lib/Target/Alpha/README.txt

   1 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   2 Fix Ordered/Unordered FP stuff
   3
   4
   5 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   6 improve bytezap opertunities
   7 ulong %foo(ulong %y) {
   8 entry:
   9         %tmp = and ulong %y,  65535
  10         %tmp2 = shr ulong %tmp,  ubyte 3
  11         ret ulong %tmp2
  12 }
  13
  14
  15 compiles to a 3 instruction sequence without instcombine
  16         zapnot $16,3,$0
  17         srl $0,3,$0
  18         ret $31,($26),1
  19
  20 After instcombine you get
  21 ulong %foo(ulong %y) {
  22 entry:
  23         %tmp = shr ulong %y, ubyte 3            ; <ulong> [#uses=1]
  24         %tmp2 = and ulong %tmp, 8191            ; <ulong> [#uses=1]
  25         ret ulong %tmp2
  26 }
  27
  28 which compiles to
  29         lda $0,8191($31)
  30         srl $16,3,$1
  31         and $1,$0,$0
  32         ret $31,($26),1
  33