From 00eb257f2e908e5ec81bbe00aeeb42ea4aa4fd79 Mon Sep 17 00:00:00 2001
From: Rui Ueyama <ruiu@google.com>
Date: Wed, 10 Dec 2014 00:33:00 +0000
Subject: Re-commit r223330: Rewrite InputGraph's Group

llvm-svn: 223867
---
 lld/lib/ReaderWriter/MachO/MachOLinkingContext.cpp | 32 ++++++++++++++++++++++
 .../ReaderWriter/PECOFF/PECOFFLinkingContext.cpp   | 19 ++++++++++++-
 2 files changed, 50 insertions(+), 1 deletion(-)

(limited to 'lld/lib/ReaderWriter')

diff --git a/lld/lib/ReaderWriter/MachO/MachOLinkingContext.cpp b/lld/lib/ReaderWriter/MachO/MachOLinkingContext.cpp
index 3e91e4a56b3..b129c033740 100644
--- a/lld/lib/ReaderWriter/MachO/MachOLinkingContext.cpp
+++ b/lld/lib/ReaderWriter/MachO/MachOLinkingContext.cpp
@@ -22,6 +22,7 @@
 #include "llvm/ADT/Triple.h"
 #include "llvm/Config/config.h"
 #include "llvm/Support/Errc.h"
+#include "llvm/Support/Debug.h"
 #include "llvm/Support/Host.h"
 #include "llvm/Support/MachO.h"
 #include "llvm/Support/Path.h"
@@ -923,4 +924,35 @@ bool MachOLinkingContext::customAtomOrderer(const DefinedAtom *left,
   return true;
 }
 
+static File *getFirstFile(const std::unique_ptr<InputElement> &elem) {
+  FileNode *e = dyn_cast<FileNode>(const_cast<InputElement *>(elem.get()));
+  if (!e || e->files().empty())
+    return nullptr;
+  return e->files()[0].get();
+}
+
+static bool isLibrary(const std::unique_ptr<InputElement> &elem) {
+  File *f = getFirstFile(elem);
+  return f && (isa<SharedLibraryFile>(f) || isa<ArchiveLibraryFile>(f));
+}
+
+// The darwin linker processes input files in two phases.  The first phase
+// links in all object (.o) files in command line order. The second phase
+// links in libraries in command line order.
+// In this function we reorder the input files so that all the object files
+// comes before any library file. We also make a group for the library files
+// so that the Resolver will reiterate over the libraries as long as we find
+// new undefines from libraries.
+void MachOLinkingContext::maybeSortInputFiles() {
+  std::vector<std::unique_ptr<InputElement>> &elements
+      = getInputGraph().inputElements();
+  std::stable_sort(elements.begin(), elements.end(),
+                   [](const std::unique_ptr<InputElement> &a,
+                      const std::unique_ptr<InputElement> &b) {
+                     return !isLibrary(a) && isLibrary(b);
+                   });
+  size_t numLibs = std::count_if(elements.begin(), elements.end(), isLibrary);
+  elements.push_back(llvm::make_unique<GroupEnd>(numLibs));
+}
+
 } // end namespace lld
diff --git a/lld/lib/ReaderWriter/PECOFF/PECOFFLinkingContext.cpp b/lld/lib/ReaderWriter/PECOFF/PECOFFLinkingContext.cpp
index ae236f475ba..7dc64d3fd5e 100644
--- a/lld/lib/ReaderWriter/PECOFF/PECOFFLinkingContext.cpp
+++ b/lld/lib/ReaderWriter/PECOFF/PECOFFLinkingContext.cpp
@@ -87,6 +87,23 @@ std::unique_ptr<File> PECOFFLinkingContext::createUndefinedSymbolFile() const {
       "<command line option /include>");
 }
 
+void PECOFFLinkingContext::addLibraryFile(std::unique_ptr<FileNode> file) {
+  GroupEnd *currentGroupEnd;
+  int pos = -1;
+  std::vector<std::unique_ptr<InputElement>> &elements
+      = getInputGraph().inputElements();
+  for (int i = 0, e = elements.size(); i < e; ++i) {
+    if ((currentGroupEnd = dyn_cast<GroupEnd>(elements[i].get()))) {
+      pos = i;
+      break;
+    }
+  }
+  assert(pos >= 0);
+  elements.insert(elements.begin() + pos, std::move(file));
+  elements[pos + 1] = llvm::make_unique<GroupEnd>(
+      currentGroupEnd->getSize() + 1);
+}
+
 bool PECOFFLinkingContext::createImplicitFiles(
     std::vector<std::unique_ptr<File>> &) {
   // Create a file for __ImageBase.
@@ -109,7 +126,7 @@ bool PECOFFLinkingContext::createImplicitFiles(
   auto exportNode = llvm::make_unique<SimpleFileNode>("<export>");
   exportNode->appendInputFile(
       llvm::make_unique<pecoff::ExportedSymbolRenameFile>(*this, syms));
-  getLibraryGroup()->addFile(std::move(exportNode));
+  addLibraryFile(std::move(exportNode));
 
   // Create a file for the entry point function.
   getEntryNode()->appendInputFile(
-- 
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