"gcc-4.1.2 - could not find spill register"

[amith pawar <amith.pawar@xxxxxxxxx>]

I'm working on fixing a defect in a port of GCC-4.1.2 and the error I
get now is as below:

error: could not find a spill register
(insn 661 660 662 5 (set (reg:SI 272 [ __zero ])
        (sign_extend:SI (reg/v:QI 235 [ __zero ]))) 40 {extendqisi2} (nil)
    (expr_list:REG_DEAD (reg/v:QI 235 [ __zero ])
        (nil)))
internal compiler error: in failed_reload, at reload1.c:5105
Please submit a full bug report,
with preprocessed source if appropriate.
See http://gcc.gnu.org/bugs.html> for instructions.

I checked the extendqisi2 RTL and it appears to be in order.
There are 64 integer registers and 64 FP registers on the machine and the
FP and integer registers can be moved to each other without going
through memory.
On the face of it, it does not appear that all the registers are used
up, though I may be wrong.
Can anyone please suggest what is possibly wrong with the port?

-- 
With best regards,
amit pawar