On 5/17/23 00:57, liuhongt via Gcc-patches wrote:
r14-172-g0368d169492017 replaces GENERAL_REGS with NO_REGS in cost
calculation when the preferred register class are not known yet.
It regressed powerpc PR109610 and PR109858, it looks too aggressive to use
NO_REGS when mode can be allocated with GENERAL_REGS.
The patch takes a step back, still use GENERAL_REGS when
hard_regno_mode_ok for mode and GENERAL_REGS, otherwise uses NO_REGS.
Kewen confirmed the patch fixed PR109858, I vefiried it also fixed PR109610.
Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,}.
No big performance impact for SPEC2017 on icelake server.
Ok for trunk?
gcc/ChangeLog:
* ira-costs.cc (scan_one_insn): Only use NO_REGS in cost
calculation when !hard_regno_mode_ok for GENERAL_REGS and
mode, otherwise still use GENERAL_REGS.
BTW, Vlad is on PTO right now. I'm sure he'll handle this after he
returns and starts digging out of all the stuff that's piled up.
jeff
