Subzero: Improved quality of ASan error messages

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
@@ skipping 18 matching lines @@
 
 namespace Ice {
 
 namespace {
 
 constexpr const char *ASanPrefix = "__asan";
 constexpr SizeT RzSize = 32;
 constexpr const char *RzPrefix = "__$rz";
 constexpr const char *RzArrayName = "__$rz_array";
 constexpr const char *RzSizesName = "__$rz_sizes";
+constexpr char RzStackPoison = -1;
 const llvm::NaClBitcodeRecord::RecordVector RzContents =
     llvm::NaClBitcodeRecord::RecordVector(RzSize, 'R');
 
 // In order to instrument the code correctly, the .pexe must not have had its
 // symbols stripped.
 using StringMap = std::unordered_map<std::string, std::string>;
 using StringSet = std::unordered_set<std::string>;
 // TODO(tlively): Handle all allocation functions
 const StringMap FuncSubstitutions = {{"malloc", "__asan_malloc"},
                                      {"free", "__asan_free"},
@@ skipping 146 matching lines @@
     Variable *RzLocVar = Func->makeVariable(IceType_i32);
     RzLocVar->setName(Func, nextRzName());
     auto *Offset = ConstantInteger32::create(Ctx, IceType_i32, VarSize);
     auto *RzLoc = InstArithmetic::create(Func, InstArithmetic::Add, RzLocVar,
                                          Dest, Offset);
 
     // instructions to poison and unpoison the redzone
     constexpr SizeT NumArgs = 2;
     constexpr Variable *Void = nullptr;
     constexpr bool NoTailcall = false;
+    auto *RzSizeConst = ConstantInteger32::create(Ctx, IceType_i32, RzPadding);
+    auto *RzPoisonConst =
+        ConstantInteger32::create(Ctx, IceType_i32, RzStackPoison);
     auto *Init = InstCall::create(Func, NumArgs, Void, InitFunc, NoTailcall);
+    Init->addArg(RzLocVar);
+    Init->addArg(RzSizeConst);
+    Init->addArg(RzPoisonConst);
     auto *Destroy =
         InstCall::create(Func, NumArgs, Void, DestroyFunc, NoTailcall);
-    Init->addArg(RzLocVar);
     Destroy->addArg(RzLocVar);
-    auto *RzSizeConst = ConstantInteger32::create(Ctx, IceType_i32, RzPadding);
-    Init->addArg(RzSizeConst);
     Destroy->addArg(RzSizeConst);
-
     Cur->setDeleted();
     C.insert(NewVar);
     ICE_TLS_GET_FIELD(LocalDtors)->emplace_back(Destroy);
     Initializations.emplace_back(RzLoc);
     Initializations.emplace_back(Init);
 
     C.advanceCur();
     C.advanceNext();
   }
 
   C.setInsertPoint(C.getCur());
 
   // add the leftmost redzone
   if (HasLocals) {
     Variable *LastRz = Func->makeVariable(IceType_i32);
     LastRz->setName(Func, nextRzName());
     auto *ByteCount = ConstantInteger32::create(Ctx, IceType_i32, RzSize);
     constexpr SizeT Alignment = 8;
     auto *RzAlloca = InstAlloca::create(Func, LastRz, ByteCount, Alignment);
 
     constexpr SizeT NumArgs = 2;
     constexpr Variable *Void = nullptr;
     constexpr bool NoTailcall = false;
+    auto *RzPoisonConst =
+        ConstantInteger32::create(Ctx, IceType_i32, RzStackPoison);
     auto *Init = InstCall::create(Func, NumArgs, Void, InitFunc, NoTailcall);
+    Init->addArg(LastRz);
+    Init->addArg(RzAlloca->getSizeInBytes());
+    Init->addArg(RzPoisonConst);
     auto *Destroy =
         InstCall::create(Func, NumArgs, Void, DestroyFunc, NoTailcall);
-    Init->addArg(LastRz);
     Destroy->addArg(LastRz);
-    Init->addArg(RzAlloca->getSizeInBytes());
     Destroy->addArg(RzAlloca->getSizeInBytes());
-
     ICE_TLS_GET_FIELD(LocalDtors)->emplace_back(Destroy);
     C.insert(RzAlloca);
     C.insert(Init);
   }
 
   // insert initializers for the redzones
   for (Inst *Init : Initializations) {
     C.insert(Init);
   }
 }
@@ skipping 106 matching lines @@
   Call->addArg(Ctx->getConstantSym(0, Ctx->getGlobalString(RzSizesName)));
 }
 
 // TODO(tlively): make this more efficient with swap idiom
 void ASanInstrumentation::finishFunc(Cfg *) {
   ICE_TLS_GET_FIELD(LocalVars)->clear();
   ICE_TLS_GET_FIELD(LocalDtors)->clear();
 }
 
 } // end of namespace Ice