> Hi,
> this patch updates znver2 costs to match reality. In particular we
> re-benchmarked memcpy strategies and it looks that glibc now wins even
> for relatively small blocks.
> Moreover I updated costs of moves to reflect that znver2 has 256 vector
> paths and faster multiplication.
>
> Bootstrapped/regtested x86_64-linux, comitted.
>
> Honza
>
> * x86-tune-costs.h (znver2_memcpy): Update.
> (znver2_costs): Update 256 bit SSE costs and multiplication.
Hello,
I have now backported the patch to gcc 9 branch.
Honza
> Index: config/i386/x86-tune-costs.h
> ===================================================================
> --- config/i386/x86-tune-costs.h (revision 273727)
> +++ config/i386/x86-tune-costs.h (working copy)
> @@ -1279,12 +1279,12 @@ struct processor_costs znver1_cost = {
> static stringop_algs znver2_memcpy[2] = {
> {libcall, {{6, loop, false}, {14, unrolled_loop, false},
> {-1, rep_prefix_4_byte, false}}},
> - {libcall, {{16, loop, false}, {8192, rep_prefix_8_byte, false},
> + {libcall, {{16, loop, false}, {64, rep_prefix_4_byte, false},
> {-1, libcall, false}}}};
> static stringop_algs znver2_memset[2] = {
> {libcall, {{8, loop, false}, {24, unrolled_loop, false},
> {2048, rep_prefix_4_byte, false}, {-1, libcall, false}}},
> - {libcall, {{48, unrolled_loop, false}, {8192, rep_prefix_8_byte, false},
> + {libcall, {{24, rep_prefix_4_byte, false}, {128, rep_prefix_8_byte, false},
> {-1, libcall, false}}}};
>
> struct processor_costs znver2_cost = {
> @@ -1335,11 +1335,11 @@ struct processor_costs znver2_cost = {
> in SImode and DImode. */
> {8, 8}, /* cost of storing MMX registers
> in SImode and DImode. */
> - 2, 3, 6, /* cost of moving XMM,YMM,ZMM
> + 2, 2, 3, /* cost of moving XMM,YMM,ZMM
> register. */
> - {6, 6, 6, 10, 20}, /* cost of loading SSE registers
> + {6, 6, 6, 6, 12}, /* cost of loading SSE registers
> in 32,64,128,256 and 512-bit. */
> - {6, 6, 6, 10, 20}, /* cost of unaligned loads. */
> + {6, 6, 6, 6, 12}, /* cost of unaligned loads. */
> {8, 8, 8, 8, 16}, /* cost of storing SSE registers
> in 32,64,128,256 and 512-bit. */
> {8, 8, 8, 8, 16}, /* cost of unaligned stores. */
> @@ -1372,7 +1372,7 @@ struct processor_costs znver2_cost = {
> COSTS_N_INSNS (1), /* cost of cheap SSE instruction. */
> COSTS_N_INSNS (3), /* cost of ADDSS/SD SUBSS/SD insns. */
> COSTS_N_INSNS (3), /* cost of MULSS instruction. */
> - COSTS_N_INSNS (4), /* cost of MULSD instruction. */
> + COSTS_N_INSNS (3), /* cost of MULSD instruction. */
> COSTS_N_INSNS (5), /* cost of FMA SS instruction. */
> COSTS_N_INSNS (5), /* cost of FMA SD instruction. */
> COSTS_N_INSNS (10), /* cost of DIVSS instruction.
> */
