Commit Graph

5 Commits

Author SHA1 Message Date
Eric Christopher cee313d288 Revert "Temporarily Revert "Add basic loop fusion pass.""
The reversion apparently deleted the test/Transforms directory.

Will be re-reverting again.

llvm-svn: 358552
2019-04-17 04:52:47 +00:00
Eric Christopher a863435128 Temporarily Revert "Add basic loop fusion pass."
As it's causing some bot failures (and per request from kbarton).

This reverts commit r358543/ab70da07286e618016e78247e4a24fcb84077fda.

llvm-svn: 358546
2019-04-17 02:12:23 +00:00
Roman Lebedev 6dc87004fa [InstCombine] Inefficient pattern for high-bits checking 2 (PR38708)
Summary:
It is sometimes important to check that some newly-computed value
is non-negative and only n bits wide (where n is a variable.)
There are many ways to check that:
https://godbolt.org/z/o4RB8D
The last variant seems best?
(I'm sure there are some other variations i haven't thought of..)

More complicated, canonical pattern:
https://rise4fun.com/Alive/uhA

We do need to have two `switch()`'es like this,
to not mismatch the swappable predicates.

https://bugs.llvm.org/show_bug.cgi?id=38708

Reviewers: spatel, craig.topper, RKSimon

Reviewed By: spatel

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D52001

llvm-svn: 342173
2018-09-13 20:33:12 +00:00
Roman Lebedev 083744852a [NFC][InstCombine] Test what happens if 'unefficient high bit check' pattern is on both sides.
Came up in https://reviews.llvm.org/D52001#1233827
While we don't do a good job here, we at least want to make
sure that we don't have any inf-loops.

llvm-svn: 342171
2018-09-13 20:33:02 +00:00
Roman Lebedev 91c668a276 [NFC][InstCombine] R38708 - inefficient pattern for high-bits checking.
More complicated, canonical pattern:
https://rise4fun.com/Alive/uhA
https://godbolt.org/z/o4RB8D

Also, we need to be careful not to skip some patters...

https://bugs.llvm.org/show_bug.cgi?id=38708

llvm-svn: 342074
2018-09-12 19:44:26 +00:00