title: Clang produces slower code when AVX is enabled?
body: <p>I use Xcode 4.5.2 with "Apple LLVM Compiler 4.1" (Clang).</p>
  
  <p>I tried to compile a code which heavily relies on SSE intrinsics with AVX enabled (no _mm256* functions and no __m256 variables yet) and got slower code then I get when only SSE 4.2 is enabled.</p>
  
  <p>Is there any reasonable explanation for this?</p>