Inserted local redzones.

src/IceASanInstrumentation.cpp

Index: src/IceASanInstrumentation.cpp
diff --git a/src/IceASanInstrumentation.cpp b/src/IceASanInstrumentation.cpp
index 9bd95553902304a10b4922519657a916f1244799..d182b128bc5ec4ed77260c5ee7eae64a65bf6144 100644
--- a/src/IceASanInstrumentation.cpp
+++ b/src/IceASanInstrumentation.cpp
@@ -15,6 +15,7 @@
 #include "IceASanInstrumentation.h"
 
 #include "IceBuildDefs.h"
+#include "IceCfg.h"
 #include "IceCfgNode.h"
 #include "IceGlobalInits.h"
 #include "IceInst.h"
@@ -95,7 +96,7 @@ void ASanInstrumentation::instrumentGlobals(VariableDeclarationList &Globals) {
     }
   }
 }
-
+// TODO(tlively): Make this thread safe
 std::string ASanInstrumentation::nextRzName() {
   std::stringstream Name;
   Name << RzPrefix << RzNum++;
@@ -122,6 +123,47 @@ ASanInstrumentation::createRz(VariableDeclarationList *List,
   return Rz;
 }
 
+// Check for an alloca signaling the presence of local variables and add a
+// redzone if it is found
+void ASanInstrumentation::instrumentFuncStart(LoweringContext &Context) {
+  auto *FirstAlloca = llvm::dyn_cast<InstAlloca>(Context.getCur());
+  if (FirstAlloca == nullptr)
+    return;
+
+  constexpr SizeT Alignment = 4;
+  InstAlloca *RzAlloca = createLocalRz(Context, RzSize, Alignment);
+
+  // insert before the current instruction
+  InstList::iterator Next = Context.getNext();
+  Context.setInsertPoint(Context.getCur());
+  Context.insert(RzAlloca);
+  Context.setNext(Next);
+}
+
+void ASanInstrumentation::instrumentAlloca(LoweringContext &Context,
+                                           InstAlloca *Instr) {
+  auto *VarSizeOp = llvm::dyn_cast<ConstantInteger32>(Instr->getSizeInBytes());
+  SizeT VarSize = (VarSizeOp == nullptr) ? RzSize : VarSizeOp->getValue();
+  SizeT Padding = (VarSize % RzSize) ? RzSize - VarSize % RzSize : 0;

[Jim Stichnoth, 2016/06/20 19:44:41]

Can you use Utils::OffsetToAlignment() here?

[tlively, 2016/06/20 22:19:33]

Done.

+  constexpr SizeT Alignment = 1;
+  InstAlloca *Rz = createLocalRz(Context, RzSize + Padding, Alignment);
+  Context.insert(Rz);
+}
+
+InstAlloca *ASanInstrumentation::createLocalRz(LoweringContext &Context,
+                                               SizeT Size, SizeT Alignment) {
+  Cfg *Func = Context.getNode()->getCfg();
+  Variable *Rz = Func->makeVariable(IceType_i32);
+  Rz->setName(Func, nextRzName());
+  // TODO(tlively): Make this unnecessary

[Jim Stichnoth, 2016/06/20 19:44:41]

I'm not sure what the exact problem is here.  Is it that the new alloca
instruction gets dead-code eliminated because of no uses of Rz?

If so, you might be able to create a FakeUse instruction after the alloca
instruction.

[tlively, 2016/06/20 22:19:33]

I'll just get rid of this now. It will be unnecessary once the redzones are
used.

+  Rz->setIgnoreLiveness();
+
+  auto *ByteCount = ConstantInteger32::create(Ctx, IceType_i32, Size);
+  auto *RzAlloca = InstAlloca::create(Func, Rz, ByteCount, Alignment);
+
+  return RzAlloca;
+}
+
 void ASanInstrumentation::instrumentCall(LoweringContext &Context,
                                          InstCall *Instr) {
   auto *CallTarget =