This directory contains code for AMD bulldozer including its piledriver update. We currently make limited use of SIMD instructions, both via the MPN_PATH and via inclusion of x86_64/fastsse files. The bd1 cores share one SIMD/FPU pipeline for two integer units. This probably means that an all-core GMP load (such as a HPC load) might run slower if there is significant SIMD dependency. We should perhaps allow a special 'bd1nosimd' pseudo cpu-name excluding any SIMD code.