[FFmpeg-devel] [PATCH] configure: Remove dcbzl check for e500v1 and e500v2 architectures

[Peter Krefting]

Hi!

>> The DCBZL instruction is not available for the e500v1 and e500v2
>> architectures, but may still be recognized by the toolchain, so we need to
>> remove the test for it explicitly for these architectures.
> Isn't this the sort of thing that's supposed ti be guarded by run-time CPU flags rather than in the configure script?

Our compiler (powerpc-btech-linux-gnuspe-gcc (crosstool-NG 1.24.0) 
8.3.0) recognizes the instruction, so the configure test succeeds, but 
the CPU (e500v2) crashes if it tries to execute it.

I previously had a patch (d5733936d857ce5c7d28c0bc9e89a2e2548f8895) to 
suppress the instruction, but it broke at some point, this patch tries 
to fix it in a slightly better way.

Having said that, the test is there due to the fix in 
a4adb60858f1fa0b35b08576ea34e531f0f83459 (from 2003), and disabling the 
instruction does not bring back the old optimizations as it just expects 
it not to work at all. But for our purposes this is not as important as h
aving a working library.

-- 
\\// Peter - http://www.softwolves.pp.se/