diff options
Diffstat (limited to 'backends/x86_64_retval.c')
| -rw-r--r-- | backends/x86_64_retval.c | 202 |
1 files changed, 202 insertions, 0 deletions
diff --git a/backends/x86_64_retval.c b/backends/x86_64_retval.c new file mode 100644 index 0000000..ba772bb --- /dev/null +++ b/backends/x86_64_retval.c @@ -0,0 +1,202 @@ +/* Function return value location for Linux/x86-64 ABI. + Copyright (C) 2005-2010 Red Hat, Inc. + This file is part of Red Hat elfutils. + + Red Hat elfutils is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by the + Free Software Foundation; version 2 of the License. + + Red Hat elfutils is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + General Public License for more details. + + You should have received a copy of the GNU General Public License along + with Red Hat elfutils; if not, write to the Free Software Foundation, + Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA. + + Red Hat elfutils is an included package of the Open Invention Network. + An included package of the Open Invention Network is a package for which + Open Invention Network licensees cross-license their patents. No patent + license is granted, either expressly or impliedly, by designation as an + included package. Should you wish to participate in the Open Invention + Network licensing program, please visit www.openinventionnetwork.com + <http://www.openinventionnetwork.com>. */ + +#ifdef HAVE_CONFIG_H +# include <config.h> +#endif + +#include <assert.h> +#include <dwarf.h> + +#define BACKEND x86_64_ +#include "libebl_CPU.h" + + +/* %rax, or pair %rax, %rdx. */ +static const Dwarf_Op loc_intreg[] = + { + { .atom = DW_OP_reg0 }, { .atom = DW_OP_piece, .number = 8 }, + { .atom = DW_OP_reg1 }, { .atom = DW_OP_piece, .number = 8 }, + }; +#define nloc_intreg 1 +#define nloc_intregpair 4 + +/* %st(0), or pair %st(0), %st(1). */ +static const Dwarf_Op loc_x87reg[] = + { + { .atom = DW_OP_regx, .number = 33 }, + { .atom = DW_OP_piece, .number = 10 }, + { .atom = DW_OP_regx, .number = 34 }, + { .atom = DW_OP_piece, .number = 10 }, + }; +#define nloc_x87reg 1 +#define nloc_x87regpair 4 + +/* %xmm0, or pair %xmm0, %xmm1. */ +static const Dwarf_Op loc_ssereg[] = + { + { .atom = DW_OP_reg17 }, { .atom = DW_OP_piece, .number = 16 }, + { .atom = DW_OP_reg18 }, { .atom = DW_OP_piece, .number = 16 }, + }; +#define nloc_ssereg 1 +#define nloc_sseregpair 4 + +/* The return value is a structure and is actually stored in stack space + passed in a hidden argument by the caller. But, the compiler + helpfully returns the address of that space in %rax. */ +static const Dwarf_Op loc_aggregate[] = + { + { .atom = DW_OP_breg0, .number = 0 } + }; +#define nloc_aggregate 1 + + +int +x86_64_return_value_location (Dwarf_Die *functypedie, const Dwarf_Op **locp) +{ + /* Start with the function's type, and get the DW_AT_type attribute, + which is the type of the return value. */ + + Dwarf_Attribute attr_mem; + Dwarf_Attribute *attr = dwarf_attr_integrate (functypedie, DW_AT_type, + &attr_mem); + if (attr == NULL) + /* The function has no return value, like a `void' function in C. */ + return 0; + + Dwarf_Die die_mem; + Dwarf_Die *typedie = dwarf_formref_die (attr, &die_mem); + int tag = dwarf_tag (typedie); + + /* Follow typedefs and qualifiers to get to the actual type. */ + while (tag == DW_TAG_typedef + || tag == DW_TAG_const_type || tag == DW_TAG_volatile_type + || tag == DW_TAG_restrict_type || tag == DW_TAG_mutable_type) + { + attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem); + typedie = dwarf_formref_die (attr, &die_mem); + tag = dwarf_tag (typedie); + } + + Dwarf_Word size; + switch (tag) + { + case -1: + return -1; + + case DW_TAG_subrange_type: + if (! dwarf_hasattr_integrate (typedie, DW_AT_byte_size)) + { + attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem); + typedie = dwarf_formref_die (attr, &die_mem); + tag = dwarf_tag (typedie); + } + /* Fall through. */ + + case DW_TAG_base_type: + case DW_TAG_enumeration_type: + case DW_TAG_pointer_type: + case DW_TAG_ptr_to_member_type: + if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_byte_size, + &attr_mem), &size) != 0) + { + if (tag == DW_TAG_pointer_type || tag == DW_TAG_ptr_to_member_type) + size = 8; + else + return -1; + } + if (tag == DW_TAG_base_type) + { + Dwarf_Word encoding; + if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_encoding, + &attr_mem), + &encoding) != 0) + return -1; + + switch (encoding) + { + case DW_ATE_complex_float: + switch (size) + { + case 4 * 2: /* complex float */ + case 8 * 2: /* complex double */ + *locp = loc_ssereg; + return nloc_sseregpair; + case 16 * 2: /* complex long double */ + *locp = loc_x87reg; + return nloc_x87regpair; + } + return -2; + + case DW_ATE_float: + switch (size) + { + case 4: /* float */ + case 8: /* double */ + *locp = loc_ssereg; + return nloc_ssereg; + case 16: /* long double */ + /* XXX distinguish __float128, which is sseregpair?? */ + *locp = loc_x87reg; + return nloc_x87reg; + } + return -2; + } + } + + intreg: + *locp = loc_intreg; + if (size <= 8) + return nloc_intreg; + if (size <= 16) + return nloc_intregpair; + + large: + *locp = loc_aggregate; + return nloc_aggregate; + + case DW_TAG_structure_type: + case DW_TAG_class_type: + case DW_TAG_union_type: + case DW_TAG_array_type: + if (dwarf_aggregate_size (typedie, &size) != 0) + goto large; + if (size > 16) + goto large; + + /* XXX + Must examine the fields in picayune ways to determine the + actual answer. This will be right for small C structs + containing integer types and similarly simple cases. + */ + + goto intreg; + } + + /* XXX We don't have a good way to return specific errors from ebl calls. + This value means we do not understand the type, but it is well-formed + DWARF and might be valid. */ + return -2; +} |