From 24cad9930709a6448c4b23194ac06bf233ed18a6 Mon Sep 17 00:00:00 2001
From: Alexey Samsonov <vonosmas@gmail.com>
Date: Thu, 17 Jul 2014 18:46:27 +0000
Subject: [UBSan] Add !nosanitize metadata to the code generated by UBSan.

This is used to mark the instructions emitted by Clang to implement
variety of UBSan checks. Generally, we don't want to instrument these
instructions with another sanitizers (like ASan).

Reviewed in http://reviews.llvm.org/D4544

llvm-svn: 213291
---
 clang/lib/CodeGen/CodeGenFunction.cpp | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

(limited to 'clang/lib/CodeGen/CodeGenFunction.cpp')

diff --git a/clang/lib/CodeGen/CodeGenFunction.cpp b/clang/lib/CodeGen/CodeGenFunction.cpp
index 0987673..5ca3a78 100644
--- a/clang/lib/CodeGen/CodeGenFunction.cpp
+++ b/clang/lib/CodeGen/CodeGenFunction.cpp
@@ -36,8 +36,9 @@ using namespace CodeGen;
 CodeGenFunction::CodeGenFunction(CodeGenModule &cgm, bool suppressNewContext)
     : CodeGenTypeCache(cgm), CGM(cgm), Target(cgm.getTarget()),
       Builder(cgm.getModule().getContext(), llvm::ConstantFolder(),
-              CGBuilderInserterTy(this)), CapturedStmtInfo(nullptr),
-      SanOpts(&CGM.getLangOpts().Sanitize), AutoreleaseResult(false), BlockInfo(nullptr),
+              CGBuilderInserterTy(this)),
+      CapturedStmtInfo(nullptr), SanOpts(&CGM.getLangOpts().Sanitize),
+      IsSanitizerScope(false), AutoreleaseResult(false), BlockInfo(nullptr),
       BlockPointer(nullptr), LambdaThisCaptureField(nullptr),
       NormalCleanupDest(nullptr), NextCleanupDestIndex(1),
       FirstBlockInfo(nullptr), EHResumeBlock(nullptr), ExceptionSlot(nullptr),
@@ -843,11 +844,12 @@ void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn,
   //   function call is used by the caller, the behavior is undefined.
   if (getLangOpts().CPlusPlus && !FD->hasImplicitReturnZero() &&
       !FD->getReturnType()->isVoidType() && Builder.GetInsertBlock()) {
-    if (SanOpts->Return)
+    if (SanOpts->Return) {
+      SanitizerScope SanScope(this);
       EmitCheck(Builder.getFalse(), "missing_return",
                 EmitCheckSourceLocation(FD->getLocation()),
                 ArrayRef<llvm::Value *>(), CRK_Unrecoverable);
-    else if (CGM.getCodeGenOpts().OptimizationLevel == 0)
+    } else if (CGM.getCodeGenOpts().OptimizationLevel == 0)
       Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::trap));
     Builder.CreateUnreachable();
     Builder.ClearInsertionPoint();
@@ -1499,6 +1501,7 @@ void CodeGenFunction::EmitVariablyModifiedType(QualType type) {
           //   greater than zero.
           if (SanOpts->VLABound &&
               size->getType()->isSignedIntegerType()) {
+            SanitizerScope SanScope(this);
             llvm::Value *Zero = llvm::Constant::getNullValue(Size->getType());
             llvm::Constant *StaticArgs[] = {
               EmitCheckSourceLocation(size->getLocStart()),
@@ -1637,11 +1640,26 @@ llvm::Value *CodeGenFunction::EmitFieldAnnotations(const FieldDecl *D,
 
 CodeGenFunction::CGCapturedStmtInfo::~CGCapturedStmtInfo() { }
 
+CodeGenFunction::SanitizerScope::SanitizerScope(CodeGenFunction *CGF)
+    : CGF(CGF) {
+  assert(!CGF->IsSanitizerScope);
+  CGF->IsSanitizerScope = true;
+}
+
+CodeGenFunction::SanitizerScope::~SanitizerScope() {
+  CGF->IsSanitizerScope = false;
+}
+
 void CodeGenFunction::InsertHelper(llvm::Instruction *I,
                                    const llvm::Twine &Name,
                                    llvm::BasicBlock *BB,
                                    llvm::BasicBlock::iterator InsertPt) const {
   LoopStack.InsertHelper(I);
+  if (IsSanitizerScope) {
+    I->setMetadata(
+        CGM.getModule().getMDKindID("nosanitize"),
+        llvm::MDNode::get(CGM.getLLVMContext(), ArrayRef<llvm::Value *>()));
+  }
 }
 
 template <bool PreserveNames>
-- 
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