[libclang] NFC, simplify clang_Cursor_Evaluate

Take advantage of early returns as suggested by Duncan in
https://reviews.llvm.org/D49051


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@336591 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit 7a9552d)

tools/libclang/CIndex.cpp

@@ -3878,36 +3878,35 @@ static const ExprEvalResult* evaluateExpr(Expr *expr, CXCursor C) {
   return nullptr;
 }
 
-CXEvalResult clang_Cursor_Evaluate(CXCursor C) {
-  if (clang_getCursorKind(C) == CXCursor_CompoundStmt) {
-    const CompoundStmt *compoundStmt = cast<CompoundStmt>(getCursorStmt(C));
-    Expr *expr = nullptr;
-    for (auto *bodyIterator : compoundStmt->body()) {
-      if ((expr = dyn_cast<Expr>(bodyIterator))) {
-        break;
-      }
-    }
-    if (expr)
-      return const_cast<CXEvalResult>(
-          reinterpret_cast<const void *>(evaluateExpr(expr, C)));
-  }
-
-  const Decl *D = getCursorDecl(C);
-  if (D) {
-    const Expr *expr = nullptr;
-    if (auto *Var = dyn_cast<VarDecl>(D)) {
-      expr = Var->getInit();
-    } else if (auto *Field = dyn_cast<FieldDecl>(D)) {
-      expr = Field->getInClassInitializer();
-    }
-    if (expr)
-      return const_cast<CXEvalResult>(reinterpret_cast<const void *>(
-          evaluateExpr(const_cast<Expr *>(expr), C)));
+static const Expr *evaluateDeclExpr(const Decl *D) {
+  if (!D)
     return nullptr;
+  if (auto *Var = dyn_cast<VarDecl>(D))
+    return Var->getInit();
+  else if (auto *Field = dyn_cast<FieldDecl>(D))
+    return Field->getInClassInitializer();
+  return nullptr;
+}
+
+static const Expr *evaluateCompoundStmtExpr(const CompoundStmt *CS) {
+  assert(CS && "invalid compound statement");
+  for (auto *bodyIterator : CS->body()) {
+    if (const auto *E = dyn_cast<Expr>(bodyIterator))
+      return E;
   }
   return nullptr;
 }
 
+CXEvalResult clang_Cursor_Evaluate(CXCursor C) {
+  if (const Expr *E =
+          clang_getCursorKind(C) == CXCursor_CompoundStmt
+              ? evaluateCompoundStmtExpr(cast<CompoundStmt>(getCursorStmt(C)))
+              : evaluateDeclExpr(getCursorDecl(C)))
+    return const_cast<CXEvalResult>(
+        reinterpret_cast<const void *>(evaluateExpr(const_cast<Expr *>(E), C)));
+  return nullptr;
+}
+
 unsigned clang_Cursor_hasAttrs(CXCursor C) {
   const Decl *D = getCursorDecl(C);
   if (!D) {