gdb错误消息:DW_OP_reg,DW_OP_piece和DW_OP_bit_piece

Question

我正在调试其他人的Qt程序并遇到以下错误消息,我不明白:

DWARF-2 expression error: DW_OP_reg operations must be used either alone or in
conjuction with DW_OP_piece or DW_OP_bit_piece.

我不确定这意味着什么,谷歌没有多大帮助.

这是上下文 - sLocation是QString之前声明的几行.但是,它是从内联的函数创建的,所以我不确定它的值,并且我在尝试检查之前被追加到:

(gdb) printqstring suffix
(QString)0xffffbd80: "sorted"
(gdb) next
1241        sLocation += suffix;
(gdb) printqstring sLocation
Can't take address of "sLocation" which isn't an lvalue.
(gdb) info local
sLocation = <error reading variable sLocation (DWARF-2 expression error:
    DW_OP_reg operations must be used either alone or in conjuction with
    DW_OP_piece or DW_OP_bit_piece.)>

有人可以解释一下该错误信息的含义或可能导致的错误信息吗？

Answer 1

该错误消息意味着正在从可执行文件GDB读取DWARF2调试信息，并拒绝该信息为无效（不遵循DWARF2标准）。

无效信息可能是由于 GCC 中的错误造成的，已在 SVN 修订版 147187 中修复：

2009-05-06  Jakub Jelinek  <jakub@redhat.com>

    * dwarf2out.c (new_reg_loc_descr): Don't ever create DW_OP_regX.
    (one_reg_loc_descriptor): Create DW_OP_regX here instead of calling
    new_reg_loc_descr.
    (loc_by_reference): If loc is DW_OP_regX, change it into DW_OP_bregX 0
    instead of appending DW_OP_deref*.