ca87579f23
This is currently only used to decide whether it's worth doing an "are all lanes running" check at the start of functions--for small functions, it's not worth the overhead. The cost is estimated relatively early in compilation (e.g. before we know if an array access is a scatter/gather or not, before constant folding, etc.), so there are many known shortcomings.
============================== Intel(r) SPMD Program Compiler ============================== Welcome to the Intel(r) SPMD Program Compiler (ispc)! ispc is a new compiler for "single program, multiple data" (SPMD) programs. Under the SPMD model, the programmer writes a program that mostly appears to be a regular serial program, though the execution model is actually that a number of program instances execute in parallel on the hardware. ispc compiles a C-based SPMD programming language to run on the SIMD units of CPUs; it frequently provides a a 3x or more speedup on CPUs with 4-wide SSE units, without any of the difficulty of writing intrinsics code. ispc is an open source compiler under the BSD license; see the file LICENSE.txt. ispc supports Windows, Mac, and Linux, with both x86 and x86-64 targets. It currently supports the SSE2 and SSE4 instruction sets, though support for AVX should be available soon. For more information and examples, as well as a wiki and the bug database, see the ispc distribution site, http://ispc.github.com.