vendor/llvm/llvm-trunk-r300422

2 files changed, 44 insertions, 85 deletions

diff --git a/lib/Linker/IRMover.cpp b/lib/Linker/IRMover.cpp
index 9f3cfc0eace4..15a46a2d0420 100644
--- a/lib/Linker/IRMover.cpp
+++ b/lib/Linker/IRMover.cpp
@@ -395,11 +395,12 @@ class IRLinker {
       Worklist.push_back(GV);
   }
 
-  /// Flag whether the ModuleInlineAsm string in Src should be linked with
-  /// (concatenated into) the ModuleInlineAsm string for the destination
-  /// module. It should be true for full LTO, but not when importing for
-  /// ThinLTO, otherwise we can have duplicate symbols.
-  bool LinkModuleInlineAsm;
+  /// Whether we are importing globals for ThinLTO, as opposed to linking the
+  /// source module. If this flag is set, it means that we can rely on some
+  /// other object file to define any non-GlobalValue entities defined by the
+  /// source module. This currently causes us to not link retained types in
+  /// debug info metadata and module inline asm.
+  bool IsPerformingImport;
 
   /// Set to true when all global value body linking is complete (including
   /// lazy linking). Used to prevent metadata linking from creating new
@@ -491,10 +492,10 @@ public:
            IRMover::IdentifiedStructTypeSet &Set, std::unique_ptr<Module> SrcM,
            ArrayRef<GlobalValue *> ValuesToLink,
            std::function<void(GlobalValue &, IRMover::ValueAdder)> AddLazyFor,
-           bool LinkModuleInlineAsm, bool IsPerformingImport)
+           bool IsPerformingImport)
       : DstM(DstM), SrcM(std::move(SrcM)), AddLazyFor(std::move(AddLazyFor)),
         TypeMap(Set), GValMaterializer(*this), LValMaterializer(*this),
-        SharedMDs(SharedMDs), LinkModuleInlineAsm(LinkModuleInlineAsm),
+        SharedMDs(SharedMDs), IsPerformingImport(IsPerformingImport),
         Mapper(ValueMap, RF_MoveDistinctMDs | RF_IgnoreMissingLocals, &TypeMap,
                &GValMaterializer),
         AliasMCID(Mapper.registerAlternateMappingContext(AliasValueMap,
@@ -870,9 +871,6 @@ bool IRLinker::shouldLink(GlobalValue *DGV, GlobalValue &SGV) {
   if (DGV && !DGV->isDeclarationForLinker())
     return false;
 
-  if (SGV.hasAvailableExternallyLinkage())
-    return true;
-
   if (SGV.isDeclaration() || DoneLinkingBodies)
     return false;
 
@@ -1297,7 +1295,7 @@ Error IRLinker::run() {
   DstM.setTargetTriple(mergeTriples(SrcTriple, DstTriple));
 
   // Append the module inline asm string.
-  if (LinkModuleInlineAsm && !SrcM->getModuleInlineAsm().empty()) {
+  if (!IsPerformingImport && !SrcM->getModuleInlineAsm().empty()) {
     if (DstM.getModuleInlineAsm().empty())
       DstM.setModuleInlineAsm(SrcM->getModuleInlineAsm());
     else
@@ -1436,10 +1434,10 @@ IRMover::IRMover(Module &M) : Composite(M) {
 Error IRMover::move(
     std::unique_ptr<Module> Src, ArrayRef<GlobalValue *> ValuesToLink,
     std::function<void(GlobalValue &, ValueAdder Add)> AddLazyFor,
-    bool LinkModuleInlineAsm, bool IsPerformingImport) {
+    bool IsPerformingImport) {
   IRLinker TheIRLinker(Composite, SharedMDs, IdentifiedStructTypes,
                        std::move(Src), ValuesToLink, std::move(AddLazyFor),
-                       LinkModuleInlineAsm, IsPerformingImport);
+                       IsPerformingImport);
   Error E = TheIRLinker.run();
   Composite.dropTriviallyDeadConstantArrays();
   return E;
diff --git a/lib/Linker/LinkModules.cpp b/lib/Linker/LinkModules.cpp
index cf2c4ccf523e..c0ce4bf76b9f 100644
--- a/lib/Linker/LinkModules.cpp
+++ b/lib/Linker/LinkModules.cpp
@@ -14,12 +14,13 @@
 #include "LinkDiagnosticInfo.h"
 #include "llvm-c/Linker.h"
 #include "llvm/ADT/SetVector.h"
-#include "llvm/ADT/StringSet.h"
+#include "llvm/IR/Comdat.h"
 #include "llvm/IR/DiagnosticPrinter.h"
+#include "llvm/IR/GlobalValue.h"
 #include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Module.h"
 #include "llvm/Linker/Linker.h"
 #include "llvm/Support/Error.h"
-#include "llvm/Transforms/Utils/FunctionImportUtils.h"
 using namespace llvm;
 
 namespace {
@@ -31,14 +32,17 @@ class ModuleLinker {
   std::unique_ptr<Module> SrcM;
 
   SetVector<GlobalValue *> ValuesToLink;
-  StringSet<> Internalize;
 
   /// For symbol clashes, prefer those from Src.
   unsigned Flags;
 
-  /// Functions to import from source module, all other functions are
-  /// imported as declarations instead of definitions.
-  DenseSet<const GlobalValue *> *GlobalsToImport;
+  /// List of global value names that should be internalized.
+  StringSet<> Internalize;
+
+  /// Function that will perform the actual internalization. The reason for a
+  /// callback is that the linker cannot call internalizeModule without
+  /// creating a circular dependency between IPO and the linker.
+  std::function<void(Module &, const StringSet<> &)> InternalizeCallback;
 
   /// Used as the callback for lazy linking.
   /// The mover has just hit GV and we have to decide if it, and other members
@@ -46,14 +50,8 @@ class ModuleLinker {
   /// to Add.
   void addLazyFor(GlobalValue &GV, const IRMover::ValueAdder &Add);
 
-  bool shouldLinkReferencedLinkOnce() {
-    return !(Flags & Linker::DontForceLinkLinkonceODR);
-  }
   bool shouldOverrideFromSrc() { return Flags & Linker::OverrideFromSrc; }
   bool shouldLinkOnlyNeeded() { return Flags & Linker::LinkOnlyNeeded; }
-  bool shouldInternalizeLinkedSymbols() {
-    return Flags & Linker::InternalizeLinkedSymbols;
-  }
 
   bool shouldLinkFromSource(bool &LinkFromSrc, const GlobalValue &Dest,
                             const GlobalValue &Src);
@@ -108,31 +106,17 @@ class ModuleLinker {
 
   bool linkIfNeeded(GlobalValue &GV);
 
-  /// Helper method to check if we are importing from the current source
-  /// module.
-  bool isPerformingImport() const { return GlobalsToImport != nullptr; }
-
-  /// If we are importing from the source module, checks if we should
-  /// import SGV as a definition, otherwise import as a declaration.
-  bool doImportAsDefinition(const GlobalValue *SGV);
-
 public:
   ModuleLinker(IRMover &Mover, std::unique_ptr<Module> SrcM, unsigned Flags,
-               DenseSet<const GlobalValue *> *GlobalsToImport = nullptr)
+               std::function<void(Module &, const StringSet<> &)>
+                   InternalizeCallback = {})
       : Mover(Mover), SrcM(std::move(SrcM)), Flags(Flags),
-        GlobalsToImport(GlobalsToImport) {}
+        InternalizeCallback(std::move(InternalizeCallback)) {}
 
   bool run();
 };
 }
 
-bool ModuleLinker::doImportAsDefinition(const GlobalValue *SGV) {
-  if (!isPerformingImport())
-    return false;
-  return FunctionImportGlobalProcessing::doImportAsDefinition(SGV,
-                                                              GlobalsToImport);
-}
-
 static GlobalValue::VisibilityTypes
 getMinVisibility(GlobalValue::VisibilityTypes A,
                  GlobalValue::VisibilityTypes B) {
@@ -266,18 +250,10 @@ bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,
 
   // We always have to add Src if it has appending linkage.
   if (Src.hasAppendingLinkage()) {
-    // Should have prevented importing for appending linkage in linkIfNeeded.
-    assert(!isPerformingImport());
     LinkFromSrc = true;
     return false;
   }
 
-  if (isPerformingImport()) {
-    // LinkFromSrc iff this is a global requested for importing.
-    LinkFromSrc = GlobalsToImport->count(&Src);
-    return false;
-  }
-
   bool SrcIsDeclaration = Src.isDeclarationForLinker();
   bool DestIsDeclaration = Dest.isDeclarationForLinker();
 
@@ -383,19 +359,9 @@ bool ModuleLinker::linkIfNeeded(GlobalValue &GV) {
     GV.setUnnamedAddr(UnnamedAddr);
   }
 
-  // Don't want to append to global_ctors list, for example, when we
-  // are importing for ThinLTO, otherwise the global ctors and dtors
-  // get executed multiple times for local variables (the latter causing
-  // double frees).
-  if (GV.hasAppendingLinkage() && isPerformingImport())
-    return false;
-
-  if (isPerformingImport()) {
-    if (!doImportAsDefinition(&GV))
-      return false;
-  } else if (!DGV && !shouldOverrideFromSrc() &&
-             (GV.hasLocalLinkage() || GV.hasLinkOnceLinkage() ||
-              GV.hasAvailableExternallyLinkage()))
+  if (!DGV && !shouldOverrideFromSrc() &&
+      (GV.hasLocalLinkage() || GV.hasLinkOnceLinkage() ||
+       GV.hasAvailableExternallyLinkage()))
     return false;
 
   if (GV.isDeclaration())
@@ -418,17 +384,12 @@ bool ModuleLinker::linkIfNeeded(GlobalValue &GV) {
 }
 
 void ModuleLinker::addLazyFor(GlobalValue &GV, const IRMover::ValueAdder &Add) {
-  if (!shouldLinkReferencedLinkOnce())
-    // For ThinLTO we don't import more than what was required.
-    // The client has to guarantee that the linkonce will be availabe at link
-    // time (by promoting it to weak for instance).
-    return;
-
   // Add these to the internalize list
-  if (!GV.hasLinkOnceLinkage() && !shouldLinkOnlyNeeded())
+  if (!GV.hasLinkOnceLinkage() && !GV.hasAvailableExternallyLinkage() &&
+      !shouldLinkOnlyNeeded())
     return;
 
-  if (shouldInternalizeLinkedSymbols())
+  if (InternalizeCallback)
     Internalize.insert(GV.getName());
   Add(GV);
 
@@ -442,7 +403,7 @@ void ModuleLinker::addLazyFor(GlobalValue &GV, const IRMover::ValueAdder &Add) {
       return;
     if (!LinkFromSrc)
       continue;
-    if (shouldInternalizeLinkedSymbols())
+    if (InternalizeCallback)
       Internalize.insert(GV2->getName());
     Add(*GV2);
   }
@@ -571,7 +532,7 @@ bool ModuleLinker::run() {
     }
   }
 
-  if (shouldInternalizeLinkedSymbols()) {
+  if (InternalizeCallback) {
     for (GlobalValue *GV : ValuesToLink)
       Internalize.insert(GV->getName());
   }
@@ -583,8 +544,7 @@ bool ModuleLinker::run() {
                            [this](GlobalValue &GV, IRMover::ValueAdder Add) {
                              addLazyFor(GV, Add);
                            },
-                           /* LinkModuleInlineAsm */ !isPerformingImport(),
-                           /* IsPerformingImport */ isPerformingImport())) {
+                           /* IsPerformingImport */ false)) {
     handleAllErrors(std::move(E), [&](ErrorInfoBase &EIB) {
       DstM.getContext().diagnose(LinkDiagnosticInfo(DS_Error, EIB.message()));
       HasErrors = true;
@@ -593,19 +553,19 @@ bool ModuleLinker::run() {
   if (HasErrors)
     return true;
 
-  for (auto &P : Internalize) {
-    GlobalValue *GV = DstM.getNamedValue(P.first());
-    GV->setLinkage(GlobalValue::InternalLinkage);
-  }
+  if (InternalizeCallback)
+    InternalizeCallback(DstM, Internalize);
 
   return false;
 }
 
 Linker::Linker(Module &M) : Mover(M) {}
 
-bool Linker::linkInModule(std::unique_ptr<Module> Src, unsigned Flags,
-                          DenseSet<const GlobalValue *> *GlobalsToImport) {
-  ModuleLinker ModLinker(Mover, std::move(Src), Flags, GlobalsToImport);
+bool Linker::linkInModule(
+    std::unique_ptr<Module> Src, unsigned Flags,
+    std::function<void(Module &, const StringSet<> &)> InternalizeCallback) {
+  ModuleLinker ModLinker(Mover, std::move(Src), Flags,
+                         std::move(InternalizeCallback));
   return ModLinker.run();
 }
 
@@ -618,10 +578,11 @@ bool Linker::linkInModule(std::unique_ptr<Module> Src, unsigned Flags,
 /// true is returned and ErrorMsg (if not null) is set to indicate the problem.
 /// Upon failure, the Dest module could be in a modified state, and shouldn't be
 /// relied on to be consistent.
-bool Linker::linkModules(Module &Dest, std::unique_ptr<Module> Src,
-                         unsigned Flags) {
+bool Linker::linkModules(
+    Module &Dest, std::unique_ptr<Module> Src, unsigned Flags,
+    std::function<void(Module &, const StringSet<> &)> InternalizeCallback) {
   Linker L(Dest);
-  return L.linkInModule(std::move(Src), Flags);
+  return L.linkInModule(std::move(Src), Flags, std::move(InternalizeCallback));
 }
 
 //===----------------------------------------------------------------------===//