1 /* Function return value location for Linux/PPC ABI. 2 Copyright (C) 2005, 2006, 2007, 2010, 2014 Red Hat, Inc. 3 This file is part of elfutils. 4 5 This file is free software; you can redistribute it and/or modify 6 it under the terms of either 7 8 * the GNU Lesser General Public License as published by the Free 9 Software Foundation; either version 3 of the License, or (at 10 your option) any later version 11 12 or 13 14 * the GNU General Public License as published by the Free 15 Software Foundation; either version 2 of the License, or (at 16 your option) any later version 17 18 or both in parallel, as here. 19 20 elfutils is distributed in the hope that it will be useful, but 21 WITHOUT ANY WARRANTY; without even the implied warranty of 22 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 23 General Public License for more details. 24 25 You should have received copies of the GNU General Public License and 26 the GNU Lesser General Public License along with this program. If 27 not, see <http://www.gnu.org/licenses/>. */ 28 29 #ifdef HAVE_CONFIG_H 30 # include <config.h> 31 #endif 32 33 #include <assert.h> 34 #include <dwarf.h> 35 36 #define BACKEND ppc_ 37 #include "libebl_CPU.h" 38 39 40 /* This is the SVR4 ELF ABI convention, but AIX and Linux do not use it. */ 41 #define SVR4_STRUCT_RETURN 0 42 43 44 /* r3, or pair r3, r4, or quad r3-r6. */ 45 static const Dwarf_Op loc_intreg[] = 46 { 47 { .atom = DW_OP_reg3 }, { .atom = DW_OP_piece, .number = 4 }, 48 { .atom = DW_OP_reg4 }, { .atom = DW_OP_piece, .number = 4 }, 49 { .atom = DW_OP_reg5 }, { .atom = DW_OP_piece, .number = 4 }, 50 { .atom = DW_OP_reg6 }, { .atom = DW_OP_piece, .number = 4 }, 51 }; 52 #define nloc_intreg 1 53 #define nloc_intregpair 4 54 #define nloc_intregquad 8 55 56 /* f1. */ 57 static const Dwarf_Op loc_fpreg[] = 58 { 59 { .atom = DW_OP_regx, .number = 33 } 60 }; 61 #define nloc_fpreg 1 62 63 /* vr2. */ 64 static const Dwarf_Op loc_vmxreg[] = 65 { 66 { .atom = DW_OP_regx, .number = 1124 + 2 } 67 }; 68 #define nloc_vmxreg 1 69 70 /* The return value is a structure and is actually stored in stack space 71 passed in a hidden argument by the caller. But, the compiler 72 helpfully returns the address of that space in r3. */ 73 static const Dwarf_Op loc_aggregate[] = 74 { 75 { .atom = DW_OP_breg3, .number = 0 } 76 }; 77 #define nloc_aggregate 1 78 79 80 /* XXX We should check the SHT_GNU_ATTRIBUTES bits here (or in ppc_init). */ 81 static bool ppc_altivec_abi(void)82 ppc_altivec_abi (void) 83 { 84 return true; 85 } 86 87 int ppc_return_value_location(Dwarf_Die * functypedie,const Dwarf_Op ** locp)88 ppc_return_value_location (Dwarf_Die *functypedie, const Dwarf_Op **locp) 89 { 90 /* Start with the function's type, and get the DW_AT_type attribute, 91 which is the type of the return value. */ 92 Dwarf_Die die_mem, *typedie = &die_mem; 93 int tag = dwarf_peeled_die_type (functypedie, typedie); 94 if (tag <= 0) 95 return tag; 96 97 Dwarf_Word size; 98 switch (tag) 99 { 100 case -1: 101 return -1; 102 103 case DW_TAG_subrange_type: 104 if (! dwarf_hasattr_integrate (typedie, DW_AT_byte_size)) 105 { 106 Dwarf_Attribute attr_mem, *attr; 107 attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem); 108 typedie = dwarf_formref_die (attr, &die_mem); 109 tag = DWARF_TAG_OR_RETURN (typedie); 110 } 111 FALLTHROUGH; 112 113 case DW_TAG_base_type: 114 case DW_TAG_enumeration_type: 115 case DW_TAG_pointer_type: 116 case DW_TAG_ptr_to_member_type: 117 { 118 Dwarf_Attribute attr_mem; 119 if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_byte_size, 120 &attr_mem), &size) != 0) 121 { 122 if (tag == DW_TAG_pointer_type || tag == DW_TAG_ptr_to_member_type) 123 size = 4; 124 else 125 return -1; 126 } 127 } 128 129 if (size <= 8) 130 { 131 if (tag == DW_TAG_base_type) 132 { 133 Dwarf_Attribute attr_mem; 134 Dwarf_Word encoding; 135 if (dwarf_formudata (dwarf_attr_integrate (typedie, 136 DW_AT_encoding, 137 &attr_mem), 138 &encoding) != 0) 139 return -1; 140 if (encoding == DW_ATE_float) 141 { 142 *locp = loc_fpreg; 143 return nloc_fpreg; 144 } 145 } 146 intreg: 147 *locp = loc_intreg; 148 return size <= 4 ? nloc_intreg : nloc_intregpair; 149 } 150 151 aggregate: 152 *locp = loc_aggregate; 153 return nloc_aggregate; 154 155 case DW_TAG_array_type: 156 { 157 Dwarf_Attribute attr_mem; 158 bool is_vector; 159 if (dwarf_formflag (dwarf_attr_integrate (typedie, DW_AT_GNU_vector, 160 &attr_mem), &is_vector) == 0 161 && is_vector 162 && dwarf_aggregate_size (typedie, &size) == 0) 163 switch (size) 164 { 165 case 16: 166 if (ppc_altivec_abi ()) 167 { 168 *locp = loc_vmxreg; 169 return nloc_vmxreg; 170 } 171 *locp = loc_intreg; 172 return nloc_intregquad; 173 } 174 } 175 FALLTHROUGH; 176 177 case DW_TAG_structure_type: 178 case DW_TAG_class_type: 179 case DW_TAG_union_type: 180 if (SVR4_STRUCT_RETURN 181 && dwarf_aggregate_size (typedie, &size) == 0 182 && size > 0 && size <= 8) 183 goto intreg; 184 goto aggregate; 185 } 186 187 /* XXX We don't have a good way to return specific errors from ebl calls. 188 This value means we do not understand the type, but it is well-formed 189 DWARF and might be valid. */ 190 return -2; 191 } 192