From 359b19bb24d048750aa5367ad56a33267300d1a8 Mon Sep 17 00:00:00 2001 From: Andreas Arnez Date: Tue, 13 Jun 2017 15:20:28 +0200 Subject: [PATCH] write_pieced_value: Transfer least significant bits into bit-field On big-endian targets, when targeting a bit-field, write_pieced_value currently transfers the source value's *most* significant bits to the target value, instead of its least significant bits. This is fixed. In particular the fix adjusts the initial value of 'offset', which can now potentially be nonzero. Thus the variable 'type_len' is renamed to 'max_offset', to avoid confusion. And for consistency, the affected logic that was mirrored in read_pieced_value is changed there in the same way. gdb/ChangeLog: * dwarf2loc.c (write_pieced_value): When writing to a bit-field, transfer the source value's least significant bits, instead of its lowest-addressed ones. Rename type_len to max_offset. (read_pieced_value): Mirror above changes to write_pieced_value as applicable. --- gdb/ChangeLog | 8 ++++++ gdb/dwarf2loc.c | 70 ++++++++++++++++++++++--------------------------- 2 files changed, 39 insertions(+), 39 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 296d187f24..cd0d43e804 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,11 @@ +2017-06-13 Andreas Arnez + + * dwarf2loc.c (write_pieced_value): When writing to a bit-field, + transfer the source value's least significant bits, instead of its + lowest-addressed ones. Rename type_len to max_offset. + (read_pieced_value): Mirror above changes to write_pieced_value as + applicable. + 2017-06-13 Andreas Arnez * dwarf2loc.c (write_pieced_value): In DWARF_VALUE_MEMORY, diff --git a/gdb/dwarf2loc.c b/gdb/dwarf2loc.c index 67a123fd42..27e6766be8 100644 --- a/gdb/dwarf2loc.c +++ b/gdb/dwarf2loc.c @@ -1756,12 +1756,11 @@ static void read_pieced_value (struct value *v) { int i; - long offset = 0; + LONGEST offset = 0, max_offset; ULONGEST bits_to_skip; gdb_byte *contents; struct piece_closure *c = (struct piece_closure *) value_computed_closure (v); - size_t type_len; size_t buffer_size = 0; std::vector buffer; int bits_big_endian @@ -1778,12 +1777,12 @@ read_pieced_value (struct value *v) { bits_to_skip += (8 * value_offset (value_parent (v)) + value_bitpos (v)); - type_len = value_bitsize (v); + max_offset = value_bitsize (v); } else - type_len = 8 * TYPE_LENGTH (value_type (v)); + max_offset = 8 * TYPE_LENGTH (value_type (v)); - for (i = 0; i < c->n_pieces && offset < type_len; i++) + for (i = 0; i < c->n_pieces && offset < max_offset; i++) { struct dwarf_expr_piece *p = &c->pieces[i]; size_t this_size, this_size_bits; @@ -1798,20 +1797,13 @@ read_pieced_value (struct value *v) bits_to_skip -= this_size_bits; continue; } - if (bits_to_skip > 0) - { - dest_offset_bits = 0; - source_offset_bits = bits_to_skip; - this_size_bits -= bits_to_skip; - bits_to_skip = 0; - } - else - { - dest_offset_bits = offset; - source_offset_bits = 0; - } - if (this_size_bits > type_len - offset) - this_size_bits = type_len - offset; + source_offset_bits = bits_to_skip; + this_size_bits -= bits_to_skip; + bits_to_skip = 0; + dest_offset_bits = offset; + + if (this_size_bits > max_offset - offset) + this_size_bits = max_offset - offset; this_size = (this_size_bits + source_offset_bits % 8 + 7) / 8; source_offset = source_offset_bits / 8; @@ -1932,12 +1924,11 @@ static void write_pieced_value (struct value *to, struct value *from) { int i; - long offset = 0; ULONGEST bits_to_skip; + LONGEST offset = 0, max_offset; const gdb_byte *contents; struct piece_closure *c = (struct piece_closure *) value_computed_closure (to); - size_t type_len; size_t buffer_size = 0; std::vector buffer; int bits_big_endian @@ -1949,12 +1940,20 @@ write_pieced_value (struct value *to, struct value *from) { bits_to_skip += (8 * value_offset (value_parent (to)) + value_bitpos (to)); - type_len = value_bitsize (to); - } + /* Use the least significant bits of FROM. */ + if (gdbarch_byte_order (get_type_arch (value_type (from))) + == BFD_ENDIAN_BIG) + { + max_offset = 8 * TYPE_LENGTH (value_type (from)); + offset = max_offset - value_bitsize (to); + } + else + max_offset = value_bitsize (to); + } else - type_len = 8 * TYPE_LENGTH (value_type (to)); + max_offset = 8 * TYPE_LENGTH (value_type (to)); - for (i = 0; i < c->n_pieces && offset < type_len; i++) + for (i = 0; i < c->n_pieces && offset < max_offset; i++) { struct dwarf_expr_piece *p = &c->pieces[i]; size_t this_size_bits, this_size; @@ -1968,20 +1967,13 @@ write_pieced_value (struct value *to, struct value *from) bits_to_skip -= this_size_bits; continue; } - if (bits_to_skip > 0) - { - dest_offset_bits = bits_to_skip; - source_offset_bits = 0; - this_size_bits -= bits_to_skip; - bits_to_skip = 0; - } - else - { - dest_offset_bits = 0; - source_offset_bits = offset; - } - if (this_size_bits > type_len - offset) - this_size_bits = type_len - offset; + dest_offset_bits = bits_to_skip; + this_size_bits -= bits_to_skip; + bits_to_skip = 0; + source_offset_bits = offset; + + if (this_size_bits > max_offset - offset) + this_size_bits = max_offset - offset; this_size = (this_size_bits + dest_offset_bits % 8 + 7) / 8; source_offset = source_offset_bits / 8;