http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52544
sebastian <oeste.sebastian at googlemail dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |oeste.sebastian at | |googlemail dot com --- Comment #2 from sebastian <oeste.sebastian at googlemail dot com> 2012-07-23 14:49:46 UTC --- I've make a similar observation, with the function __mm_xor_si128 from emmintrin.h and the flag -finstrument-functions. gcc Version 4.7.0 (same results with 4.7.1) $ gcc -v Using built-in specs. COLLECT_GCC=gcc COLLECT_LTO_WRAPPER=/home/oeste/gcc/libexec/gcc/x86_64-unknown-linux-gnu/4.7.0/lto-wrapper Target: x86_64-unknown-linux-gnu Configured with: ./configure --prefix=/home/oeste/gcc/ Thread model: posix gcc version 4.7.0 (GCC) $ gcc -Wall -Wextra -fno-strict-aliasing -fwrapv -save-temps -finstrument-functions ./test.c test.o: In function `main': test.c:(.text+0x50): undefined reference to `_mm_xor_si128' test.c:(.text+0x61): undefined reference to `_mm_xor_si128' collect2: error: ld returned 1 exit status When compile without -finstrument-functions all will be done.