Rebased PNaCl localmods in LLVM to 223109

lib/Transforms/MinSFI/RenameEntryPoint.cpp

+//===- RenameEntryPoint.cpp - Rename _start to avoid linking collisions ---===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// MinSFI compiles PNaCl bitcode into a native object file and links it into
+// a standard C program. However, both C and PNaCl name their entry points
+// '_start' which causes a linking collision. This pass therefore renames the
+// entry function of the MinSFI module to '_start_minsfi'. By changing the name
+// in the bitcode, we also avoid relying on objcopy.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Pass.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Transforms/MinSFI.h"
+
+using namespace llvm;
+
+static const char PNaClEntryPointName[] = "_start";
+const char minsfi::EntryFunctionName[] = "_start_minsfi";
+
+namespace {
+class RenameEntryPoint : public ModulePass {
+ public:
+  static char ID;
+  RenameEntryPoint() : ModulePass(ID) {
+    initializeRenameEntryPointPass(*PassRegistry::getPassRegistry());
+  }
+
+  virtual bool runOnModule(Module &M);
+};
+}  // namespace
+
+bool RenameEntryPoint::runOnModule(Module &M) {
+  if (M.getNamedValue(minsfi::EntryFunctionName)) {
+    report_fatal_error(std::string("RenameEntryPoint: The module already "
+                       "contains a value named '") +
+                       minsfi::EntryFunctionName + "'");
+  }
+
+  Function *EntryFunc = M.getFunction(PNaClEntryPointName);
+  if (!EntryFunc) {
+    report_fatal_error(std::string("RenameEntryPoint: The module does not "
+                       "contain a function named '") +
+                       PNaClEntryPointName + "'");
+  }
+
+  EntryFunc->setName(minsfi::EntryFunctionName);
+  return true;
+}
+
+char RenameEntryPoint::ID = 0;
+INITIALIZE_PASS(RenameEntryPoint, "minsfi-rename-entry-point",
+                "Rename _start to avoid linking collisions", false, false)
+
+ModulePass *llvm::createRenameEntryPointPass() {
+  return new RenameEntryPoint();
+}