https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68664
--- Comment #18 from Segher Boessenkool <segher at gcc dot gnu.org> --- Author: segher Date: Mon Feb 6 19:19:49 2017 New Revision: 245215 URL: https://gcc.gnu.org/viewcvs?rev=245215&root=gcc&view=rev Log: sched: Do not move expensive insns speculatively (PR68664) Scheduling should never move very expensive instructions to places they are executed more frequently. This patch fixes that, reducing the execution time of c-ray by over 40% (I tested on a BE Power7 system). This introduces a new target hook sched.can_speculate_insn which returns whether the scheduler is allowed to speculate a given instruction. The rs6000 implementation disallows all divide and square root instructions. PR rtl-optimization/68664 * target.def (can_speculate_insn): New hook. * doc/tm.texi.in (TARGET_SCHED_CAN_SPECULATE_INSN): New hook. * doc/tm.texi: Regenerate. * sched-rgn.c (can_schedule_ready_p): Use the new hook. * config/rs6000/rs6000.c (TARGET_SCHED_CAN_SPECULATE_INSN): New macro. (rs6000_sched_can_speculate_insn): New function. Modified: trunk/gcc/ChangeLog trunk/gcc/config/rs6000/rs6000.c trunk/gcc/doc/tm.texi trunk/gcc/doc/tm.texi.in trunk/gcc/sched-rgn.c trunk/gcc/target.def
