[Llvm-bgq-discuss] Limitation in bgclang's QPX support

[Hal Finkel]

Phil,

I'll look into this. There may be a way to enable the 'splat' behavior here. In the mean time, you can just write:
vector4double fullvirial_v0 = (vector4double) { 0.0, 0.0, 0.0, 0.0 };

 -Hal

----- Original Message -----
> From: "Phil Miller" <mille121 at illinois.edu>
> To: llvm-bgq-discuss at lists.alcf.anl.gov
> Sent: Wednesday, May 14, 2014 1:37:09 PM
> Subject: [Llvm-bgq-discuss] Limitation in bgclang's QPX support
> 
> 
> 
> 
> Aside from the optimization errors I recently reported, the only
> other impediment to compiling unmodified NAMD with bgclang is a big
> pile of errors of the following nature:
> ====
> error: C-style cast from 'double' to 'vector4double' is not allowed
> vector4double fullvirial_v0 = (vector4double) (0.0);
> ====
> 
> The desired semantics of statements like this are pretty
> straightforward, and don't seem to conflict with anything else.
> bgxlc is happy to accept these statements, so this can be viewed as
> a (hopefully unintended) compatibility limitation.
> 
> 
> 
> If there's a more portable way to express this construct, I might be
> able to pass a patch up to the NAMD developers.
> 
> 
> These were avoided by disabling the QPX-specialized code, and using
> the portable C/C++ versions instead. So, I was finally able to
> compile and link a NAMD binary using purely the bgclang toolchain.
> If I encounter subsequent runtime trouble, I'll follow up with
> another post.
> 
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> 

-- 
Hal Finkel
Assistant Computational Scientist
Leadership Computing Facility
Argonne National Laboratory