[Serialization] Serialize the SDK path and -Xcc arguments for an app.

...so that the debugger has the best possible chance of being able to load
the app properly.

We don't do this for frameworks today because we don't want to leak this
information into the public module; once we have a distinction between
"the module that ships with the framework" and "the module that goes into
the debug info" we can do this for frameworks as well.

Part of rdar://problem/17670778

Swift SVN r25204

lib/Serialization/ModuleFile.cpp

@@ -30,6 +30,9 @@ using namespace swift;
 using namespace swift::serialization;
 using namespace llvm::support;
 
+using ValidationInfo = SerializedModuleLoader::ValidationInfo;
+using ExtendedValidationInfo = SerializedModuleLoader::ExtendedValidationInfo;
+
 static bool checkModuleSignature(llvm::BitstreamCursor &cursor) {
   for (unsigned char byte : MODULE_SIGNATURE)
     if (cursor.AtEndOfStream() || cursor.Read(8) != byte)
@@ -70,12 +73,55 @@ static bool enterTopLevelModuleBlock(llvm::BitstreamCursor &cursor,
   return true;
 }
 
-static SerializedModuleLoader::ValidationInfo
+/// Populate \p extendedInfo with the data from the options block.
+///
+/// Returns true on success.
+static bool readOptionsBlock(llvm::BitstreamCursor &cursor,
+                             SmallVectorImpl<uint64_t> &scratch,
+                             ExtendedValidationInfo &extendedInfo) {
+  auto next = cursor.advance();
+  while (next.Kind != llvm::BitstreamEntry::EndBlock) {
+    if (next.Kind == llvm::BitstreamEntry::Error)
+      return false;
+
+    if (next.Kind == llvm::BitstreamEntry::SubBlock) {
+      // Unknown metadata sub-block, possibly for use by a future version of
+      // the module format.
+      if (cursor.SkipBlock())
+        return false;
+      next = cursor.advance();
+      continue;
+    }
+
+    scratch.clear();
+    StringRef blobData;
+    unsigned kind = cursor.readRecord(next.ID, scratch, &blobData);
+    switch (kind) {
+    case options_block::SDK_PATH:
+      extendedInfo.setSDKPath(blobData);
+      break;
+    case options_block::XCC:
+      extendedInfo.addClangImporterOption(blobData);
+      break;
+    default:
+      // Unknown options record, possibly for use by a future version of the
+      // module format.
+      break;
+    }
+
+    next = cursor.advance();
+  }
+
+  return true;
+}
+
+static ValidationInfo
 validateControlBlock(llvm::BitstreamCursor &cursor,
-                     SmallVectorImpl<uint64_t> &scratch) {
+                     SmallVectorImpl<uint64_t> &scratch,
+                     ExtendedValidationInfo *extendedInfo) {
   // The control block is malformed until we've at least read a major version
   // number.
-  SerializedModuleLoader::ValidationInfo result;
+  ValidationInfo result;
   bool versionSeen = false;
 
   auto next = cursor.advance();
@@ -86,11 +132,19 @@ validateControlBlock(llvm::BitstreamCursor &cursor,
     }
 
     if (next.Kind == llvm::BitstreamEntry::SubBlock) {
-      // Unknown metadata sub-block, possibly for use by a future version of the
-      // module format.
-      if (cursor.SkipBlock()) {
-        result.status = ModuleStatus::Malformed;
-        return result;
+      if (next.ID == OPTIONS_BLOCK_ID && extendedInfo) {
+        cursor.EnterSubBlock(OPTIONS_BLOCK_ID);
+        if (!readOptionsBlock(cursor, scratch, *extendedInfo)) {
+          result.status = ModuleStatus::Malformed;
+          return result;
+        }
+      } else {
+        // Unknown metadata sub-block, possibly for use by a future version of
+        // the module format.
+        if (cursor.SkipBlock()) {
+          result.status = ModuleStatus::Malformed;
+          return result;
+        }
       }
       next = cursor.advance();
       continue;
@@ -146,8 +200,9 @@ validateControlBlock(llvm::BitstreamCursor &cursor,
   return result;
 }
 
-SerializedModuleLoader::ValidationInfo
-SerializedModuleLoader::validateSerializedAST(StringRef data) {
+ValidationInfo SerializedModuleLoader::validateSerializedAST(
+    StringRef data,
+    ExtendedValidationInfo *extendedInfo) {
   ValidationInfo result;
 
   // Check 32-bit alignment.
@@ -168,7 +223,7 @@ SerializedModuleLoader::validateSerializedAST(StringRef data) {
   while (topLevelEntry.Kind == llvm::BitstreamEntry::SubBlock) {
     if (topLevelEntry.ID == CONTROL_BLOCK_ID) {
       cursor.EnterSubBlock(CONTROL_BLOCK_ID);
-      result = validateControlBlock(cursor, scratch);
+      result = validateControlBlock(cursor, scratch, extendedInfo);
       if (result.status == ModuleStatus::Malformed)
         return result;
 
@@ -677,7 +732,7 @@ ModuleFile::ModuleFile(
     case CONTROL_BLOCK_ID: {
       cursor.EnterSubBlock(CONTROL_BLOCK_ID);
 
-      auto info = validateControlBlock(cursor, scratch);
+      auto info = validateControlBlock(cursor, scratch, nullptr);
       if (info.status != ModuleStatus::Valid) {
         error(info.status);
         return;