Roland McGrath | eb9ba47 | 2009-04-14 18:44:45 -0700 | [diff] [blame] | 1 | /* Function return value location for ARM EABI. |
Roland McGrath | 0c16c58 | 2010-01-05 22:59:32 -0800 | [diff] [blame^] | 2 | Copyright (C) 2009-2010 Red Hat, Inc. |
Roland McGrath | eb9ba47 | 2009-04-14 18:44:45 -0700 | [diff] [blame] | 3 | This file is part of Red Hat elfutils. |
| 4 | |
| 5 | Red Hat elfutils is free software; you can redistribute it and/or modify |
| 6 | it under the terms of the GNU General Public License as published by the |
| 7 | Free Software Foundation; version 2 of the License. |
| 8 | |
| 9 | Red Hat elfutils is distributed in the hope that it will be useful, but |
| 10 | WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 12 | General Public License for more details. |
| 13 | |
| 14 | You should have received a copy of the GNU General Public License along |
| 15 | with Red Hat elfutils; if not, write to the Free Software Foundation, |
| 16 | Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA. |
| 17 | |
| 18 | Red Hat elfutils is an included package of the Open Invention Network. |
| 19 | An included package of the Open Invention Network is a package for which |
| 20 | Open Invention Network licensees cross-license their patents. No patent |
| 21 | license is granted, either expressly or impliedly, by designation as an |
| 22 | included package. Should you wish to participate in the Open Invention |
| 23 | Network licensing program, please visit www.openinventionnetwork.com |
| 24 | <http://www.openinventionnetwork.com>. */ |
| 25 | |
| 26 | #ifdef HAVE_CONFIG_H |
| 27 | # include <config.h> |
| 28 | #endif |
| 29 | |
| 30 | #include <assert.h> |
| 31 | #include <dwarf.h> |
| 32 | |
| 33 | #define BACKEND arm_ |
| 34 | #include "libebl_CPU.h" |
| 35 | |
| 36 | |
| 37 | /* r0, or pair r0, r1, or aggregate up to r0-r3. */ |
| 38 | static const Dwarf_Op loc_intreg[] = |
| 39 | { |
| 40 | { .atom = DW_OP_reg0 }, { .atom = DW_OP_piece, .number = 4 }, |
| 41 | { .atom = DW_OP_reg1 }, { .atom = DW_OP_piece, .number = 4 }, |
| 42 | { .atom = DW_OP_reg2 }, { .atom = DW_OP_piece, .number = 4 }, |
| 43 | { .atom = DW_OP_reg3 }, { .atom = DW_OP_piece, .number = 4 }, |
| 44 | }; |
| 45 | #define nloc_intreg 1 |
| 46 | #define nloc_intregs(n) (2 * (n)) |
| 47 | |
| 48 | /* The return value is a structure and is actually stored in stack space |
| 49 | passed in a hidden argument by the caller. But, the compiler |
| 50 | helpfully returns the address of that space in r0. */ |
| 51 | static const Dwarf_Op loc_aggregate[] = |
| 52 | { |
| 53 | { .atom = DW_OP_breg0, .number = 0 } |
| 54 | }; |
| 55 | #define nloc_aggregate 1 |
| 56 | |
| 57 | |
| 58 | int |
| 59 | arm_return_value_location (Dwarf_Die *functypedie, const Dwarf_Op **locp) |
| 60 | { |
| 61 | /* Start with the function's type, and get the DW_AT_type attribute, |
| 62 | which is the type of the return value. */ |
| 63 | |
| 64 | Dwarf_Attribute attr_mem; |
| 65 | Dwarf_Attribute *attr = dwarf_attr_integrate (functypedie, DW_AT_type, |
| 66 | &attr_mem); |
| 67 | if (attr == NULL) |
| 68 | /* The function has no return value, like a `void' function in C. */ |
| 69 | return 0; |
| 70 | |
| 71 | Dwarf_Die die_mem; |
| 72 | Dwarf_Die *typedie = dwarf_formref_die (attr, &die_mem); |
| 73 | int tag = dwarf_tag (typedie); |
| 74 | |
| 75 | /* Follow typedefs and qualifiers to get to the actual type. */ |
| 76 | while (tag == DW_TAG_typedef |
| 77 | || tag == DW_TAG_const_type || tag == DW_TAG_volatile_type |
| 78 | || tag == DW_TAG_restrict_type || tag == DW_TAG_mutable_type) |
| 79 | { |
| 80 | attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem); |
| 81 | typedie = dwarf_formref_die (attr, &die_mem); |
| 82 | tag = dwarf_tag (typedie); |
| 83 | } |
| 84 | |
| 85 | Dwarf_Word size; |
| 86 | switch (tag) |
| 87 | { |
| 88 | case -1: |
| 89 | return -1; |
| 90 | |
| 91 | case DW_TAG_subrange_type: |
| 92 | if (! dwarf_hasattr_integrate (typedie, DW_AT_byte_size)) |
| 93 | { |
| 94 | attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem); |
| 95 | typedie = dwarf_formref_die (attr, &die_mem); |
| 96 | tag = dwarf_tag (typedie); |
| 97 | } |
| 98 | /* Fall through. */ |
| 99 | |
| 100 | case DW_TAG_base_type: |
| 101 | case DW_TAG_enumeration_type: |
| 102 | case DW_TAG_pointer_type: |
| 103 | case DW_TAG_ptr_to_member_type: |
| 104 | if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_byte_size, |
| 105 | &attr_mem), &size) != 0) |
| 106 | { |
| 107 | if (tag == DW_TAG_pointer_type || tag == DW_TAG_ptr_to_member_type) |
| 108 | size = 4; |
| 109 | else |
| 110 | return -1; |
| 111 | } |
| 112 | if (size <= 16) |
| 113 | { |
| 114 | intreg: |
| 115 | *locp = loc_intreg; |
| 116 | return size <= 4 ? nloc_intreg : nloc_intregs ((size + 3) / 4); |
| 117 | } |
| 118 | |
| 119 | aggregate: |
| 120 | *locp = loc_aggregate; |
| 121 | return nloc_aggregate; |
| 122 | |
| 123 | case DW_TAG_structure_type: |
| 124 | case DW_TAG_class_type: |
| 125 | case DW_TAG_union_type: |
| 126 | case DW_TAG_array_type: |
Roland McGrath | 0c16c58 | 2010-01-05 22:59:32 -0800 | [diff] [blame^] | 127 | if (dwarf_aggregate_size (typedie, &size) == 0 |
Roland McGrath | eb9ba47 | 2009-04-14 18:44:45 -0700 | [diff] [blame] | 128 | && size > 0 && size <= 4) |
| 129 | goto intreg; |
| 130 | goto aggregate; |
| 131 | } |
| 132 | |
| 133 | /* XXX We don't have a good way to return specific errors from ebl calls. |
| 134 | This value means we do not understand the type, but it is well-formed |
| 135 | DWARF and might be valid. */ |
| 136 | return -2; |
| 137 | } |