search for: zz_0000728f

...C functions. We then compiled each of these functions with 7 compilers: llvm-gcc, clang, Intel cc, Sun cc, various versions of gcc. We then looked for functions where a particular pair of compilers exhibited widely differing abilities to optimize. For example, consider this function: int ZZ_0000728f(int x,int y){return o1s(m8s(x,-2),(x?1:y));} gcc-3.4 can see that it always returns 0, and emits code doing that. On the other hand, llvm-gcc emits 228 bytes of object code (at -Os) to compute the same zeroes. The funny-named functions are little safe-math utilities that avoid undefined behav...

So it would appear that llvm-gcc and clang are both slower than gcc4 which is infamous for being slow at compiling code, and yes this is with a release build/--enable-optimizations. This seems to go against notes such as http://clang.llvm.org/features.html#performance which claim clang is signifcantly faster than gcc. Below are some times and the larger object files when compiling an i386

...h of these functions with 7 compilers: > llvm-gcc, clang, Intel cc, Sun cc, various versions of gcc. > > We then looked for functions where a particular pair of compilers > exhibited widely differing abilities to optimize. For example, consider > this function: > > int ZZ_0000728f(int x,int y){return o1s(m8s(x,-2),(x?1:y));} > > gcc-3.4 can see that it always returns 0, and emits code doing that. On > the other hand, llvm-gcc emits 228 bytes of object code (at -Os) to > compute the same zeroes. > > The funny-named functions are little safe-math utiliti...

...ed each of these functions with 7 compilers: > llvm-gcc, clang, Intel cc, Sun cc, various versions of gcc. > > We then looked for functions where a particular pair of compilers > exhibited widely differing abilities to optimize. For example, consider > this function: > > int ZZ_0000728f(int x,int y){return o1s(m8s(x,-2),(x?1:y));} > > gcc-3.4 can see that it always returns 0, and emits code doing that. On > the other hand, llvm-gcc emits 228 bytes of object code (at -Os) to > compute the same zeroes. > > The funny-named functions are little safe-math utilities t...