[PATCH] D38313: [InstCombine] Introducing Pattern Instruction Combine plug-in into InstCombine pass

[Amjad Aboud via Phabricator via llvm-commits]

aaboud added a comment.

In https://reviews.llvm.org/D38313#903090, @spatel wrote:

> If I'm seeing this correctly, it's an independent pass within InstCombine. It sits outside InstCombine's iteration loop, so it doesn't interact with the rest of the pass. What is the advantage of this approach vs. making a standalone pass?


Hi Sanjay,
This code, which I am suggested below, intends to replace (and improve) the "canEvaluateTruncated" from the current instCombine implementation.
The logic of this code is similar to what instcombine does, but different in the way of implementation.
Saying that, I believe that running all current instcombine tests with this new functionality is a must, in order to make that possible, it is obvious that we need to be part of instcombine pass.

Note that the implementation is done in a way that moving it to a separate pass can be done with zero effort, but in a cost of ignoring/dropping few hundreds of LIT tests.

Do you think still that it should be in a separate pass?


https://reviews.llvm.org/D38313