Hi, Due to pressing requirements of our target processor/application, I am implementing several popular loop pragmas in our private porting. I've already implemented "unroll" and "ivdep", and am now working on "loop_count" to give GCC hints about number of iterations.
The problem I am now facing is that GCC has many loop optimizations in both tree and rtl levels that change loop property. For example, loop versioning by unrolling called by predom pass and loop fissions by graphite passes. This makes loop_count simply wrong for transformed loop(s). What is best strategy? Updating loop count pragma to track changed loops, or disable loop optimizations altogether in presence of loop pragma? To less extent, loop optimizations also affect other loop pragmas. For example, I have to disable cunroll pass in presence of #pragma unroll because it is confusing for user. Does anyone know how other compilers, e.g., icc, handle such issues? Thanks for any input, Bingfeng Mei Broadcom UK
