[LTO] Change addSaveTemps API: do not add dot to the supplied prefix path

[mehdi_amini]

Summary

It does not play well with directories (end up with a bunch of hidden
files).
Also, do not strip the 0 suffix for the first task, especially since
0 can be used by ThinLTO as well now.

[tejohnson]

lib/LTO/LTOBackend.cpp

64

With this change we won't get the "." between the module ID and the suffix in the case when we have set UseInputModulePath to true. I suspect that will cause gold tests to fail (and is less pretty overall).

Instead, can the new addition of "." after the Task Id on line 61 be removed?

[mehdi_amini]

Fix the "." for the UseInputModulePath case

[mehdi_amini]

lib/LTO/LTOBackend.cpp

64

Done!

[tejohnson]

LGTM with two fixes. One compile failure in gold-plugin.cc noted below, and one test needs the following fix:

diff --git a/test/tools/gold/X86/opt-level.ll b/test/tools/gold/X86/opt-level.ll
index a680a16..66935b4 100644

• a/test/tools/gold/X86/opt-level.ll

+++ b/test/tools/gold/X86/opt-level.ll
@@ -1,13 +1,13 @@
; RUN: llvm-as -o %t.bc %s
; RUN: %gold -plugin %llvmshlibdir/LLVMgold.so -plugin-opt=save-temps \
; RUN: -plugin-opt=O0 -r -o %t.o %t.bc
-; RUN: llvm-dis < %t.o.4.opt.bc -o - | FileCheck --check-prefix=CHECK-O0 %s
+; RUN: llvm-dis < %t.o.0.4.opt.bc -o - | FileCheck --check-prefix=CHECK-O0 %s
; RUN: %gold -plugin %llvmshlibdir/LLVMgold.so -plugin-opt=save-temps \
; RUN: -plugin-opt=O1 -r -o %t.o %t.bc
-; RUN: llvm-dis < %t.o.4.opt.bc -o - | FileCheck --check-prefix=CHECK-O1 %s
+; RUN: llvm-dis < %t.o.0.4.opt.bc -o - | FileCheck --check-prefix=CHECK-O1 %s
; RUN: %gold -plugin %llvmshlibdir/LLVMgold.so -plugin-opt=save-temps \
; RUN: -plugin-opt=O2 -r -o %t.o %t.bc
-; RUN: llvm-dis < %t.o.4.opt.bc -o - | FileCheck --check-prefix=CHECK-O2 %s
+; RUN: llvm-dis < %t.o.0.4.opt.bc -o - | FileCheck --check-prefix=CHECK-O2 %s

; CHECK-O0: define internal void @foo(
; CHECK-O1: define internal void @foo(

tools/gold/gold-plugin.cpp

799–800

Won't build until Twine removed.

lib/LTO/LTOBackend.cpp

 using namespace lto;
 
 Error Config::addSaveTemps(std::string OutputFileName,
                            bool UseInputModulePath) {
   ShouldDiscardValueNames = false;
 
   std::error_code EC;
   ResolutionFile = llvm::make_unique<raw_fd_ostream>(
-      OutputFileName + ".resolution.txt", EC, sys::fs::OpenFlags::F_Text);
+      OutputFileName + "resolution.txt", EC, sys::fs::OpenFlags::F_Text);
   if (EC)
     return errorCodeToError(EC);
 
   auto setHook = [&](std::string PathSuffix, ModuleHookFn &Hook) {
     // Keep track of the hook provided by the linker, which also needs to run.
     ModuleHookFn LinkerHook = Hook;
     Hook = [=](unsigned Task, Module &M) {
       // If the linker's hook returned false, we need to pass that result
       // through.
       if (LinkerHook && !LinkerHook(Task, M))
         return false;
 
       std::string PathPrefix;
       // If this is the combined module (not a ThinLTO backend compile) or the
       // user hasn't requested using the input module's path, emit to a file
       // named from the provided OutputFileName with the Task ID appended.
       if (M.getModuleIdentifier() == "ld-temp.o" || !UseInputModulePath) {
-        PathPrefix = OutputFileName;
-        if (Task != 0)
-          PathPrefix += "." + utostr(Task);
+        PathPrefix = OutputFileName + utostr(Task) + ".";
       } else
         PathPrefix = M.getModuleIdentifier();
-      std::string Path = PathPrefix + "." + PathSuffix + ".bc";
+      std::string Path = PathPrefix + PathSuffix + ".bc";
       std::error_code EC;
       raw_fd_ostream OS(Path, EC, sys::fs::OpenFlags::F_None);
       if (EC) {
         // Because -save-temps is a debugging feature, we report the error
         // directly and exit.
         llvm::errs() << "failed to open " << Path << ": " << EC.message()
                      << '\n';
         exit(1);
       }
       WriteBitcodeToFile(&M, OS, /*ShouldPreserveUseListOrder=*/false);
       return true;
     };
   };
 
   setHook("0.preopt", PreOptModuleHook);
   setHook("1.promote", PostPromoteModuleHook);
   setHook("2.internalize", PostInternalizeModuleHook);
   setHook("3.import", PostImportModuleHook);
   setHook("4.opt", PostOptModuleHook);
   setHook("5.precodegen", PreCodeGenModuleHook);
 
   CombinedIndexHook = [=](const ModuleSummaryIndex &Index) {
-    std::string Path = OutputFileName + ".index.bc";
+    std::string Path = OutputFileName + "index.bc";
     std::error_code EC;
     raw_fd_ostream OS(Path, EC, sys::fs::OpenFlags::F_None);
     if (EC) {
       // Because -save-temps is a debugging feature, we report the error
       // directly and exit.
       llvm::errs() << "failed to open " << Path << ": " << EC.message() << '\n';
       exit(1);
     }

tools/gold/gold-plugin.cpp

Conf.PostInternalizeModuleHook = [](size_t Task, Module &M) {
       if (EC)
         message(LDPL_FATAL, "Failed to write the output file.");
       WriteBitcodeToFile(&M, OS, /* ShouldPreserveUseListOrder */ false);
       return false;
     };
     break;
 
   case options::OT_SAVE_TEMPS:
-    check(Conf.addSaveTemps(output_name, /* UseInputModulePath */ true));
+    check(Conf.addSaveTemps(Twine(output_name) + ".",
+                            /* UseInputModulePath */ true));
     break;
   }
 
   return llvm::make_unique<LTO>(std::move(Conf), Backend,
                                 ParallelCodeGenParallelismLevel);
 }
 
 /// gold informs us that all symbols have been read. At this point, we use

tools/llvm-lto2/llvm-lto2.cpp

int main(int argc, char **argv) {
   std::vector<std::unique_ptr<MemoryBuffer>> MBs;
 
   Config Conf;
   Conf.DiagHandler = [](const DiagnosticInfo &) {
     exit(1);
   };
 
   if (SaveTemps)
-    check(Conf.addSaveTemps(OutputFilename), "Config::addSaveTemps failed");
+    check(Conf.addSaveTemps(OutputFilename + "."),
+          "Config::addSaveTemps failed");
 
   LTO Lto(std::move(Conf));
 
   bool HasErrors = false;
   for (std::string F : InputFilenames) {
     std::unique_ptr<MemoryBuffer> MB = check(MemoryBuffer::getFile(F), F);
     std::unique_ptr<InputFile> Input =
         check(InputFile::create(MB->getMemBufferRef()), F);