刚输入函数时会导致分段错误的原因是什么?
输入的函数如下所示:
21: void eesu3(Matrix & iQ)
22: {
哪里Matrix
是struct
。使用 GDB 运行时,回溯会产生:
(gdb) backtrace
#0 eesu3 (iQ=...) at /home/.../eesu3.cc:22
#1 ...
GDB 没有说是什么iQ
。从...
字面上看。什么可能导致这种情况?
GCC:(Ubuntu/Linaro 4.6.3-1ubuntu5)4.6.3
构建的程序-O3 -g
调用者是这样的:
Matrix q;
// do some stuff with q
eesu3(q);
这里没什么特别的
我用 valgrind 重新运行了程序:
valgrind --tool=memcheck --leak-check=yes --show-reachable=yes --num-callers=20 --track-fds=yes <prgname>
输出:
==2240== Warning: client switching stacks? SP change: 0x7fef7ef68 --> 0x7fe5e3000
==2240== to suppress, use: --max-stackframe=10076008 or greater
==2240== Invalid write of size 8
==2240== at 0x14C765B: eesu3( Matrix &) (eesu3.cc:22)
...
==2240== Address 0x7fe5e3fd8 is on thread 1's stack
==2240==
==2240== Can't extend stack to 0x7fe5e2420 during signal delivery for thread 1:
==2240== no stack segment
==2240==
==2240== Process terminating with default action of signal 11 (SIGSEGV)
==2240== Access not within mapped region at address 0x7FE5E2420
==2240== at 0x14C765B: eesu3( Matrix&) (eesu3.cc:22)
==2240== If you believe this happened as a result of a stack
==2240== overflow in your program's main thread (unlikely but
==2240== possible), you can try to increase the size of the
==2240== main thread stack using the --main-stacksize= flag.
==2240== The main thread stack size used in this run was 8388608.
看起来它是一个损坏的堆栈。
Dump of assembler code for function eesu3( Matrix & ):
0x00000000014c7640 <+0>: push %rbp
0x00000000014c7641 <+1>: mov %rsp,%rbp
0x00000000014c7644 <+4>: push %r15
0x00000000014c7646 <+6>: push %r14
0x00000000014c7648 <+8>: push %r13
0x00000000014c764a <+10>: push %r12
0x00000000014c764c <+12>: push %rbx
0x00000000014c764d <+13>: and $0xfffffffffffff000,%rsp
0x00000000014c7654 <+20>: sub $0x99b000,%rsp
=> 0x00000000014c765b <+27>: mov %rdi,0xfd8(%rsp)
好的,明确一点:Matrix 的数据存在于堆中。它基本上包含一个指向数据的指针。该结构很小,只有 32 个字节。(刚刚检查)
现在,我用不同的优化选项重建了程序:
-O0
: 错误不显示。
-O1
: 错误确实显示。
-O3
: 错误确实显示。
- 更新
-O3 -fno-inline -fno-inline-functions
: 错误不显示。
That explains it. Too many inlines into the function led to excessive stack usage.
The problem was due to a stack overflow