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Re: Fix PR64876, regressions in powerpc64 Go testsuite


On Tue, Feb 3, 2015 at 7:16 PM, Alan Modra <amodra@gmail.com> wrote:
> On Tue, Feb 03, 2015 at 11:14:49AM -0500, David Edelsohn wrote:
>> On Tue, Feb 3, 2015 at 8:57 AM, Alan Modra <amodra@gmail.com> wrote:
>> >         PR target/64876
>> >         * config/rs6000/rs6000.c (chain_already_loaded): New function.
>> >         (rs6000_call_aix): Use it.
>>
>> Okay with Jakub's suggested change.
>
> No, Jakub's change doesn't work, even if I add the looping in
> chain_already_loaded that would need.  We really do want to look at
> just (the last insn in) the previous sequence.
>
> The trouble is that the current sequence, ie. the one emitted for
> gen_call or gen_call_value, might be empty, *and* the previous
> sequence, the one emitted by calls.c:emit_call_1, might be empty at
> this point.  (I found that fact out when my first implementation of
> chain_already_loaded lacked the "last != NULL" test.)  In that case
> get_last_insn_anywhere() will give you rtl insns that aren't part of a
> call sequence, and r11 is a general register that might be used for
> anything.  So a test for setting r11 is no longer a test for setting
> the static chain.

What is the proposal?  Testing only crtl->emit.sequence_stack->last
does not seem to be sufficient.  It seems like it really needs to test
for more of the CALL sequence.

Thanks, David


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