On Sun, Sep 20, 2009 at 3:43 PM, Maxim Kuvyrkov <ma...@codesourcery.com> wrote: > Amker.Cheng wrote: >> >> Hi : >> I'm puzzled when looking into speculative scheduling in gcc, the 4.2.4 >> version. >> >> First, I noticed the document describing IBM haifa instruction >> scheduler(as PowerPC Reference Compiler Optimization Project). >> >> It presents that the instruction motion from bb s(dominated by t) >> to t is speculative when split_blocks(s, t) not empty. >> >> Second, There is SCED_FLAGS like DO_SPECULATION in codes. > > These are two different types of speculative optimizations. > >> >> Here goes questions. >> 1, Does the DO_SPECULATION flag constrol whether do the >> mentioned speculative motion or not? > > DO_SPECULATION flag controls generation of IA64 data and control speculative > instructions. It is not used on other architectures. > > Speculative instruction moves from the split blocks are controlled by > flag_schedule_speculative. > > -- > Maxim >
Yes! I've just found it's used for IA64 and was merged into gcc in version 4.2.0. Thanks. -- Best Regards.
