[PATCH] D66052: [DAGCombiner] Add simple folds for SMULFIX/UMULFIX/SMULFIXSAT

Fri Aug 16 04:41:46 PDT 2019

bjope added a comment.

In D66052#1632812 <https://reviews.llvm.org/D66052#1632812>, @RKSimon wrote:

> LGTM - do we have constant folding coverage btw?

Thanks!

ConstantFolding is handling smul_fix and smul_fix_sat on IR level. But I do not think we do much folds for umul_fix yet (umul_fix_sat has not yet landed - https://reviews.llvm.org/D57836). To complete the work with Embedded-C support in Clang umul_fix_sat will be needed (unfortunately the embedded-C additions has stalled a bit - I'll see if I can find time to finalize D57836 <https://reviews.llvm.org/D57836> to get things going again - and then I think the next step would be to complete the fixed point multiplication support in clang).

Constant folding in DAG combiner is probably easy to implement as well. But I haven't seen any need for that yet.

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https://reviews.llvm.org/D66052