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chenglin.bi dd31a3b3a5 [InstCombine] fold icmp of the sum of ext bool based on limited range

For the pattern `(zext i1 X) + (sext i1 Y)`, the constant range is [-1, 1].
We can simplify the pattern by logical operations. Like:

```
    (zext i1 X) + (sext i1 Y) == -1 -->  ~X & Y
    (zext i1 X) + (sext i1 Y) == 0  --> ~(X ^ Y)
    (zext i1 X) + (sext i1 Y) == 1 --> X & ~Y
```
And other predicates can the combination of these results:

```
    (zext i1 X) + (sext i1 Y)) != -1 --> X | ~Y
    (zext i1 X) + (sext i1 Y)) s> -1 --> X | ~Y
    (zext i1 X) + (sext i1 Y)) u< -1 --> X | ~Y
    (zext i1 X) + (sext i1 Y)) s> 0 --> X & ~Y
    (zext i1 X) + (sext i1 Y)) s< 0 --> ~X & Y
    (zext i1 X) + (sext i1 Y)) != 1 --> ~X | Y
    (zext i1 X) + (sext i1 Y)) s< 1 --> ~X | Y
    (zext i1 X) + (sext i1 Y)) u> 1 --> ~X & Y
```

All alive proofs:
https://alive2.llvm.org/ce/z/KmgDpF
https://alive2.llvm.org/ce/z/fLwWa9
https://alive2.llvm.org/ce/z/ZKQn2P

Fix: https://github.com/llvm/llvm-project/issues/59666

Reviewed By: spatel

Differential Revision: https://reviews.llvm.org/D143373

2023-02-15 10:34:00 +08:00

CMakeLists.txt

…

InstCombineAddSub.cpp

[InstCombine][LV] Fold (add (zext (add X, -1)), 1) -> (zext X) if X is non-zero.

2023-01-30 17:45:01 -08:00

InstCombineAndOrXor.cpp

[InstCombine] combine intersection for inequality icmps

2023-02-10 12:50:39 +08:00

InstCombineAtomicRMW.cpp

[InstCombine][NFC] Fold variable into assert

2023-02-01 12:04:19 +01:00