From 3ecd8c0aabd30107d4fff8fdd9547f77b3b66d1a Mon Sep 17 00:00:00 2001
From: Manuel Klimek <klimek@google.com>
Date: Tue, 8 Sep 2015 15:14:06 +0000
Subject: Fix performance regression when running clang tools.

Brings tool start time for a large synthetic test case down from (on my
machine) 4 seconds to 0.5 seconds.

llvm-svn: 247018
---
 clang/lib/Tooling/JSONCompilationDatabase.cpp | 52 +++++++++++++++------------
 1 file changed, 30 insertions(+), 22 deletions(-)

(limited to 'clang/lib/Tooling/JSONCompilationDatabase.cpp')

diff --git a/clang/lib/Tooling/JSONCompilationDatabase.cpp b/clang/lib/Tooling/JSONCompilationDatabase.cpp
index 421651c..3ac6f69 100644
--- a/clang/lib/Tooling/JSONCompilationDatabase.cpp
+++ b/clang/lib/Tooling/JSONCompilationDatabase.cpp
@@ -214,15 +214,26 @@ JSONCompilationDatabase::getAllCompileCommands() const {
   return Commands;
 }
 
+static std::vector<std::string>
+nodeToCommandLine(const std::vector<llvm::yaml::ScalarNode *> &Nodes) {
+  SmallString<1024> Storage;
+  if (Nodes.size() == 1) {
+    return unescapeCommandLine(Nodes[0]->getValue(Storage));
+  }
+  std::vector<std::string> Arguments;
+  for (auto *Node : Nodes) {
+    Arguments.push_back(Node->getValue(Storage));
+  }
+  return Arguments;
+}
+
 void JSONCompilationDatabase::getCommands(
-                                  ArrayRef<CompileCommandRef> CommandsRef,
-                                  std::vector<CompileCommand> &Commands) const {
+    ArrayRef<CompileCommandRef> CommandsRef,
+    std::vector<CompileCommand> &Commands) const {
   for (int I = 0, E = CommandsRef.size(); I != E; ++I) {
     SmallString<8> DirectoryStorage;
-    SmallString<1024> CommandStorage;
-    Commands.emplace_back(
-      CommandsRef[I].first->getValue(DirectoryStorage),
-      CommandsRef[I].second);
+    Commands.emplace_back(CommandsRef[I].first->getValue(DirectoryStorage),
+                          nodeToCommandLine(CommandsRef[I].second));
   }
 }
 
@@ -249,11 +260,8 @@ bool JSONCompilationDatabase::parse(std::string &ErrorMessage) {
       return false;
     }
     llvm::yaml::ScalarNode *Directory = nullptr;
-    std::vector<std::string> Arguments;
-    std::vector<std::string> Command;
+    llvm::Optional<std::vector<llvm::yaml::ScalarNode *>> Command;
     llvm::yaml::ScalarNode *File = nullptr;
-    bool ArgumentsFound = false;
-    bool CommandFound = false;
     for (auto& NextKeyValue : *Object) {
       llvm::yaml::ScalarNode *KeyString =
           dyn_cast<llvm::yaml::ScalarNode>(NextKeyValue.getKey());
@@ -282,18 +290,18 @@ bool JSONCompilationDatabase::parse(std::string &ErrorMessage) {
       if (KeyValue == "directory") {
         Directory = ValueString;
       } else if (KeyValue == "arguments") {
-        for (auto& NextArgument : *SequenceString) {
-          SmallString<128> CommandStorage;
-          auto ValueString = dyn_cast<llvm::yaml::ScalarNode>(&NextArgument);
-
-          Arguments.push_back(ValueString->getValue(CommandStorage));
+        Command = std::vector<llvm::yaml::ScalarNode *>();
+        for (auto &Argument : *SequenceString) {
+          auto Scalar = dyn_cast<llvm::yaml::ScalarNode>(&Argument);
+          if (!Scalar) {
+            ErrorMessage = "Only strings are allowed in 'arguments'.";
+            return false;
+          }
+          Command->push_back(Scalar);
         }
-        ArgumentsFound = true;
       } else if (KeyValue == "command") {
-        SmallString<1024> CommandStorage;
-        // FIXME: Escape correctly:
-        Command = unescapeCommandLine(ValueString->getValue(CommandStorage));
-        CommandFound = true;
+        if (!Command)
+          Command = std::vector<llvm::yaml::ScalarNode *>(1, ValueString);
       } else if (KeyValue == "file") {
         File = ValueString;
       } else {
@@ -306,7 +314,7 @@ bool JSONCompilationDatabase::parse(std::string &ErrorMessage) {
       ErrorMessage = "Missing key: \"file\".";
       return false;
     }
-    if (!ArgumentsFound && !CommandFound) {
+    if (!Command) {
       ErrorMessage = "Missing key: \"command\" or \"arguments\".";
       return false;
     }
@@ -327,7 +335,7 @@ bool JSONCompilationDatabase::parse(std::string &ErrorMessage) {
       llvm::sys::path::native(FileName, NativeFilePath);
     }
     IndexByFile[NativeFilePath].push_back(
-        CompileCommandRef(Directory, ArgumentsFound ? Arguments : Command));
+        CompileCommandRef(Directory, *Command));
     MatchTrie.insert(NativeFilePath);
   }
   return true;
-- 
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