Huihui Zhang
|
b90cb57b63
|
[InstCombine] Simplify icmp ult/uge (shl %x, C2), C1 iff C1 is power of two -> icmp eq/ne (and %x, (lshr -C1, C2)), 0.
Simplify 'shl' inequality test into 'and' equality test.
This pattern happens in the middle-end while simplifying bitfield access,
Exposed in https://reviews.llvm.org/D63505
https://rise4fun.com/Alive/6uz
Reviewers: lebedev.ri, efriedma
Reviewed By: lebedev.ri
Subscribers: spatel, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63675
llvm-svn: 364348
|
2019-06-25 20:44:52 +00:00 |
|
Huihui Zhang
|
2cc3b3856e
|
[InstCombine][NFC] Add test to show missing fold for icmp ult/uge (shl %x, C2), C1.
Summary:
'shl' inequality test
```
icmp ult/uge (shl %x, C2), C1 iff C1 is power of two
```
can be simplified as 'and' equality test
```
icmp eq/ne (and %x, (lshr -C1, C2)), 0.
```
Reviewers: lebedev.ri, efriedma
Reviewed By: lebedev.ri
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63670
llvm-svn: 364256
|
2019-06-25 00:14:02 +00:00 |