Improve clang-format's memoization behavior.

Deeply nested expressions basically break clang-format's memoization.
This patch slightly improves the situations and makes expressions like

  aaaaa(aaaaa(aaaaa(aaaaa(aaaaa(aaaaa(aaaaa(aaaaa(
      aaaaa(aaaaa(aaaaa(aaaaa(aaaaa(aaaaa(aaaaa(aaaaa(aaaaa(aaaaa(aaaaa(
          aaaaa(aaaaa(aaaaa(aaaaa(aaaaa(aaaaa(aaaaa(aaaaa(aaaaa(aaaaa(
              aaaaa(aaaaa(aaaaa(aaaaa(aaaaa(aaaaa(aaaaa(aaaaa(aaaaa(
                  aaaaa(aaaaa())))))))))))))))))))))))))))))))))))))));

work.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@180264 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 25 insertions, 1 deletions

diff --git a/lib/Format/Format.cpp b/lib/Format/Format.cpp
index 7d2041cd3c..a76e0d48a4 100644
--- a/lib/Format/Format.cpp
+++ b/lib/Format/Format.cpp
@@ -569,6 +569,15 @@ private:
       State.Stack.push_back(
           ParenState(NewIndent, State.Stack.back().LastSpace, AvoidBinPacking,
                      State.Stack.back().NoLineBreak));
+
+      if (Current.NoMoreTokensOnLevel && Current.FakeLParens.empty()) {
+        // This parenthesis was the last token possibly making use of Indent and
+        // LastSpace of the next higher ParenLevel. Thus, erase them to acieve
+        // better memoization results.
+        State.Stack[State.Stack.size() - 2].Indent = 0;
+        State.Stack[State.Stack.size() - 2].LastSpace = 0;
+      }
+
       ++State.ParenLevel;
     }
 
diff --git a/lib/Format/TokenAnnotator.cpp b/lib/Format/TokenAnnotator.cpp
index 276921795a..3e67182f87 100644
--- a/lib/Format/TokenAnnotator.cpp
+++ b/lib/Format/TokenAnnotator.cpp
@@ -155,6 +155,8 @@ private:
       }
 
       if (CurrentToken->is(tok::r_paren)) {
+        if (CurrentToken->Parent->closesScope())
+          CurrentToken->Parent->MatchingParen->NoMoreTokensOnLevel = true;
         Left->MatchingParen = CurrentToken;
         CurrentToken->MatchingParen = Left;
 
diff --git a/lib/Format/TokenAnnotator.h b/lib/Format/TokenAnnotator.h
index 0dde1fa903..fbb65b6254 100644
--- a/lib/Format/TokenAnnotator.h
+++ b/lib/Format/TokenAnnotator.h
@@ -77,7 +77,7 @@ public:
         ParameterCount(0), BindingStrength(0), SplitPenalty(0),
         LongestObjCSelectorName(0), Parent(NULL),
         FakeRParens(0), LastInChainOfCalls(false),
-        PartOfMultiVariableDeclStmt(false) {}
+        PartOfMultiVariableDeclStmt(false), NoMoreTokensOnLevel(false) {}
 
   bool is(tok::TokenKind Kind) const { return FormatTok.Tok.is(Kind); }
 
@@ -184,6 +184,19 @@ public:
   /// Only set if \c Type == \c TT_StartOfName.
   bool PartOfMultiVariableDeclStmt;
 
+  /// \brief Set to \c true for "("-tokens if this is the last token other than
+  /// ")" in the next higher parenthesis level.
+  ///
+  /// If this is \c true, no more formatting decisions have to be made on the
+  /// next higher parenthesis level, enabling optimizations.
+  ///
+  /// Example:
+  /// \code
+  /// aaaaaa(aaaaaa());
+  ///              ^  // Set to true for this parenthesis.
+  /// \endcode
+  bool NoMoreTokensOnLevel;
+
   /// \brief Returns the previous token ignoring comments.
   AnnotatedToken *getPreviousNoneComment() const;