Is it worth adding a test to llvm/unittests/IR/IRBuilderTest.cpp for this change?

LGTM!

Thanks for the review @bmahjour and @dmgreen!

Other than my comment on two missing tests, the patch looks good to me.

LGTM, thanks @CarolineConcatto

Changed back to having isMoreProfitable in LV CostModel.

Thanks for the changes @CarolineConcatto

Thanks, that looks quite neat. Can you also add a few tests when there is >1 use of the stepvector (e.g. using the stepvector in two adds), so we can test the fold indeed doesn't happen?
One test for each of the instructions should be sufficient.

Can you also add support for predicates?

Removed another case of .getValue()

• Addressed nits.
• s/MaxVectorSize/MaxVectorElementCount/ (because it's not actually a size, but an element count).

In D100107#2682168, @junparser wrote:

What I want know something more is what is the boundary between tablegen pattern match and dag combine? I never figure this out. Just use this case as example, we can implement the feature in both place, but I don't know how to handle commutivity in tablegen (maybe SDNPCommutative? I don't know.) , and their effects on the next step: combine load/store with index_vector.

There isn't a firm rule to follow re tablegen pattern vs manual dag combine, but I think the steer is that when the combine is needed after legalization and it's possible to specify as a pattern, a pattern is preferred. In this case, probably a pattern would be a clean way to implement it. I haven't used SDNPCommutative before, but that looks like it should do the trick.

It's not entirely clear what original intent of this function argument was since the doxygen comment doesn't describe it.
If the argument also isn't used anywhere then it seems sensible to me to remove it, so LGTM.

Thanks for the review @dmgreen!

After reading the summary/intent of the patch, I thought the same thing as @rjmccall. Simply returning an i32 for the above example and removing the rounding-up seems right to me.

Removed unnecessary .getValue()

Addressed review comments.

Merged patch with D100207

Thanks for taking time from your weekend to look into this @tambre, much appreciated!

Removed forgetBuiltin and the code using it.

Revert InstructionCost change for Num variable.

Thanks, LGTM!