Revert "[asan] Poor man's coverage that works with ASan"

This reverts commit 194701. Apple's bootstrapped LTO builds have been failing,
and this change (along with compiler-rt 194702-194704) is the only thing on
the blamelist.  I will either reappy these changes or help debug the problem,
depending on whether this fixes the buildbots.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194780 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Instrumentation/AddressSanitizer.cpp

@@ -77,7 +77,6 @@ static const char *const kAsanUnregisterGlobalsName =
 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
 static const char *const kAsanInitName = "__asan_init_v3";
-static const char *const kAsanCovName = "__sanitizer_cov";
 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
 static const char *const kAsanMappingOffsetName = "__asan_mapping_offset";
 static const char *const kAsanMappingScaleName = "__asan_mapping_scale";
@@ -135,8 +134,6 @@ static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
 // This flag may need to be replaced with -f[no]asan-globals.
 static cl::opt<bool> ClGlobals("asan-globals",
        cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
-static cl::opt<bool> ClCoverage("asan-coverage",
-       cl::desc("ASan coverage"), cl::Hidden, cl::init(false));
 static cl::opt<bool> ClInitializers("asan-initialization-order",
        cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
 static cl::opt<bool> ClMemIntrin("asan-memintrin",
@@ -327,7 +324,6 @@ struct AddressSanitizer : public FunctionPass {
   bool LooksLikeCodeInBug11395(Instruction *I);
   void FindDynamicInitializers(Module &M);
   bool GlobalIsLinkerInitialized(GlobalVariable *G);
-  bool InjectCoverage(Function &F);
 
   bool CheckInitOrder;
   bool CheckUseAfterReturn;
@@ -343,7 +339,6 @@ struct AddressSanitizer : public FunctionPass {
   Function *AsanCtorFunction;
   Function *AsanInitFunction;
   Function *AsanHandleNoReturnFunc;
-  Function *AsanCovFunction;
   OwningPtr<SpecialCaseList> BL;
   // This array is indexed by AccessIsWrite and log2(AccessSize).
   Function *AsanErrorCallback[2][kNumberOfAccessSizes];
@@ -1090,8 +1085,6 @@ void AddressSanitizer::initializeCallbacks(Module &M) {
 
   AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction(
       kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
-  AsanCovFunction = checkInterfaceFunction(M.getOrInsertFunction(
-      kAsanCovName, IRB.getVoidTy(), IntptrTy, NULL));
   // We insert an empty inline asm after __asan_report* to avoid callback merge.
   EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
                             StringRef(""), StringRef(""),
@@ -1163,47 +1156,6 @@ bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
   return false;
 }
 
-// Poor man's coverage that works with ASan.
-// We create a Guard boolean variable with the same linkage
-// as the function and inject this code into the entry block:
-// if (*Guard) {
-//    __sanitizer_cov(&F);
-//    *Guard = 1;
-// }
-// The accesses to Guard are atomic. The rest of the logic is
-// in __sanitizer_cov (it's fine to call it more than once).
-//
-// This coverage implementation provides very limited data:
-// it only tells if a given function was ever executed.
-// No counters, no per-basic-block or per-edge data.
-// But for many use cases this is what we need and the added slowdown
-// is negligible. This simple implementation will probably be obsoleted
-// by the upcoming Clang-based coverage implementation.
-// By having it here and now we hope to
-//  a) get the functionality to users earlier and
-//  b) collect usage statistics to help improve Clang coverage design.
-bool AddressSanitizer::InjectCoverage(Function &F) {
-  if (!ClCoverage) return false;
-  IRBuilder<> IRB(F.getEntryBlock().getFirstInsertionPt());
-  Type *Int8Ty = IRB.getInt8Ty();
-  GlobalVariable *Guard = new GlobalVariable(
-      *F.getParent(), Int8Ty, false, F.getLinkage(),
-      Constant::getNullValue(Int8Ty), "__asan_gen_cov_" + F.getName());
-  LoadInst *Load = IRB.CreateLoad(Guard);
-  Load->setAtomic(Monotonic);
-  Load->setAlignment(1);
-  Value *Cmp = IRB.CreateICmpEQ(Constant::getNullValue(Int8Ty), Load);
-  Instruction *Ins = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
-  IRB.SetInsertPoint(Ins);
-  // We pass &F to __sanitizer_cov. We could avoid this and rely on
-  // GET_CALLER_PC, but having the PC of the first instruction is just nice.
-  IRB.CreateCall(AsanCovFunction, IRB.CreatePointerCast(&F, IntptrTy));
-  StoreInst *Store = IRB.CreateStore(ConstantInt::get(Int8Ty, 1), Guard);
-  Store->setAtomic(Monotonic);
-  Store->setAlignment(1);
-  return true;
-}
-
 bool AddressSanitizer::runOnFunction(Function &F) {
   if (BL->isIn(F)) return false;
   if (&F == AsanCtorFunction) return false;
@@ -1299,10 +1251,6 @@ bool AddressSanitizer::runOnFunction(Function &F) {
   }
 
   bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
-
-  if (InjectCoverage(F))
-    res = true;
-
   DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
 
   if (ClKeepUninstrumented) {