[PATCH] D40353: [Loop Predication] Teach LP about reverse loops

[Anna Thomas via Phabricator via llvm-commits]

anna created this revision.

Currently, we only support predication for forward loops with step
of 1.  This patch enables loop predication for reverse or
countdownLoops, which satisfy the following conditions:

1. The step of the IV is -1.
2. The loop has a singe latch as B(X) = X <pred>

latchLimit with pred as s> or u>

3. The IV of the guard is the decrement

IV of the latch condition (Guard is: G(X) = X-1 u< guardLimit).

This patch was downstream for a while and is the last series of patches
that's from our LP implementation downstream.


https://reviews.llvm.org/D40353

Files:
  lib/Transforms/Scalar/LoopPredication.cpp
  test/Transforms/LoopPredication/reverse.ll

-------------- next part --------------
A non-text attachment was scrubbed...
Name: D40353.123931.patch
Type: text/x-patch
Size: 17534 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20171122/7bb6d938/attachment-0001.bin>