1 /* Function return value location for Linux/PPC ABI. 2 Copyright (C) 2005, 2006, 2007, 2010 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 ppc_ 34 #include "libebl_CPU.h" 35 36 37 /* This is the SVR4 ELF ABI convention, but AIX and Linux do not use it. */ 38 #define SVR4_STRUCT_RETURN 0 39 40 41 /* r3, or pair r3, r4, or quad r3-r6. */ 42 static const Dwarf_Op loc_intreg[] = 43 { 44 { .atom = DW_OP_reg3 }, { .atom = DW_OP_piece, .number = 4 }, 45 { .atom = DW_OP_reg4 }, { .atom = DW_OP_piece, .number = 4 }, 46 { .atom = DW_OP_reg5 }, { .atom = DW_OP_piece, .number = 4 }, 47 { .atom = DW_OP_reg6 }, { .atom = DW_OP_piece, .number = 4 }, 48 }; 49 #define nloc_intreg 1 50 #define nloc_intregpair 4 51 #define nloc_intregquad 8 52 53 /* f1. */ 54 static const Dwarf_Op loc_fpreg[] = 55 { 56 { .atom = DW_OP_regx, .number = 33 } 57 }; 58 #define nloc_fpreg 1 59 60 /* vr2. */ 61 static const Dwarf_Op loc_vmxreg[] = 62 { 63 { .atom = DW_OP_regx, .number = 1124 + 2 } 64 }; 65 #define nloc_vmxreg 1 66 67 /* The return value is a structure and is actually stored in stack space 68 passed in a hidden argument by the caller. But, the compiler 69 helpfully returns the address of that space in r3. */ 70 static const Dwarf_Op loc_aggregate[] = 71 { 72 { .atom = DW_OP_breg3, .number = 0 } 73 }; 74 #define nloc_aggregate 1 75 76 77 /* XXX We should check the SHT_GNU_ATTRIBUTES bits here (or in ppc_init). */ 78 static bool 79 ppc_altivec_abi (void) 80 { 81 return true; 82 } 83 84 int 85 ppc_return_value_location (Dwarf_Die *functypedie, const Dwarf_Op **locp) 86 { 87 /* Start with the function's type, and get the DW_AT_type attribute, 88 which is the type of the return value. */ 89 90 Dwarf_Attribute attr_mem; 91 Dwarf_Attribute *attr = dwarf_attr_integrate (functypedie, DW_AT_type, 92 &attr_mem); 93 if (attr == NULL) 94 /* The function has no return value, like a `void' function in C. */ 95 return 0; 96 97 Dwarf_Die die_mem; 98 Dwarf_Die *typedie = dwarf_formref_die (attr, &die_mem); 99 int tag = dwarf_tag (typedie); 100 101 /* Follow typedefs and qualifiers to get to the actual type. */ 102 while (tag == DW_TAG_typedef 103 || tag == DW_TAG_const_type || tag == DW_TAG_volatile_type 104 || tag == DW_TAG_restrict_type || tag == DW_TAG_mutable_type) 105 { 106 attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem); 107 typedie = dwarf_formref_die (attr, &die_mem); 108 tag = dwarf_tag (typedie); 109 } 110 111 Dwarf_Word size; 112 switch (tag) 113 { 114 case -1: 115 return -1; 116 117 case DW_TAG_subrange_type: 118 if (! dwarf_hasattr_integrate (typedie, DW_AT_byte_size)) 119 { 120 attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem); 121 typedie = dwarf_formref_die (attr, &die_mem); 122 tag = dwarf_tag (typedie); 123 } 124 /* Fall through. */ 125 126 case DW_TAG_base_type: 127 case DW_TAG_enumeration_type: 128 case DW_TAG_pointer_type: 129 case DW_TAG_ptr_to_member_type: 130 if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_byte_size, 131 &attr_mem), &size) != 0) 132 { 133 if (tag == DW_TAG_pointer_type || tag == DW_TAG_ptr_to_member_type) 134 size = 4; 135 else 136 return -1; 137 } 138 if (size <= 8) 139 { 140 if (tag == DW_TAG_base_type) 141 { 142 Dwarf_Word encoding; 143 if (dwarf_formudata (dwarf_attr_integrate (typedie, 144 DW_AT_encoding, 145 &attr_mem), 146 &encoding) != 0) 147 return -1; 148 if (encoding == DW_ATE_float) 149 { 150 *locp = loc_fpreg; 151 return nloc_fpreg; 152 } 153 } 154 intreg: 155 *locp = loc_intreg; 156 return size <= 4 ? nloc_intreg : nloc_intregpair; 157 } 158 159 aggregate: 160 *locp = loc_aggregate; 161 return nloc_aggregate; 162 163 case DW_TAG_array_type: 164 { 165 bool is_vector; 166 if (dwarf_formflag (dwarf_attr_integrate (typedie, DW_AT_GNU_vector, 167 &attr_mem), &is_vector) == 0 168 && is_vector 169 && dwarf_aggregate_size (typedie, &size) == 0) 170 switch (size) 171 { 172 case 16: 173 if (ppc_altivec_abi ()) 174 { 175 *locp = loc_vmxreg; 176 return nloc_vmxreg; 177 } 178 *locp = loc_intreg; 179 return nloc_intregquad; 180 } 181 } 182 /* Fall through. */ 183 184 case DW_TAG_structure_type: 185 case DW_TAG_class_type: 186 case DW_TAG_union_type: 187 if (SVR4_STRUCT_RETURN 188 && dwarf_aggregate_size (typedie, &size) == 0 189 && size > 0 && size <= 8) 190 goto intreg; 191 goto aggregate; 192 } 193 194 /* XXX We don't have a good way to return specific errors from ebl calls. 195 This value means we do not understand the type, but it is well-formed 196 DWARF and might be valid. */ 197 return -2; 198 } 199
