gcc/config/sh/divcost-analysis

   1 Analysis of cycle costs for SH4:
   2
   3 -> udiv_le128:            5
   4 -> udiv_ge64k:            6
   5 -> udiv udiv_25:         10
   6 -> pos_divisor:           3
   7 -> pos_result linear:     5
   8 -> pos_result - -:        5
   9 -> div_le128:             7
  10 -> div_ge64k:             9
  11 sdivsi3 -> udiv_25             13
  12 udiv25 -> div_ge64k_end:       15
  13 div_ge64k_end -> rts:          13
  14 div_le128 -> div_le128_2:       2, r1 latency 3
  15 udiv_le128 -> div_le128_2:      2, r1 latency 3
  16 (u)div_le128 -> div_by_1:       9
  17 (u)div_le128 -> rts:           17
  18 div_by_1(_neg) -> rts:          4
  19 div_ge64k -> div_r8:            2
  20 div_ge64k -> div_ge64k_2:       3
  21 udiv_ge64k -> udiv_r8:          3
  22 udiv_ge64k -> div_ge64k_2:      3 + LS
  23 (u)div_ge64k -> div_ge64k_end: 13
  24 div_r8 -> div_r8_2:             2
  25 udiv_r8 -> div_r8_2:            2 + LS
  26 (u)div_r8 -> rts:              21
  27
  28 -> - + neg_result:             5
  29 -> + - neg_result:             5
  30 -> div_le128_neg:              7
  31 -> div_ge64k_neg:              9
  32 -> div_r8_neg:                11
  33 -> <64k div_ge64k_neg_end:    28
  34 -> >=64k div_ge64k_neg_end:   22
  35 div_ge64k_neg_end ft -> rts:  14
  36 div_r8_neg_end -> rts:         4
  37 div_r8_neg -> div_r8_neg_end: 18
  38 div_le128_neg -> div_by_1_neg: 4
  39 div_le128_neg -> rts          18
  40
  41          sh4-200    absolute divisor range:
  42             1  [2..128]  [129..64K) [64K..|dividend|/256] >=64K,>|dividend/256|
  43 udiv       18     22         38            32                   30
  44 sdiv pos:  20     24         41            35                   32
  45 sdiv neg:  15     25         42            36                   33
  46
  47          sh4-300    absolute divisor range:
  48                  8 bit      16 bit       24 bit              > 24 bit
  49 udiv              15         35            28                   25
  50 sdiv              14         36            34                   31
  51
  52
  53 fp-based:
  54
  55 unsigned: 42 + 3 + 3 (lingering ftrc latency + sts fpul,rx) at caller's site
  56 signed: 33 + 3 + 3 (lingering ftrc latency + sts fpul,rx) at caller's site
  57
  58 call-div1:    divisor range:
  59               [1..64K)  >= 64K
  60 unsigned:       63        58
  61 signed:         76        76
  62
  63 SFUNC_STATIC call overhead:
  64 mov.l 0f,r1
  65 bsrf r1
  66
  67 SFUNC_GOT call overhead - current:
  68 mov.l 0f,r1
  69 mova 0f,r0
  70 mov.l 1f,r2
  71 add r1,r0
  72 mov.l @(r0,r2),r0
  73 jmp @r0
  74 ; 3 cycles worse than SFUNC_STATIC
  75
  76 SFUNC_GOT call overhead - improved assembler:
  77 mov.l 0f,r1
  78 mova 0f,r0
  79 mov.l @(r0,r1),r0
  80 jmp @r0
  81 ; 2 cycles worse than SFUNC_STATIC
  82
  83 \f
  84 Copyright (C) 2006, 2007 Free Software Foundation, Inc.
  85
  86 Copying and distribution of this file, with or without modification,
  87 are permitted in any medium without royalty provided the copyright
  88 notice and this notice are preserved.