[Clang][DebugInfo] Use CGDebugInfo::createFile in CGDebugInfo::CreateCompileUnit (#83174)

[noxwell]

Use CGDebugInfo::createFile wrapper that handles file remapping and corner cases instead of directly using DBuilder.createFile in CGDebugInfo::CreateCompileUnit.

Fixes #83174

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Author: Aleksei Vetrov (noxwell)

Changes

Use CGDebugInfo::createFile wrapper that handles file remapping and corner cases instead of directly using DBuilder.createFile in CGDebugInfo::CreateCompileUnit.

Fixes #83174

---

Full diff: https://github.com/llvm/llvm-project/pull/83175.diff

1 Files Affected:

• (modified) clang/lib/CodeGen/CGDebugInfo.cpp (+2-3)

diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index c2c01439f2dc99..2a24cc1a9dc020 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -628,9 +628,8 @@ void CGDebugInfo::CreateCompileUnit() {
   // file was specified with an absolute path.
   if (CSKind)
     CSInfo.emplace(*CSKind, Checksum);
-  llvm::DIFile *CUFile = DBuilder.createFile(
-      remapDIPath(MainFileName), remapDIPath(getCurrentDirname()), CSInfo,
-      getSource(SM, SM.getMainFileID()));
+  llvm::DIFile *CUFile = createFile(
+      MainFileName, CSInfo, getSource(SM, SM.getMainFileID()));
 
   StringRef Sysroot, SDK;
   if (CGM.getCodeGenOpts().getDebuggerTuning() == llvm::DebuggerKind::LLDB) {

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[adrian-prantl]

Can you add a test for this?

[adrian-prantl]

Why is MainFileName no longer being remapped here?

[noxwell]

CGDebugInfo::createFile takes care of remapping, see std::string RemappedFile = remapDIPath(FileName).

[noxwell]

Can you add a test for this?

I added a test for remapping of absolute path. It passes with this PR and fails on trunk.

However, I found much bigger problem. This fix fails test debug-info-abspath.c, more specifically the last case, which checks that CU file has absolute path to source file as well as absolute path to current working directory. @adrian-prantl should now better, but I think it is done to satisfy DWARF standard:

A DW_AT_name attribute whose value is a null-terminated string containing the full or relative path name (relative to the value of the DW_AT_comp_dir attribute, see below) of the primary source file from which the compilation unit was derived.
A DW_AT_comp_dir attribute whose value is a null-terminated string containing the current working directory of the compilation command

It looks like there may be a problem in the standard: you can't have DW_TAG_compile_unit that references file by relative path, but not relative to DW_AT_comp_dir. What do you think?

[adrian-prantl]

Can you compare this to other tests with paths in them? In my memory you need to do some fancy regex for the / path separator work under Windows.

[noxwell]

Closing this PR, because these changes are incompatible to DWARF standard, see 83175#issuecomment-1969473992