[MSan] Disable sanitization for __sanitizer_dtor_callback.

[morehouse]

Summary

Eliminate unnecessary instrumentation at __sanitizer_dtor_callback
call sites. Fixes https://github.com/google/sanitizers/issues/861.

[eugenis]

A test, please.

clang/lib/CodeGen/CGClass.cpp

1592 ↗

(On Diff #115929)

Use SanitizerScope.

[morehouse]

• Add test case.
• Use SanitizerScope.

[eugenis]

Please also add a tiny LLVM test that call instructions with nosanitize metadata are not instrumented.

[morehouse]

• Add LLVM test.

cfe/trunk/lib/CodeGen/CGClass.cpp

void Emit(CodeGenFunction &CGF, Flags flags) override {
 
       CGF.emitDestroy(LV.getAddress(), field->getType(), destroyer,
                       flags.isForNormalCleanup() && useEHCleanupForArray);
     }
   };
 
  static void EmitSanitizerDtorCallback(CodeGenFunction &CGF, llvm::Value *Ptr,
              CharUnits::QuantityType PoisonSize) {
+   CodeGenFunction::SanitizerScope SanScope(&CGF);
    // Pass in void pointer and size of region as arguments to runtime
    // function
    llvm::Value *Args[] = {CGF.Builder.CreateBitCast(Ptr, CGF.VoidPtrTy),
                           llvm::ConstantInt::get(CGF.SizeTy, PoisonSize)};
 
    llvm::Type *ArgTypes[] = {CGF.VoidPtrTy, CGF.SizeTy};
 
    llvm::FunctionType *FnType =

cfe/trunk/test/CodeGenCXX/sanitize-dtor-callback.cpp

 // CHECK: ret void
 
 
 // Note: ordering is important. In the emitted bytecode, these
 // second dtors defined after the first. Explicitly checked here
 // to confirm that all invoked dtors have member poisoning
 // instrumentation inserted.
 // CHECK-LABEL: define {{.*}}SimpleD2Ev
+// CHECK-NOT: store i{{[0-9]+}} 0, {{.*}}@__msan_param_tls
 // CHECK: call void @__sanitizer_dtor_callback
 // CHECK-NOT: call void @__sanitizer_dtor_callback
 // CHECK: ret void
 
 // CHECK-LABEL: define {{.*}}InlinedD2Ev
+// CHECK-NOT: store i{{[0-9]+}} 0, {{.*}}@__msan_param_tls
 // CHECK: call void @__sanitizer_dtor_callback
 // CHECK-NOT: call void @__sanitizer_dtor_callback
 // CHECK: ret void
 
 // CHECK-LABEL: define {{.*}}Defaulted_Non_TrivialD2Ev
+// CHECK-NOT: store i{{[0-9]+}} 0, {{.*}}@__msan_param_tls
 // CHECK: call void @__sanitizer_dtor_callback
 // CHECK-NOT: call void @__sanitizer_dtor_callback
 // CHECK: ret void

llvm/trunk/lib/Transforms/Instrumentation/MemorySanitizer.cpp

default:
       if (!handleUnknownIntrinsic(I))
         visitInstruction(I);
       break;
     }
   }
 
   void visitCallSite(CallSite CS) {
     Instruction &I = *CS.getInstruction();
+    if (I.getMetadata("nosanitize")) return;
     assert((CS.isCall() || CS.isInvoke()) && "Unknown type of CallSite");
     if (CS.isCall()) {
       CallInst *Call = cast<CallInst>(&I);
 
       // For inline asm, do the usual thing: check argument shadow and mark all
       // outputs as clean. Note that any side effects of the inline asm that are
       // not immediately visible in its constraints are not handled.
       if (Call->isInlineAsm()) {

llvm/trunk/test/Instrumentation/MemorySanitizer/call-nosanitize.ll

+; Verify that calls with !nosanitize are not instrumented by MSan.
+; RUN: opt < %s -msan -S | FileCheck %s
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+declare void @bar(i32 %x)
+
+define void @foo() {
+  call void @bar(i32 7), !nosanitize !{}
+  ret void
+}
+
+; CHECK-LABEL: define void @foo
+; CHECK-NOT: store i{{[0-9]+}} 0, {{.*}} @__msan_param_tls
+; CHECK: call void @bar
+; CHECK: ret void