[HashRecognize] Don't const-qualify Values in result (#144752)

Const-qualifying Values in the analysis result makes them unusable with
IRBuilder. The issue was discovered when attempting to use the result of
the analysis for a transform.

Author: artagnon

llvm/include/llvm/Analysis/HashRecognize.h

@@ -53,27 +53,27 @@ struct PolynomialInfo {
   // division in the case of CRC. Since polynomial division is an XOR in
   // GF(2^m), this variable must be XOR'ed with RHS in a loop to yield the
   // ComputedValue.
-  const Value *LHS;
+  Value *LHS;
 
   // The generating polynomial, or the RHS of the polynomial division in the
   // case of CRC.
   APInt RHS;
 
   // The final computed value. This is a remainder of a polynomial division in
   // the case of CRC, which must be zero.
-  const Value *ComputedValue;
+  Value *ComputedValue;
 
   // Set to true in the case of big-endian.
   bool ByteOrderSwapped;
 
   // An optional auxiliary checksum that augments the LHS. In the case of CRC,
   // it is XOR'ed with the LHS, so that the computation's final remainder is
   // zero.
-  const Value *LHSAux;
+  Value *LHSAux;
 
-  PolynomialInfo(unsigned TripCount, const Value *LHS, const APInt &RHS,
-                 const Value *ComputedValue, bool ByteOrderSwapped,
-                 const Value *LHSAux = nullptr);
+  PolynomialInfo(unsigned TripCount, Value *LHS, const APInt &RHS,
+                 Value *ComputedValue, bool ByteOrderSwapped,
+                 Value *LHSAux = nullptr);
 };
 
 /// The analysis.

llvm/lib/Analysis/HashRecognize.cpp

@@ -442,9 +442,9 @@ getRecurrences(BasicBlock *LoopLatch, const PHINode *IndVar, const Loop &L) {
   return std::make_pair(SimpleRecurrence, ConditionalRecurrence);
 }
 
-PolynomialInfo::PolynomialInfo(unsigned TripCount, const Value *LHS,
-                               const APInt &RHS, const Value *ComputedValue,
-                               bool ByteOrderSwapped, const Value *LHSAux)
+PolynomialInfo::PolynomialInfo(unsigned TripCount, Value *LHS, const APInt &RHS,
+                               Value *ComputedValue, bool ByteOrderSwapped,
+                               Value *LHSAux)
     : TripCount(TripCount), LHS(LHS), RHS(RHS), ComputedValue(ComputedValue),
       ByteOrderSwapped(ByteOrderSwapped), LHSAux(LHSAux) {}
 
@@ -623,7 +623,7 @@ 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;
   return PolynomialInfo(TC, ConditionalRecurrence.Start, GenPoly, ComputedValue,
                         *ByteOrderSwapped, LHSAux);
 }