Re: middle-end/6180: Infinite loop in cc1 during dbr pass

[law at redhat dot com]

In message <200204051935.g35JZdxl014766@hiauly1.hia.nrc.ca>, "John David Anglin
" writes:
 > > Infinite loop occurs compiling nm.c (binutils 2.12.90
 > > 20020404).  The final loop in dbr_sequence loops forever
 > > because of a loop in the insn chain that occurs compiling
 > > the function filter_symbols.  The insn chain appears ok
 > > when dbr_sequence is called.
 > 
 > This is what is causing the problem.  There is a millicode call
 > insn in the function "return" just before the epilogue begin note.
 > dbr_schedule puts the first insn in the epilogue into the delay
 > slot of the call.  This insn restores %r2 from the stack.  It's
 > probably ok to put it into the delay slot of the millicode call
 > since it doesn't use %r2, but the start of the epilogue is now
 > in an indeterminate position.  reposition_prologue_and_epilogue_notes
 > moves the epilogue begin note before the sequence.  However, in
 > fixing the insn chain, it apparently doesn't check for a sequence
 > and the chain is left in a corrupt state.  In particular, it doesn't
 > touch the numbering inside the sequence.
 > 
 > I probably can fix this by adding a blockage at the beginning
 > of the epilogue.  However, this seems like overkill and simply
 > avoids the problem.
 > 
 > Suggestions?
I think reposition_prologue_and_epilogue_notes really needs to understand
SEQUENCEs and deal with them properly.  

jeff