[SCCP] Make it possible to remove predicate info for a given instruction.

[labrinea]

Summary

Discussion: https://discourse.llvm.org/t/rfc-should-we-enable-function-specialization/61518

[labrinea]

Abandoning in favor of D126455.

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

public:
 
   void dump() const;
   void print(raw_ostream &) const;
 
   const PredicateBase *getPredicateInfoFor(const Value *V) const {
     return PredicateMap.lookup(V);
   }
 
+  bool removePredicateInfoFor(const Value *V) { return PredicateMap.erase(V); }
+
 protected:
   // Used by PredicateInfo annotater, dumpers, and wrapper pass.
   friend class PredicateInfoAnnotatedWriter;
   friend class PredicateInfoPrinterLegacyPass;
   friend class PredicateInfoBuilder;
 
 private:
   Function &F;

llvm/lib/Transforms/Utils/SCCPSolver.cpp

public:
 
   const PredicateBase *getPredicateInfoFor(Instruction *I) {
     auto A = AnalysisResults.find(I->getParent()->getParent());
     if (A == AnalysisResults.end())
       return nullptr;
     return A->second.PredInfo->getPredicateInfoFor(I);
   }
 
+  bool removePredicateInfoFor(Instruction *I) {
+    auto A = AnalysisResults.find(I->getParent()->getParent());
+    if (A == AnalysisResults.end())
+      return false;
+    return A->second.PredInfo->removePredicateInfoFor(I);
+  }
+
   DomTreeUpdater getDTU(Function &F) {
     auto A = AnalysisResults.find(&F);
     assert(A != AnalysisResults.end() && "Need analysis results for function.");
     return {A->second.DT, A->second.PDT, DomTreeUpdater::UpdateStrategy::Lazy};
   }
 
   SCCPInstVisitor(const DataLayout &DL,
                   std::function<const TargetLibraryInfo &(Function &)> GetTLI,