[PATCH] D93423: [GlobalISel] Use slot indexes to speed up huge block compile time

[Amara Emerson via Phabricator via llvm-commits]

aemerson added a comment.

In D93423#2458972 <https://reviews.llvm.org/D93423#2458972>, @arsenm wrote:

> I still think the CSE MIR builder shouldn't be required to CSE and can bail early on long dominance queries

Agreed.

Another approach I tried which also worked is to prevent the IRTranslator from merging the constant entry block with it's successor, and delaying that until after the legalizer finished. Combined with also forcing the MIRBuilder to always look for constants to CSE in the entry block of the function, that fixed the issue. Quentin didn't think that was the right approach from a design POV. We have 3 options here, I think SlotIndexes are reasonable but they do seem to incur a slight compile time cost.


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