openpower/isa/branch.mdwn

   1 # Branch
   2
   3 I-Form
   4
   5 * b target_addr (AA=0 LK=0)
   6 * ba target_addr (AA=1 LK=0)
   7 * bl target_addr (AA=0 LK=1)
   8 * bla target_addr (AA=1 LK=1)
   9
  10     if AA then NIA  <-iea EXTS(LI || 0b00)
  11     else       NIA  <-iea CIA + EXTS(LI || 0b00)
  12     if LK then LR <-iea  CIA + 4
  13
  14 Special Registers Altered:
  15
  16     LR                       (if LK=1)
  17
  18 # Branch Conditional
  19
  20 B-Form
  21
  22 * bc BO,BI,target_addr (AA=0 LK=0)
  23 * bca BO,BI,target_addr (AA=1 LK=0)
  24 * bcl BO,BI,target_addr (AA=0 LK=1)
  25 * bcla BO,BI,target_addr (AA=1 LK=1)
  26
  27     if (mode_is_64bit) then M <- 0
  28     else M <- 32
  29     if ¬BO[2] then CTR <- CTR - 1
  30     ctr_ok <- BO[2] | ((CTR[M:63] != 0) ^ BO[3])
  31     cond_ok <- BO[0] | ¬(CRBI+32 ^ BO[1])
  32     if ctr_ok & cond_ok then
  33       if AA then NIA <-iea EXTS(BD || 0b00)
  34       else       NIA <-iea CIA + EXTS(BD || 0b00)
  35     if LK then LR  <-iea  CIA + 4
  36
  37 Special Registers Altered:
  38
  39     CTR                    (if BO2=0)
  40     LR                       (if LK=1)
  41
  42 # Branch Conditional to Link Register
  43
  44 XL-Form
  45
  46 * bclr BO,BI,BH (LK=0)
  47 * bclrl BO,BI,BH (LK=1)
  48
  49     if (mode_is_64bit) then M <- 0
  50     else M <- 32
  51     if ¬BO[2]  then CTR <- CTR - 1
  52     ctr_ok <- BO[2] | ((CTR[M:63] != 0) ^ BO[3])
  53     cond_ok <- BO[0] | ¬(CR[BI+32] ^  BO[1])
  54     if ctr_ok & cond_ok then NIA <-iea LR[0:61] || 0b00
  55     if LK then LR <-iea CIA + 4
  56
  57 Special Registers Altered:
  58
  59     CTR                    (if BO2=0)
  60     LR                       (if LK=1)
  61
  62 # Branch Conditional to Count Register
  63
  64 XL-Form
  65
  66 * bcctr BO,BI,BH (LK=0)
  67 * bcctrl BO,BI,BH (LK=1)
  68
  69     cond_ok <- BO[0] | ¬(CR[BI+32] ^ BO[1])
  70     if cond_ok then NIA <-iea CTR[0:61] || 0b00
  71     if LK then LR <-iea CIA + 4
  72
  73 Special Registers Altered:
  74
  75     LR                     (if LK=1)
  76
  77 # Branch Conditional to Branch Target Address Register
  78
  79 XL-Form
  80
  81 * bctar BO,BI,BH (LK=0)
  82 * bctarl BO,BI,BH (LK=1)
  83
  84     if (mode_is_64bit) then M <- 0
  85     else M <- 32
  86     if ¬BO[2] then CTR <- CTR - 1
  87     ctr_ok <- BO[2]  | ((CTR[M:63] != 0) ^ BO[3])
  88     cond_ok <- BO[0] | ¬(CR[BI+32] ^ BO[1])
  89     if ctr_ok & cond_ok then NIA <-iea TAR[0:61]  || 0b00
  90     if LK then LR <-iea  CIA + 4
  91
  92 Special Registers Altered:
  93
  94     CTR                    (if BO2=0)
  95     LR                       (if LK=1)