diff --git a/clang/include/clang/AST/IgnoreExpr.h b/clang/include/clang/AST/IgnoreExpr.h
new file mode 100644
--- /dev/null
+++ b/clang/include/clang/AST/IgnoreExpr.h
@@ -0,0 +1,61 @@
+//===--- IgnoreExpr.h - Ignore intermediate Expressions -----------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines common functions to ignore intermediate expression nodes
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_AST_IGNOREEXPR_H
+#define LLVM_CLANG_AST_IGNOREEXPR_H
+
+#include "clang/AST/Expr.h"
+
+namespace clang {
+namespace {
+/// Given an expression E and functions Fn_1,...,Fn_n : Expr * -> Expr *,
+/// Return Fn_n(...(Fn_1(E)))
+inline Expr *IgnoreExprNodesImpl(Expr *E) { return E; };
+template <typename FnTy, typename... FnTys>
+Expr *IgnoreExprNodesImpl(Expr *E, FnTy &&Fn, FnTys &&... Fns) {
+  return IgnoreExprNodesImpl(Fn(E), std::forward<FnTys>(Fns)...);
+}
+} // namespace
+
+/// Given an expression E and functions Fn_1,...,Fn_n : Expr * -> Expr *,
+/// Recursively apply each of the functions to E until reaching a fixed point.
+/// Note that a null E is valid; in this case nothing is done.
+template <typename... FnTys> Expr *IgnoreExprNodes(Expr *E, FnTys &&... Fns) {
+  Expr *LastE = nullptr;
+  while (E != LastE) {
+    LastE = E;
+    E = IgnoreExprNodesImpl(E, std::forward<FnTys>(Fns)...);
+  }
+  return E;
+}
+
+Expr *IgnoreImpCastsSingleStep(Expr *E);
+
+Expr *IgnoreImpCastsExtraSingleStep(Expr *E);
+
+Expr *IgnoreCastsSingleStep(Expr *E);
+
+Expr *IgnoreLValueCastsSingleStep(Expr *E);
+
+Expr *IgnoreBaseCastsSingleStep(Expr *E);
+
+Expr *IgnoreImplicitSingleStep(Expr *E);
+
+Expr *IgnoreImplicitAsWrittenSingleStep(Expr *E);
+
+Expr *IgnoreParensOnlySingleStep(Expr *E);
+
+Expr *IgnoreParensSingleStep(Expr *E);
+
+} // namespace clang
+
+#endif // LLVM_CLANG_AST_IGNOREEXPR_H
diff --git a/clang/lib/AST/CMakeLists.txt b/clang/lib/AST/CMakeLists.txt
--- a/clang/lib/AST/CMakeLists.txt
+++ b/clang/lib/AST/CMakeLists.txt
@@ -55,6 +55,7 @@
   ExternalASTMerger.cpp
   ExternalASTSource.cpp
   FormatString.cpp
+  IgnoreExpr.cpp
   InheritViz.cpp
   Interp/ByteCodeEmitter.cpp
   Interp/ByteCodeExprGen.cpp
diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -21,6 +21,7 @@
 #include "clang/AST/DependenceFlags.h"
 #include "clang/AST/EvaluatedExprVisitor.h"
 #include "clang/AST/ExprCXX.h"
+#include "clang/AST/IgnoreExpr.h"
 #include "clang/AST/Mangle.h"
 #include "clang/AST/RecordLayout.h"
 #include "clang/AST/StmtVisitor.h"
@@ -2779,118 +2780,6 @@
   return QualType();
 }
 
-static Expr *IgnoreImpCastsSingleStep(Expr *E) {
-  if (auto *ICE = dyn_cast<ImplicitCastExpr>(E))
-    return ICE->getSubExpr();
-
-  if (auto *FE = dyn_cast<FullExpr>(E))
-    return FE->getSubExpr();
-
-  return E;
-}
-
-static Expr *IgnoreImpCastsExtraSingleStep(Expr *E) {
-  // FIXME: Skip MaterializeTemporaryExpr and SubstNonTypeTemplateParmExpr in
-  // addition to what IgnoreImpCasts() skips to account for the current
-  // behaviour of IgnoreParenImpCasts().
-  Expr *SubE = IgnoreImpCastsSingleStep(E);
-  if (SubE != E)
-    return SubE;
-
-  if (auto *MTE = dyn_cast<MaterializeTemporaryExpr>(E))
-    return MTE->getSubExpr();
-
-  if (auto *NTTP = dyn_cast<SubstNonTypeTemplateParmExpr>(E))
-    return NTTP->getReplacement();
-
-  return E;
-}
-
-static Expr *IgnoreCastsSingleStep(Expr *E) {
-  if (auto *CE = dyn_cast<CastExpr>(E))
-    return CE->getSubExpr();
-
-  if (auto *FE = dyn_cast<FullExpr>(E))
-    return FE->getSubExpr();
-
-  if (auto *MTE = dyn_cast<MaterializeTemporaryExpr>(E))
-    return MTE->getSubExpr();
-
-  if (auto *NTTP = dyn_cast<SubstNonTypeTemplateParmExpr>(E))
-    return NTTP->getReplacement();
-
-  return E;
-}
-
-static Expr *IgnoreLValueCastsSingleStep(Expr *E) {
-  // Skip what IgnoreCastsSingleStep skips, except that only
-  // lvalue-to-rvalue casts are skipped.
-  if (auto *CE = dyn_cast<CastExpr>(E))
-    if (CE->getCastKind() != CK_LValueToRValue)
-      return E;
-
-  return IgnoreCastsSingleStep(E);
-}
-
-static Expr *IgnoreBaseCastsSingleStep(Expr *E) {
-  if (auto *CE = dyn_cast<CastExpr>(E))
-    if (CE->getCastKind() == CK_DerivedToBase ||
-        CE->getCastKind() == CK_UncheckedDerivedToBase ||
-        CE->getCastKind() == CK_NoOp)
-      return CE->getSubExpr();
-
-  return E;
-}
-
-static Expr *IgnoreImplicitSingleStep(Expr *E) {
-  Expr *SubE = IgnoreImpCastsSingleStep(E);
-  if (SubE != E)
-    return SubE;
-
-  if (auto *MTE = dyn_cast<MaterializeTemporaryExpr>(E))
-    return MTE->getSubExpr();
-
-  if (auto *BTE = dyn_cast<CXXBindTemporaryExpr>(E))
-    return BTE->getSubExpr();
-
-  return E;
-}
-
-static Expr *IgnoreImplicitAsWrittenSingleStep(Expr *E) {
-  if (auto *ICE = dyn_cast<ImplicitCastExpr>(E))
-    return ICE->getSubExprAsWritten();
-
-  return IgnoreImplicitSingleStep(E);
-}
-
-static Expr *IgnoreParensOnlySingleStep(Expr *E) {
-  if (auto *PE = dyn_cast<ParenExpr>(E))
-    return PE->getSubExpr();
-  return E;
-}
-
-static Expr *IgnoreParensSingleStep(Expr *E) {
-  if (auto *PE = dyn_cast<ParenExpr>(E))
-    return PE->getSubExpr();
-
-  if (auto *UO = dyn_cast<UnaryOperator>(E)) {
-    if (UO->getOpcode() == UO_Extension)
-      return UO->getSubExpr();
-  }
-
-  else if (auto *GSE = dyn_cast<GenericSelectionExpr>(E)) {
-    if (!GSE->isResultDependent())
-      return GSE->getResultExpr();
-  }
-
-  else if (auto *CE = dyn_cast<ChooseExpr>(E)) {
-    if (!CE->isConditionDependent())
-      return CE->getChosenSubExpr();
-  }
-
-  return E;
-}
-
 static Expr *IgnoreNoopCastsSingleStep(const ASTContext &Ctx, Expr *E) {
   if (auto *CE = dyn_cast<CastExpr>(E)) {
     // We ignore integer <-> casts that are of the same width, ptr<->ptr and
@@ -2914,25 +2803,6 @@
   return E;
 }
 
-static Expr *IgnoreExprNodesImpl(Expr *E) { return E; }
-template <typename FnTy, typename... FnTys>
-static Expr *IgnoreExprNodesImpl(Expr *E, FnTy &&Fn, FnTys &&... Fns) {
-  return IgnoreExprNodesImpl(Fn(E), std::forward<FnTys>(Fns)...);
-}
-
-/// Given an expression E and functions Fn_1,...,Fn_n : Expr * -> Expr *,
-/// Recursively apply each of the functions to E until reaching a fixed point.
-/// Note that a null E is valid; in this case nothing is done.
-template <typename... FnTys>
-static Expr *IgnoreExprNodes(Expr *E, FnTys &&... Fns) {
-  Expr *LastE = nullptr;
-  while (E != LastE) {
-    LastE = E;
-    E = IgnoreExprNodesImpl(E, std::forward<FnTys>(Fns)...);
-  }
-  return E;
-}
-
 Expr *Expr::IgnoreImpCasts() {
   return IgnoreExprNodes(this, IgnoreImpCastsSingleStep);
 }
diff --git a/clang/lib/AST/IgnoreExpr.cpp b/clang/lib/AST/IgnoreExpr.cpp
new file mode 100644
--- /dev/null
+++ b/clang/lib/AST/IgnoreExpr.cpp
@@ -0,0 +1,129 @@
+//===--- IgnoreExpr.cpp - Ignore intermediate Expressions -----------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements common functions to ignore intermediate expression nodes
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/AST/IgnoreExpr.h"
+#include "clang/AST/Expr.h"
+#include "clang/AST/ExprCXX.h"
+
+using namespace clang;
+
+Expr *clang::IgnoreImpCastsSingleStep(Expr *E) {
+  if (auto *ICE = dyn_cast<ImplicitCastExpr>(E))
+    return ICE->getSubExpr();
+
+  if (auto *FE = dyn_cast<FullExpr>(E))
+    return FE->getSubExpr();
+
+  return E;
+}
+
+Expr *clang::IgnoreImpCastsExtraSingleStep(Expr *E) {
+  // FIXME: Skip MaterializeTemporaryExpr and SubstNonTypeTemplateParmExpr in
+  // addition to what IgnoreImpCasts() skips to account for the current
+  // behaviour of IgnoreParenImpCasts().
+  Expr *SubE = IgnoreImpCastsSingleStep(E);
+  if (SubE != E)
+    return SubE;
+
+  if (auto *MTE = dyn_cast<MaterializeTemporaryExpr>(E))
+    return MTE->getSubExpr();
+
+  if (auto *NTTP = dyn_cast<SubstNonTypeTemplateParmExpr>(E))
+    return NTTP->getReplacement();
+
+  return E;
+}
+
+Expr *clang::IgnoreCastsSingleStep(Expr *E) {
+  if (auto *CE = dyn_cast<CastExpr>(E))
+    return CE->getSubExpr();
+
+  if (auto *FE = dyn_cast<FullExpr>(E))
+    return FE->getSubExpr();
+
+  if (auto *MTE = dyn_cast<MaterializeTemporaryExpr>(E))
+    return MTE->getSubExpr();
+
+  if (auto *NTTP = dyn_cast<SubstNonTypeTemplateParmExpr>(E))
+    return NTTP->getReplacement();
+
+  return E;
+}
+
+Expr *clang::IgnoreLValueCastsSingleStep(Expr *E) {
+  // Skip what IgnoreCastsSingleStep skips, except that only
+  // lvalue-to-rvalue casts are skipped.
+  if (auto *CE = dyn_cast<CastExpr>(E))
+    if (CE->getCastKind() != CK_LValueToRValue)
+      return E;
+
+  return IgnoreCastsSingleStep(E);
+}
+
+Expr *clang::IgnoreBaseCastsSingleStep(Expr *E) {
+  if (auto *CE = dyn_cast<CastExpr>(E))
+    if (CE->getCastKind() == CK_DerivedToBase ||
+        CE->getCastKind() == CK_UncheckedDerivedToBase ||
+        CE->getCastKind() == CK_NoOp)
+      return CE->getSubExpr();
+
+  return E;
+}
+
+Expr *clang::IgnoreImplicitSingleStep(Expr *E) {
+  Expr *SubE = IgnoreImpCastsSingleStep(E);
+  if (SubE != E)
+    return SubE;
+
+  if (auto *MTE = dyn_cast<MaterializeTemporaryExpr>(E))
+    return MTE->getSubExpr();
+
+  if (auto *BTE = dyn_cast<CXXBindTemporaryExpr>(E))
+    return BTE->getSubExpr();
+
+  return E;
+}
+
+Expr *clang::IgnoreImplicitAsWrittenSingleStep(Expr *E) {
+  if (auto *ICE = dyn_cast<ImplicitCastExpr>(E))
+    return ICE->getSubExprAsWritten();
+
+  return IgnoreImplicitSingleStep(E);
+}
+
+Expr *clang::IgnoreParensOnlySingleStep(Expr *E) {
+  if (auto *PE = dyn_cast<ParenExpr>(E))
+    return PE->getSubExpr();
+  return E;
+}
+
+Expr *clang::IgnoreParensSingleStep(Expr *E) {
+  if (auto *PE = dyn_cast<ParenExpr>(E))
+    return PE->getSubExpr();
+
+  if (auto *UO = dyn_cast<UnaryOperator>(E)) {
+    if (UO->getOpcode() == UO_Extension)
+      return UO->getSubExpr();
+  }
+
+  else if (auto *GSE = dyn_cast<GenericSelectionExpr>(E)) {
+    if (!GSE->isResultDependent())
+      return GSE->getResultExpr();
+  }
+
+  else if (auto *CE = dyn_cast<ChooseExpr>(E)) {
+    if (!CE->isConditionDependent())
+      return CE->getChosenSubExpr();
+  }
+
+  return E;
+}