K 10
svn:author
V 3
jhb
K 8
svn:date
V 27
2006-09-28T19:38:02.000000Z
K 7
svn:log
V 754
Optimize the int 15/87 handler for space to shave another 16 bytes off of
BTX (and thus boot2):
- Don't bother saving %eax, %ebx, or %ecx as it is not necessary.
- Use a more compact sequence to load the base value out of a GDT entry
  by loading the contiguous low 24 bits into the upper 24 bits of %eax,
  loading the high 8 bits into %al, and using a ror to rotate the bits
  (2 mov's and a ror) rather than loading the pieces in smaller chunks
  (3 mov's and a shl).
- Use movzwl + leal instead of movl + movw + shll + addl.
- Use 'xchgl %eax,%foo' rather than 'movl %eax,%foo' for cases where
  it's ok to trash %eax.  xchgl %eax, foo is a 1-byte opcode whereas the
  mov is a 2-byte opcode.
- Use movzwl rather than xorl + movw.

MFC after:	1 week

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