[llvm] [LoopIdiom] Use HashRecognize to optimize CRC (PR #143208)

[Ramkumar Ramachandra via llvm-commits]

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@@ -620,9 +624,10 @@ HashRecognize::recognizeCRC() const {
   if (!checkExtractBits(ResultBits, TC, IsZero, *ByteOrderSwapped))
     return ErrBits(ResultBits, TC, *ByteOrderSwapped);
 
-  const Value *LHSAux = SimpleRecurrence ? SimpleRecurrence.Start : nullptr;
+  Value *LHSAux = SimpleRecurrence ? SimpleRecurrence.Start : nullptr;
+  const CRCTable &SarwateTable = genSarwateTable(GenPoly, *ByteOrderSwapped);
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artagnon wrote:

We compute the i-th element using a runtime-value of i, which would require IRBuilder to emit the instructions: hence, we cannot do this in the analysis.

https://github.com/llvm/llvm-project/pull/143208