1 files changed, 35 insertions, 22 deletions

diff --git a/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp b/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
index f0cf5581ba8a..5ccfb29b01a1 100644
--- a/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
+++ b/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
@@ -80,10 +80,12 @@
 #include "llvm/IR/Metadata.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/ModuleSummaryIndexYAML.h"
+#include "llvm/InitializePasses.h"
 #include "llvm/Pass.h"
 #include "llvm/PassRegistry.h"
 #include "llvm/PassSupport.h"
 #include "llvm/Support/Casting.h"
+#include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/MathExtras.h"
@@ -486,7 +488,7 @@ struct DevirtModule {
 
   bool areRemarksEnabled();
 
-  void scanTypeTestUsers(Function *TypeTestFunc, Function *AssumeFunc);
+  void scanTypeTestUsers(Function *TypeTestFunc);
   void scanTypeCheckedLoadUsers(Function *TypeCheckedLoadFunc);
 
   void buildTypeIdentifierMap(
@@ -615,8 +617,8 @@ struct WholeProgramDevirt : public ModulePass {
 
   bool UseCommandLine = false;
 
-  ModuleSummaryIndex *ExportSummary;
-  const ModuleSummaryIndex *ImportSummary;
+  ModuleSummaryIndex *ExportSummary = nullptr;
+  const ModuleSummaryIndex *ImportSummary = nullptr;
 
   WholeProgramDevirt() : ModulePass(ID), UseCommandLine(true) {
     initializeWholeProgramDevirtPass(*PassRegistry::getPassRegistry());
@@ -709,7 +711,7 @@ void runWholeProgramDevirtOnIndex(
 
 void updateIndexWPDForExports(
     ModuleSummaryIndex &Summary,
-    function_ref<bool(StringRef, GlobalValue::GUID)> isExported,
+    function_ref<bool(StringRef, ValueInfo)> isExported,
     std::map<ValueInfo, std::vector<VTableSlotSummary>> &LocalWPDTargetsMap) {
   for (auto &T : LocalWPDTargetsMap) {
     auto &VI = T.first;
@@ -717,7 +719,7 @@ void updateIndexWPDForExports(
     assert(VI.getSummaryList().size() == 1 &&
            "Devirt of local target has more than one copy");
     auto &S = VI.getSummaryList()[0];
-    if (!isExported(S->modulePath(), VI.getGUID()))
+    if (!isExported(S->modulePath(), VI))
       continue;
 
     // It's been exported by a cross module import.
@@ -840,18 +842,31 @@ bool DevirtModule::tryFindVirtualCallTargets(
 bool DevirtIndex::tryFindVirtualCallTargets(
     std::vector<ValueInfo> &TargetsForSlot, const TypeIdCompatibleVtableInfo TIdInfo,
     uint64_t ByteOffset) {
-  for (const TypeIdOffsetVtableInfo P : TIdInfo) {
-    // VTable initializer should have only one summary, or all copies must be
-    // linkonce/weak ODR.
-    assert(P.VTableVI.getSummaryList().size() == 1 ||
-           llvm::all_of(
-               P.VTableVI.getSummaryList(),
-               [&](const std::unique_ptr<GlobalValueSummary> &Summary) {
-                 return GlobalValue::isLinkOnceODRLinkage(Summary->linkage()) ||
-                        GlobalValue::isWeakODRLinkage(Summary->linkage());
-               }));
-    const auto *VS = cast<GlobalVarSummary>(P.VTableVI.getSummaryList()[0].get());
-    if (!P.VTableVI.getSummaryList()[0]->isLive())
+  for (const TypeIdOffsetVtableInfo &P : TIdInfo) {
+    // Find the first non-available_externally linkage vtable initializer.
+    // We can have multiple available_externally, linkonce_odr and weak_odr
+    // vtable initializers, however we want to skip available_externally as they
+    // do not have type metadata attached, and therefore the summary will not
+    // contain any vtable functions. We can also have multiple external
+    // vtable initializers in the case of comdats, which we cannot check here.
+    // The linker should give an error in this case.
+    //
+    // Also, handle the case of same-named local Vtables with the same path
+    // and therefore the same GUID. This can happen if there isn't enough
+    // distinguishing path when compiling the source file. In that case we
+    // conservatively return false early.
+    const GlobalVarSummary *VS = nullptr;
+    bool LocalFound = false;
+    for (auto &S : P.VTableVI.getSummaryList()) {
+      if (GlobalValue::isLocalLinkage(S->linkage())) {
+        if (LocalFound)
+          return false;
+        LocalFound = true;
+      }
+      if (!GlobalValue::isAvailableExternallyLinkage(S->linkage()))
+        VS = cast<GlobalVarSummary>(S->getBaseObject());
+    }
+    if (!VS->isLive())
       continue;
     for (auto VTP : VS->vTableFuncs()) {
       if (VTP.VTableOffset != P.AddressPointOffset + ByteOffset)
@@ -1233,8 +1248,7 @@ std::string DevirtModule::getGlobalName(VTableSlot Slot,
 
 bool DevirtModule::shouldExportConstantsAsAbsoluteSymbols() {
   Triple T(M.getTargetTriple());
-  return (T.getArch() == Triple::x86 || T.getArch() == Triple::x86_64) &&
-         T.getObjectFormat() == Triple::ELF;
+  return T.isX86() && T.getObjectFormat() == Triple::ELF;
 }
 
 void DevirtModule::exportGlobal(VTableSlot Slot, ArrayRef<uint64_t> Args,
@@ -1548,8 +1562,7 @@ bool DevirtModule::areRemarksEnabled() {
   return false;
 }
 
-void DevirtModule::scanTypeTestUsers(Function *TypeTestFunc,
-                                     Function *AssumeFunc) {
+void DevirtModule::scanTypeTestUsers(Function *TypeTestFunc) {
   // Find all virtual calls via a virtual table pointer %p under an assumption
   // of the form llvm.assume(llvm.type.test(%p, %md)). This indicates that %p
   // points to a member of the type identifier %md. Group calls by (type ID,
@@ -1784,7 +1797,7 @@ bool DevirtModule::run() {
     return false;
 
   if (TypeTestFunc && AssumeFunc)
-    scanTypeTestUsers(TypeTestFunc, AssumeFunc);
+    scanTypeTestUsers(TypeTestFunc);
 
   if (TypeCheckedLoadFunc)
     scanTypeCheckedLoadUsers(TypeCheckedLoadFunc);