1 /* Function return value location for Alpha ELF ABI. 2 Copyright (C) 2005, 2007 Red Hat, Inc. 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 alpha_ 34 #include "libebl_CPU.h" 35 36 37 /* $0. */ 38 static const Dwarf_Op loc_intreg[] = 39 { 40 { .atom = DW_OP_reg0 } 41 }; 42 #define nloc_intreg 1 43 44 /* $f0, or pair $f0, $f1. */ 45 static const Dwarf_Op loc_fpreg[] = 46 { 47 { .atom = DW_OP_regx, .number = 32 }, { .atom = DW_OP_piece, .number = 4 }, 48 { .atom = DW_OP_regx, .number = 33 }, { .atom = DW_OP_piece, .number = 4 }, 49 }; 50 #define nloc_fpreg 1 51 #define nloc_fpregpair 4 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 $0. */ 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 alpha_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_integrate (functypedie, DW_AT_type, 70 &attr_mem); 71 if (attr == NULL) 72 /* The function has no return value, like a `void' function in C. */ 73 return 0; 74 75 Dwarf_Die die_mem; 76 Dwarf_Die *typedie = dwarf_formref_die (attr, &die_mem); 77 int tag = dwarf_tag (typedie); 78 79 /* Follow typedefs and qualifiers to get to the actual type. */ 80 while (tag == DW_TAG_typedef 81 || tag == DW_TAG_const_type || tag == DW_TAG_volatile_type 82 || tag == DW_TAG_restrict_type || tag == DW_TAG_mutable_type) 83 { 84 attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem); 85 typedie = dwarf_formref_die (attr, &die_mem); 86 tag = dwarf_tag (typedie); 87 } 88 89 switch (tag) 90 { 91 case -1: 92 return -1; 93 94 case DW_TAG_subrange_type: 95 if (! dwarf_hasattr_integrate (typedie, DW_AT_byte_size)) 96 { 97 attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem); 98 typedie = dwarf_formref_die (attr, &die_mem); 99 tag = dwarf_tag (typedie); 100 } 101 /* Fall through. */ 102 103 case DW_TAG_base_type: 104 case DW_TAG_enumeration_type: 105 case DW_TAG_pointer_type: 106 case DW_TAG_ptr_to_member_type: 107 { 108 Dwarf_Word size; 109 if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_byte_size, 110 &attr_mem), &size) != 0) 111 { 112 if (tag == DW_TAG_pointer_type || tag == DW_TAG_ptr_to_member_type) 113 size = 8; 114 else 115 return -1; 116 } 117 if (tag == DW_TAG_base_type) 118 { 119 Dwarf_Word encoding; 120 if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_encoding, 121 &attr_mem), 122 &encoding) != 0) 123 return -1; 124 125 *locp = loc_fpreg; 126 if (encoding == DW_ATE_float) 127 { 128 if (size <= 8) 129 return nloc_fpreg; 130 goto aggregate; 131 } 132 if (encoding == DW_ATE_complex_float) 133 { 134 if (size <= 8 * 2) 135 return nloc_fpregpair; 136 goto aggregate; 137 } 138 } 139 if (size <= 8) 140 { 141 *locp = loc_intreg; 142 return nloc_intreg; 143 } 144 } 145 146 /* Else fall through. */ 147 148 case DW_TAG_structure_type: 149 case DW_TAG_class_type: 150 case DW_TAG_union_type: 151 case DW_TAG_string_type: 152 case DW_TAG_array_type: 153 aggregate: 154 *locp = loc_aggregate; 155 return nloc_aggregate; 156 } 157 158 /* XXX We don't have a good way to return specific errors from ebl calls. 159 This value means we do not understand the type, but it is well-formed 160 DWARF and might be valid. */ 161 return -2; 162 } 163
