This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
Re: other/7114: ICE building strcoll.op from glibc-2.2.5
On Tue, Jul 16, 2002 at 09:20:27AM +0930, Alan Modra wrote:
> The testcase saves r30 and r31, but both are marked unused (don't
> appear in regs_ever_live). Later rtl analysis decides that the
> save instruction can be eliminated, thus the ICE. The real bug is
> that r30 is not marked used when current_function_needs_context.
> This is also the reason for PR5967.
>
> The code that I copied from the !using_store_multiple case just
> papers over this bug. So the above patch merely makes -mmultiple
> and -mno-multiple consistently wrong.
It gets worse. rs6000/sysv4.h sets PROFILE_BEFORE_PROLOGUE. That
means it is completely wrong for first_reg_to_save to decide r30
needs saving when profiling and current_function_needs_context.
It's too late to think about saving r30. What really needs to
happen is one of
a) Don't use PROFILE_BEFORE_PROLOGUE.
or
b) Save the static chain reg on the stack somewhere before the mcount
call.
or
c) Clobber r30 in a call to a nested function when profiling is
enabled.
People would probably scream if we went with (a) as special purpose
implementations of mcount might make assumptions about the stack.
So, anyone want to speak up on the best way to solve this?
--
Alan Modra
IBM OzLabs - Linux Technology Centre