From: Adrian Prantl <aprantl@apple.com>
Date: Mon, 5 Oct 2015 23:11:20 +0000 (+0000)
Subject: dsymutil: Don't prune forward declarations inside of an imported TAG_module
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=fce2219764f00e1b6de75bca08d9b10a212165b5;p=oota-llvm.git

dsymutil: Don't prune forward declarations inside of an imported TAG_module
if there exists not definition for the type.
For this to work, we need to clone the imported modules before building
the decl context chains of the DIEs in the non-skeleton CUs.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@249362 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/test/tools/dsymutil/Inputs/submodules/1.o b/test/tools/dsymutil/Inputs/submodules/1.o
index f95b70cd05c..d38e30f67c2 100644
Binary files a/test/tools/dsymutil/Inputs/submodules/1.o and b/test/tools/dsymutil/Inputs/submodules/1.o differ
diff --git a/test/tools/dsymutil/Inputs/submodules/Parent.pcm b/test/tools/dsymutil/Inputs/submodules/Parent.pcm
index dca33af4268..e6909d7afa5 100644
Binary files a/test/tools/dsymutil/Inputs/submodules/Parent.pcm and b/test/tools/dsymutil/Inputs/submodules/Parent.pcm differ
diff --git a/test/tools/dsymutil/X86/submodules.m b/test/tools/dsymutil/X86/submodules.m
index 64efc2f54ba..4cb5bcfaee2 100644
--- a/test/tools/dsymutil/X86/submodules.m
+++ b/test/tools/dsymutil/X86/submodules.m
@@ -4,9 +4,13 @@
      module Child {
        header "Child.h"
      }
+     module Empty {
+       header "Empty.h"
+     }
    }
 EOF
    clang -D CHILD_H -E -o Child.h submodules.m
+   touch empty.h
    clang -cc1 -emit-obj -fmodules -fmodule-map-file=modules.modulemap \
      -fmodule-format=obj -g -dwarf-ext-refs -fmodules-cache-path=. \
      -fdisable-module-hash submodules.m -o 1.o
@@ -19,6 +23,7 @@ EOF
 // ---------------------------------------------------------------------
 #ifdef CHILD_H
 // ---------------------------------------------------------------------
+
 // CHECK:            DW_TAG_compile_unit
 // CHECK-NOT:        DW_TAG
 // CHECK:              DW_TAG_module
@@ -28,13 +33,22 @@ EOF
 // CHECK:                  DW_TAG_structure_type
 // CHECK-NOT:                DW_TAG
 // CHECK:                    DW_AT_name {{.*}}"PruneMeNot"
-
 struct PruneMeNot;
 
 // ---------------------------------------------------------------------
 #else
 // ---------------------------------------------------------------------
 
+// CHECK:            DW_TAG_compile_unit
+// CHECK:              DW_TAG_module
+// CHECK-NEXT:           DW_AT_name{{.*}}"Parent"
+// CHECK:              DW_TAG_module
+// CHECK-NEXT:           DW_AT_name{{.*}}"Child"
+// CHECK: 0x0[[EMPTY:.*]]: DW_TAG_module
+// CHECK-NEXT:             DW_AT_name{{.*}}"Empty"
+
+// CHECK:     DW_AT_import  {{.*}}0x{{0*}}[[EMPTY]]
 @import Parent.Child;
+@import Parent.Empty;
 int main(int argc, char **argv) { return 0; }
 #endif
diff --git a/tools/dsymutil/DwarfLinker.cpp b/tools/dsymutil/DwarfLinker.cpp
index c877264a067..52c480ec4f1 100644
--- a/tools/dsymutil/DwarfLinker.cpp
+++ b/tools/dsymutil/DwarfLinker.cpp
@@ -1807,6 +1807,9 @@ static bool analyzeContextInfo(const DWARFDebugInfoEntryMinimal *DIE,
                 DIE->getAttributeValueAsUnsignedConstant(
                     &CU.getOrigUnit(), dwarf::DW_AT_declaration, 0);
 
+  // Don't prune it if there is no definition for the DIE.
+  Info.Prune &= Info.Ctxt && Info.Ctxt->getCanonicalDIEOffset();
+
   return Info.Prune;
 }
 
@@ -3338,21 +3341,23 @@ bool DwarfLinker::link(const DebugMap &Map) {
     DWARFContextInMemory DwarfContext(*ErrOrObj);
     startDebugObject(DwarfContext, *Obj);
 
-    // In a first phase, just read in the debug info and store the DIE
-    // parent links that we will use during the next phase.
+    // In a first phase, just read in the debug info and load all clang modules.
     for (const auto &CU : DwarfContext.compile_units()) {
       auto *CUDie = CU->getUnitDIE(false);
       if (Options.Verbose) {
         outs() << "Input compilation unit:";
         CUDie->dump(outs(), CU.get(), 0);
       }
-      if (!registerModuleReference(*CUDie, *CU, ModuleMap)) {
+
+      if (!registerModuleReference(*CUDie, *CU, ModuleMap))
         Units.emplace_back(*CU, UnitID++, !Options.NoODR, "");
-        analyzeContextInfo(CUDie, 0, Units.back(), &ODRContexts.getRoot(),
-                           StringPool, ODRContexts);
-      }
     }
 
+    // Now build the DIE parent links that we will use during the next phase.
+    for (auto &CurrentUnit : Units)
+      analyzeContextInfo(CurrentUnit.getOrigUnit().getUnitDIE(), 0, CurrentUnit,
+                         &ODRContexts.getRoot(), StringPool, ODRContexts);
+
     // Then mark all the DIEs that need to be present in the linked
     // output and collect some information about them. Note that this
     // loop can not be merged with the previous one becaue cross-cu