[DebugInfo] Fix file path separator when targeting windows.

This fixes two problems:

1. When crossing compiling for windows on linux, source file path in debug info is concatenated with directory by host native separator ('/'). For windows local build, they are concatenated by '\'. This causes non-determinism bug.

  The solution here is to let `LangOptions.UseTargetPathSeparator` to control if we should use host native separator or not.

2. Objectfile path in CodeView also uses host native separator when generated.

 It's fixed by changing the path separator in `/Fo` to '\' if the path is not an absolute path when adding the `-object-file-name=` flag.

Reviewed By: hans

Differential Revision: https://reviews.llvm.org/D147256

1 files changed, 10 insertions, 4 deletions

diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index cd0fece..5100d6c 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -528,6 +528,7 @@ void CGDebugInfo::CreateCompileUnit() {
   // Get absolute path name.
   SourceManager &SM = CGM.getContext().getSourceManager();
   auto &CGO = CGM.getCodeGenOpts();
+  const LangOptions &LO = CGM.getLangOpts();
   std::string MainFileName = CGO.MainFileName;
   if (MainFileName.empty())
     MainFileName = "<stdin>";
@@ -542,9 +543,15 @@ void CGDebugInfo::CreateCompileUnit() {
     MainFileDir = std::string(MainFile->getDir().getName());
     if (!llvm::sys::path::is_absolute(MainFileName)) {
       llvm::SmallString<1024> MainFileDirSS(MainFileDir);
-      llvm::sys::path::append(MainFileDirSS, MainFileName);
-      MainFileName =
-          std::string(llvm::sys::path::remove_leading_dotslash(MainFileDirSS));
+      llvm::sys::path::Style Style =
+          LO.UseTargetPathSeparator
+              ? (CGM.getTarget().getTriple().isOSWindows()
+                     ? llvm::sys::path::Style::windows_backslash
+                     : llvm::sys::path::Style::posix)
+              : llvm::sys::path::Style::native;
+      llvm::sys::path::append(MainFileDirSS, Style, MainFileName);
+      MainFileName = std::string(
+          llvm::sys::path::remove_leading_dotslash(MainFileDirSS, Style));
     }
     // If the main file name provided is identical to the input file name, and
     // if the input file is a preprocessed source, use the module name for
@@ -560,7 +567,6 @@ void CGDebugInfo::CreateCompileUnit() {
   }
 
   llvm::dwarf::SourceLanguage LangTag;
-  const LangOptions &LO = CGM.getLangOpts();
   if (LO.CPlusPlus) {
     if (LO.ObjC)
       LangTag = llvm::dwarf::DW_LANG_ObjC_plus_plus;