From b597c318b86b5ad2bca1f72ee8c0fbe33cbb7dad Mon Sep 17 00:00:00 2001 From: Yao Qi Date: Sun, 28 Dec 2014 16:12:53 +0800 Subject: always read synthetic pointers as signed integers I see the error message "access outside bounds of object referenced via synthetic pointer" in the two fails below of mips gdb testing print d[-2]^M access outside bounds of object referenced via synthetic pointer^M (gdb) FAIL: gdb.dwarf2/implptrconst.exp: print d[-2] (gdb) print/d p[-1]^M access outside bounds of object referenced via synthetic pointer^M (gdb) FAIL: gdb.dwarf2/implptrpiece.exp: print/d p[-1] in the first test, 'd[-2]' is processed by GDB as '* (&d[-2])'. 'd' is a synthetic pointer, so its value is zero, the address of 'd[-2]' is -2. In dwarf2loc.c:indirect_pieced_value, /* This is an offset requested by GDB, such as value subscripts. However, due to how synthetic pointers are implemented, this is always presented to us as a pointer type. This means we have to sign-extend it manually as appropriate. */ byte_offset = value_as_address (value); if (TYPE_LENGTH (value_type (value)) < sizeof (LONGEST)) byte_offset = gdb_sign_extend (byte_offset, 8 * TYPE_LENGTH (value_type (value))); byte_offset += piece->v.ptr.offset; We know that the value is really an offset instead of address, so the fix is to extract the value as an (signed) offset. gdb: 2015-01-08 Pedro Alves Yao Qi * dwarf2loc.c (indirect_pieced_value): Don't call gdb_sign_extend. Call extract_signed_integer instead. * utils.c (gdb_sign_extend): Remove. * utils.h (gdb_sign_extend): Remove declaration. --- gdb/dwarf2loc.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) (limited to 'gdb/dwarf2loc.c') diff --git a/gdb/dwarf2loc.c b/gdb/dwarf2loc.c index 2bd12d6..bdb2160 100644 --- a/gdb/dwarf2loc.c +++ b/gdb/dwarf2loc.c @@ -2012,6 +2012,7 @@ indirect_pieced_value (struct value *value) int i, bit_offset, bit_length; struct dwarf_expr_piece *piece = NULL; LONGEST byte_offset; + enum bfd_endian byte_order; type = check_typedef (value_type (value)); if (TYPE_CODE (type) != TYPE_CODE_PTR) @@ -2056,11 +2057,16 @@ indirect_pieced_value (struct value *value) /* This is an offset requested by GDB, such as value subscripts. However, due to how synthetic pointers are implemented, this is always presented to us as a pointer type. This means we have to - sign-extend it manually as appropriate. */ - byte_offset = value_as_address (value); - if (TYPE_LENGTH (value_type (value)) < sizeof (LONGEST)) - byte_offset = gdb_sign_extend (byte_offset, - 8 * TYPE_LENGTH (value_type (value))); + sign-extend it manually as appropriate. Use raw + extract_signed_integer directly rather than value_as_address and + sign extend afterwards on architectures that would need it + (mostly everywhere except MIPS, which has signed addresses) as + the later would go through gdbarch_pointer_to_address and thus + return a CORE_ADDR with high bits set on architectures that + encode address spaces and other things in CORE_ADDR. */ + byte_order = gdbarch_byte_order (get_frame_arch (frame)); + byte_offset = extract_signed_integer (value_contents (value), + TYPE_LENGTH (type), byte_order); byte_offset += piece->v.ptr.offset; gdb_assert (piece); -- cgit v1.1