Huihui Zhang
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4626613ffe
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[InstCombine] Fold icmp eq/ne (and %x, C), 0 iff (-C) is power of two -> %x u</u>= (-C) earlier.
Summary:
To generate simplified IR, make sure fold
(X & ~C) ==/!= 0 --> X u</u>= C+1
is scheduled before fold
((X << Y) & C) == 0 -> (X & (C >> Y)) == 0.
https://rise4fun.com/Alive/7ZN
Reviewers: lebedev.ri, efriedma, spatel, craig.topper
Reviewed By: lebedev.ri
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63505
llvm-svn: 364255
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2019-06-25 00:09:10 +00:00 |
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Huihui Zhang
|
dc2fd6a14e
|
[InstCombine] Add tests to show missing fold opportunity for "icmp and shift" (nfc).
Summary:
For icmp pred (and (sh X, Y), C), 0
When C is signbit, expect to fold (X << Y) & signbit ==/!= 0 into (X << Y) >=/< 0,
rather than (X & (signbit >> Y)) != 0.
When C+1 is power of 2, expect to fold (X << Y) & ~C ==/!= 0 into (X << Y) </>= C+1,
rather than (X & (~C >> Y)) == 0.
For icmp pred (and X, (sh signbit, Y)), 0
Expect to fold (X & (signbit l>> Y)) ==/!= 0 into (X << Y) >=/< 0
Expect to fold (X & (signbit << Y)) ==/!= 0 into (X l>> Y) >=/< 0
Reviewers: lebedev.ri, efriedma, spatel, craig.topper
Reviewed By: lebedev.ri
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63025
llvm-svn: 363479
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2019-06-15 00:33:41 +00:00 |