compiler-flags

I'd like to know what switch you pass to the gcc compiler to turn off unused variable warnings? I'm getting errors out of boost on windows and I do not want to touch the boost code: C:\boost_1_52_0/boost/system/error_code.hpp: At global scope: C:\boost_1_52_0/boost/system/error_code.hpp:214:36: error: 'boost::system::posix_category' defined but not used [-Werror=unused-variable] C:\boost_1_52_0/boost/system/error_code.hpp:215:36: error: 'boost::system::errno_ecat' defined but not used [-Werror=unused-variable] C:\boost_1_52_0/boost/system/error_code.hpp:216:36: error: 'boost::system::native

After persistently getting error : identifier "atomicAdd" is undefined , I've found the solution to be to compile with -arch sm_20 flag. But how to pass this compiler flag in VS 2010? I have tried like so under Project > Properties : But this apparently has had no effect and the error persists - what am I doing wrong? Many thanks. You can select the options for the GPU Code Generation in this dialog: In this case "compute_20" means that i am compiling for the virtual compute architecture 2.0 - virtual architecture influences the PTX generation stage. The second part that comes after the coma

Beyond setting -Wall , and setting -std=XXX , what other really useful, but less known compiler flags are there for use in C? I'm particularly interested in any additional warnings, and/or and turning warnings into errors in some cases to absolutely minimize any accidental type mismatches. Several of the -f code generation options are interesting: The -ftrapv function will cause the program to abort on signed integer overflow (formally "undefined behaviour" in C). -fverbose-asm is useful if you're compiling with -S to examine the assembly output - it adds some informative comments.

I have heard from various sources (though mostly from a colleague of mine), that compiling with an optimisation level of -O3 in g++ is somehow 'dangerous', and should be avoided in general unless proven to be necessary. Is this true, and if so, why? Should I just be sticking to -O2 ? PlasmaHH In the early days of gcc (2.8 etc.) and in the times of egcs, and redhat 2.96 -O3 was quite buggy sometimes. But this is over a decade ago, and -O3 is not much different than other levels of optimizations (in buggyness). It does however tend to reveal cases where people rely on undefined behavior, due to

I'm compiling my C++ app using GCC 4.3. Instead of manually selecting the optimization flags I'm using -march=native , which in theory should add all optimization flags applicable to the hardware I'm compiling on. But how can I check which flags is it actually using? You can use the -Q --help=target options: gcc -march=native -Q --help=target ... The -v option may also be of use. You can see the documentation on the --help option here . elias To see command-line flags, use: gcc -march=native -E -v - </dev/null 2>&1 | grep cc1 If you want to see the compiler/precompiler defines set by certain