[LLVMdev] [RFC] Upstreaming LLVM/SPIR-V converter

[Sean Silva]

On Tue, May 19, 2015 at 4:05 PM, Owen Anderson <resistor at mac.com> wrote:

>
> On May 19, 2015, at 9:48 AM, Neil Henning <llvm at duskborn.com> wrote:
>
> The 'backend' in this context is purely so that we can then enable Clang
> to target SPIR-V in the same consistent manner to all the other targets it
> supports.
>
>
> This seems like a terrible reason to choose the architecture of how it’s
> implemented in LLVM.  The clang driver is part of the LLVM project.  If we
> need to add support for some kind of special SPIR-V flag akin to
> -emit-llvm, we can do that.  If a particular frontend vendor wants to
> customize the flags, they can always do so themselves.
>

What do you envision as the triple and datalayout when a frontend is
compiling to SPIR-V? I'm pretty sure that a wide class of frontends for
SPIR-V will literally be interested in just generating SPIR-V, with no
knowledge about what the ultimate GPU target is; it is in that sense that
they are "targeting" SPIR-V. That is, their frontend isn't generating
$SPECIFICGPU targeted IR, and then being merely asking to have it
serialized in a specific way (a la -emit-llvm); they are generating IR that
is meant to be turned into SPIR-V. That is fundamentally different from
-emit-llvm (on the other hand, it may not be a target; but it sure smells
like one).

-- Sean Silva


>
> —Owen
>
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