Displaying 4 results from an estimated 4 matches for "fma_w_chain".
2020 Jul 16
2
Selection DAG chain question
...atively.
>
>
> You can’t add arbitrary chains or glue to the regular nodes, but you can
> define a custom node you select the same way with your chain/glue. You
> don’t need to preprocess the IR and can do in the custom lowering. This is
> what AMDGPU does for FDIV (see AMDGPUISD::FMA_W_CHAIN). GlobalISel avoids
> these complications by not having nodes or chains, and just instructions
> with side effects, so in that sense this is a solved problem.
>
> -Matt
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2020 Jul 16
2
Selection DAG chain question
> No, non-sideeffecting operations can be legalized as compiler-rt calls
Right, but not as "regular" nodes with side-effects? I guess you could
search and analyze the DAG manually but that seems hacky. Maybe something
that one day LLVM could support natively.
On Thu, Jul 16, 2020 at 11:55 AM Matt Arsenault <arsenm2 at gmail.com> wrote:
>
>
> On Jul 16, 2020, at
2020 Jul 17
2
Selection DAG chain question
...atively.
>
>
> You can’t add arbitrary chains or glue to the regular nodes, but you can
> define a custom node you select the same way with your chain/glue. You
> don’t need to preprocess the IR and can do in the custom lowering. This is
> what AMDGPU does for FDIV (see AMDGPUISD::FMA_W_CHAIN). GlobalISel avoids
> these complications by not having nodes or chains, and just instructions
> with side effects, so in that sense this is a solved problem.
>
> -Matt
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llv...
2020 Jul 20
2
Selection DAG chain question
...You can’t add arbitrary chains or glue to the regular nodes, but you can
>>> define a custom node you select the same way with your chain/glue. You
>>> don’t need to preprocess the IR and can do in the custom lowering. This is
>>> what AMDGPU does for FDIV (see AMDGPUISD::FMA_W_CHAIN). GlobalISel avoids
>>> these complications by not having nodes or chains, and just instructions
>>> with side effects, so in that sense this is a solved problem.
>>>
>>> -Matt
>>>
>>> _______________________________________________
>>>...