[llvm-dev] [RFC] Eliminating non-IR floating-point controls in the selection DAG

[Renato Golin via llvm-dev]

On Sat, 30 Oct 2021 at 17:15, Wang, Pengfei <pengfei.wang at intel.com> wrote:

> SelectionDAG has many overloaded methods of “getNode”, some of which don’t
> need to specify the Flags argument. This is reasonable because only FP
> nodes need that. But it also easily results in losing the Flags in the FP
> nodes too.
>
> Here’s an example https://reviews.llvm.org/D84518
>
> This problem has been greatly improved since
> https://reviews.llvm.org/D87361
>
> I think we have the similar problem in MIR based optimizations, but I
> didn’t dig into it.
>

This sounds like a somewhat large, but mostly mechanical problem to solve,
correct?

Once we have a way to propagate the flags down to instruction selection,
then we don't need the target info overriding IR semantics.

Andrew, is that what you're proposing originally? (Sorry if I'm slow to
catch, I worried about changing the IR for front-ends but it seems it was
misplaced).

>
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