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 {
+
+namespace {
+constexpr SizeT RzSize = 32;
+const std::string RzPrefix = "__$rz";
+const llvm::NaClBitcodeRecord::RecordVector RzContents =
+    llvm::NaClBitcodeRecord::RecordVector(RzSize, 'R');
+} // end of anonymous namespace
+
+// 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
+  auto *RzArray = VariableDeclaration::create(&NewGlobals);
+  // Global holding the size of RzArray
+  auto *RzArraySizeVar = VariableDeclaration::create(&NewGlobals);
+  SizeT RzArraySize = 0;
+
+  RzArray->setName(Ctx, nextRzName());
+  RzArraySizeVar->setName(Ctx, nextRzName());
+  RzArray->setIsConstant(true);
+  RzArraySizeVar->setIsConstant(true);
+  NewGlobals.push_back(RzArray);
+  NewGlobals.push_back(RzArraySizeVar);
+
+  for (VariableDeclaration *Global : Globals) {
+    auto *RzLeft = createRz(&NewGlobals, RzArray, RzArraySize, Global);

[Jim Stichnoth, 2016/06/11 14:26:41]

I personally would not use "auto" here, because it's not clear to the casual
reader that createRz() returns VariableDeclaration* .

This is in contrast to a "Foo::create()" method, which is likely to be a factory
method returning Foo* or unique_ptr<Foo> or something similar.

[tlively, 2016/06/13 17:35:53]

Done.

+    auto *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() && (getFlags().getVerbose() & IceV_GlobalInit)) {
+    OstreamLocker _(Ctx);
+    Ctx->getStrDump() << "========= Instrumented Globals =========\n";
+    for (VariableDeclaration *Global : Globals) {
+      Global->dump(Ctx->getStrDump());
+    }
+  }
+}
+
+std::string ASanInstrumentation::nextRzName() {
+  if (BuildDefs::minimal())
+    return "";
+  std::stringstream Name;
+  Name << RzPrefix << RzNum++;
+  return Name.str();
+}
+
+VariableDeclaration *
+ASanInstrumentation::createRz(VariableDeclarationList *List,
+                              VariableDeclaration *RzArray, SizeT &RzArraySize,
+                              VariableDeclaration *Global) {
+  if (BuildDefs::minimal())
+    return nullptr;
+  auto *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