[DWARFLinker] Move __debug_str to the last section

Signed-off-by: Peter Rong <[email protected]>

Author: DataCorrupted

llvm/lib/DWARFLinker/Classic/DWARFLinker.cpp

@@ -3129,7 +3129,6 @@ Error DWARFLinker::link() {
     // Emit everything that's global.
     if (TheDwarfEmitter != nullptr) {
       TheDwarfEmitter->emitAbbrevs(Abbreviations, Options.TargetDWARFVersion);
-      TheDwarfEmitter->emitStrings(DebugStrPool);
       TheDwarfEmitter->emitStringOffsets(StringOffsetPool.getValues(),
                                          Options.TargetDWARFVersion);
       TheDwarfEmitter->emitLineStrings(DebugLineStrPool);
@@ -3150,6 +3149,7 @@ Error DWARFLinker::link() {
           break;
         }
       }
+      TheDwarfEmitter->emitStrings(DebugStrPool);
     }
   };
 

llvm/test/tools/dsymutil/X86/swift-ast-section-order.test

@@ -0,0 +1,17 @@
+# Check that the __debug_str section is last in the output
+
+# RUN: rm -rf %t && mkdir %t
+# RUN: dsymutil -oso-prepend-path %p/.. %p/../Inputs/swift-ast.macho.x86_64 -o %t/swift-ast.dSYM -verbose -no-swiftmodule-timestamp
+# RUN: llvm-dwarfdump --show-section-sizes %t/swift-ast.dSYM/Contents/Resources/DWARF/swift-ast.macho.x86_64 | FileCheck %s
+
+# This test verifies that the __debug_str section appears last in the section list.
+
+# CHECK: SECTION
+# CHECK: __swift_ast
+# CHECK: __debug_abbrev
+# CHECK: __apple_namespac
+# CHECK: __apple_names
+# CHECK: __apple_types
+# CHECK: __apple_objc
+# CHECK-NOT: __apple
+# CHECK: __debug_str