2.2.1 : How to get all the value of nbElement
To get this value, we have to disable the variable optimisation done by the compiler.
So we have to change the compilation options from :
1 |
add_definitions(-O3 -g)
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to
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add_definitions(-O0 -g)
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And then we recompile :
1 2 3 4 5 6 7 |
make -- Configuring done -- Generating done -- Build files have been written to: XXX/build [ 50%] Building CXX object CMakeFiles/hadamard_product.dir/main.cpp.o [100%] Linking CXX executable hadamard_product [100%] Built target hadamard_product |
Recall gdb :
gdb ./hadamard_product GNU gdb (Ubuntu 7.11.1-0ubuntu1~16.04) 7.11.1 Copyright (C) 2016 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Type "show copying" and "show warranty" for details. This GDB was configured as "x86_64-linux-gnu". Type "show configuration" for configuration details. For bug reporting instructions, please see: <http://www.gnu.org/software/gdb/bugs/>. Find the GDB manual and other documentation resources online at: <http://www.gnu.org/software/gdb/documentation/>. For help, type "help". Type "apropos word" to search for commands related to "word"... Reading symbols from ./hadamard_product...done.
Launch the program in gdb :
(gdb) r Starting program: XXX/build/hadamard_product Hadamard product tabResult[0] = 0 *** Error in `XXX/build/hadamard_product': double free or corruption (!prev): 0x0000000000615030 *** ======= Backtrace: ========= /lib/x86_64-linux-gnu/libc.so.6(+0x777e5)[0x7ffff77037e5] /lib/x86_64-linux-gnu/libc.so.6(+0x7fe0a)[0x7ffff770be0a] /lib/x86_64-linux-gnu/libc.so.6(cfree+0x4c)[0x7ffff770f98c] XXX/build/hadamard_product(_Z23evaluateHadamardProductm+0x209)[0x400e18] XXX/build/hadamard_product(main+0x35)[0x400e7b] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf0)[0x7ffff76ac830] XXX/build/hadamard_product(_start+0x29)[0x400ac9] ======= Memory map: ======== 00400000-00402000 r-xp 00000000 08:01 6963416 XXX/build/hadamard_product 00601000-00602000 r--p 00001000 08:01 6963416 XXX/build/hadamard_product 00602000-00603000 rw-p 00002000 08:01 6963416 XXX/build/hadamard_product 00603000-00635000 rw-p 00000000 00:00 0 [heap] 7ffff0000000-7ffff0021000 rw-p 00000000 00:00 0 7ffff0021000-7ffff4000000 ---p 00000000 00:00 0 7ffff716d000-7ffff7183000 r-xp 00000000 08:01 8651671 /lib/x86_64-linux-gnu/libgcc_s.so.1 7ffff7183000-7ffff7382000 ---p 00016000 08:01 8651671 /lib/x86_64-linux-gnu/libgcc_s.so.1 7ffff7382000-7ffff7383000 rw-p 00015000 08:01 8651671 /lib/x86_64-linux-gnu/libgcc_s.so.1 7ffff7383000-7ffff748b000 r-xp 00000000 08:01 8652856 /lib/x86_64-linux-gnu/libm-2.23.so 7ffff748b000-7ffff768a000 ---p 00108000 08:01 8652856 /lib/x86_64-linux-gnu/libm-2.23.so 7ffff768a000-7ffff768b000 r--p 00107000 08:01 8652856 /lib/x86_64-linux-gnu/libm-2.23.so 7ffff768b000-7ffff768c000 rw-p 00108000 08:01 8652856 /lib/x86_64-linux-gnu/libm-2.23.so 7ffff768c000-7ffff784b000 r-xp 00000000 08:01 8652890 /lib/x86_64-linux-gnu/libc-2.23.so 7ffff784b000-7ffff7a4b000 ---p 001bf000 08:01 8652890 /lib/x86_64-linux-gnu/libc-2.23.so 7ffff7a4b000-7ffff7a4f000 r--p 001bf000 08:01 8652890 /lib/x86_64-linux-gnu/libc-2.23.so 7ffff7a4f000-7ffff7a51000 rw-p 001c3000 08:01 8652890 /lib/x86_64-linux-gnu/libc-2.23.so 7ffff7a51000-7ffff7a55000 rw-p 00000000 00:00 0 7ffff7a55000-7ffff7bc7000 r-xp 00000000 08:01 10356490 /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.21 7ffff7bc7000-7ffff7dc7000 ---p 00172000 08:01 10356490 /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.21 7ffff7dc7000-7ffff7dd1000 r--p 00172000 08:01 10356490 /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.21 7ffff7dd1000-7ffff7dd3000 rw-p 0017c000 08:01 10356490 /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.21 7ffff7dd3000-7ffff7dd7000 rw-p 00000000 00:00 0 7ffff7dd7000-7ffff7dfd000 r-xp 00000000 08:01 8652926 /lib/x86_64-linux-gnu/ld-2.23.so 7ffff7fc2000-7ffff7fc7000 rw-p 00000000 00:00 0 7ffff7ff5000-7ffff7ff8000 rw-p 00000000 00:00 0 7ffff7ff8000-7ffff7ffa000 r--p 00000000 00:00 0 [vvar] 7ffff7ffa000-7ffff7ffc000 r-xp 00000000 00:00 0 [vdso] 7ffff7ffc000-7ffff7ffd000 r--p 00025000 08:01 8652926 /lib/x86_64-linux-gnu/ld-2.23.so 7ffff7ffd000-7ffff7ffe000 rw-p 00026000 08:01 8652926 /lib/x86_64-linux-gnu/ld-2.23.so 7ffff7ffe000-7ffff7fff000 rw-p 00000000 00:00 0 7ffffffdd000-7ffffffff000 rw-p 00000000 00:00 0 [stack] ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vsyscall]
Program received signal SIGABRT, Aborted. 0x00007ffff76c1428 in __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:54 54 ../sysdeps/unix/sysv/linux/raise.c: Aucun fichier ou dossier de ce type.
Then, ge the back trace :
(gdb) bt #0 0x00007ffff76c1428 in __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:54 #1 0x00007ffff76c302a in __GI_abort () at abort.c:89 #2 0x00007ffff77037ea in __libc_message (do_abort=do_abort@entry=2, fmt=fmt@entry=0x7ffff781c2e0 "*** Error in `%s': %s: 0x%s ***\n") at ../sysdeps/posix/libc_fatal.c:175 #3 0x00007ffff770be0a in malloc_printerr (ar_ptr=<optimized out>, ptr=<optimized out>, str=0x7ffff781c410 "double free or corruption (!prev)", action=3) at malloc.c:5004 #4 _int_free (av=<optimized out>, p=<optimized out>, have_lock=0) at malloc.c:3865 #5 0x00007ffff770f98c in __GI___libc_free (mem=<optimized out>) at malloc.c:2966 #6 0x0000000000400e18 in evaluateHadamardProduct (nbElement=1000) at XXX/main.cpp:54 #7 0x0000000000400e7b in main (argc=1, argv=0x7fffffffdb48) at XXX/main.cpp:65
To go to the level 6 :
(gdb) up #1 0x00007ffff76c302a in __GI_abort () at abort.c:89 89 abort.c: Aucun fichier ou dossier de ce type. (gdb) #2 0x00007ffff77037ea in __libc_message (do_abort=do_abort@entry=2, fmt=fmt@entry=0x7ffff781c2e0 "*** Error in `%s': %s: 0x%s ***\n") at ../sysdeps/posix/libc_fatal.c:175 175 ../sysdeps/posix/libc_fatal.c: Aucun fichier ou dossier de ce type. (gdb) #3 0x00007ffff770be0a in malloc_printerr (ar_ptr=<optimized out>, ptr=<optimized out>, str=0x7ffff781c410 "double free or corruption (!prev)", action=3) at malloc.c:5004 5004 malloc.c: Aucun fichier ou dossier de ce type. (gdb) #4 _int_free (av=<optimized out>, p=<optimized out>, have_lock=0) at malloc.c:3865 3865 in malloc.c (gdb) #5 0x00007ffff770f98c in __GI___libc_free (mem=<optimized out>) at malloc.c:2966 2966 in malloc.c (gdb) #6 0x0000000000400e18 in evaluateHadamardProduct (nbElement=1000) at /home/pierre/projects/COURS/TEST/hadamardGDB/main.cpp:54 54 delete[] tabResult;
And print the value of nbElement :
(gdb) print nbElement $1 = 1000
Ok, so we have a bug at the very first call of the function evaluateHadamardProduct.