[PATCH] D111571: [X86] `detectAVGPattern()`: support basic case of PAVG chaining (PR52131)

[Craig Topper via Phabricator via llvm-commits]

craig.topper added inline comments.


================
Comment at: llvm/lib/Target/X86/X86ISelLowering.cpp:46758
+    KnownBits Known = DAG->computeKnownBits(V);
+    unsigned MaxActiveBits = Known.getBitWidth() - Known.countMinLeadingZeros();
+    return MaxActiveBits <= ScalarVT.getSizeInBits();
----------------
RKSimon wrote:
> Is it worth adding a KnownBits get/countMaxActiveBits wrapper?
Looking at other uses of countMinLeadingZeros() in X86ISelLowering we often write it more like this

```
return Known.countMinLeadingZeros() >= (Known.getBitWidth() - ScalarVT.getSizeInBits());
```


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  https://reviews.llvm.org/D111571/new/

https://reviews.llvm.org/D111571