Hello, I am trying to vectorize this loop with gcc-4.4.2 under 64-bit linux ubuntu : for (i = 0; i < 1024; i++) d[i] = (a[i] > 0 ? b[i] : c[i]); but it is not vectorized. For compiling that, I use these flags: gcc -O3 -fprefetch-loop-arrays -lstdc++ -ftree-vectorize -ftree-vectorizer-verbose=2 -ffast-math -mfpmath=sse -march=core2 according to http://gcc.gnu.org/projects/tree-ssa/vectorization.html, it must be vectorized. Would you please tell me what I do wrong? Thanks in advance, Best regards, Fahimeh