> On Oct 7, 2016, at 6:08 PM, Pat Haugen <pthau...@linux.vnet.ibm.com> wrote: > > The patch here, https://gcc.gnu.org/ml/gcc-patches/2014-10/msg01872.html, > attempted to scale down the register limit used by -fsched-pressure for the > case where the block in question executes as frequently as the entry block to > just the call_clobbered (i.e. call_used) regs. But the code is actually > scaling toward call_saved registers. The following patch corrects that by > computing call_saved regs per class and subtracting out some scaled portion > of that. > > Bootstrap/regtest on powerpc64le with no new failures. Ok for trunk?
Hi Pat, I stared at your patch and current code for good 30 minutes, and I still don't see what is wrong with the current code. With your patch the number of registers from class CL that scheduler has at its disposal for a single-basic-block function will be: sched_call_regs_num[CL] = ira_class_hard_regs_num[CL] - call_saved_regs_num[CL]; where call_saved_regs_num is number of registers in class CL that need to be saved in the prologue (i.e., "free" registers). I can see some logic in setting sched_call_regs_num[CL] = call_saved_regs_num[CL]; but not in subtracting number of such registers from the number of total available hard registers. Am I missing something? Also, could you share the testcase that you used to investigate the problem with register-aware scheduling? I wonder if there is a problem lurking. Thank you, -- Maxim Kuvyrkov www.linaro.org > > -Pat > > > 2016-10-07 Pat Haugen <pthau...@us.ibm.com> > > * haifa-sched.c call_used_regs_num: Rename to... > call_saved_regs_num: ...this. > (sched_pressure_start_bb): Scale call_saved regs not call_used. > (alloc_global_sched_pressure_data): Compute call_saved regs. > > > <sched-pressure-reg-limit.diff>
