why Dr memory recommand building application with static libstdc++ libraries under MinGW?

[asm warrior]

Hi, I see in the Dr memory document, you recommend linking static libstdc++ libraries. http://drmemory.org/docs/page_prep.html

For MinGW C++ applications, we recommending building with static libstdc++ libraries. Pass -static-libgcc -static-libstdc++ to g++ to request this.

I just test a simple project and see what are the differences with application with shared libstdc++ and static libstdc++ libraries.

Test code:

#include <iostream>
#include <cstring>
using namespace std;

char * f() {
    char * p = new char[100];
    strcpy( p, "foobar" );
    return p;
}

int main() {
    for( int i = 0; i < 10; i++ ) {
        cout << f() << endl;
    }
}

When build with MinGW-Build-4.7.3 (shared libstdc++), I get the result:

Dr. Memory version 1.6.0 build 2 built on Sep  7 2013 03:37:07
Dr. Memory results for pid 7460: "test-memory-leak.exe"
Application cmdline: "test-memory-leak.exe"
Recorded 97 suppression(s) from default D:\DrMemory-Windows-1.6.0-2\bin\suppress-default.txt

Error #1: POSSIBLE LEAK 30 direct bytes 0x014f00f8-0x014f0116 + 0 indirect bytes
# 0 replace_malloc                                     [d:\drmemory_package\common\alloc_replace.c:2292]
# 1 msvcrt.dll!__setargv
# 2 msvcrt.dll!__getmainargs
# 3 pre_cpp_init       
# 4 _fu0___set_invalid_parameter_handler
# 5 KERNEL32.dll!RegisterWaitForInputIdle             +0x48     (0x7c81776f <KERNEL32.dll+0x1776f>)

Error #2: LEAK 100 direct bytes 0x014f04f8-0x014f055c + 0 indirect bytes
# 0 replace_malloc               [d:\drmemory_package\common\alloc_replace.c:2292]
# 1 libstdc++-6.dll!Znwj        +0x26     (0x6fcae8a7 <libstdc++-6.dll+0x6e8a7>)
# 2 main                         [E:/code/cb/test_code/test-memory-leak/main.cpp:13]

===========================================================================
FINAL SUMMARY:

DUPLICATE ERROR COUNTS:
    Error #   2:     10

SUPPRESSIONS USED:

ERRORS FOUND:
      0 unique,     0 total unaddressable access(es)
      0 unique,     0 total uninitialized access(es)
      0 unique,     0 total invalid heap argument(s)
      0 unique,     0 total GDI usage error(s)
      0 unique,     0 total warning(s)
      1 unique,    10 total,   1000 byte(s) of leak(s)
      1 unique,     1 total,     30 byte(s) of possible leak(s)
ERRORS IGNORED:
      5 unique,     5 total,    377 byte(s) of still-reachable allocation(s)
         (re-run with "-show_reachable" for details)
Details: D:\DrMemory-Windows-1.6.0-2\drmemory\logs\DrMemory-test-memory-leak.exe.7460.000\results.txt

When build with TDM-4.8.1 (static libstdc++ library)

Dr. Memory version 1.6.0 build 2 built on Sep  7 2013 03:37:07
Dr. Memory results for pid 4972: "test-memory-leak.exe"
Application cmdline: "test-memory-leak.exe"
Recorded 97 suppression(s) from default D:\DrMemory-Windows-1.6.0-2\bin\suppress-default.txt

Error #1: LEAK 100 direct bytes 0x011b0748-0x011b07ac + 0 indirect bytes
# 0 replace_operator_new_array               [d:\drmemory_package\common\alloc_replace.c:2450]
# 1 f()                                      [E:/code/cb/test_code/test-memory-leak/main.cpp:6]
# 2 main                                     [E:/code/cb/test_code/test-memory-leak/main.cpp:13]

===========================================================================
FINAL SUMMARY:

DUPLICATE ERROR COUNTS:
    Error #   1:     10

SUPPRESSIONS USED:

ERRORS FOUND:
      0 unique,     0 total unaddressable access(es)
      0 unique,     0 total uninitialized access(es)
      0 unique,     0 total invalid heap argument(s)
      0 unique,     0 total GDI usage error(s)
      0 unique,     0 total warning(s)
      1 unique,    10 total,   1000 byte(s) of leak(s)
      0 unique,     0 total,      0 byte(s) of possible leak(s)
ERRORS IGNORED:
      9 potential leak(s) (suspected false positives)
         (details: D:\DrMemory-Windows-1.6.0-2\drmemory\logs\DrMemory-test-memory-leak.exe.4972.000\potential_errors.txt)
      7 unique,     7 total,     52 byte(s) of still-reachable allocation(s)
         (re-run with "-show_reachable" for details)
Details: D:\DrMemory-Windows-1.6.0-2\drmemory\logs\DrMemory-test-memory-leak.exe.4972.000\results.txt

Look, in the later result, the call stack (back trace) show correctly, the function call

# 1 f()                                      [E:/code/cb/test_code/test-memory-leak/main.cpp:6]

Is correctly listed in the report, but in the former test, there is no call-stack mention the f() function.

Thanks.
Yuanhui Zhang

 

 

[Derek Bruening]

Note that older MinGW (4.5.x, e.g.) does not exhibit these problems.  But there are several issues with recent MinGW, as you hit:

1) Symbol mangling for operators is not properly handled: hence the operators are not replaced, causing DrMem to not report certain types of bugs (such as delete vs delete[] mismatch).

2) The FPO opts in the operators can cause missing frames, as you observed.

Hence, the recommendation to use static libstdc++ with MinGW.

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[Derek Bruening]

The latest Dr. Memory builds from http://build.chromium.org/p/client.drmemory/builds/ (r1644+) should work fairly well with shared libstdc++ on MinGW.

- Derek

[asm warrior]

On Thursday, December 5, 2013 3:17:50 AM UTC+8, Derek Bruening wrote:

The latest Dr. Memory builds from http://build.chromium.org/p/client.drmemory/builds/ (r1644+) should work fairly well with shared libstdc++ on MinGW.

- Derek

Hi, Derek, Many thanks. I have checked the "Email notification", but I don't receive emails about your reply. So, sorry for the late reply.

I have tried the latest DrMemory from the above link, and yes, it does not have the issue now, Many thanks for your work!

Yuanhui Zhang