[Bug target/69648] [5/6 Regression] wrong code with -O -mtune=winchip-c6 -fPIC -fexpensive-optimizations -msse4 @ i686

[ubizjak at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69648

Uroš Bizjak <ubizjak at gmail dot com> changed:

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                 CC|                            |ienkovich at gcc dot gnu.org

--- Comment #6 from Uroš Bizjak <ubizjak at gmail dot com> ---
(In reply to Bernd Schmidt from comment #5)
> Yeah, my current theory is that r87 is spilled at the start, then the spill
> reg is inherited in all the existing uses of it, and lra thinks it can avoid
> storing it to memory.
> 
> Then we add a new reference to it for the pinsrw insn, and that isn't
> initialized.
> 
> I seem to recall that this is a general problem with the idea of using a
> pseudo for the PIC register, so surely there must have been some attempt to
> address this when x86 was converted. So far I can't find anything though.
> Uroš - any pointers?

Let's ask Ilya.