Revert "Revert "PR14606: debug info imported_module support""

This reverts commit r179840 with a fix to test/DebugInfo/two-cus-from-same-file.ll

I'm not sure why that test only failed on ARM & MIPS and not X86 Linux, even
though the debug info was clearly invalid on all of them, but this ought to fix
it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179996 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 25 insertions, 0 deletions

diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 762c475c8e..c3f475178b 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -763,6 +763,23 @@ void DwarfDebug::constructSubprogramDIE(CompileUnit *TheCU,
     TheCU->addGlobalName(SP.getName(), SubprogramDie);
 }
 
+void DwarfDebug::constructImportedModuleDIE(CompileUnit *TheCU,
+                                            const MDNode *N) {
+  DIImportedModule Module(N);
+  if (!Module.Verify())
+    return;
+  DIE *IMDie = new DIE(dwarf::DW_TAG_imported_module);
+  TheCU->insertDIE(Module, IMDie);
+  DIE *NSDie = TheCU->getOrCreateNameSpace(Module.getNameSpace());
+  unsigned FileID = getOrCreateSourceID(Module.getContext().getFilename(),
+                                        Module.getContext().getDirectory(),
+                                        TheCU->getUniqueID());
+  TheCU->addUInt(IMDie, dwarf::DW_AT_decl_file, 0, FileID);
+  TheCU->addUInt(IMDie, dwarf::DW_AT_decl_line, 0, Module.getLineNumber());
+  TheCU->addDIEEntry(IMDie, dwarf::DW_AT_import, dwarf::DW_FORM_ref4, NSDie);
+  TheCU->addToContextOwner(IMDie, Module.getContext());
+}
+
 // Emit all Dwarf sections that should come prior to the content. Create
 // global DIEs and emit initial debug info sections. This is invoked by
 // the target AsmPrinter.
@@ -796,6 +813,11 @@ void DwarfDebug::beginModule() {
     DIArray RetainedTypes = CUNode.getRetainedTypes();
     for (unsigned i = 0, e = RetainedTypes.getNumElements(); i != e; ++i)
       CU->getOrCreateTypeDIE(RetainedTypes.getElement(i));
+    // Emit imported_modules last so that the relevant context is already
+    // available.
+    DIArray ImportedModules = CUNode.getImportedModules();
+    for (unsigned i = 0, e = ImportedModules.getNumElements(); i != e; ++i)
+      constructImportedModuleDIE(CU, ImportedModules.getElement(i));
     // If we're splitting the dwarf out now that we've got the entire
     // CU then construct a skeleton CU based upon it.
     if (useSplitDwarf()) {
diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.h b/lib/CodeGen/AsmPrinter/DwarfDebug.h
index 9a38256d8e..1eb7e3ecea 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -555,6 +555,9 @@ private:
   /// \brief Construct subprogram DIE.
   void constructSubprogramDIE(CompileUnit *TheCU, const MDNode *N);
 
+  /// \brief Construct import_module DIE.
+  void constructImportedModuleDIE(CompileUnit *TheCU, const MDNode *N);
+
   /// \brief Register a source line with debug info. Returns the unique
   /// label that was emitted and which provides correspondence to the
   /// source line list.