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GDB infinite loop when stepping on "while (1) i++;"
- From: qinwei<qinwei at sunnorth dot com dot cn>
- To: gdb at sourceware dot org
- Date: Thu, 22 Mar 2007 15:44:26 +0800
- Subject: GDB infinite loop when stepping on "while (1) i++;"
Dears, problems are here:
gcc -o t -gdwarf-2 tp_while1.c
gdb t
(gdb) b main
Breakpoint 1 at 0x8048350: file tp_while1.c, line 3.
(gdb) r
Starting program: /home/qinwei/GJ283/code/build_linux/debug-gdb/t
Breakpoint 1, main () at tp_while1.c:3
3 int i = 10;
(gdb) n
4 while (1) i++;
(gdb) n
When program stops at "while (1) i++;", and printing "next" command will
cause gdb infinite loop.
The target are x86, score, or other? (gdb-6.6 release version)
Is the reason that the following dwarf-2 info:
"Special opcode 104: advance Address by 7 to 0x8048357 and Line by 1 to
4"
"Advance PC by 7 to 804835e"
which makes "while (1)" and "i++;" the same line number? And gdb will get
"stop_pc" from the range [0x8048357, 0x804835e] and will not stop?
How to solve it? Thanks!
int main (void)
{
int i = 10;
while (1) i++;
return 0;
}
Line Number Statements:
Extended opcode 2: set Address to 0x8048334
Special opcode 6: advance Address by 0 to 0x8048334 and Line by 1 to 2
Advance PC by constant 17 to 0x8048345
Special opcode 160: advance Address by 11 to 0x8048350 and Line by 1 to
3
Special opcode 104: advance Address by 7 to 0x8048357 and Line by 1 to 4
Advance PC by 7 to 804835e
Extended opcode 1: End of Sequence
08048334 <main>:
8048334: 55 push %ebp
8048335: 89 e5 mov %esp,%ebp
8048337: 83 ec 08 sub $0x8,%esp
804833a: 83 e4 f0 and $0xfffffff0,%esp
804833d: b8 00 00 00 00 mov $0x0,%eax
8048342: 83 c0 0f add $0xf,%eax
8048345: 83 c0 0f add $0xf,%eax
8048348: c1 e8 04 shr $0x4,%eax
804834b: c1 e0 04 shl $0x4,%eax
804834e: 29 c4 sub %eax,%esp
8048350: c7 45 fc 0a 00 00 00 movl $0xa,0xfffffffc(%ebp)
8048357: 8d 45 fc lea 0xfffffffc(%ebp),%eax
804835a: ff 00 incl (%eax)
804835c: eb f9 jmp 8048357 <main+0x23>
804835e: 90 nop
804835f: 90 nop
Best regards,
Qinwei
Mail qinwei@sunnorth.com.cn
Phone +86-010-62981668-2708
Fax +86-010-62985972