extv, extzv and insv patterns

[Roman Lechtchinsky <rl at cs dot tu-berlin dot de>]

Hi,

I'm somewhat confused about the arguments to the above patterns. md.texi
has the following to say about extv (the others are similar):

Extract a bit-field from operand 1 (a register or memory operand), where
operand 2 specifies the width in bits and operand 3 the starting bit, and
store it in operand 0.  Operand 0 must have mode word_mode. Operand 1 may
have mode byte_mode or word_mode; often word_mode is allowed only for
registers.  Operands 2 and 3 must be valid for word_mode.

Which mode is operand 3 (the starting bit) supposed to be relative to
(which is important if BITS_BIG_ENDIAN is 1)? Is it the mode of operand 1
or word_mode? The code which calls these patterns seems to generally (but
not always :-) assume the latter.

Bye

Roman