infinite loop in calculate_global_regs_live

[Michael Staudenmaier (r46720)]

hello,
i am currently working on a port of gcc to a new platform using the
latest snapshot of gcc-core (20010205).
Trying to compile testsuites/gcc.c-torture/compile/920501-4.c ends up in
an infinite loop in calculate_global_regs_live.

The produced rtl code looks quite reasonable, the problem seems to be
that the graph of the basic_blocks contains something like a loop.
Queuing all predecessors of the actual basic_block (at the end of the
while loop) causes an infinite analysis of a sequence of 7 basic_blocks.

Questions: 
Is there any prerequisite to the form of the graph of basic_blocks?
Any proposals where i should continue digging for that bug?

regards,

Michael