> which is not the case with core_cost (and similar with skylake_cost):
>
> 2, 2, 4, /* cost of moving XMM,YMM,ZMM register */
> {6, 6, 6, 6, 12}, /* cost of loading SSE registers
> in 32,64,128,256 and 512-bit */
> {6, 6, 6, 6, 12}, /* cost of storing SSE registers
> in 32,64,128,256 and 512-bit */
> 2, 2, /* SSE->integer and integer->SSE moves */
>
> We have the same cost of moving between integer registers (by default
> set to 2), between SSE registers and between integer and SSE register
> sets. I think that at least the cost of moves between regsets should
> be substantially higher, rs6000 uses 3x cost of intra-regset moves;
> that would translate to the value of 6. The value should be low enough
> to keep the cost below the value that forces move through the memory.
> Changing core register allocation cost of SSE <-> integer to:
>
> --cut here--
> Index: config/i386/x86-tune-costs.h
> ===================================================================
> --- config/i386/x86-tune-costs.h (revision 275281)
> +++ config/i386/x86-tune-costs.h (working copy)
> @@ -2555,7 +2555,7 @@ struct processor_costs core_cost = {
> in 32,64,128,256 and 512-bit */
> {6, 6, 6, 6, 12}, /* cost of storing SSE registers
> in 32,64,128,256 and 512-bit */
> - 2, 2, /* SSE->integer and
> integer->SSE moves */
> + 6, 6, /* SSE->integer and
> integer->SSE moves */
> /* End of register allocator costs. */
> },
>
> --cut here--
>
> still produces direct move in gcc.target/i386/minmax-6.c
>
> I think that in addition to attached patch, values between 2 and 6
> should be considered in benchmarking. Unfortunately, without access to
> regressed SPEC tests, I can't analyse these changes by myself.
>
> Uros.
Apply similar change to skylake_cost, on skylake workstation we got
performance like:
---------------------------
version |
548_exchange_r score
gcc10_20180822: | 10
apply remove_max8 | 8.9
also apply increase integer_tofrom_sse cost | 9.69
-----------------------------
Still 3% regression which is related to _gfortran_mminloc0_4_i4 in
libgfortran.so.5.0.0.
I found suspicious code as bellow, does it affect?
------------------
modified gcc/config/i386/i386-features.c
@@ -590,7 +590,7 @@ general_scalar_chain::compute_convert_gain ()
if (dump_file)
fprintf (dump_file, " Instruction conversion gain: %d\n", gain);
- /* ??? What about integer to SSE? */
+ /* ??? What about integer to SSE? */???
EXECUTE_IF_SET_IN_BITMAP (defs_conv, 0, insn_uid, bi)
cost += DF_REG_DEF_COUNT (insn_uid) * ix86_cost->sse_to_integer;
------------------
--
BR,
Hongtao
