> -----Original Message----- > From: Richard Henderson <richard.hender...@linaro.org> > Sent: Friday, November 4, 2022 8:44 PM > To: Taylor Simpson <tsimp...@quicinc.com>; qemu-devel@nongnu.org > Cc: phi...@linaro.org; a...@rev.ng; a...@rev.ng; Brian Cain > <bc...@quicinc.com>; Matheus Bernardino (QUIC) > <quic_mathb...@quicinc.com> > Subject: Re: [PATCH v3 11/11] Hexagon (target/hexagon) Use direct block > chaining for tight loops > > On 11/5/22 06:26, Taylor Simpson wrote: > > Direct block chaining is documented here > > https://qemu.readthedocs.io/en/latest/devel/tcg.html#direct-block-chai > > ning > > > > Hexagon inner loops end with the endloop0 instruction To go back to > > the beginning of the loop, this instructions writes to PC from > > register SA0 (start address 0). To use direct block chaining, we have > > to assign PC with a constant value. So, we specialize the code > > generation when the start of the translation block is equal to SA0. > > > > When this is the case, we defer the compare/branch from endloop0 to > > gen_end_tb. When this is done, we can assign the start address of the > > TB to PC. > > > > Signed-off-by: Taylor Simpson <tsimp...@quicinc.com> > > --- > > target/hexagon/cpu.h | 17 ++++++++---- > > target/hexagon/gen_tcg.h | 3 ++ > > target/hexagon/translate.h | 1 + > > target/hexagon/genptr.c | 57 > ++++++++++++++++++++++++++++++++++++++ > > target/hexagon/translate.c | 34 +++++++++++++++++++++++ > > 5 files changed, 107 insertions(+), 5 deletions(-) > > > > diff --git a/target/hexagon/cpu.h b/target/hexagon/cpu.h index > > ff8c26272d..5260e0f127 100644 > > --- a/target/hexagon/cpu.h > > +++ b/target/hexagon/cpu.h > > @@ -152,16 +152,23 @@ struct ArchCPU { > > > > #include "cpu_bits.h" > > > > +typedef union { > > + uint32_t i; > > + struct { > > + bool is_tight_loop:1; > > + }; > > +} HexStateFlags; > > I don't see this as an improvement on manual flags handling, as it makes the > flags value be dependent on host bit-field ordering. This makes it more > difficult to compare traces across hosts.
I coded this originally with manual handling but decided this would be easier to read/understand/maintain - especially as we add more flags and some have more than 1 bit. I haven't noticed the flags in any of the logs. Where are they printed? > > Otherwise, > Reviewed-by: Richard Henderson <richard.hender...@linaro.org> > > > r~
