redundant divmodsi4 not optimized away

[Greg McGary]

I have a port without div or mod machine instructions.  I wrote 
divmodsi4 patterns that do the libcall directly, hoping that GCC would 
recognize the opportunity to use a single divmodsi4 to compute both 
quotient and remainder.  Alas, GCC calls divmodsi4 twice with the same 
divisor and dividend operands.  Is this supposed to work?  Is there a 
special trick to help the optimizer recognize the redundant insn?  I saw 
the 4yr-old thread regarding picochip's desire for the same effect and 
followed the same approach implemented in the current picochip.md (as 
well as my own approach) but no luck.

G