Speed up code-completion by skipping function bodies.

When we are in code-completion mode, skip parsing of all function bodies except the one where the
code-completion point resides.

For big .cpp files like 'SemaExpr.cpp' the improvement makes a huge difference, in some cases cutting down
code-completion time -62% !

We don't get diagnostics for the bodies though, so modify the code-completion tests that check for errors.

See rdar://8814203.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@122765 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 20 insertions, 5 deletions

diff --git a/lib/Parse/ParseStmt.cpp b/lib/Parse/ParseStmt.cpp
index dafe373778..d25cc110a8 100644
--- a/lib/Parse/ParseStmt.cpp
+++ b/lib/Parse/ParseStmt.cpp
@@ -1466,6 +1466,19 @@ Decl *Parser::ParseFunctionStatementBody(Decl *Decl) {
   assert(Tok.is(tok::l_brace));
   SourceLocation LBraceLoc = Tok.getLocation();
 
+  // When in code-completion, skip parsing for all function bodies unless
+  // the body contains the code-completion point.
+  if (PP.isCodeCompletionEnabled()) {
+    TentativeParsingAction PA(*this);
+    ConsumeBrace();
+    if (SkipUntil(tok::r_brace, /*StopAtSemi=*/false, /*DontConsume=*/false,
+                  /*StopAtCodeCompletion=*/true)) {
+      PA.Commit();
+      return Actions.ActOnFinishFunctionBody(Decl, 0);
+    }
+    PA.Revert();
+  }
+
   PrettyDeclStackTraceEntry CrashInfo(Actions, Decl, LBraceLoc,
                                       "parsing function body");
 
diff --git a/lib/Parse/Parser.cpp b/lib/Parse/Parser.cpp
index 2a569b58d8..aa0ad795ca 100644
--- a/lib/Parse/Parser.cpp
+++ b/lib/Parse/Parser.cpp
@@ -214,7 +214,8 @@ bool Parser::ExpectAndConsumeSemi(unsigned DiagID) {
 /// If SkipUntil finds the specified token, it returns true, otherwise it
 /// returns false.
 bool Parser::SkipUntil(const tok::TokenKind *Toks, unsigned NumToks,
-                       bool StopAtSemi, bool DontConsume) {
+                       bool StopAtSemi, bool DontConsume,
+                       bool StopAtCodeCompletion) {
   // We always want this function to skip at least one token if the first token
   // isn't T and if not at EOF.
   bool isFirstTokenSkipped = true;
@@ -237,23 +238,24 @@ bool Parser::SkipUntil(const tok::TokenKind *Toks, unsigned NumToks,
       return false;
         
     case tok::code_completion:
-      ConsumeToken();
+      if (!StopAtCodeCompletion)
+        ConsumeToken();
       return false;
         
     case tok::l_paren:
       // Recursively skip properly-nested parens.
       ConsumeParen();
-      SkipUntil(tok::r_paren, false);
+      SkipUntil(tok::r_paren, false, false, StopAtCodeCompletion);
       break;
     case tok::l_square:
       // Recursively skip properly-nested square brackets.
       ConsumeBracket();
-      SkipUntil(tok::r_square, false);
+      SkipUntil(tok::r_square, false, false, StopAtCodeCompletion);
       break;
     case tok::l_brace:
       // Recursively skip properly-nested braces.
       ConsumeBrace();
-      SkipUntil(tok::r_brace, false);
+      SkipUntil(tok::r_brace, false, false, StopAtCodeCompletion);
       break;
 
     // Okay, we found a ']' or '}' or ')', which we think should be balanced.