SUBREG_BYTE question

[Bernd Schmidt]

I need to know the exact meaning of the SUBREG_BYTE field of a SUBREG.

Suppose I have a big-endian target, an SImode (which is the word size)
register, and I want to use the part of the register in a narrower mode.
Should SUBREG_BYTE be zero, or should it be equal to the offset that
would be used if the value were in memory?

The problem I have is that I've got two testcases, and in one of these I
get (subreg:HI (reg:SI xyz) 0) for the lowpart, and in the other I get
(subreg:QI (reg:SI abc) 3).  Fixing one breaks the other.  Which one is
correct?


Bernd