Nikunj A Dadhania <nik...@linux.vnet.ibm.com> writes: > Richard Henderson <r...@twiddle.net> writes: > >> On 02/24/2017 01:58 PM, David Gibson wrote: >>> On Fri, Feb 24, 2017 at 06:18:22AM +0530, Nikunj A Dadhania wrote: >>>> Richard Henderson <r...@twiddle.net> writes: >>>> >>>>> On 02/24/2017 06:56 AM, Nikunj A Dadhania wrote: >>>>>> Now get rid all the split out variables so, ca, ov. After this patch, >>>>>> all the bits are stored in CPUPPCState::xer at appropriate places. >>>>>> >>>>>> Signed-off-by: Nikunj A Dadhania <nik...@linux.vnet.ibm.com> >>>>>> --- >>>>>> target/ppc/cpu.c | 8 +--- >>>>>> target/ppc/cpu.h | 26 ++++++------ >>>>>> target/ppc/int_helper.c | 12 +++--- >>>>>> target/ppc/translate.c | 106 >>>>>> +++++++++++++++++++++++++----------------------- >>>>>> 4 files changed, 78 insertions(+), 74 deletions(-) >>>>> >>>>> I do not think this is a good direction to take this. >>>> >>>> Hmm, any particular reason? >>> >>> Right, I suggested this, but based only a suspicion that the split >>> variables weren't worth the complexity. I'm happy to be corrected by >>> someone with better knowledge of TCG, but it'd be nice to know why. >> >> Normally we're interested in minimizing the size of the generated code, >> delaying computation until we can show it being used. >> >> Now, ppc is a bit different from other targets (which might compute overflow >> for any addition insn) in that it only computes overflow when someone asks >> for >> it. Moreover, it's fairly rare for the addo/subo/nego instructions to >> be used. > >> Therefore, I'm not 100% sure what the "best" solution is. > > Agreed, with that logic, wont it be more efficient to move the OV/CA > updationg to respective callers, and when xer_read/write happens, its > just one tcg_ops.
BTW, i haven't seen remarkable difference in the boot time after this change. Regards Nikunj
