[ThinLTO] Adding architecture name into saved object filename

Summary:
For ThinLTOCodegenerator, it has an option to save the object file
outputs into a directory which is essential for debug info. Tools like lldb
and dsymutil will look for these object files for debug info.

On Darwin platform, you can link fat binaries with one single clang
driver invocation like:
 $ clang -arch x86_64 -arch i386 -Wl,-object_path_lto,$TMPDIR ...
Unfornately, the output object files for one architecture is going to
overwrite the previous ones and one architecture slice will end up with
no debug info. One example for this is to turn on ThinLTO for sanitizer
dylibs in compiler-rt project.

To fix the issue, add the name for the architecture into the name of the
output object file.

rdar://problem/35482935

Reviewers: tejohnson, bd1976llvm, dexonsmith, JDevlieghere

Reviewed By: dexonsmith

Subscribers: mehdi_amini, aprantl, inglorion, eraman, hiraditya, jkorous, dang, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D60924

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@359508 91177308-0d34-0410-b5e6-96231b3b80d8

Author: cachemeifyoucan

include/llvm/LTO/legacy/ThinLTOCodeGenerator.h

@@ -299,6 +299,13 @@ class ThinLTOCodeGenerator {
    */
   void optimize(Module &Module);
 
+  /**
+   * Write temporary object file to SavedObjectDirectoryPath, write symlink
+   * to Cache directory if needed. Returns the path to the generated file in
+   * SavedObjectsDirectoryPath.
+   */
+  std::string writeGeneratedObject(int count, StringRef CacheEntryPath,
+                                   const MemoryBuffer &OutputBuffer);
   /**@}*/
 
 private:

lib/LTO/ThinLTOCodeGenerator.cpp

@@ -777,11 +777,13 @@ void ThinLTOCodeGenerator::optimize(Module &TheModule) {
 /// Write out the generated object file, either from CacheEntryPath or from
 /// OutputBuffer, preferring hard-link when possible.
 /// Returns the path to the generated file in SavedObjectsDirectoryPath.
-static std::string writeGeneratedObject(int count, StringRef CacheEntryPath,
-                                        StringRef SavedObjectsDirectoryPath,
-                                        const MemoryBuffer &OutputBuffer) {
+std::string
+ThinLTOCodeGenerator::writeGeneratedObject(int count, StringRef CacheEntryPath,
+                                           const MemoryBuffer &OutputBuffer) {
+  auto ArchName = TMBuilder.TheTriple.getArchName();
   SmallString<128> OutputPath(SavedObjectsDirectoryPath);
-  llvm::sys::path::append(OutputPath, Twine(count) + ".thinlto.o");
+  llvm::sys::path::append(OutputPath,
+                          Twine(count) + "." + ArchName + ".thinlto.o");
   OutputPath.c_str(); // Ensure the string is null terminated.
   if (sys::fs::exists(OutputPath))
     sys::fs::remove(OutputPath);
@@ -845,8 +847,8 @@ void ThinLTOCodeGenerator::run() {
         if (SavedObjectsDirectoryPath.empty())
           ProducedBinaries[count] = std::move(OutputBuffer);
         else
-          ProducedBinaryFiles[count] = writeGeneratedObject(
-              count, "", SavedObjectsDirectoryPath, *OutputBuffer);
+          ProducedBinaryFiles[count] =
+              writeGeneratedObject(count, "", *OutputBuffer);
       }, count++);
     }
 
@@ -963,8 +965,7 @@ void ThinLTOCodeGenerator::run() {
               ProducedBinaries[count] = std::move(ErrOrBuffer.get());
             else
               ProducedBinaryFiles[count] = writeGeneratedObject(
-                  count, CacheEntryPath, SavedObjectsDirectoryPath,
-                  *ErrOrBuffer.get());
+                  count, CacheEntryPath, *ErrOrBuffer.get());
             return;
           }
         }
@@ -1021,7 +1022,7 @@ void ThinLTOCodeGenerator::run() {
           return;
         }
         ProducedBinaryFiles[count] = writeGeneratedObject(
-            count, CacheEntryPath, SavedObjectsDirectoryPath, *OutputBuffer);
+            count, CacheEntryPath, *OutputBuffer);
       }, IndexCount);
     }
   }

test/ThinLTO/X86/save_objects.ll

@@ -20,6 +20,9 @@
 ; RUN: ls %t.thin.out | count 2
 ; RUN: ls %t.cache | count 3
 
+; Check the name of object in directory has arch name included.
+; RUN: ls %t.thin.out | grep x86_64.thinlto.o | count 2
+
 
 target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-apple-macosx10.11.0"