> In some benchmark, I notice stv failed due to cost unprofitable, but the igain
> is inside the loop, but sse<->integer conversion is outside the loop, current
> cost
> model doesn't consider the frequency of those gain/cost.
> The patch weights those cost with frequency just like LRA does.
>
> Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,}.
> Ok for GCC16?
>
> gcc/ChangeLog:
>
> * config/i386/i386-features.cc (scalar_chain::mark_dual_mode_def):
> (general_scalar_chain::compute_convert_gain):
> ---
> gcc/config/i386/i386-features.cc | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/gcc/config/i386/i386-features.cc
> b/gcc/config/i386/i386-features.cc
> index c35ac24fd8a..ae0844a70c2 100644
> --- a/gcc/config/i386/i386-features.cc
> +++ b/gcc/config/i386/i386-features.cc
> @@ -337,18 +337,20 @@ scalar_chain::mark_dual_mode_def (df_ref def)
> /* Record the def/insn pair so we can later efficiently iterate over
> the defs to convert on insns not in the chain. */
> bool reg_new = bitmap_set_bit (defs_conv, DF_REF_REGNO (def));
> + unsigned frequency
> + = REG_FREQ_FROM_BB (BLOCK_FOR_INSN (DF_REF_INSN (def)));
I am generally trying to get rid of remaing uses of REG_FREQ since the
10000 based fixed point arithmetics iot always working that well.
You can do the sums in profile_count type (doing something reasonable
when count is uninitialized) and then convert it to sreal for the final
heuristics.
Typically such code also wants skip scaling by count when optimizing for
size (since in this case we want to count statically). Not sure how
important it is for vector code but I suppose it can happen.
Honza
> if (!bitmap_bit_p (insns, DF_REF_INSN_UID (def)))
> {
> if (!bitmap_set_bit (insns_conv, DF_REF_INSN_UID (def))
> && !reg_new)
> return;
> - n_integer_to_sse++;
> + n_integer_to_sse += frequency;
> }
> else
> {
> if (!reg_new)
> return;
> - n_sse_to_integer++;
> + n_sse_to_integer += frequency;
> }
>
> if (dump_file)
> @@ -556,6 +558,8 @@ general_scalar_chain::compute_convert_gain ()
> rtx src = SET_SRC (def_set);
> rtx dst = SET_DEST (def_set);
> int igain = 0;
> + unsigned frequency
> + = REG_FREQ_FROM_BB (BLOCK_FOR_INSN (insn));
>
> if (REG_P (src) && REG_P (dst))
> igain += 2 * m - ix86_cost->xmm_move;
> @@ -755,6 +759,7 @@ general_scalar_chain::compute_convert_gain ()
> }
> }
>
> + igain *= frequency;
> if (igain != 0 && dump_file)
> {
> fprintf (dump_file, " Instruction gain %d for ", igain);
> --
> 2.34.1
>
