[llvm] r363496 - [Clang] Harmonize Split DWARF options with llc

[Aaron Puchert via llvm-commits]

Author: aaronpuchert
Date: Sat Jun 15 08:38:51 2019
New Revision: 363496

URL: http://llvm.org/viewvc/llvm-project?rev=363496&view=rev
Log:
[Clang] Harmonize Split DWARF options with llc

Summary:
With Split DWARF the resulting object file (then called skeleton CU)
contains the file name of another ("DWO") file with the debug info.
This can be a problem for remote compilation, as it will contain the
name of the file on the compilation server, not on the client.

To use Split DWARF with remote compilation, one needs to either

* make sure only relative paths are used, and mirror the build directory
  structure of the client on the server,
* inject the desired file name on the client directly.

Since llc already supports the latter solution, we're just copying that
over. We allow setting the actual output filename separately from the
value of the DW_AT_[GNU_]dwo_name attribute in the skeleton CU.

Fixes PR40276.

Reviewers: dblaikie, echristo, tejohnson

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D59673

Modified:
    llvm/trunk/include/llvm/LTO/Config.h
    llvm/trunk/lib/LTO/LTOBackend.cpp

Modified: llvm/trunk/include/llvm/LTO/Config.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/LTO/Config.h?rev=363496&r1=363495&r2=363496&view=diff
==============================================================================
--- llvm/trunk/include/llvm/LTO/Config.h (original)
+++ llvm/trunk/include/llvm/LTO/Config.h Sat Jun 15 08:38:51 2019
@@ -88,10 +88,16 @@ struct Config {
   /// The directory to store .dwo files.
   std::string DwoDir;
 
+  /// The name for the split debug info file used for the DW_AT_[GNU_]dwo_name
+  /// attribute in the skeleton CU. This should generally only be used when
+  /// running an individual backend directly via thinBackend(), as otherwise
+  /// all objects would use the same .dwo file. Not used as output path.
+  std::string SplitDwarfFile;
+
   /// The path to write a .dwo file to. This should generally only be used when
   /// running an individual backend directly via thinBackend(), as otherwise
-  /// all .dwo files will be written to the same path.
-  std::string DwoPath;
+  /// all .dwo files will be written to the same path. Not used in skeleton CU.
+  std::string SplitDwarfOutput;
 
   /// Optimization remarks file path.
   std::string RemarksFilename = "";

Modified: llvm/trunk/lib/LTO/LTOBackend.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/LTO/LTOBackend.cpp?rev=363496&r1=363495&r2=363496&view=diff
==============================================================================
--- llvm/trunk/lib/LTO/LTOBackend.cpp (original)
+++ llvm/trunk/lib/LTO/LTOBackend.cpp Sat Jun 15 08:38:51 2019
@@ -314,7 +314,7 @@ void codegen(Config &Conf, TargetMachine
     return;
 
   std::unique_ptr<ToolOutputFile> DwoOut;
-  SmallString<1024> DwoFile(Conf.DwoPath);
+  SmallString<1024> DwoFile(Conf.SplitDwarfOutput);
   if (!Conf.DwoDir.empty()) {
     std::error_code EC;
     if (auto EC = llvm::sys::fs::create_directories(Conf.DwoDir))
@@ -323,11 +323,12 @@ void codegen(Config &Conf, TargetMachine
 
     DwoFile = Conf.DwoDir;
     sys::path::append(DwoFile, std::to_string(Task) + ".dwo");
-  }
+    TM->Options.MCOptions.SplitDwarfFile = DwoFile.str().str();
+  } else
+    TM->Options.MCOptions.SplitDwarfFile = Conf.SplitDwarfFile;
 
   if (!DwoFile.empty()) {
     std::error_code EC;
-    TM->Options.MCOptions.SplitDwarfFile = DwoFile.str().str();
     DwoOut = llvm::make_unique<ToolOutputFile>(DwoFile, EC, sys::fs::F_None);
     if (EC)
       report_fatal_error("Failed to open " + DwoFile + ": " + EC.message());