Revert [Debuginfo][LSR] Add salvaging variadic dbg.value intrinsics[2/2]

This reverts commit 8f55036.

Author: Chris Jackson

llvm/include/llvm/Analysis/ScalarEvolution.h

@@ -545,10 +545,6 @@ class ScalarEvolution {
   /// Return true if the SCEV expression contains an undef value.
   bool containsUndefs(const SCEV *S) const;
 
-  /// Return true if the SCEV expression contains a Value that has been
-  /// optimised out and is now a nullptr.
-  bool containsErasedValue(const SCEV *S) const;
-
   /// Return a SCEV expression for the full generality of the specified
   /// expression.
   const SCEV *getSCEV(Value *V);

llvm/lib/Analysis/ScalarEvolution.cpp

@@ -12688,15 +12688,6 @@ bool ScalarEvolution::containsUndefs(const SCEV *S) const {
   });
 }
 
-// Return true when S contains a value that is a nullptr.
-bool ScalarEvolution::containsErasedValue(const SCEV *S) const {
-  return SCEVExprContains(S, [](const SCEV *S) {
-    if (const auto *SU = dyn_cast<SCEVUnknown>(S))
-      return SU->getValue() == nullptr;
-    return false;
-  });
-}
-
 /// Return the size of an element read or written by Inst.
 const SCEV *ScalarEvolution::getElementSize(Instruction *Inst) {
   Type *Ty;