[PredicateInfo] Fold PredicateWithCondition into PredicateBase (NFC).

[fhahn]

Summary

Each concrete instance of a predicate has a condition (also noted in the
original PredicateBase comment) and to me it seems like there is no
clear benefit of having both PredicateBase and PredicateWithCondition
and they can be folded together.

[nikic]

llvm/lib/Transforms/Scalar/NewGVN.cpp

1541–1542

This shouldn't be needed anymore -- PI is already PredicateBase.

[nikic]

LG. We can always reintroduce the split it it should become useful in the future. It isn't right now.

llvm/include/llvm/Transforms/Utils/PredicateInfo.h

public:
   // The original operand before we renamed it.
   // This can be use by passes, when destroying predicateinfo, to know
   // whether they can just drop the intrinsic, or have to merge metadata.
   Value *OriginalOp;
   // The renamed operand in the condition used for this predicate. For nested
   // predicates, this is different to OriginalOp which refers to the initial
   // operand.
   Value *RenamedOp;
+  // The condition associated with this predicate.
+  Value *Condition;
+
   PredicateBase(const PredicateBase &) = delete;
   PredicateBase &operator=(const PredicateBase &) = delete;
   PredicateBase() = delete;
   virtual ~PredicateBase() = default;
-
-protected:
-  PredicateBase(PredicateType PT, Value *Op) : Type(PT), OriginalOp(Op) {}
-};
-
-class PredicateWithCondition : public PredicateBase {
-public:
-  Value *Condition;
   static bool classof(const PredicateBase *PB) {
     return PB->Type == PT_Assume || PB->Type == PT_Branch ||
            PB->Type == PT_Switch;
   }
 
 protected:
-  PredicateWithCondition(PredicateType PT, Value *Op, Value *Condition)
-      : PredicateBase(PT, Op), Condition(Condition) {}
+  PredicateBase(PredicateType PT, Value *Op, Value *Condition)
+      : Type(PT), OriginalOp(Op), Condition(Condition) {}
 };
 
 // Provides predicate information for assumes.  Since assumes are always true,
 // we simply provide the assume instruction, so you can tell your relative
 // position to it.
-class PredicateAssume : public PredicateWithCondition {
+class PredicateAssume : public PredicateBase {
 public:
   IntrinsicInst *AssumeInst;
   PredicateAssume(Value *Op, IntrinsicInst *AssumeInst, Value *Condition)
-      : PredicateWithCondition(PT_Assume, Op, Condition),
-        AssumeInst(AssumeInst) {}
+      : PredicateBase(PT_Assume, Op, Condition), AssumeInst(AssumeInst) {}
   PredicateAssume() = delete;
   static bool classof(const PredicateBase *PB) {
     return PB->Type == PT_Assume;
   }
 };
 
 // Mixin class for edge predicates.  The FROM block is the block where the
 // predicate originates, and the TO block is the block where the predicate is
 // valid.
-class PredicateWithEdge : public PredicateWithCondition {
+class PredicateWithEdge : public PredicateBase {
 public:
   BasicBlock *From;
   BasicBlock *To;
   PredicateWithEdge() = delete;
   static bool classof(const PredicateBase *PB) {
     return PB->Type == PT_Branch || PB->Type == PT_Switch;
   }
 
 protected:
   PredicateWithEdge(PredicateType PType, Value *Op, BasicBlock *From,
                     BasicBlock *To, Value *Cond)
-      : PredicateWithCondition(PType, Op, Cond), From(From), To(To) {}
+      : PredicateBase(PType, Op, Cond), From(From), To(To) {}
 };
 
 // Provides predicate information for branches.
 class PredicateBranch : public PredicateWithEdge {
 public:
   // If true, SplitBB is the true successor, otherwise it's the false successor.
   bool TrueEdge;
   PredicateBranch(Value *Op, BasicBlock *BranchBB, BasicBlock *SplitBB,

llvm/lib/Transforms/Scalar/NewGVN.cpp

 
 const Expression *
 NewGVN::performSymbolicPredicateInfoEvaluation(Instruction *I) const {
   auto *PI = PredInfo->getPredicateInfoFor(I);
   if (!PI)
     return nullptr;
 
   LLVM_DEBUG(dbgs() << "Found predicate info from instruction !\n");
 
-  auto *PWC = dyn_cast<PredicateWithCondition>(PI);
-  if (!PWC)
-    return nullptr;
-
   auto *CopyOf = I->getOperand(0);
-  auto *Cond = PWC->Condition;
+  auto *Cond = PI->Condition;
 
   // If this a copy of the condition, it must be either true or false depending
   // on the predicate info type and edge.
   if (CopyOf == Cond) {
     // We should not need to add predicate users because the predicate info is
     // already a use of this operand.
     if (isa<PredicateAssume>(PI))
       return createConstantExpression(ConstantInt::getTrue(Cond->getType()));