1 files changed, 119 insertions, 0 deletions
diff --git a/contrib/llvm/lib/LTO/LTO.cpp b/contrib/llvm/lib/LTO/LTO.cpp
new file mode 100644
index 0000000..10226c4
--- /dev/null
+++ b/contrib/llvm/lib/LTO/LTO.cpp
@@ -0,0 +1,119 @@
+//===-LTO.cpp - LLVM Link Time Optimizer ----------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements functions and classes used to support LTO.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/LTO/LTO.h"
+#include "llvm/Bitcode/ReaderWriter.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/SourceMgr.h"
+#include "llvm/Support/raw_ostream.h"
+
+namespace llvm {
+
+// Simple helper to load a module from bitcode
+std::unique_ptr<Module> loadModuleFromBuffer(const MemoryBufferRef &Buffer,
+                                             LLVMContext &Context, bool Lazy) {
+  SMDiagnostic Err;
+  ErrorOr<std::unique_ptr<Module>> ModuleOrErr(nullptr);
+  if (Lazy) {
+    ModuleOrErr =
+        getLazyBitcodeModule(MemoryBuffer::getMemBuffer(Buffer, false), Context,
+                             /* ShouldLazyLoadMetadata */ Lazy);
+  } else {
+    ModuleOrErr = parseBitcodeFile(Buffer, Context);
+  }
+  if (std::error_code EC = ModuleOrErr.getError()) {
+    Err = SMDiagnostic(Buffer.getBufferIdentifier(), SourceMgr::DK_Error,
+                       EC.message());
+    Err.print("ThinLTO", errs());
+    report_fatal_error("Can't load module, abort.");
+  }
+  return std::move(ModuleOrErr.get());
+}
+
+static void thinLTOResolveWeakForLinkerGUID(
+    GlobalValueSummaryList &GVSummaryList, GlobalValue::GUID GUID,
+    DenseSet<GlobalValueSummary *> &GlobalInvolvedWithAlias,
+    function_ref<bool(GlobalValue::GUID, const GlobalValueSummary *)>
+        isPrevailing,
+    function_ref<void(StringRef, GlobalValue::GUID, GlobalValue::LinkageTypes)>
+        recordNewLinkage) {
+  for (auto &S : GVSummaryList) {
+    if (GlobalInvolvedWithAlias.count(S.get()))
+      continue;
+    GlobalValue::LinkageTypes OriginalLinkage = S->linkage();
+    if (!GlobalValue::isWeakForLinker(OriginalLinkage))
+      continue;
+    // We need to emit only one of these. The prevailing module will keep it,
+    // but turned into a weak, while the others will drop it when possible.
+    if (isPrevailing(GUID, S.get())) {
+      if (GlobalValue::isLinkOnceLinkage(OriginalLinkage))
+        S->setLinkage(GlobalValue::getWeakLinkage(
+            GlobalValue::isLinkOnceODRLinkage(OriginalLinkage)));
+    }
+    // Alias can't be turned into available_externally.
+    else if (!isa<AliasSummary>(S.get()) &&
+             (GlobalValue::isLinkOnceODRLinkage(OriginalLinkage) ||
+              GlobalValue::isWeakODRLinkage(OriginalLinkage)))
+      S->setLinkage(GlobalValue::AvailableExternallyLinkage);
+    if (S->linkage() != OriginalLinkage)
+      recordNewLinkage(S->modulePath(), GUID, S->linkage());
+  }
+}
+
+// Resolve Weak and LinkOnce values in the \p Index.
+//
+// We'd like to drop these functions if they are no longer referenced in the
+// current module. However there is a chance that another module is still
+// referencing them because of the import. We make sure we always emit at least
+// one copy.
+void thinLTOResolveWeakForLinkerInIndex(
+    ModuleSummaryIndex &Index,
+    function_ref<bool(GlobalValue::GUID, const GlobalValueSummary *)>
+        isPrevailing,
+    function_ref<void(StringRef, GlobalValue::GUID, GlobalValue::LinkageTypes)>
+        recordNewLinkage) {
+  // We won't optimize the globals that are referenced by an alias for now
+  // Ideally we should turn the alias into a global and duplicate the definition
+  // when needed.
+  DenseSet<GlobalValueSummary *> GlobalInvolvedWithAlias;
+  for (auto &I : Index)
+    for (auto &S : I.second)
+      if (auto AS = dyn_cast<AliasSummary>(S.get()))
+        GlobalInvolvedWithAlias.insert(&AS->getAliasee());
+
+  for (auto &I : Index)
+    thinLTOResolveWeakForLinkerGUID(I.second, I.first, GlobalInvolvedWithAlias,
+                                    isPrevailing, recordNewLinkage);
+}
+
+static void thinLTOInternalizeAndPromoteGUID(
+    GlobalValueSummaryList &GVSummaryList, GlobalValue::GUID GUID,
+    function_ref<bool(StringRef, GlobalValue::GUID)> isExported) {
+  for (auto &S : GVSummaryList) {
+    if (isExported(S->modulePath(), GUID)) {
+      if (GlobalValue::isLocalLinkage(S->linkage()))
+        S->setLinkage(GlobalValue::ExternalLinkage);
+    } else if (!GlobalValue::isLocalLinkage(S->linkage()))
+      S->setLinkage(GlobalValue::InternalLinkage);
+  }
+}
+
+// Update the linkages in the given \p Index to mark exported values
+// as external and non-exported values as internal.
+void thinLTOInternalizeAndPromoteInIndex(
+    ModuleSummaryIndex &Index,
+    function_ref<bool(StringRef, GlobalValue::GUID)> isExported) {
+  for (auto &I : Index)
+    thinLTOInternalizeAndPromoteGUID(I.second, I.first, isExported);
+}
+}