tree d0fac63a6aa240e17bbefd8e455475d7710b5576
parent b24c0a4e91e39506a3e182ec74a9f09e76561430
author Congzhe Cao <congzhe.cao@huawei.com> 1659569850 -0400
committer Copybara-Service <copybara-worker@google.com> 1659571697 -0700

[DependenceAnalysis][PR56275] Normalize negative dependence analysis results

This patch is the first of the two-patch series (D130188, D130179) that
resolve PR56275 (https://github.com/llvm/llvm-project/issues/56275)
which is a missed opportunity, where a perfrectly valid case for loop
interchange failed interchange legality.

If the distance/direction vector produced by dependence analysis (DA) is
negative, it needs to be normalized (reversed). This patch provides helper
functions `isDirectionNegative()` and `normalize()` in DA that does the
normalization, and clients can query DA to do normalization if needed.

A pass option `<normalized-results>` is added to DependenceAnalysisPrinterPass,
and we leverage it to update DA test cases to make sure of test coverage. The
test cases added in `Banerjee.ll` shows that negative vectors are normalized
with `print<da><normalized-results>`.

Reviewed By: bmahjour, Meinersbur, #loopoptwg

Differential Revision: https://reviews.llvm.org/D130188

GitOrigin-RevId: 76be5549318a9e5aa3bdc2b3e0ae8ed5a16bfe59