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Diffstat (limited to 'backends/aarch64_retval.c')
| -rw-r--r-- | backends/aarch64_retval.c | 375 |
1 files changed, 375 insertions, 0 deletions
diff --git a/backends/aarch64_retval.c b/backends/aarch64_retval.c new file mode 100644 index 00000000..0ed7d561 --- /dev/null +++ b/backends/aarch64_retval.c @@ -0,0 +1,375 @@ +/* Function return value location for Linux/AArch64 ABI. + Copyright (C) 2013 Red Hat, Inc. + This file is part of elfutils. + + This file is free software; you can redistribute it and/or modify + it under the terms of either + + * the GNU Lesser General Public License as published by the Free + Software Foundation; either version 3 of the License, or (at + your option) any later version + + or + + * the GNU General Public License as published by the Free + Software Foundation; either version 2 of the License, or (at + your option) any later version + + or both in parallel, as here. + + 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 copies of the GNU General Public License and + the GNU Lesser General Public License along with this program. If + not, see <http://www.gnu.org/licenses/>. */ + +#ifdef HAVE_CONFIG_H +# include <config.h> +#endif + +#include <stdio.h> +#include <inttypes.h> + +#include <assert.h> +#include <dwarf.h> + +#define BACKEND aarch64_ +#include "libebl_CPU.h" + +static int +skip_until (Dwarf_Die *child, int tag) +{ + int i; + while (DWARF_TAG_OR_RETURN (child) != tag) + if ((i = dwarf_siblingof (child, child)) != 0) + /* If there are no members, then this is not a HFA. Errors + are propagated. */ + return i; + return 0; +} + +static int +dwarf_bytesize_aux (Dwarf_Die *die, Dwarf_Word *sizep) +{ + int bits; + if (((bits = 8 * dwarf_bytesize (die)) < 0 + && (bits = dwarf_bitsize (die)) < 0) + || bits % 8 != 0) + return -1; + + *sizep = bits / 8; + return 0; +} + +/* HFA (Homogeneous Floating-point Aggregate) is an aggregate type + whose members are all of the same floating-point type, which is + then base type of this HFA. Instead of being floating-point types + directly, members can instead themselves be HFA. Such HFA fields + are handled as if their type were HFA base type. + + This function returns 0 if TYPEDIE is HFA, 1 if it is not, or -1 if + there were errors. In the former case, *SIZEP contains byte size + of the base type (e.g. 8 for IEEE double). *COUNT is set to the + number of leaf members of the HFA. */ +static int hfa_type (Dwarf_Die *ftypedie, int tag, + Dwarf_Word *sizep, Dwarf_Word *countp); + +/* Return 0 if MEMBDIE refers to a member with a floating-point or HFA + type, or 1 if it's not. Return -1 for errors. The meaning of the + remaining arguments is as documented at hfa_type. */ +static int +member_is_fp (Dwarf_Die *membdie, Dwarf_Word *sizep, Dwarf_Word *countp) +{ + Dwarf_Die typedie; + int tag = dwarf_peeled_die_type (membdie, &typedie); + switch (tag) + { + case DW_TAG_base_type:; + Dwarf_Word encoding; + Dwarf_Attribute attr_mem; + if (dwarf_attr_integrate (&typedie, DW_AT_encoding, &attr_mem) == NULL + || dwarf_formudata (&attr_mem, &encoding) != 0) + return -1; + + switch (encoding) + { + case DW_ATE_complex_float: + *countp = 2; + break; + + case DW_ATE_float: + *countp = 1; + break; + + default: + return 1; + } + + if (dwarf_bytesize_aux (&typedie, sizep) < 0) + return -1; + + *sizep /= *countp; + return 0; + + case DW_TAG_structure_type: + case DW_TAG_union_type: + case DW_TAG_array_type: + return hfa_type (&typedie, tag, sizep, countp); + } + + return 1; +} + +static int +hfa_type (Dwarf_Die *ftypedie, int tag, Dwarf_Word *sizep, Dwarf_Word *countp) +{ + assert (tag == DW_TAG_structure_type || tag == DW_TAG_class_type + || tag == DW_TAG_union_type || tag == DW_TAG_array_type); + + int i; + if (tag == DW_TAG_array_type) + { + Dwarf_Word tot_size; + if (dwarf_aggregate_size (ftypedie, &tot_size) < 0) + return -1; + + /* For vector types, we don't care about the underlying + type, but only about the vector type itself. */ + bool vec; + Dwarf_Attribute attr_mem; + if (dwarf_formflag (dwarf_attr_integrate (ftypedie, DW_AT_GNU_vector, + &attr_mem), &vec) == 0 + && vec) + { + *sizep = tot_size; + *countp = 1; + + return 0; + } + + if ((i = member_is_fp (ftypedie, sizep, countp)) == 0) + { + *countp = tot_size / *sizep; + return 0; + } + + return i; + } + + /* Find first DW_TAG_member and determine its type. */ + Dwarf_Die member; + if ((i = dwarf_child (ftypedie, &member) != 0)) + return i; + + if ((i = skip_until (&member, DW_TAG_member)) != 0) + return i; + + *countp = 0; + if ((i = member_is_fp (&member, sizep, countp)) != 0) + return i; + + while ((i = dwarf_siblingof (&member, &member)) == 0 + && (i = skip_until (&member, DW_TAG_member)) == 0) + { + Dwarf_Word size, count; + if ((i = member_is_fp (&member, &size, &count)) != 0) + return i; + + if (*sizep != size) + return 1; + + *countp += count; + } + + /* At this point we already have at least one FP member, which means + FTYPEDIE is an HFA. So either return 0, or propagate error. */ + return i < 0 ? i : 0; +} + +static int +pass_in_gpr (const Dwarf_Op **locp, Dwarf_Word size) +{ + static const Dwarf_Op loc[] = + { + { .atom = DW_OP_reg0 }, { .atom = DW_OP_piece, .number = 8 }, + { .atom = DW_OP_reg1 }, { .atom = DW_OP_piece, .number = 8 } + }; + + *locp = loc; + return size <= 8 ? 1 : 4; +} + +static int +pass_by_ref (const Dwarf_Op **locp) +{ + static const Dwarf_Op loc[] = { { .atom = DW_OP_breg0 } }; + + *locp = loc; + return 1; +} + +static int +pass_hfa (const Dwarf_Op **locp, Dwarf_Word size, Dwarf_Word count) +{ + assert (count >= 1 && count <= 4); + assert (size == 2 || size == 4 || size == 8 || size == 16); + +#define DEFINE_FPREG(NAME, SIZE) \ + static const Dwarf_Op NAME[] = { \ + { .atom = DW_OP_regx, .number = 64 }, \ + { .atom = DW_OP_piece, .number = SIZE }, \ + { .atom = DW_OP_regx, .number = 65 }, \ + { .atom = DW_OP_piece, .number = SIZE }, \ + { .atom = DW_OP_regx, .number = 66 }, \ + { .atom = DW_OP_piece, .number = SIZE }, \ + { .atom = DW_OP_regx, .number = 67 }, \ + { .atom = DW_OP_piece, .number = SIZE } \ + } + + switch (size) + { + case 2:; + DEFINE_FPREG (loc_hfa_2, 2); + *locp = loc_hfa_2; + break; + + case 4:; + DEFINE_FPREG (loc_hfa_4, 4); + *locp = loc_hfa_4; + break; + + case 8:; + DEFINE_FPREG (loc_hfa_8, 8); + *locp = loc_hfa_8; + break; + + case 16:; + DEFINE_FPREG (loc_hfa_16, 16); + *locp = loc_hfa_16; + break; + } +#undef DEFINE_FPREG + + return count == 1 ? 1 : 2 * count; +} + +static int +pass_in_simd (const Dwarf_Op **locp) +{ + /* This is like passing single-element HFA. Size doesn't matter, so + pretend it's for example double. */ + return pass_hfa (locp, 8, 1); +} + +int +aarch64_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_Die typedie; + int tag = dwarf_peeled_die_type (functypedie, &typedie); + if (tag <= 0) + return tag; + + Dwarf_Word size = (Dwarf_Word)-1; + + /* If the argument type is a Composite Type that is larger than 16 + bytes, then the argument is copied to memory allocated by the + caller and the argument is replaced by a pointer to the copy. */ + if (tag == DW_TAG_structure_type || tag == DW_TAG_union_type + || tag == DW_TAG_class_type || tag == DW_TAG_array_type) + { + Dwarf_Word base_size, count; + switch (hfa_type (&typedie, tag, &base_size, &count)) + { + default: + return -1; + + case 0: + assert (count > 0); + if (count <= 4) + return pass_hfa (locp, base_size, count); + /* Fall through. */ + + case 1: + /* Not a HFA. */ + if (dwarf_aggregate_size (&typedie, &size) < 0) + return -1; + if (size > 16) + return pass_by_ref (locp); + } + } + + if (tag == DW_TAG_base_type + || tag == DW_TAG_pointer_type || tag == DW_TAG_ptr_to_member_type) + { + if (dwarf_bytesize_aux (&typedie, &size) < 0) + { + if (tag == DW_TAG_pointer_type || tag == DW_TAG_ptr_to_member_type) + size = 8; + else + return -1; + } + + Dwarf_Attribute attr_mem; + 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) + { + /* If the argument is a Half-, Single-, Double- or Quad- + precision Floating-point [...] the argument is allocated + to the least significant bits of register v[NSRN]. */ + case DW_ATE_float: + switch (size) + { + case 2: /* half */ + case 4: /* sigle */ + case 8: /* double */ + case 16: /* quad */ + return pass_in_simd (locp); + + default: + return -2; + } + + case DW_ATE_complex_float: + switch (size) + { + case 8: /* float _Complex */ + case 16: /* double _Complex */ + case 32: /* long double _Complex */ + return pass_hfa (locp, size / 2, 2); + + default: + return -2; + } + + /* If the argument is an Integral or Pointer Type, the + size of the argument is less than or equal to 8 bytes + [...] the argument is copied to the least significant + bits in x[NGRN]. */ + case DW_ATE_signed: + case DW_ATE_unsigned: + case DW_ATE_unsigned_char: + case DW_ATE_signed_char: + return pass_in_gpr (locp, size); + } + + return -2; + } + else + return pass_in_gpr (locp, size); + } + + *locp = NULL; + return 0; +} |