[InstCombine] Improve folds for and/or cmp, cmp
#72965
Open
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Make recursive matcher that is able to detect a lot more patterns. Proofs for all supported patterns: https://alive2.llvm.org/ce/z/fSQ3nZ Differential Revision: https://reviews.llvm.org/D159058
…foldICmpWithLowBitMaskedVal` `(icmp eq/ne (and X, ~Mask), 0)` is equivilent to `(icmp eq/ne (and X, Mask), X` and we sometimes generate the former pattern intentionally to reduce number of uses of `X`. Proof: https://alive2.llvm.org/ce/z/3u-usC Differential Revision: https://reviews.llvm.org/D159329
…work for non-const operands
We currently do:
`(icmp eq/ne (and X, Y), Y)` -> `(icmp eq/ne (and ~X, Y), 0)`
if `X` is constant. We can make this more general and do it if `X` is
freely invertable (i.e say `X = ~Z`).
As well, we can also do:
`(icmp eq/ne (and X, Y), Y)` -> `(icmp eq/ne (or X, ~Y), -1)`
If `Y` is freely invertible.
Proofs: https://alive2.llvm.org/ce/z/yeWH3E
Differential Revision: https://reviews.llvm.org/D159059
This is prep for using `getKnownSign` outside of just InstCombineCalls. Differential Revision: https://reviews.llvm.org/D159060
…Y` are known signed/unsigned
Several transforms:
1) If known `Y < 0`:
- slt -> ult: https://alive2.llvm.org/ce/z/unpsxu
- sle -> ule: https://alive2.llvm.org/ce/z/a5cpmr
- sgt -> ugt: https://alive2.llvm.org/ce/z/qgsgya
- sge -> uge: https://alive2.llvm.org/ce/z/ek_3ls
2) If known `Y > 0`:
- `(X & PosY) s> X --> X s< 0`
- https://alive2.llvm.org/ce/z/drewij
- `(X & PosY) s> X --> X s< 0`
- https://alive2.llvm.org/ce/z/9arL3D
3) If known `X < 0`:
- `(NegX & Y) s> NegX --> Y s>= 0`
- https://alive2.llvm.org/ce/z/ApkaEh
- `(NegX & Y) s<= NegX --> Y s< 0`
- https://alive2.llvm.org/ce/z/oRnfHp
Differential Revision: https://reviews.llvm.org/D145426
…Y)`; NFC Differential Revision: https://reviews.llvm.org/D159061
… of `Y` The fold will replace 2 uses of `Y` we should also do fold if `Y` has 2 uses (not only oneuse). Reviewed By: nikic Differential Revision: https://reviews.llvm.org/D159062
…cmp eq/ne X,Pow2OrZero))`; NFC Differential Revision: https://reviews.llvm.org/D157311
…e X,Pow2OrZero))`
`(or (icmp eq X, 0), (icmp eq X, Pow2OrZero))`
--> `(icmp eq (and X, Pow2OrZero), X)`
`(and (icmp ne X, 0), (icmp ne X, Pow2OrZero))`
--> `(icmp ne (and X, Pow2OrZero), X)`
Proofs: https://alive2.llvm.org/ce/z/nPo2BN
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D157312
goldsteinn
changed the title
and/or cmp, cmp
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
foldICmpWithLowBitMaskedVal; NFCfoldICmpWithLowBitMaskedVal(icmp eq/ne (and X, ~Mask), 0)pattern infoldICmpWithLowBitMaskedVal(icmp eq/ne (and X, Y), X)canonicalization work for non-const operandsgetKnownSigna member function of InstCombiner; NFC(icmp spred (and X, Y), X)ifXorYare known signed/unsigned(icmp eq/ne (or X, Y), Y); NFC(icmp eq/ne (or X, Y), Y)for 2 uses ofY(or/and (icmp eq/ne X,0),(icmp eq/ne X,Pow2OrZero)); NFC(or/and (icmp eq/ne X,0),(icmp eq/ne X,Pow2OrZero))