Re: devel/freebsd-gcc9@powerpc (for example) : it has the clang vs. gcc vec_step name conflict (for powerpc families): build fails under clang

Thu, 26 Dec 2019 23:40:42 -0800 


On 2019-Dec-26, at 20:49, Gerald Pfeifer <[email protected]> wrote:

> On Thu, 26 Dec 2019, Mark Millard wrote:
>> I tried to build devel/freebsd-gcc9@powerpc on a powerpc64 (in an
>> ELFv1 clang environment) and it reported (listing just one of the
>> examples that pointed to vec_step):
> 
> I maintain this is a bug in clang which should be address there.
> 
> https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=239266

I wish they would, but . . .

Unfortunately, this is likely a hard sell to the upstream
clang folks because

https://www.nxp.com/docs/en/reference-manual/ALTIVECPIM.pdf

defines vec_step in "2.5.3 Value for Adjusting Pointers" and
does not bother with specifying language namespace niceties,
as I remember. That dates back to 1999-June. (The "POWER
expert" quoted in comment 11 was wrong about the Altivec
PIM not having a definition.)

Clang has been this way for a long time and ends up considering
how many AltiVec related builds would be broken by such a
breaking change for those builds.

The later OpenCL specification of its vec_step has the same
sort of status as I remember. Thus, the same type of
considerations likely are involved again.

So I expect that, if devel/freebsd-gcc[69] waits for clang to be
fixed, instead of having a (hopefully temporary) workaround, then
for a significant time those ports likely will not work for being
built via clang for targeting powerpc64 or powerpc.

An unfortunate context, for sure.

>> It turns out that:
>> 
>> # ls -laT /usr/ports/devel/freebsd-gcc9/files/
>> total 44
>> drwxr-xr-x  2 root  wheel    512 Dec 25 19:25:26 2019 .
>> drwxr-xr-x  3 root  wheel    512 Dec 25 19:25:26 2019 ..
>> -rw-r--r--  1 root  wheel   4781 Dec 25 19:25:26 2019 
>> patch-freebsd-format-extensions
>> -rw-r--r--  1 root  wheel   1413 Dec 25 19:25:26 2019 patch-freebsd-libdir
>> -rw-r--r--  1 root  wheel    588 Dec 25 19:25:26 2019 patch-gcc-configure
>> -rw-r--r--  1 root  wheel  16346 Dec 25 19:25:26 2019 patch-gcc-freebsd-mips
>> -rw-r--r--  1 root  wheel    231 Dec 25 19:25:26 2019 xtoolchain.mk.in
>> 
>> is missing the patch-clang-vec_step that is in:
>> 
>> FBSDG5L2# ls -laT /usr/ports/lang/gcc9/files/
> 
> That is a hack that can be used to work around the issue; I strongly
> recommend addressing this in clang properly, though.
> 


===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)

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