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Re: [RFC] PowerPC select_section / unique_section
- From: David Edelsohn <dje at watson dot ibm dot com>
- To: Geoff Keating <geoffk at redhat dot com>
- Cc: amodra at bigpond dot net dot au, rth at redhat dot com, Franz dot Sirl-kernel at lauterbach dot com, gcc-patches at gcc dot gnu dot org
- Date: Tue, 03 Sep 2002 12:50:02 -0400
- Subject: Re: [RFC] PowerPC select_section / unique_section
>>>>> Geoff Keating writes:
Geoff> Do you need to do this for AIX? I thought the symbol binding rules
Geoff> for AIX shared libraries were different, they didn't permit overriding
Geoff> a symbol in a shared library.
Because AIX does support a run-time linking mode, this could be an
issue. IBM's compilers currently do not change their code generation to
make this easier or more difficult.
The two issues for both AIX and linuxppc64 are placing certain
types of data in writeable versus read-only sections and the ability to
interpose functions (binds_local_p).
My current belief is that AIX and linuxppc64 always should default
to PIC and shareable, and that -fpic should only affect binds_local_p to
ensure that symbols can be interposed. The 64-bit PowerPC SVR4 ABI
already does have a non-PIC mode which GCC does not generate, so having a
non-PIC mode for PIC code would add confusion. Some of the choice of
sections depends on the PowerPC architecture and how best to utilize it.
I don't think that any policy change from the current defaults
should be made without a lot more investigation -- which I am doing.
Thanks, David