From f236533e3c6a2693bea879b2a4d24d1229864ac9 Mon Sep 17 00:00:00 2001 From: Andreas Arnez Date: Tue, 13 Jun 2017 15:20:31 +0200 Subject: [PATCH] read/write_pieced_value: Remove unnecessary variable copies In read_pieced_value's main loop, the variables `dest_offset_bits' and `source_offset_bits' are basically just copies of `offset' and `bits_to_skip', respectively. In write_pieced_value the copies are reversed. This is not very helpful when trying to keep the logic between these functions in sync. Since the copies are unnecessary, this patch just removes them. gdb/ChangeLog: * dwarf2loc.c (read_pieced_value): Remove unnecessary variables dest_offset_bits and source_offset_bits. (write_pieced_value): Likewise. --- gdb/ChangeLog | 6 +++ gdb/dwarf2loc.c | 120 +++++++++++++++++++++--------------------------- 2 files changed, 58 insertions(+), 68 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 1d383cc0be0..6ca4b5ccca2 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,9 @@ +2017-06-13 Andreas Arnez + + * dwarf2loc.c (read_pieced_value): Remove unnecessary variables + dest_offset_bits and source_offset_bits. + (write_pieced_value): Likewise. + 2017-06-13 Andreas Arnez * dwarf2loc.c (read_pieced_value): Respect the piece offset, as diff --git a/gdb/dwarf2loc.c b/gdb/dwarf2loc.c index 23901f0e7c1..ed5b29ced33 100644 --- a/gdb/dwarf2loc.c +++ b/gdb/dwarf2loc.c @@ -1790,25 +1790,16 @@ read_pieced_value (struct value *v) else max_offset = 8 * TYPE_LENGTH (value_type (v)); - for (i = 0; i < c->n_pieces && offset < max_offset; i++) + /* Advance to the first non-skipped piece. */ + for (i = 0; i < c->n_pieces && bits_to_skip >= c->pieces[i].size; i++) + bits_to_skip -= c->pieces[i].size; + + for (; i < c->n_pieces && offset < max_offset; i++) { struct dwarf_expr_piece *p = &c->pieces[i]; size_t this_size, this_size_bits; - long dest_offset_bits, source_offset_bits; - - /* Compute size, source, and destination offsets for copying, in - bits. */ - this_size_bits = p->size; - if (bits_to_skip > 0 && bits_to_skip >= this_size_bits) - { - bits_to_skip -= this_size_bits; - continue; - } - source_offset_bits = bits_to_skip; - this_size_bits -= bits_to_skip; - bits_to_skip = 0; - dest_offset_bits = offset; + this_size_bits = p->size - bits_to_skip; if (this_size_bits > max_offset - offset) this_size_bits = max_offset - offset; @@ -1827,16 +1818,16 @@ read_pieced_value (struct value *v) && p->offset + p->size < reg_bits) { /* Big-endian, and we want less than full size. */ - source_offset_bits += reg_bits - (p->offset + p->size); + bits_to_skip += reg_bits - (p->offset + p->size); } else - source_offset_bits += p->offset; + bits_to_skip += p->offset; - this_size = bits_to_bytes (source_offset_bits, this_size_bits); + this_size = bits_to_bytes (bits_to_skip, this_size_bits); buffer.reserve (this_size); if (!get_frame_register_bytes (frame, gdb_regnum, - source_offset_bits / 8, + bits_to_skip / 8, this_size, buffer.data (), &optim, &unavail)) { @@ -1846,24 +1837,23 @@ read_pieced_value (struct value *v) mark_value_bits_unavailable (v, offset, this_size_bits); break; } - - copy_bitwise (contents, dest_offset_bits, - buffer.data (), source_offset_bits % 8, + copy_bitwise (contents, offset, + buffer.data (), bits_to_skip % 8, this_size_bits, bits_big_endian); } break; case DWARF_VALUE_MEMORY: - source_offset_bits += p->offset; - this_size = bits_to_bytes (source_offset_bits, this_size_bits); + bits_to_skip += p->offset; + this_size = bits_to_bytes (bits_to_skip, this_size_bits); buffer.reserve (this_size); read_value_memory (v, offset, p->v.mem.in_stack_memory, - p->v.mem.addr + source_offset_bits / 8, + p->v.mem.addr + bits_to_skip / 8, buffer.data (), this_size); - copy_bitwise (contents, dest_offset_bits, - buffer.data (), source_offset_bits % 8, + copy_bitwise (contents, offset, + buffer.data (), bits_to_skip % 8, this_size_bits, bits_big_endian); break; @@ -1880,14 +1870,13 @@ read_pieced_value (struct value *v) /* Piece is anchored at least significant bit end. */ if (gdbarch_byte_order (objfile_gdbarch) == BFD_ENDIAN_BIG) - source_offset_bits += (stack_value_size_bits - - p->offset - p->size); + bits_to_skip += stack_value_size_bits - p->offset - p->size; else - source_offset_bits += p->offset; + bits_to_skip += p->offset; - copy_bitwise (contents, dest_offset_bits, + copy_bitwise (contents, offset, value_contents_all (p->v.value), - source_offset_bits, + bits_to_skip, this_size_bits, bits_big_endian); } break; @@ -1898,14 +1887,14 @@ read_pieced_value (struct value *v) size_t n = this_size_bits; /* Cut off at the end of the implicit value. */ - source_offset_bits += p->offset; - if (source_offset_bits >= literal_size_bits) + bits_to_skip += p->offset; + if (bits_to_skip >= literal_size_bits) break; - if (n > literal_size_bits - source_offset_bits) - n = literal_size_bits - source_offset_bits; + if (n > literal_size_bits - bits_to_skip) + n = literal_size_bits - bits_to_skip; - copy_bitwise (contents, dest_offset_bits, - p->v.literal.data, source_offset_bits, + copy_bitwise (contents, offset, + p->v.literal.data, bits_to_skip, n, bits_big_endian); } break; @@ -1924,6 +1913,7 @@ read_pieced_value (struct value *v) } offset += this_size_bits; + bits_to_skip = 0; } } @@ -1959,23 +1949,16 @@ write_pieced_value (struct value *to, struct value *from) else max_offset = 8 * TYPE_LENGTH (value_type (to)); - for (i = 0; i < c->n_pieces && offset < max_offset; i++) + /* Advance to the first non-skipped piece. */ + for (i = 0; i < c->n_pieces && bits_to_skip >= c->pieces[i].size; i++) + bits_to_skip -= c->pieces[i].size; + + for (; i < c->n_pieces && offset < max_offset; i++) { struct dwarf_expr_piece *p = &c->pieces[i]; size_t this_size_bits, this_size; - long dest_offset_bits, source_offset_bits; - - this_size_bits = p->size; - if (bits_to_skip > 0 && bits_to_skip >= this_size_bits) - { - bits_to_skip -= this_size_bits; - continue; - } - dest_offset_bits = bits_to_skip; - this_size_bits -= bits_to_skip; - bits_to_skip = 0; - source_offset_bits = offset; + this_size_bits = p->size - bits_to_skip; if (this_size_bits > max_offset - offset) this_size_bits = max_offset - offset; @@ -1992,22 +1975,22 @@ write_pieced_value (struct value *to, struct value *from) && p->offset + p->size < reg_bits) { /* Big-endian, and we want less than full size. */ - dest_offset_bits += reg_bits - (p->offset + p->size); + bits_to_skip += reg_bits - (p->offset + p->size); } else - dest_offset_bits += p->offset; + bits_to_skip += p->offset; - this_size = bits_to_bytes (dest_offset_bits, this_size_bits); + this_size = bits_to_bytes (bits_to_skip, this_size_bits); buffer.reserve (this_size); - if (dest_offset_bits % 8 != 0 || this_size_bits % 8 != 0) + if (bits_to_skip % 8 != 0 || this_size_bits % 8 != 0) { /* Data is copied non-byte-aligned into the register. Need some bits from original register value. */ int optim, unavail; if (!get_frame_register_bytes (frame, gdb_regnum, - dest_offset_bits / 8, + bits_to_skip / 8, this_size, buffer.data (), &optim, &unavail)) { @@ -2024,34 +2007,34 @@ write_pieced_value (struct value *to, struct value *from) } } - copy_bitwise (buffer.data (), dest_offset_bits % 8, - contents, source_offset_bits, + copy_bitwise (buffer.data (), bits_to_skip % 8, + contents, offset, this_size_bits, bits_big_endian); put_frame_register_bytes (frame, gdb_regnum, - dest_offset_bits / 8, + bits_to_skip / 8, this_size, buffer.data ()); } break; case DWARF_VALUE_MEMORY: { - dest_offset_bits += p->offset; + bits_to_skip += p->offset; - CORE_ADDR start_addr = p->v.mem.addr + dest_offset_bits / 8; + CORE_ADDR start_addr = p->v.mem.addr + bits_to_skip / 8; - if (dest_offset_bits % 8 == 0 && this_size_bits % 8 == 0 - && source_offset_bits % 8 == 0) + if (bits_to_skip % 8 == 0 && this_size_bits % 8 == 0 + && offset % 8 == 0) { /* Everything is byte-aligned; no buffer needed. */ write_memory (start_addr, - contents + source_offset_bits / 8, + contents + offset / 8, this_size_bits / 8); break; } - this_size = bits_to_bytes (dest_offset_bits, this_size_bits); + this_size = bits_to_bytes (bits_to_skip, this_size_bits); buffer.reserve (this_size); - if (dest_offset_bits % 8 != 0 || this_size_bits % 8 != 0) + if (bits_to_skip % 8 != 0 || this_size_bits % 8 != 0) { if (this_size <= 8) { @@ -2068,8 +2051,8 @@ write_pieced_value (struct value *to, struct value *from) } } - copy_bitwise (buffer.data (), dest_offset_bits % 8, - contents, source_offset_bits, + copy_bitwise (buffer.data (), bits_to_skip % 8, + contents, offset, this_size_bits, bits_big_endian); write_memory (start_addr, buffer.data (), this_size); } @@ -2079,6 +2062,7 @@ write_pieced_value (struct value *to, struct value *from) break; } offset += this_size_bits; + bits_to_skip = 0; } } -- 2.30.2