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Re: [RFC] Fix recent popcount change is breaking

On 07/10/2018 07:27 AM, Jakub Jelinek wrote:
> On Tue, Jul 10, 2018 at 03:17:48PM +0200, Richard Biener wrote:
>> On Tue, Jul 10, 2018 at 3:06 PM Kugan Vivekanandarajah
>>> Jeff told me that the recent popcount built-in detection is causing
>>> kernel build issues as
>>> ERROR: "__popcountsi2"
>>> [drivers/net/wireless/broadcom/brcm80211/brcmfmac/brcmfmac.ko] undefined!
>>> I could also reproduce this. AFIK, we should check if the libfunc is
>>> defined while checking popcount?
>>> I am testing the attached RFC patch. Is this reasonable?
>> It doesn't work that way, all targets have this libfunc in libgcc.  This means
>> the kernel has to provide it.  The only thing you could do is restrict
>> replacement of CALL_EXPRs (in SCEV cprop) to those the target
>> natively supports.
> Yeah, that is what we've done in the past in other cases, e.g. PR82981
> is somewhat similar.  So perhaps just check the optab and use it only if it
> is supported?
And I could live with this too.  Essentially I'm just looking to get the
issue raised and addressed now rather than waiting for stage3/stage4 :-)


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