Revert "Set the Compilation directory when generating the Skeleton CU"

This reverts commit b286b1c.

Reverted because fix for rdar://131726681 broke rdar://154247270

Reverting and will try to fix properly later.

We will not land this in 6.2

(cherry picked from commit 5b4fdd6)

Author: rastogishubham

lib/IRGen/IRGenDebugInfo.cpp

@@ -847,7 +847,6 @@ class IRGenDebugInfoImpl : public IRGenDebugInfo {
 
   llvm::DIModule *getOrCreateModule(const void *Key, llvm::DIScope *Parent,
                                     StringRef Name, StringRef IncludePath,
-                                    StringRef CompDir,
                                     uint64_t Signature = ~1ULL,
                                     StringRef ASTFile = StringRef()) {
     // Look in the cache first.
@@ -857,7 +856,6 @@ class IRGenDebugInfoImpl : public IRGenDebugInfo {
 
     std::string RemappedIncludePath = DebugPrefixMap.remapPath(IncludePath);
     std::string RemappedASTFile = DebugPrefixMap.remapPath(ASTFile);
-    std::string RemappedCompDir = DebugPrefixMap.remapPath(CompDir);
 
     // For Clang modules / PCH, create a Skeleton CU pointing to the PCM/PCH.
     if (!Opts.DisableClangModuleSkeletonCUs) {
@@ -867,7 +865,7 @@ class IRGenDebugInfoImpl : public IRGenDebugInfo {
         llvm::DIBuilder DIB(M);
         DIB.createCompileUnit(IGM.ObjCInterop ? llvm::dwarf::DW_LANG_ObjC
                                               : llvm::dwarf::DW_LANG_C99,
-                              DIB.createFile(Name, RemappedCompDir),
+                              DIB.createFile(Name, RemappedIncludePath),
                               TheCU->getProducer(), true, StringRef(), 0,
                               RemappedASTFile, llvm::DICompileUnit::FullDebug,
                               Signature);
@@ -894,8 +892,12 @@ class IRGenDebugInfoImpl : public IRGenDebugInfo {
     uint64_t Signature =
       Desc.getSignature() ? Desc.getSignature().truncatedValue() : ~1ULL;
 
-    StringRef CompDir = Opts.DebugCompilationDir;
-    StringRef IncludePath = Desc.getPath();
+    // Clang modules using fmodule-file-home-is-cwd should have their
+    // include path set to the working directory.
+    auto &HSI =
+        CI.getClangPreprocessor().getHeaderSearchInfo().getHeaderSearchOpts();
+    StringRef IncludePath =
+        HSI.ModuleFileHomeIsCwd ? Opts.DebugCompilationDir : Desc.getPath();
 
     // Handle Clang modules.
     if (ClangModule) {
@@ -917,13 +919,12 @@ class IRGenDebugInfoImpl : public IRGenDebugInfo {
                                    ClangModule->Parent);
       }
       return getOrCreateModule(ClangModule, Parent, Desc.getModuleName(),
-                               IncludePath, CompDir, Signature,
-                               Desc.getASTFile());
+                               IncludePath, Signature, Desc.getASTFile());
     }
     // Handle PCH.
     return getOrCreateModule(Desc.getASTFile().bytes_begin(), nullptr,
-                             Desc.getModuleName(), IncludePath, CompDir,
-                             Signature, Desc.getASTFile());
+                             Desc.getModuleName(), IncludePath, Signature,
+                             Desc.getASTFile());
   };
 
   static std::optional<ASTSourceDescriptor>
@@ -946,7 +947,7 @@ class IRGenDebugInfoImpl : public IRGenDebugInfo {
     // the module on disk is Bar (.swiftmodule or .swiftinterface), and is used
     // for loading and mangling.
     StringRef Name = M->getRealName().str();
-    return getOrCreateModule(M, TheCU, Name, Path, Opts.DebugCompilationDir);
+    return getOrCreateModule(M, TheCU, Name, Path);
   }
 
   TypeAliasDecl *getMetadataType(StringRef ArchetypeName) {
@@ -2542,8 +2543,8 @@ class IRGenDebugInfoImpl : public IRGenDebugInfo {
         auto Identifier = IGM.getSILModule().getASTContext().getIdentifier(
             Attribute->ManglingModuleName);
         void *Key = (void *)Identifier.get();
-        Scope = getOrCreateModule(Key, TheCU, Attribute->ManglingModuleName, {},
-                                  {});
+        Scope =
+            getOrCreateModule(Key, TheCU, Attribute->ManglingModuleName, {});
       } else {
         Context = ND->getParent();
       }
@@ -2790,8 +2791,7 @@ IRGenDebugInfoImpl::IRGenDebugInfoImpl(const IRGenOptions &Opts,
   // Create a module for the current compile unit.
   auto *MDecl = IGM.getSwiftModule();
   llvm::sys::path::remove_filename(SourcePath);
-  MainModule = getOrCreateModule(MDecl, TheCU, Opts.ModuleName, SourcePath,
-                                 Opts.DebugCompilationDir);
+  MainModule = getOrCreateModule(MDecl, TheCU, Opts.ModuleName, SourcePath);
   DBuilder.createImportedModule(MainFile, MainModule, MainFile, 0);
 
   // Macro definitions that were defined by the user with "-Xcc -D" on the