[ThinLTO] Import globals

[evgeny777]

Summary

This patch imports external global variables references by a function, so that instcombine and globalopt can do some useful work (constant folding and static constructor evaluation) before elim-avail-extern either remove imported declarations or convert them back to externals. To simplify things this version only imports globals which have no outgoing references, so I don't have to care about promotion and importing debug info.

I've tested this on several large in-house projects and got 0.7-0.8% size improvement for each of them. I've also tried building LLVM/clang using this patch and also got some size improvement which is however much less impressive (several KB for some executables, about 56K for all of them in Release configuration). LLVM/clang built with this patch pass all tests successfully.

[tejohnson]

Nice! Glad to hear there are some measurable improvements. A few comments/suggestions below.

lib/Linker/IRMover.cpp

1442 ↗

(On Diff #133431)

I'm not as familiar with the struct mapping - what happens without this change? Why did importing variables necessitate it?

lib/Transforms/IPO/FunctionImport.cpp

245 ↗

(On Diff #133431)

Why would the modulePath be empty? I think we should only have summaries during the thin link for defs in IR. Oh - answering my own question, I think - this is for regular LTO module summaries which are added to a dummy module. Please add comment.

257 ↗

(On Diff #133431)

Add a comment about why we are limiting to only variable refs with external linkage and no other refs.

test/Transforms/FunctionImport/funcimport.ll

109 ↗

(On Diff #133431)

This stat is not labeled correctly. It at least needs to change to the number of globals imported. It would be nice to have separate stats for functions and variables imported though.

Please also fix the debug import dumping code in dumpImportListForModule and at the end of ComputeCrossModuleImport to report functions and variables separately.

[evgeny777]

FYI: Here are some results from running LLVM test suite:

[evgeny777]

lib/Linker/IRMover.cpp

1442 ↗

(On Diff #133431)

Consider this C++ program, which consists of three TUs:

main.cpp:

struct Bar { i64 a,b; } B; // Do not optimize this out
struct Foo { i64 a, b; }; // Foo is isomorphic to Bar

Foo *getFoo(); // We'll import this function from foo.cpp
struct S { Foo *_f } instance = { getFoo(); };

void main() { return instance._f->a; }

foo.cpp

struct Foo { i64 a, b; }; // Same as in main.cpp
struct Baz { i64 a, b; Foo f; }; 

Foo *gFoo;
extern Baz *gBaz;

Foo *getFoo() {
  return gFoo ? gFoo : &gBaz->f;
}

baz.cpp

struct Foo { i64 a, b; };
struct Baz { i64 a, b; Foo f; };  // Same as in foo.cpp

Baz *gBaz;

Now you perform thinlto import and get following definition of Baz in main.o0.3.import.bc when no name mapping used:

%struct.Bar = type { i64, i64 }
%struct.Foo = type { i64, i64 }

; This is incorrect. We should have %struct.Foo in the 3rd field
; This happens because Foo and Bar are recursively isomorphic
; and Bar is seen first by IRLinker.
%struct.Baz = type { i64, i64, %struct.Bar }

The faulted import causes bitcast created in static constructor:

; This static constructor can't be evaluated  due to a bitcast (Bar -> Foo)
define internal void @_GLOBAL__sub_I_main.cpp() #1 section ".text.startup" {
entry:
  %call.i.i = tail call %struct.Foo* bitcast (%struct.Bar* ()* @_Z6getFoov to %struct.Foo* ()*)()
  store %struct.Foo* %call.i.i, %struct.Foo** getelementptr inbounds (%struct.S, %struct.S* @instance, i64 0, i32 0), align 8, !tbaa !2
  ret void
}

Adding name mapping fixes the problem:

%struct.Baz = type { i64, i64, %struct.Foo } ; Good

; No bitcast - evaluator is happy.
define internal void @_GLOBAL__sub_I_main.cpp() section ".text.startup" {
entry:
  %call.i.i = tail call %struct.Foo* @getFoo()
  store %struct.Foo* %call.i.i, %struct.Foo** getelementptr inbounds (%struct.S, %struct.S* @instance, i64 0, i32 0), align 8
  ret void
}

The problem isn't specific at all to importing globals. You can easily rewrite this example to using functions (i.e gBaz -> getBaz) and get the same result. (it probably makes sense to divide this patch into two separate ones).

BTW the negative impact of those bitcasts isn't limited to evaluator. It also affects inliner behavior - see D38896

[tejohnson]

lib/Linker/IRMover.cpp

1442 ↗

(On Diff #133431)

Thanks for the detailed explanation. Since this isn't specific to the importing of variables, and can happen already with functions, please do separate out into a different patch.

[evgeny777]

lib/Transforms/IPO/FunctionImport.cpp

257 ↗

(On Diff #133431)

I think we can use !GlobalValue::isInterposableLinkage(RefSummary->linkage()) here just like we use for functions. I'll check

[evgeny777]

Addressed review comments

[tejohnson]

LGTM with a request for a comment below.

lib/Transforms/IPO/FunctionImport.cpp

259 ↗

(On Diff #134079)

Please add comment about why the restriction on having no outgoing refs.

llvm/trunk/lib/Linker/IRMover.cpp

for (unsigned I = 0, E = SrcCompileUnits->getNumOperands(); I != E; ++I) {
     // Enums, macros, and retained types don't need to be listed on the
     // imported DICompileUnit. This means they will only be imported
     // if reached from the mapped IR. Do this by setting their value map
     // entries to nullptr, which will automatically prevent their importing
     // when reached from the DICompileUnit during metadata mapping.
     ValueMap.MD()[CU->getRawEnumTypes()].reset(nullptr);
     ValueMap.MD()[CU->getRawMacros()].reset(nullptr);
     ValueMap.MD()[CU->getRawRetainedTypes()].reset(nullptr);
-    // If we ever start importing global variable defs, we'll need to
-    // add their DIGlobalVariable to the globals list on the imported
-    // DICompileUnit. Confirm none are imported, and then we can
-    // map the list of global variables to nullptr.
-    assert(none_of(
-               ValuesToLink,
-               [](const GlobalValue *GV) { return isa<GlobalVariable>(GV); }) &&
-           "Unexpected importing of a GlobalVariable definition");
+    // We import global variables only temporarily in order for instcombine
+    // and globalopt to perform constant folding and static constructor
+    // evaluation. After that elim-avail-extern will covert imported globals
+    // back to declarations, so we don't need debug info for them.
     ValueMap.MD()[CU->getRawGlobalVariables()].reset(nullptr);
 
     // Imported entities only need to be mapped in if they have local
     // scope, as those might correspond to an imported entity inside a
     // function being imported (any locally scoped imported entities that
     // don't end up referenced by an imported function will not be emitted
     // into the object). Imported entities not in a local scope
     // (e.g. on the namespace) only need to be emitted by the originating

llvm/trunk/lib/Transforms/IPO/FunctionImport.cpp

 #include <tuple>
 #include <utility>
 
 using namespace llvm;
 
 #define DEBUG_TYPE "function-import"
 
 STATISTIC(NumImportedFunctions, "Number of functions imported");
+STATISTIC(NumImportedGlobalVars, "Number of global variables imported");
 STATISTIC(NumImportedModules, "Number of modules imported from");
 STATISTIC(NumDeadSymbols, "Number of dead stripped symbols in index");
 STATISTIC(NumLiveSymbols, "Number of live symbols in index");
 
 /// Limit on instruction count of imported functions.
 static cl::opt<unsigned> ImportInstrLimit(
     "import-instr-limit", cl::init(100), cl::Hidden, cl::value_desc("N"),
     cl::desc("Only import functions with less than N instructions"));
updateValueInfoForIndirectCalls(const ModuleSummaryIndex &Index, ValueInfo VI) {
   // FIXME: Consider updating the edges in the graph after building
   // it, rather than needing to perform this mapping on each walk.
   auto GUID = Index.getGUIDFromOriginalID(VI.getGUID());
   if (GUID == 0)
     return ValueInfo();
   return Index.getValueInfo(GUID);
 }
 
+static void computeImportForReferencedGlobals(
+    const FunctionSummary &Summary, const GVSummaryMapTy &DefinedGVSummaries,
+    FunctionImporter::ImportMapTy &ImportList,
+    StringMap<FunctionImporter::ExportSetTy> *ExportLists) {
+  for (auto &VI : Summary.refs()) {
+    if (DefinedGVSummaries.count(VI.getGUID())) {
+      DEBUG(dbgs() << "Ref ignored! Target already in destination module.\n");
+      continue;
+    }
+
+    DEBUG(dbgs() << " ref -> " << VI.getGUID() << "\n");
+
+    for (auto &RefSummary : VI.getSummaryList())
+      if (RefSummary->getSummaryKind() == GlobalValueSummary::GlobalVarKind &&
+          // Don't try to import regular LTO summaries added to dummy module.
+          !RefSummary->modulePath().empty() &&
+          !GlobalValue::isInterposableLinkage(RefSummary->linkage()) &&
+          // For now we don't import global variables which have outgoing
+          // refs. Otherwise we have to promote referenced vars/functions.
+          RefSummary->refs().empty()) {
+        ImportList[RefSummary->modulePath()][VI.getGUID()] = 1;
+        if (ExportLists)
+          (*ExportLists)[RefSummary->modulePath()].insert(VI.getGUID());
+      }
+  }
+}
+
 /// Compute the list of functions to import for a given caller. Mark these
 /// imported functions and the symbols they reference in their source module as
 /// exported from their source module.
 static void computeImportForFunction(
     const FunctionSummary &Summary, const ModuleSummaryIndex &Index,
     const unsigned Threshold, const GVSummaryMapTy &DefinedGVSummaries,
     SmallVectorImpl<EdgeInfo> &Worklist,
     FunctionImporter::ImportMapTy &ImportList,
     StringMap<FunctionImporter::ExportSetTy> *ExportLists = nullptr) {
+  computeImportForReferencedGlobals(Summary, DefinedGVSummaries, ImportList,
+                                    ExportLists);
   for (auto &Edge : Summary.calls()) {
     ValueInfo VI = Edge.first;
     DEBUG(dbgs() << " edge -> " << VI.getGUID() << " Threshold:" << Threshold
                  << "\n");
 
     VI = updateValueInfoForIndirectCalls(Index, VI);
     if (!VI)
       continue;
while (!Worklist.empty()) {
     if (LatestProcessedThreshold > Threshold)
       continue;
 
     computeImportForFunction(*Summary, Index, Threshold, DefinedGVSummaries,
                              Worklist, ImportList, ExportLists);
   }
 }
 
+#ifndef NDEBUG
+static bool isGlobalVarSummary(const ModuleSummaryIndex &Index,
+                               GlobalValue::GUID G) {
+  if (const auto &VI = Index.getValueInfo(G)) {
+    auto SL = VI.getSummaryList();
+    if (!SL.empty())
+      return SL[0]->getSummaryKind() == GlobalValueSummary::GlobalVarKind;
+  }
+  return false;
+}
+
+static GlobalValue::GUID getGUID(GlobalValue::GUID G) { return G; }
+
+static GlobalValue::GUID
+getGUID(const std::pair<const GlobalValue::GUID, unsigned> &P) {
+  return P.first;
+}
+
+template <class T>
+unsigned numGlobalVarSummaries(const ModuleSummaryIndex &Index, T &Cont) {
+  unsigned NumGVS = 0;
+  for (auto &V : Cont)
+    if (isGlobalVarSummary(Index, getGUID(V)))
+      ++NumGVS;
+  return NumGVS;
+}
+#endif
+
 /// Compute all the import and export for every module using the Index.
 void llvm::ComputeCrossModuleImport(
     const ModuleSummaryIndex &Index,
     const StringMap<GVSummaryMapTy> &ModuleToDefinedGVSummaries,
     StringMap<FunctionImporter::ImportMapTy> &ImportLists,
     StringMap<FunctionImporter::ExportSetTy> &ExportLists) {
   // For each module that has function defined, compute the import/export lists.
   for (auto &DefinedGVSummaries : ModuleToDefinedGVSummaries) {
void llvm::ComputeCrossModuleImport(
   }
 
 #ifndef NDEBUG
   DEBUG(dbgs() << "Import/Export lists for " << ImportLists.size()
                << " modules:\n");
   for (auto &ModuleImports : ImportLists) {
     auto ModName = ModuleImports.first();
     auto &Exports = ExportLists[ModName];
-    DEBUG(dbgs() << "* Module " << ModName << " exports " << Exports.size()
-                 << " functions. Imports from " << ModuleImports.second.size()
-                 << " modules.\n");
+    unsigned NumGVS = numGlobalVarSummaries(Index, Exports);
+        DEBUG(dbgs() << "* Module " << ModName << " exports "
+                     << Exports.size() - NumGVS << " functions and " << NumGVS
+                     << " vars. Imports from "
+                     << ModuleImports.second.size() << " modules.\n");
     for (auto &Src : ModuleImports.second) {
       auto SrcModName = Src.first();
-      DEBUG(dbgs() << " - " << Src.second.size() << " functions imported from "
+      unsigned NumGVSPerMod = numGlobalVarSummaries(Index, Src.second);
+      DEBUG(dbgs() << " - " << Src.second.size() - NumGVSPerMod
+                   << " functions imported from " << SrcModName << "\n");
+      DEBUG(dbgs() << " - " << NumGVSPerMod << " global vars imported from "
                    << SrcModName << "\n");
     }
   }
 #endif
 }
 
 #ifndef NDEBUG
-static void dumpImportListForModule(StringRef ModulePath,
+static void dumpImportListForModule(const ModuleSummaryIndex &Index,
+                                    StringRef ModulePath,
                                     FunctionImporter::ImportMapTy &ImportList) {
   DEBUG(dbgs() << "* Module " << ModulePath << " imports from "
                << ImportList.size() << " modules.\n");
   for (auto &Src : ImportList) {
     auto SrcModName = Src.first();
-    DEBUG(dbgs() << " - " << Src.second.size() << " functions imported from "
+    unsigned NumGVSPerMod = numGlobalVarSummaries(Index, Src.second);
+    DEBUG(dbgs() << " - " << Src.second.size() - NumGVSPerMod
+                 << " functions imported from " << SrcModName << "\n");
+    DEBUG(dbgs() << " - " << NumGVSPerMod << " vars imported from "
                  << SrcModName << "\n");
   }
 }
 #endif
 
 /// Compute all the imports for the given module in the Index.
 void llvm::ComputeCrossModuleImportForModule(
     StringRef ModulePath, const ModuleSummaryIndex &Index,
     FunctionImporter::ImportMapTy &ImportList) {
   // Collect the list of functions this module defines.
   // GUID -> Summary
   GVSummaryMapTy FunctionSummaryMap;
   Index.collectDefinedFunctionsForModule(ModulePath, FunctionSummaryMap);
 
   // Compute the import list for this module.
   DEBUG(dbgs() << "Computing import for Module '" << ModulePath << "'\n");
   ComputeImportForModule(FunctionSummaryMap, Index, ImportList);
 
 #ifndef NDEBUG
-  dumpImportListForModule(ModulePath, ImportList);
+  dumpImportListForModule(Index, ModulePath, ImportList);
 #endif
 }
 
 // Mark all external summaries in Index for import into the given module.
 // Used for distributed builds using a distributed index.
 void llvm::ComputeCrossModuleImportForModuleFromIndex(
     StringRef ModulePath, const ModuleSummaryIndex &Index,
     FunctionImporter::ImportMapTy &ImportList) {
for (auto &GlobalList : Index) {
     // e.g. record required linkage changes.
     if (Summary->modulePath() == ModulePath)
       continue;
     // Doesn't matter what value we plug in to the map, just needs an entry
     // to provoke importing by thinBackend.
     ImportList[Summary->modulePath()][GUID] = 1;
   }
 #ifndef NDEBUG
-  dumpImportListForModule(ModulePath, ImportList);
+  dumpImportListForModule(Index, ModulePath, ImportList);
 #endif
 }
 
 void llvm::computeDeadSymbols(
     ModuleSummaryIndex &Index,
     const DenseSet<GlobalValue::GUID> &GUIDPreservedSymbols,
     function_ref<PrevailingType(GlobalValue::GUID)> isPrevailing) {
   assert(!Index.withGlobalValueDeadStripping());

 }
 
 // Automatically import functions in Module \p DestModule based on the summaries
 // index.
 Expected<bool> FunctionImporter::importFunctions(
     Module &DestModule, const FunctionImporter::ImportMapTy &ImportList) {
   DEBUG(dbgs() << "Starting import for Module "
                << DestModule.getModuleIdentifier() << "\n");
-  unsigned ImportedCount = 0;
+  unsigned ImportedCount = 0, ImportedGVCount = 0;
 
   IRMover Mover(DestModule);
   // Do the actual import of functions now, one Module at a time
   std::set<StringRef> ModuleNameOrderedList;
   for (auto &FunctionsToImportPerModule : ImportList) {
     ModuleNameOrderedList.insert(FunctionsToImportPerModule.first());
   }
   for (auto &Name : ModuleNameOrderedList) {
for (GlobalVariable &GV : SrcModule->globals()) {
       auto GUID = GV.getGUID();
       auto Import = ImportGUIDs.count(GUID);
       DEBUG(dbgs() << (Import ? "Is" : "Not") << " importing global " << GUID
                    << " " << GV.getName() << " from "
                    << SrcModule->getSourceFileName() << "\n");
       if (Import) {
         if (Error Err = GV.materialize())
           return std::move(Err);
-        GlobalsToImport.insert(&GV);
+        ImportedGVCount += GlobalsToImport.insert(&GV);
       }
     }
     for (GlobalAlias &GA : SrcModule->aliases()) {
       if (!GA.hasName())
         continue;
       auto GUID = GA.getGUID();
       auto Import = ImportGUIDs.count(GUID);
       DEBUG(dbgs() << (Import ? "Is" : "Not") << " importing alias " << GUID
if (Mover.move(std::move(SrcModule), GlobalsToImport.getArrayRef(),
                    [](GlobalValue &, IRMover::ValueAdder) {},
                    /*IsPerformingImport=*/true))
       report_fatal_error("Function Import: link error");
 
     ImportedCount += GlobalsToImport.size();
     NumImportedModules++;
   }
 
-  NumImportedFunctions += ImportedCount;
+  NumImportedFunctions += (ImportedCount - ImportedGVCount);
+  NumImportedGlobalVars += ImportedGVCount;
 
-  DEBUG(dbgs() << "Imported " << ImportedCount << " functions for Module "
+  DEBUG(dbgs() << "Imported " << ImportedCount - ImportedGVCount
+               << " functions for Module " << DestModule.getModuleIdentifier()
+               << "\n");
+  DEBUG(dbgs() << "Imported " << ImportedGVCount
+               << " global variables for Module "
                << DestModule.getModuleIdentifier() << "\n");
   return ImportedCount;
 }
 
 static bool doImportingForModule(Module &M) {
   if (SummaryFile.empty())
     report_fatal_error("error: -function-import requires -summary-file\n");
   Expected<std::unique_ptr<ModuleSummaryIndex>> IndexPtrOrErr =

llvm/trunk/test/ThinLTO/X86/Inputs/globals-import-cf-baz.ll

+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-pc-linux-gnu"
+
+@baz = local_unnamed_addr constant i32 10, align 4

llvm/trunk/test/ThinLTO/X86/globals-import-const-fold.ll

+; RUN: opt -module-summary %s -o %t1.bc
+; RUN: opt -module-summary %p/Inputs/globals-import-cf-baz.ll -o %t2.bc
+; RUN: llvm-lto -thinlto-action=thinlink %t1.bc %t2.bc -o %t3.index.bc
+
+; RUN: llvm-lto -thinlto-action=import %t1.bc %t2.bc -thinlto-index=%t3.index.bc
+; RUN: llvm-dis %t1.bc.thinlto.imported.bc -o - | FileCheck --check-prefix=IMPORT %s
+; RUN: llvm-lto -thinlto-action=optimize %t1.bc.thinlto.imported.bc -o %t1.bc.thinlto.opt.bc
+; RUN: llvm-dis %t1.bc.thinlto.opt.bc -o - | FileCheck --check-prefix=OPTIMIZE %s
+
+; IMPORT: @baz = available_externally local_unnamed_addr constant i32 10
+
+; OPTIMIZE:       define i32 @main()
+; OPTIMIZE-NEXT:    ret i32 10
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-pc-linux-gnu"
+
+@baz = external local_unnamed_addr constant i32, align 4
+
+define i32 @main() local_unnamed_addr {
+  %1 = load i32, i32* @baz, align 4
+  ret i32 %1
+}

llvm/trunk/test/Transforms/FunctionImport/funcimport.ll

 ; Do setup work for all below tests: generate bitcode and combined index
 ; RUN: opt -module-summary %s -o %t.bc
 ; RUN: opt -module-summary %p/Inputs/funcimport.ll -o %t2.bc
 ; RUN: llvm-lto -thinlto -print-summary-global-ids -o %t3 %t.bc %t2.bc 2>&1 | FileCheck %s --check-prefix=GUID
 
 ; Do the import now
 ; RUN: opt -function-import -stats -print-imports -enable-import-metadata -summary-file %t3.thinlto.bc %t.bc -S 2>&1 | FileCheck %s --check-prefix=CHECK --check-prefix=INSTLIMDEF
 ; Try again with new pass manager
 ; RUN: opt -passes='function-import' -stats -print-imports -enable-import-metadata -summary-file %t3.thinlto.bc %t.bc -S 2>&1 | FileCheck %s --check-prefix=CHECK --check-prefix=INSTLIMDEF
-; "-stats" requires +Asserts.
+; RUN: opt -passes='function-import' -debug-only=function-import -enable-import-metadata -summary-file %t3.thinlto.bc %t.bc -S 2>&1 | FileCheck %s --check-prefix=DUMP
+; "-stats" and "-debug-only" require +Asserts.
 ; REQUIRES: asserts
 
 ; Test import with smaller instruction limit
 ; RUN: opt -function-import -enable-import-metadata  -summary-file %t3.thinlto.bc %t.bc -import-instr-limit=5 -S | FileCheck %s --check-prefix=CHECK --check-prefix=INSTLIM5
 ; INSTLIM5-NOT: @staticfunc.llvm.
 
 
 define i32 @main() #0 {

 declare void @setfuncptr(...) #1
 
 ; INSTLIMDEF-DAG: Import callfuncptr
 ; CHECK-DAG: define available_externally void @callfuncptr() !thinlto_src_module !0 {
 declare void @callfuncptr(...) #1
 
 ; Ensure that all uses of local variable @P which has used in setfuncptr
 ; and callfuncptr are to the same promoted/renamed global.
-; CHECK-DAG: @P.llvm.{{.*}} = external hidden global void ()*
+; CHECK-DAG: @P.llvm.{{.*}} = available_externally hidden global void ()* null
 ; CHECK-DAG: %0 = load void ()*, void ()** @P.llvm.
 ; CHECK-DAG: store void ()* @staticfunc2.llvm.{{.*}}, void ()** @P.llvm.
 
 ; Ensure that @referencelargelinkonce definition is pulled in, but later we
 ; also check that the linkonceodr function is not.
 ; CHECK-DAG: define available_externally void @referencelargelinkonce() !thinlto_src_module !0 {
 ; INSTLIM5-DAG: declare void @linkonceodr()
 declare void @referencelargelinkonce(...)

 ; INSTLIMDEF-DAG: define available_externally hidden void @funcwithpersonality.llvm.{{.*}}() personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) !thinlto_src_module !0 {
 ; INSTLIM5-DAG: declare hidden void @funcwithpersonality.llvm.{{.*}}()
 
 ; CHECK-DAG: declare void @variadic(...)
 declare void @variadic(...)
 
 ; INSTLIMDEF-DAG: Import globalfunc2
 ; INSTLIMDEF-DAG: 13 function-import - Number of functions imported
+; INSTLIMDEF-DAG: 4 function-import - Number of global variables imported
+
 ; CHECK-DAG: !0 = !{!"{{.*}}/Inputs/funcimport.ll"}
 
 ; The actual GUID values will depend on path to test.
 ; GUID-DAG: GUID {{.*}} is weakalias
 ; GUID-DAG: GUID {{.*}} is referenceglobals
 ; GUID-DAG: GUID {{.*}} is weakfunc
 ; GUID-DAG: GUID {{.*}} is main
 ; GUID-DAG: GUID {{.*}} is referencecommon

 ; GUID-DAG: GUID {{.*}} is weakvar
 ; GUID-DAG: GUID {{.*}} is staticconstvar
 ; GUID-DAG: GUID {{.*}} is analias
 ; GUID-DAG: GUID {{.*}} is globalvar
 ; GUID-DAG: GUID {{.*}} is referencecommon
 ; GUID-DAG: GUID {{.*}} is linkoncealias
 ; GUID-DAG: GUID {{.*}} is callfuncptr
 ; GUID-DAG: GUID {{.*}} is linkoncefunc
+
+; DUMP:       Module [[M1:.*]] imports from 1 module
+; DUMP-NEXT:  13 functions imported from [[M2:.*]]
+; DUMP-NEXT:  4 vars imported from [[M2]]
+; DUMP:       Imported 13 functions for Module [[M1]]
+; DUMP-NEXT:  Imported 4 global variables for Module [[M1]]