Finding an access violation in an optimized build, that does not show up in debug build (gcc)
gcc optimization levels
which shortcut key is used to debug a program in microsoft visual studio
gcc optimization techniques
I have (probably quite common) issue that my code crashes with:
unknown location(0): fatal error in "BaumIteration_OneDimensionCase": memory access violation at address: 0xfffffff8: no mapping at fault address
for an optimized build (-O3 in gcc under Linux), but works fine in a debug build. I tried to debug the release build, but it just doesn't give any useful information. What are the standard techniques to solve this issue?
In some other question someone suggested using valgrind. How do I use it in this particular circumstances (if this is the right way forward anyways...)?
As mentioned , there is some code bug , but it so happens that due to different code generated, memory addresses used, it does not show up in unoptimized, debug build.
Since you asked about valgrind, the specific valgrind tool you should use is memcheck. It does a run time analysis of the code. It sure would help to find any possible errors or warnings in heap errors like memory leaks, array overbound access(Read/write), double frees ...
If you are on Linux platform , this is how to run your binary under valgrind:
valgrind --tool=memcheck --leak-check=full --show-reachable=yes --log-file=valgrind-log.txt -v --track-origins=yes <your binary file>
Read more about valgrind memcheck here.
Also if possible and if you use g++ to build , add these compiler options to your build process:
-Wall -Wextra -pedantic -Wuninitialized
Analyze the errors/warnings thrown by g++. It might show possible cause of error.
Common reasons for bugs in release version not present in debug , What's up with you people? Many times, in debug mode in C++ all variables are null initialized, then optimization can also cause some issues in release mode. like mem access violation in VC++, but the same can be a issue at Try to reproduce anomalous behaviour in a debug build if you can, and� With this information, finding the line number where an access violation occurred is a two step process. First, find from the map listing the largest code symbol address (A base ) that is less than the address at which the crash occurs (A crash ).
It's probably a problem that exists even in the debug build, but due to memory layout and what is being corrupted, it probably doesn't show up. As start point look at all the dynamic allocations, frees, arrays, pointers, uninitialized variable!
If i face this problem I will reduce the code size step by step to see if the problem exists this way I can find the location which is causing problem!
Using the GNU Compiler Collection (GCC): Debugging Options, Nevertheless it proves possible to debug optimized output. This option allows the build system to avoid linking files with debug See also -frecord-gcc- switches for another way of storing compiler options -gdwarf-2 does not accept a concatenated debug level, because GCC used to An entry is made up of three fields:. I'm developing a computer game and I *was* geting an Access Violation in release mode. I had literaly thousands of lines of code to go thru, and I was almost giving it up. Simply by turning the Warning Level to 4, I detected the problem.
Another option is Intel Inspector which has similar capabilities to Valgrind. It comes with parallel studio and is really good at tracking memory errors down and pointing right to the problems.
If you're working on the cheap that may be no help but we all use the intel compiler where I work so it was a dream to save a bunch of time vs trying to hunt this down otherwise
Using the GNU Compiler Collection (GCC): Optimize Options, Most optimizations are completely disabled at -O0 or if an -O level is not set You can invoke GCC with -Q --help=optimizers to find out the exact set of See Overall Options, for examples. -O; -O1. Optimize. Optimizing compilation -Og should be the optimization level of choice for the standard edit-compile-debug cycle,� Select Build->Build Solution. Go to Debug->Graphics->Start Diagnostics Install the Graphics Tools if a popup shows up. The standalone build should fire up and this message should appear in the top left: "Frames captured: 0. Use Print Screen key to capture a frame". Press the Print Screen key. Alt-Tab out of the standalone build and go to Visual
Access violation on Windows PGO Release builds compiled by , Access violation on Windows PGO Release builds compiled by VS2015 #8336 Locally, I did a build of CoreCLR without CFG and the crash did not repro, so I Now I am helping them debug this from the GC's POV (ie, debug it like a heap MSVC , clang , icc , and gcc will all do this optimization: https://godbolt.org/g/� Debug information being "on" does not affect the size or speed of the executable program - debug information is compiled into the DCUs and does not get linked into the executable. Delphi Compiler - Compiling - Debugging - Local symbols ON - When a program or unit is compiled with this option enabled, the integrated debugger lets you examine and
Debug vs. Release, You get memory access failures, dialogs don't come up, controls don't work, results come out incorrectly, A bit of background: I have been working with optimizing compiler since 1969. There error might not even show up until the program exits! Debug/whatever.dll, and make a similar change in the release build. If I try to run usr/bin/clonetest from build_Release_segfaults a second time, then it works properly. It only seems to segfault if Example.bare does not exist yet. It is able to create Example.bare before segfaulting, but leaves a config.lock instead of a HEAD like the successful Debug build.
Debugging with GDB, Many of our most important programs do not come with free reference manuals and free Next: Commands, Previous: Sample Session, Up: Top [Contents][ Index] This will cause gdb to debug gcc , and to set gcc 's command-line arguments (see This option causes GDB to print details about its build-time configuration� The bug happens using an ASM optimized static zlib 1.2.5 or 1.2.7 on Windows x86. Supposed is to have no output, but currently it outs "%Cë". Non ASM versions on Windows do that right, as well both ASM and non ASM builds on Linux.
- Have you tried gcc -O3 -g? It may not generate the same code, but it could be a good starting point for tracking down the problem. Or it could be a compiler bug. Good luck with that.
- Acually, now that I think about it, sounds like maybe some UB that is gleefully optimized into a seg fault by gcc.