From f3994e4dfa0214b2a09a0e327ba37e6b38bbcdb3 Mon Sep 17 00:00:00 2001
From: Fangrui Song <maskray@google.com>
Date: Tue, 7 May 2019 10:40:26 +0000
Subject: [PATCH] [ELF] Reorder BitcodeFiles.empty() to call
 thinLTOCreateEmptyIndexFiles() in only one place

It makes the --plugin-opt=obj-path= and --plugin-opt=thinlto-index-only=
behavior more consistent - the files will be created in the
BitcodeFiles.empty() case, but I assume whether it behaves this way is
not required by anyone.

LTOObj->run() cannot run with empty BitcodeFiles. There would be an error:

    ld.lld: error: No available targets are compatible with triple ""

Differential Revision: https://reviews.llvm.org/D61635

llvm-svn: 360129
---
 lld/ELF/LTO.cpp         | 15 ++++++++-------
 lld/ELF/LTO.h           |  2 --
 lld/ELF/SymbolTable.cpp |  6 ------
 3 files changed, 8 insertions(+), 15 deletions(-)

diff --git a/lld/ELF/LTO.cpp b/lld/ELF/LTO.cpp
index 4f641d647de3..ea0d17e81aab 100644
--- a/lld/ELF/LTO.cpp
+++ b/lld/ELF/LTO.cpp
@@ -214,7 +214,7 @@ void BitcodeCompiler::add(BitcodeFile &F) {
 // If LazyObjFile has not been added to link, emit empty index files.
 // This is needed because this is what GNU gold plugin does and we have a
 // distributed build system that depends on that behavior.
-void elf::thinLTOCreateEmptyIndexFiles() {
+static void thinLTOCreateEmptyIndexFiles() {
   for (LazyObjFile *F : LazyObjFiles) {
     if (F->AddedToLink || !isBitcode(F->MB))
       continue;
@@ -249,12 +249,13 @@ std::vector<InputFile *> BitcodeCompiler::compile() {
                           Files[Task] = std::move(MB);
                         }));
 
-  checkError(LTOObj->run(
-      [&](size_t Task) {
-        return llvm::make_unique<lto::NativeObjectStream>(
-            llvm::make_unique<raw_svector_ostream>(Buf[Task]));
-      },
-      Cache));
+  if (!BitcodeFiles.empty())
+    checkError(LTOObj->run(
+        [&](size_t Task) {
+          return llvm::make_unique<lto::NativeObjectStream>(
+              llvm::make_unique<raw_svector_ostream>(Buf[Task]));
+        },
+        Cache));
 
   // Emit empty index files for non-indexed files
   for (StringRef S : ThinIndices) {
diff --git a/lld/ELF/LTO.h b/lld/ELF/LTO.h
index 1df1d2bbcfd5..0f0b5bce7180 100644
--- a/lld/ELF/LTO.h
+++ b/lld/ELF/LTO.h
@@ -56,8 +56,6 @@ private:
   std::unique_ptr<llvm::raw_fd_ostream> IndexFile;
   llvm::DenseSet<StringRef> ThinIndices;
 };
-
-void thinLTOCreateEmptyIndexFiles();
 } // namespace elf
 } // namespace lld
 
diff --git a/lld/ELF/SymbolTable.cpp b/lld/ELF/SymbolTable.cpp
index 1b017b07f584..6e69b25c61e0 100644
--- a/lld/ELF/SymbolTable.cpp
+++ b/lld/ELF/SymbolTable.cpp
@@ -115,12 +115,6 @@ template <class ELFT> void SymbolTable::addFile(InputFile *File) {
 // Because all bitcode files that the program consists of are passed
 // to the compiler at once, it can do whole-program optimization.
 template <class ELFT> void SymbolTable::addCombinedLTOObject() {
-  if (BitcodeFiles.empty()) {
-    if (Config->ThinLTOIndexOnly)
-      thinLTOCreateEmptyIndexFiles();
-    return;
-  }
-
   // Compile bitcode files and replace bitcode symbols.
   LTO.reset(new BitcodeCompiler);
   for (BitcodeFile *F : BitcodeFiles)