef ADJUST_FIELD_ALIGN
  57   {
  58     tree field ATTRIBUTE_UNUSED;
  59     field = build_decl (UNKNOWN_LOCATION, FIELD_DECL, NULL, t);
  60     v = ADJUST_FIELD_ALIGN (field, v);
  61   }
  62 #endif
  63
  64   return v / BITS_PER_UNIT;
  65 }
  66
  67 /* Return the size and alignment of a trampoline.  */
  68
  69 void
  70 go_trampoline_info (unsigned int *size, unsigned int *alignment)
  71 {
  72   *size = TRAMPOLINE_SIZE;
  73   *alignment = TRAMPOLINE_ALIGNMENT;
  74 }
  75
  76 /* This is called by the Go frontend proper if the unsafe package was
  77    imported.  When that happens we can not do type-based alias
  78    analysis.  */
  79
  80 void
  81 go_imported_unsafe (void)
  82 {
  83   flag_strict_aliasing = false;
  84
  85   /* This is a real hack.  init_varasm_once has already grabbed an
  86      alias set, which we don't want when we aren't doing strict
  87      aliasing.  We reinitialize to make it do it again.  This should
  88      be OK in practice since we haven't really done anything yet.  */
  89   init_varasm_once ();
  90
  91   /* Let the backend know that the options have changed.  */
  92   targetm.override_options_after_change ();
  93 }