Remove ignore-empty-index-file option

Summary:
As discussed in the D32195 review thread and on IRC, remove this option
and replace with parameter, which will be set to true when invoked
from clang in the context of a ThinLTO distributed backend.

Reviewers: pcc

Subscribers: mehdi_amini, llvm-commits

Differential Revision: https://reviews.llvm.org/D33133

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@302939 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Bitcode/BitcodeReader.h

@@ -152,10 +152,11 @@ namespace llvm {
 
   /// Parse the module summary index out of an IR file and return the module
   /// summary index object if found, or an empty summary if not. If Path refers
-  /// to an empty file and the -ignore-empty-index-file cl::opt flag is passed
+  /// to an empty file and IgnoreEmptyThinLTOIndexFile is true, then
   /// this function will return nullptr.
   Expected<std::unique_ptr<ModuleSummaryIndex>>
-  getModuleSummaryIndexForFile(StringRef Path);
+  getModuleSummaryIndexForFile(StringRef Path,
+                               bool IgnoreEmptyThinLTOIndexFile = false);
 
   /// isBitcodeWrapper - Return true if the given bytes are the magic bytes
   /// for an LLVM IR bitcode wrapper.

lib/Bitcode/Reader/BitcodeReader.cpp

@@ -93,13 +93,6 @@ static cl::opt<bool> PrintSummaryGUIDs(
     cl::desc(
         "Print the global id for each value when reading the module summary"));
 
-// FIXME: This flag should either be removed or moved to clang as a driver flag.
-static llvm::cl::opt<bool> IgnoreEmptyThinLTOIndexFile(
-    "ignore-empty-index-file", llvm::cl::ZeroOrMore,
-    llvm::cl::desc(
-        "Ignore an empty index file and perform non-ThinLTO compilation"),
-    llvm::cl::init(false));
-
 namespace {
 
 enum {
@@ -5663,7 +5656,8 @@ Expected<bool> llvm::hasGlobalValueSummary(MemoryBufferRef Buffer) {
 }
 
 Expected<std::unique_ptr<ModuleSummaryIndex>>
-llvm::getModuleSummaryIndexForFile(StringRef Path) {
+llvm::getModuleSummaryIndexForFile(StringRef Path,
+                                   bool IgnoreEmptyThinLTOIndexFile) {
   ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr =
       MemoryBuffer::getFileOrSTDIN(Path);
   if (!FileOrErr)