[DA] Let getConstantPart return optional APInt (NFC) (#146135)

To use the result of an SCEVConstant, we need to extract the APInt,
which callers anyway do.

Author: artagnon

llvm/lib/Analysis/DependenceAnalysis.cpp

@@ -2372,20 +2372,17 @@ bool DependenceInfo::testMIV(const SCEV *Src, const SCEV *Dst,
     banerjeeMIVtest(Src, Dst, Loops, Result);
 }
 
-
 // Given a product, e.g., 10*X*Y, returns the first constant operand,
-// in this case 10. If there is no constant part, returns NULL.
-static
-const SCEVConstant *getConstantPart(const SCEV *Expr) {
+// in this case 10. If there is no constant part, returns std::nullopt.
+static std::optional<APInt> getConstantPart(const SCEV *Expr) {
   if (const auto *Constant = dyn_cast<SCEVConstant>(Expr))
-    return Constant;
-  else if (const auto *Product = dyn_cast<SCEVMulExpr>(Expr))
+    return Constant->getAPInt();
+  if (const auto *Product = dyn_cast<SCEVMulExpr>(Expr))
     if (const auto *Constant = dyn_cast<SCEVConstant>(Product->getOperand(0)))
-      return Constant;
-  return nullptr;
+      return Constant->getAPInt();
+  return std::nullopt;
 }
 
-
 //===----------------------------------------------------------------------===//
 // gcdMIVtest -
 // Tests an MIV subscript pair for dependence.
@@ -2421,11 +2418,10 @@ bool DependenceInfo::gcdMIVtest(const SCEV *Src, const SCEV *Dst,
     const SCEV *Coeff = AddRec->getStepRecurrence(*SE);
     // If the coefficient is the product of a constant and other stuff,
     // we can use the constant in the GCD computation.
-    const auto *Constant = getConstantPart(Coeff);
-    if (!Constant)
+    std::optional<APInt> ConstCoeff = getConstantPart(Coeff);
+    if (!ConstCoeff)
       return false;
-    APInt ConstCoeff = Constant->getAPInt();
-    RunningGCD = APIntOps::GreatestCommonDivisor(RunningGCD, ConstCoeff.abs());
+    RunningGCD = APIntOps::GreatestCommonDivisor(RunningGCD, ConstCoeff->abs());
     Coefficients = AddRec->getStart();
   }
   const SCEV *SrcConst = Coefficients;
@@ -2440,11 +2436,10 @@ bool DependenceInfo::gcdMIVtest(const SCEV *Src, const SCEV *Dst,
     const SCEV *Coeff = AddRec->getStepRecurrence(*SE);
     // If the coefficient is the product of a constant and other stuff,
     // we can use the constant in the GCD computation.
-    const auto *Constant = getConstantPart(Coeff);
-    if (!Constant)
+    std::optional<APInt> ConstCoeff = getConstantPart(Coeff);
+    if (!ConstCoeff)
       return false;
-    APInt ConstCoeff = Constant->getAPInt();
-    RunningGCD = APIntOps::GreatestCommonDivisor(RunningGCD, ConstCoeff.abs());
+    RunningGCD = APIntOps::GreatestCommonDivisor(RunningGCD, ConstCoeff->abs());
     Coefficients = AddRec->getStart();
   }
   const SCEV *DstConst = Coefficients;
@@ -2463,12 +2458,10 @@ bool DependenceInfo::gcdMIVtest(const SCEV *Src, const SCEV *Dst,
       else if (const SCEVMulExpr *Product = dyn_cast<SCEVMulExpr>(Operand)) {
         // Search for constant operand to participate in GCD;
         // If none found; return false.
-        const SCEVConstant *ConstOp = getConstantPart(Product);
+        std::optional<APInt> ConstOp = getConstantPart(Product);
         if (!ConstOp)
           return false;
-        APInt ConstOpValue = ConstOp->getAPInt();
-        ExtraGCD = APIntOps::GreatestCommonDivisor(ExtraGCD,
-                                                   ConstOpValue.abs());
+        ExtraGCD = APIntOps::GreatestCommonDivisor(ExtraGCD, ConstOp->abs());
       }
       else
         return false;
@@ -2520,11 +2513,11 @@ bool DependenceInfo::gcdMIVtest(const SCEV *Src, const SCEV *Dst,
       else {
         // If the coefficient is the product of a constant and other stuff,
         // we can use the constant in the GCD computation.
-        Constant = getConstantPart(Coeff);
-        if (!Constant)
+        std::optional<APInt> ConstCoeff = getConstantPart(Coeff);
+        if (!ConstCoeff)
           return false;
-        APInt ConstCoeff = Constant->getAPInt();
-        RunningGCD = APIntOps::GreatestCommonDivisor(RunningGCD, ConstCoeff.abs());
+        RunningGCD =
+            APIntOps::GreatestCommonDivisor(RunningGCD, ConstCoeff->abs());
       }
       Inner = AddRec->getStart();
     }
@@ -2537,24 +2530,23 @@ bool DependenceInfo::gcdMIVtest(const SCEV *Src, const SCEV *Dst,
       else {
         // If the coefficient is the product of a constant and other stuff,
         // we can use the constant in the GCD computation.
-        Constant = getConstantPart(Coeff);
-        if (!Constant)
+        std::optional<APInt> ConstCoeff = getConstantPart(Coeff);
+        if (!ConstCoeff)
           return false;
-        APInt ConstCoeff = Constant->getAPInt();
-        RunningGCD = APIntOps::GreatestCommonDivisor(RunningGCD, ConstCoeff.abs());
+        RunningGCD =
+            APIntOps::GreatestCommonDivisor(RunningGCD, ConstCoeff->abs());
       }
       Inner = AddRec->getStart();
     }
     Delta = SE->getMinusSCEV(SrcCoeff, DstCoeff);
     // If the coefficient is the product of a constant and other stuff,
     // we can use the constant in the GCD computation.
-    Constant = getConstantPart(Delta);
-    if (!Constant)
+    std::optional<APInt> ConstCoeff = getConstantPart(Delta);
+    if (!ConstCoeff)
       // The difference of the two coefficients might not be a product
       // or constant, in which case we give up on this direction.
       continue;
-    APInt ConstCoeff = Constant->getAPInt();
-    RunningGCD = APIntOps::GreatestCommonDivisor(RunningGCD, ConstCoeff.abs());
+    RunningGCD = APIntOps::GreatestCommonDivisor(RunningGCD, ConstCoeff->abs());
     LLVM_DEBUG(dbgs() << "\tRunningGCD = " << RunningGCD << "\n");
     if (RunningGCD != 0) {
       Remainder = ConstDelta.srem(RunningGCD);