gdb，为什么“下一个”显示每个源代码行两次？ [英] gdb,why "next" show each source line twice?

问题描述

大家，当在gdb中使用next指令时，我发现源代码的每行显示两次-----我确定这些代码不在任何循环中。这是现象：

 （gdb）frame 
＃0 ap_get_client_block（r = 0x8560d48，
 buffer = 0xb68501b7<？xml version = < Root>< OperCode> SMS101< / OperCode>< AppId> SMSMsgFilterReq< / AppId>< Req>< UserMobile> 13925237429< / UserMobile>< SENDMSG> ABC圲34圲23A露07\214圲21¢<237朲11东215圲10°<214朲27¥応227露07\214正常，浩？。 ...，bufsiz = 81920）at http_filters.c：1540 
 1540 if（r->剩余< 0 ||（！r-> read_chunked&& r->剩余== 0） ）{
（gdb）n 
 1544 bb = apr_brigade_create（r-> pool，r-> connection-> bucket_alloc）; （bb == NULL）{
（gdb）
 1544 bb = apr_brigade_create（r-> pool，r-> connection-> bucket_alloc）; 
（gdb）
 1545 if（bb == NULL）{
  

- ---- 1544,1545行不在任何循环中，但它们重复。
有人能给我什么启发吗？

解决方案

即使是最低级别的优化，也可能导致您的调试程序像编译器内联，重新排序以及通常使用您的代码一样疯狂地绕过源代码行。

everyone,when use "next" instruction within gdb,i found each line of sourcecode display twice-----i am quite sure,these code are not in any loop.this is the phenomenon:

(gdb) frame
#0  ap_get_client_block (r=0x8560d48, 
    buffer=0xb68501b7 "<?xml version=\"1.0\" encoding=\"utf-8\"?><Root><OperCode>SMS101</OperCode><AppId>SMSMsgFilterReq</AppId><Req><UserMobile>13925237429</UserMobile><SendMsg>abc圲34¨圲23a露07\214圲21￠＜237朲11?东215圲10°＜214朲27￥応227露07\214正常,hao"..., bufsiz=81920) at http_filters.c:1540
1540        if (r->remaining < 0 || (!r->read_chunked && r->remaining == 0)) {
(gdb) n
1544        bb = apr_brigade_create(r->pool, r->connection->bucket_alloc);
(gdb) 
1545        if (bb == NULL) {
(gdb) 
1544        bb = apr_brigade_create(r->pool, r->connection->bucket_alloc);
(gdb) 
1545        if (bb == NULL) {

-----the line 1544,1545 are not in any loop,but they got repeated. May anybody enlighten me?

解决方案

What level of optimisation did you have when you compiled this?

Even a minimal level of optimisation can cause your debugger to jump around the source lines like crazy as the compiler inlines, reorders and generally plays with your code.

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