Implemented global redzones.

src/IceASanInstrumentation.cpp

+//===- subzero/src/IceASanInstrumentation.cpp - ASan ------------*- C++ -*-===//
+//
+//                        The Subzero Code Generator
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// \brief Implements the AddressSanitizer instrumentation class.
+///
+//===----------------------------------------------------------------------===//
+
+#include "IceASanInstrumentation.h"
+
+#include "IceBuildDefs.h"
+#include "IceGlobalInits.h"
+
+#include <sstream>
+
+namespace Ice {
+
+const std::string ASanInstrumentation::RzPrefix = "__$rz";
+const llvm::NaClBitcodeRecord::RecordVector ASanInstrumentation::RzContents =
+    llvm::NaClBitcodeRecord::RecordVector(RzSize, 'R');

[Karl, 2016/06/10 18:04:50]

Minor nit. Since these globals are not needed in the header file, why not limit
the scope by moving these constants out of the class and define in an anonymous
namespace. That will limit them to this source file in terms of access.

[tlively, 2016/06/10 19:17:22]

Done.

+
+// Create redzones between all global variables, ensuring that the initializer
+// types of the redzones and their associated globals match so that they are
+// laid out together in memory.
+void ASanInstrumentation::instrumentGlobals(VariableDeclarationList &Globals) {
+  if (BuildDefs::minimal() || DidInsertRedZones)
+    return;
+
+  VariableDeclarationList NewGlobals;
+  // Global holding pointers to all redzones
+  VariableDeclaration *RzArray = VariableDeclaration::create(&NewGlobals);
+  // Global holding the size of RzArray
+  VariableDeclaration *RzArraySizeVar =
+      VariableDeclaration::create(&NewGlobals);
+  static SizeT RzArraySize = 0;
+
+  RzArray->setName(Ctx, nextRzName());
+  RzArraySizeVar->setName(Ctx, nextRzName());
+  NewGlobals.push_back(RzArray);
+  NewGlobals.push_back(RzArraySizeVar);
+
+  // TODO(tlively): Consider alignment when determining redzone layout.
+  for (VariableDeclaration *Global : Globals) {
+    VariableDeclaration *RzLeft =
+        createRz(&NewGlobals, RzArray, RzArraySize, Global);
+    VariableDeclaration *RzRight =
+        createRz(&NewGlobals, RzArray, RzArraySize, Global);
+    NewGlobals.push_back(RzLeft);
+    NewGlobals.push_back(Global);
+    NewGlobals.push_back(RzRight);
+  }
+
+  // update the contents of the RzArraySize global
+  llvm::NaClBitcodeRecord::RecordVector SizeContents;
+  for (unsigned i = 0; i < sizeof(RzArraySize); i++) {
+    SizeContents.emplace_back(RzArraySize % (1 << CHAR_BIT));
+    RzArraySize >>= CHAR_BIT;
+  }
+  RzArraySizeVar->addInitializer(
+      VariableDeclaration::DataInitializer::create(&NewGlobals, SizeContents));
+
+  // Replace old list of globals, without messing up arena allocators
+  Globals.clear();
+  Globals.merge(&NewGlobals);
+  DidInsertRedZones = true;
+
+  // Log the new set of globals
+  if (BuildDefs::dump()) {
+    OstreamLocker _(Ctx);
+    Ctx->getStrDump() << "========= Instrumented Globals =========\n";
+    for (VariableDeclaration *Global : Globals) {
+      Global->dump(Ctx->getStrDump());
+    }
+  }
+}
+
+std::string ASanInstrumentation::nextRzName() {
+  std::stringstream Name;
+  Name << RzPrefix << RzNum++;
+  return Name.str();
+}
+
+VariableDeclaration *
+ASanInstrumentation::createRz(VariableDeclarationList *List,
+                              VariableDeclaration *RzArray, SizeT &RzArraySize,
+                              VariableDeclaration *Global) {
+  VariableDeclaration *Rz = VariableDeclaration::create(List);
+  Rz->setName(Ctx, nextRzName());
+  if (Global->hasNonzeroInitializer()) {
+    Rz->addInitializer(
+        VariableDeclaration::DataInitializer::create(List, RzContents));
+  } else {
+    Rz->addInitializer(
+        VariableDeclaration::ZeroInitializer::create(List, RzSize));
+  }
+  Rz->setIsConstant(Global->getIsConstant());
+  RzArray->addInitializer(VariableDeclaration::RelocInitializer::create(
+      List, Rz, RelocOffsetArray(0)));
+  ++RzArraySize;
+  return Rz;
+}
+
+} // end of namespace Ice