Roland McGrath | e47ab76 | 2005-11-17 03:16:00 +0000 | [diff] [blame] | 1 | /* Function return value location for Linux/i386 ABI. |
| 2 | Copyright (C) 2005 Red Hat, Inc. |
Ulrich Drepper | 361df7d | 2006-04-04 21:38:57 +0000 | [diff] [blame^] | 3 | This file is part of Red Hat elfutils. |
Roland McGrath | e47ab76 | 2005-11-17 03:16:00 +0000 | [diff] [blame] | 4 | |
Ulrich Drepper | 361df7d | 2006-04-04 21:38:57 +0000 | [diff] [blame^] | 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. |
Roland McGrath | e47ab76 | 2005-11-17 03:16:00 +0000 | [diff] [blame] | 8 | |
Ulrich Drepper | 361df7d | 2006-04-04 21:38:57 +0000 | [diff] [blame^] | 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 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>. */ |
Roland McGrath | e47ab76 | 2005-11-17 03:16:00 +0000 | [diff] [blame] | 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 i386_ |
| 34 | #include "libebl_CPU.h" |
| 35 | |
| 36 | |
| 37 | /* %eax, or pair %eax, %edx. */ |
| 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 | }; |
| 43 | #define nloc_intreg 1 |
| 44 | #define nloc_intregpair 4 |
| 45 | |
| 46 | /* %st(0). */ |
| 47 | static const Dwarf_Op loc_fpreg[] = |
| 48 | { |
| 49 | { .atom = DW_OP_reg11 } |
| 50 | }; |
| 51 | #define nloc_fpreg 1 |
| 52 | |
| 53 | /* The return value is a structure and is actually stored in stack space |
| 54 | passed in a hidden argument by the caller. But, the compiler |
| 55 | helpfully returns the address of that space in %eax. */ |
| 56 | static const Dwarf_Op loc_aggregate[] = |
| 57 | { |
| 58 | { .atom = DW_OP_breg0, .number = 0 } |
| 59 | }; |
| 60 | #define nloc_aggregate 1 |
| 61 | |
| 62 | int |
| 63 | i386_return_value_location (Dwarf_Die *functypedie, const Dwarf_Op **locp) |
| 64 | { |
| 65 | /* Start with the function's type, and get the DW_AT_type attribute, |
| 66 | which is the type of the return value. */ |
| 67 | |
| 68 | Dwarf_Attribute attr_mem; |
| 69 | Dwarf_Attribute *attr = dwarf_attr (functypedie, DW_AT_type, &attr_mem); |
| 70 | if (attr == NULL) |
| 71 | /* The function has no return value, like a `void' function in C. */ |
| 72 | return 0; |
| 73 | |
| 74 | Dwarf_Die die_mem; |
| 75 | Dwarf_Die *typedie = dwarf_formref_die (attr, &die_mem); |
| 76 | int tag = dwarf_tag (typedie); |
| 77 | |
| 78 | /* Follow typedefs and qualifiers to get to the actual type. */ |
| 79 | while (tag == DW_TAG_typedef |
| 80 | || tag == DW_TAG_const_type || tag == DW_TAG_volatile_type |
| 81 | || tag == DW_TAG_restrict_type || tag == DW_TAG_mutable_type) |
| 82 | { |
| 83 | attr = dwarf_attr (typedie, DW_AT_type, &attr_mem); |
| 84 | typedie = dwarf_formref_die (attr, &die_mem); |
| 85 | tag = dwarf_tag (typedie); |
| 86 | } |
| 87 | |
| 88 | switch (tag) |
| 89 | { |
| 90 | case -1: |
| 91 | return -1; |
| 92 | |
| 93 | case DW_TAG_subrange_type: |
| 94 | if (! dwarf_hasattr (typedie, DW_AT_byte_size)) |
| 95 | { |
| 96 | attr = dwarf_attr (typedie, DW_AT_type, &attr_mem); |
| 97 | typedie = dwarf_formref_die (attr, &die_mem); |
| 98 | tag = dwarf_tag (typedie); |
| 99 | } |
| 100 | /* Fall through. */ |
| 101 | |
| 102 | case DW_TAG_base_type: |
| 103 | case DW_TAG_enumeration_type: |
| 104 | case DW_TAG_pointer_type: |
| 105 | case DW_TAG_ptr_to_member_type: |
| 106 | { |
| 107 | Dwarf_Word size; |
| 108 | if (dwarf_formudata (dwarf_attr (typedie, DW_AT_byte_size, |
| 109 | &attr_mem), &size) != 0) |
| 110 | { |
| 111 | if (tag == DW_TAG_pointer_type || tag == DW_TAG_ptr_to_member_type) |
| 112 | size = 4; |
| 113 | else |
| 114 | return -1; |
| 115 | } |
| 116 | if (tag == DW_TAG_base_type) |
| 117 | { |
| 118 | Dwarf_Word encoding; |
| 119 | if (dwarf_formudata (dwarf_attr (typedie, DW_AT_encoding, |
| 120 | &attr_mem), &encoding) != 0) |
| 121 | return -1; |
| 122 | if (encoding == DW_ATE_float) |
| 123 | { |
| 124 | if (size > 16) |
| 125 | return -2; |
| 126 | *locp = loc_fpreg; |
| 127 | return nloc_fpreg; |
| 128 | } |
| 129 | } |
| 130 | *locp = loc_intreg; |
| 131 | if (size <= 4) |
| 132 | return nloc_intreg; |
| 133 | if (size <= 8) |
| 134 | return nloc_intregpair; |
| 135 | |
| 136 | /* Else fall through. */ |
| 137 | } |
| 138 | |
| 139 | case DW_TAG_structure_type: |
| 140 | case DW_TAG_class_type: |
| 141 | case DW_TAG_union_type: |
| 142 | case DW_TAG_array_type: |
| 143 | *locp = loc_aggregate; |
| 144 | return nloc_aggregate; |
| 145 | } |
| 146 | |
| 147 | /* XXX We don't have a good way to return specific errors from ebl calls. |
| 148 | This value means we do not understand the type, but it is well-formed |
| 149 | DWARF and might be valid. */ |
| 150 | return -2; |
| 151 | } |