[all-commits] [llvm/llvm-project] 0a5240: [LoopUnrollAndJam] Changed safety checks to consid...

[whitneywhtsang via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 0a52401ad68b084e52e535541ebff1e9cb6d3869
      https://github.com/llvm/llvm-project/commit/0a52401ad68b084e52e535541ebff1e9cb6d3869
  Author: Whitney Tsang <whitneyt at ca.ibm.com>
  Date:   2020-05-06 (Wed, 06 May 2020)

  Changed paths:
    M llvm/include/llvm/Transforms/Utils/UnrollLoop.h
    M llvm/lib/Transforms/Scalar/LoopUnrollAndJamPass.cpp
    M llvm/lib/Transforms/Utils/LoopUnrollAndJam.cpp
    M llvm/test/Transforms/LoopUnrollAndJam/dependencies.ll
    A llvm/test/Transforms/LoopUnrollAndJam/dependencies_multidims.ll

  Log Message:
  -----------
  [LoopUnrollAndJam] Changed safety checks to consider more than 2-levels
loop nest.

Summary: As discussed in https://reviews.llvm.org/D73129.

Example
Before unroll and jam:

for
  A
  for
    B
    for
      C
    D
  E
After unroll and jam (currently):

for
  A
  A'
  for
    B
    for
      C
    D
    B'
    for
      C'
    D'
  E
  E'
After unroll and jam (Ideal):

for
  A
  A'
  for
    B
    B'
    for
      C
      C'
    D
    D'
  E
  E'
This is the first patch to change unroll and jam to work in the ideal
way.
This patch change the safety checks needed to make sure is safe to
unroll and jam in the ideal way.

Reviewer: dmgreen, jdoerfert, Meinersbur, kbarton, bmahjour, etiotto
Reviewed By: Meinersbur
Subscribers: fhahn, hiraditya, zzheng, llvm-commits, anhtuyen, prithayan
Tag: LLVM
Differential Revision: https://reviews.llvm.org/D76132