| commit | 4c3db1c1e8deebfb3f68c114edab3ef5c5806ad7 | [log] [tgz] |
|---|---|---|
| author | Roman Lebedev <lebedev.ri@gmail.com> | Sat Sep 15 12:04:13 2018 +0000 |
| committer | Roman Lebedev <lebedev.ri@gmail.com> | Sat Sep 15 12:04:13 2018 +0000 |
| tree | 87b07897be1e172acfe448e78b2300330a97528e | |
| parent | bfa7594241bb1e946a562855af2633986ddeb7a4 [diff] |
[InstCombine] Inefficient pattern for high-bits checking 3 (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..) The last (as far i know?) pattern, non-canonical due to the extra use. https://godbolt.org/z/aCMsPk https://rise4fun.com/Alive/I6f 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/D52062 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@342321 91177308-0d34-0410-b5e6-96231b3b80d8