[llvm] [PowerPC] replace vector compare equal to with vector compare greater than (PR #150422)

[Tony Varghese via llvm-commits]

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@@ -4570,6 +4570,16 @@ bool PPCDAGToDAGISel::trySETCC(SDNode *N) {
     if (Subtarget->hasSPE())
       return false;
 
+    // To optimize zero-vector comparisons and avoid the extra step of negation,
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tonykuttai wrote:

Please improve the comment to specify what the code snippet does.

https://github.com/llvm/llvm-project/pull/150422