[PATCH] D57584: [DebugInfo][DAG] Reduce SelectionDAGs reordering of variables referring to Arguments

Bjorn Pettersson via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Wed Feb 13 04:12:33 PST 2019

bjope added a comment.

In D57584#1395982 <https://reviews.llvm.org/D57584#1395982>, @jmorse wrote:

> The filtering from r353735 happily makes the sparc test change un-necessary.
> I also tested whether filtering parameters so that they can't take VReg SDDbgValues is necessary any more. Removing the if block around the relevant code still makes DebugInfo/X86/sdag-split-arg.ll change behaviour. This doesn't surprise me: how fast-isel interacts with SelectionDAG is a mystery to me.

I have little experience of fast-isel myself, so I agree that it is kind of a mystery. Ideally when making changes in this area we probably should add test cases for fast-isel and non fast-isel. And I think the various scheduling modes for the SelectionDAG also could impact the result sometimes, as well as endianess and calling convention. So one might need to write lots of test cases to cover all scenarios.



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