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Re: Does gcc violate the ia64 ABI?
On Sat, May 17, 2003 at 11:15:59AM -0700, Richard Henderson wrote:
> On Fri, May 16, 2003 at 06:45:22PM -0700, H. J. Lu wrote:
> > Gcc can skip gp save/restore across a local call. Right now, gcc
> > saves and restores gp across a local call.
>
> Indeed, but it also tail-calls to non-local functions, so
> gcc is going to have a compatibility problem if we change
> the ABI.
>
That is very unfortunate. We have several choices:
1. Do nothing. It is very bad.
2. Fix gcc and use a bit in ELF header to indicate the ABI change.
Linker will make sure no mixed .o/.so files.
3. Fix gcc and use a special empty note section to indicate the ABI
change. Linker will make sure no mixed .o/.so files.
I prefer 3, 2, 1, in that order.
BTW, Clause 'd' is in my Sept. 2000 copy of the runtime guide. It may
have been there for a long time. We must have missed it somehow.
H.J.