[clang][UBSan] Sanitization for alignment assumptions.

[lebedev.ri]

Summary

UB isn't nice. It's cool and powerful, but not nice.
Having a way to detect it is nice though.
P1007R3: std::assume_aligned / http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1007r2.pdf says:

We propose to add this functionality via a library function instead of a core language attribute.
...
If the pointer passed in is not aligned to at least N bytes, calling assume_aligned results in undefined behaviour.

This differential teaches clang to sanitize all the various variants of this assume-aligned attribute.

Requires D54588 for LLVM IRBuilder changes.
The compiler-rt part is D54590.

[lebedev.ri]

Adapt to D54588 no longer providing the actual pointer.
The handled itself will have to deal with subtracting the offset.

[lebedev.ri]

ping

[rjmccall]

docs/UndefinedBehaviorSanitizer.rst

75

assume_aligned-like

199

Is there a reason for this exception?

lib/CodeGen/CGBuiltin.cpp

1855–1856

Is this {}-initializing a SourceLocation? Please use SourceLocation() instead and put the comment before it.

lib/CodeGen/CodeGenFunction.cpp

2511

What's the deal with the two different source locations?

lib/CodeGen/CodeGenFunction.h

2827

dyn_cast, please. And these two methods should really be defined out-of-line.

[lebedev.ri]

docs/UndefinedBehaviorSanitizer.rst

199

Are you asking about the LHS of the diff, or about adding an exception to that for this sanitizer?
I'm adding an exception here because i don't know what should be done here.
Does it make sense to emit an assumptions for volatile pointers, but do not sanitize these assumptions?

lib/CodeGen/CGBuiltin.cpp

1855–1856

Is this {}-initializing a SourceLocation?

Yes

Ok.

lib/CodeGen/CodeGenFunction.cpp

2511

The first one points to the source-location of this alignment assumption.
The second one *may* point to the location where the alignment was specified.
See e.g. "test/ubsan/TestCases/Pointer/alignment-assumption-attribute-align_value-on-lvalue.cpp" in https://reviews.llvm.org/D54590#change-jI44M13yrBNo

[rjmccall]

docs/UndefinedBehaviorSanitizer.rst

199

Are you asking about the LHS of the diff, or about adding an exception to that for this sanitizer?

I'm asking about adding a new exception for one portion of one sanitizer.

I'm adding an exception here because i don't know what should be done here.

Okay, that's not a good enough reason.

The overall rule for annotation-based language/tool designs is that explicit/specific/close wins over implicit/general/distant. So the question is: how does that rule apply here?

You can't end up with a pointer to volatile completely implicitly — at some point, a programmer was explicit about requesting volatile semantics, and that has somehow propagated to this particular access/assumption site. So that's a pretty strong piece of information, and if we have a general rule for the sanitizers that volatile bypasses the check, it's generally a good idea to be consistent with that.

On the other hand, these assumption annotations are themselves always explicit, right? If you have to be explicit about putting align_value on a specific pointer variable, and that pointer just happens to be volatile-qualified, we probably *shouldn't* bypass the check: that's about an explicit, specific, and close as a programmer can get, just short of literally writing it on every access to the variable. The only counter-argument is that maybe the pointer is only volatile-qualified because of template instantiation or something.

So I think it makes sense to enforce it for at least some of these annotations and/or builtin calls, but we should be clear about *why* it makes sense. However, it's possible that I may be misunderstanding part of the motivation behind the general exception for volatile, so you should reach out for input from the UBSan etc. people.

lib/CodeGen/CodeGenFunction.cpp

2511

I see, so the runtime diagnostic can point to the second location if it's known.

The parameter names do not make that clear at all. It should at least be documented, and you should probably change the variable names to be clearer.

[lebedev.ri]

docs/UndefinedBehaviorSanitizer.rst

199

Tried with nullability attributes https://godbolt.org/z/rJUb9U
They do not bypass this "ignore volatile".
So i guess i will drop this exception.

[lebedev.ri]

docs/UndefinedBehaviorSanitizer.rst

199

Whoops, i meant nullable of course, showed the wrong snippet https://godbolt.org/z/DbzKK0

[lebedev.ri]

Address @rjmccall review notes.

[rjmccall]

docs/ReleaseNotes.rst

310

unfinished

docs/UndefinedBehaviorSanitizer.rst

199

Okay, WFM.

lib/CodeGen/CGStmtOpenMP.cpp

1476

Same comment here about SourceLocation().

lib/CodeGen/CodeGenFunction.cpp

2508

typo

[lebedev.ri]

Address @rjmccall review notes.

[rjmccall]

LGTM.

[lebedev.ri]

In D54589#1309929, @rjmccall wrote:

LGTM.

Thank you for the review!

[lebedev.ri]

Rebased, NFC.

[lebedev.ri]

Rebased before commit, NFC.

docs/ReleaseNotes.rst

* The Implicit Conversion Sanitizer (``-fsanitize=implicit-conversion``) group
   hard to track down. This group is **not** enabled by ``-fsanitize=undefined``,
   but the ``-fsanitize=implicit-integer-sign-change`` check
   is enabled by ``-fsanitize=integer``.
   (as is ``-fsanitize=implicit-integer-truncation`` check)
 
 * The Implicit Conversion Sanitizer (``-fsanitize=implicit-conversion``) has
   learned to sanitize compound assignment operators.
 
+* ``alignment`` check has learned to sanitize the assume_aligned-like attributes:
+
+  .. code-block:: c++
+
+      typedef char **__attribute__((align_value(1024))) aligned_char;
+      struct ac_struct {
+        aligned_char a;
+      };
+      char **load_from_ac_struct(struct ac_struct *x) {
+        return x->a; // <- check that loaded 'a' is aligned
+      }
+
+      char **passthrough(__attribute__((align_value(1024))) char **x) {
+        return x; // <- check the
+      }
+
+      char **__attribute__((alloc_align(2)))
+      alloc_align(int size, unsigned long alignment);
+
+      char **caller(int size) {
+        return alloc_align(size, 1024); // <- check returned pointer
+      }
+
+      char **__attribute__((assume_aligned(1024))) get_ptr();
+
+      char **caller2() {
+        return get_ptr(); // <- check returned pointer
+      }
+
+      void *caller3(char **x) {
+        return __builtin_assume_aligned(x, 1024);  // <- check returned pointer
+      }
+
+      void *caller4(char **x, unsigned long offset) {
+        return __builtin_assume_aligned(x, 1024, offset);  // <- check returned pointer accounting for the offest
+      }
+
+      void process(char *data, int width) {
+          #pragma omp for simd aligned(data : 1024) // <- aligned clause will be checked.
+          for (int x = 0; x < width; x++)
+          data[x] *= data[x];
+      }
+
 Core Analysis Improvements
 ==========================
 
 - ...
 
 New Issues Found
 ================
 

docs/UndefinedBehaviorSanitizer.rst

 .. _ubsan-checks:
 
 Available checks
 ================
 
 Available checks are:
 
   -  ``-fsanitize=alignment``: Use of a misaligned pointer or creation
-     of a misaligned reference.
+     of a misaligned reference. Also sanitizes assume_aligned-like attributes.
   -  ``-fsanitize=bool``: Load of a ``bool`` value which is neither
      ``true`` nor ``false``.
   -  ``-fsanitize=builtin``: Passing invalid values to compiler builtins.
   -  ``-fsanitize=bounds``: Out of bounds array indexing, in cases
      where the array bound can be statically determined.
   -  ``-fsanitize=enum``: Load of a value of an enumerated type which
      is not in the range of representable values for that enumerated
      type.
-  ``-fsanitize=nullability``: Enables ``nullability-arg``,
      so UBSan offers to catch it.
 
 Volatile
 --------
 
 The ``null``, ``alignment``, ``object-size``, and ``vptr`` checks do not apply
 to pointers to types with the ``volatile`` qualifier.
 
 Minimal Runtime
 ===============
 
 There is a minimal UBSan runtime available suitable for use in production
 environments. This runtime has a small attack surface. It only provides very
 basic issue logging and deduplication, and does not support ``-fsanitize=vptr``
 checking.
 
 To use the minimal runtime, add ``-fsanitize-minimal-runtime`` to the clang

lib/CodeGen/CGBuiltin.cpp

if (CGM.getCodeGenOpts().OptimizationLevel == 0)
       return RValue::get(ArgValue);
 
     Value *FnExpect = CGM.getIntrinsic(Intrinsic::expect, ArgType);
     Value *Result =
         Builder.CreateCall(FnExpect, {ArgValue, ExpectedValue}, "expval");
     return RValue::get(Result);
   }
   case Builtin::BI__builtin_assume_aligned: {
-    Value *PtrValue = EmitScalarExpr(E->getArg(0));
+    const Expr *Ptr = E->getArg(0);
+    Value *PtrValue = EmitScalarExpr(Ptr);
     Value *OffsetValue =
       (E->getNumArgs() > 2) ? EmitScalarExpr(E->getArg(2)) : nullptr;
 
     Value *AlignmentValue = EmitScalarExpr(E->getArg(1));
     ConstantInt *AlignmentCI = cast<ConstantInt>(AlignmentValue);
-    unsigned Alignment = (unsigned) AlignmentCI->getZExtValue();
+    unsigned Alignment = (unsigned)AlignmentCI->getZExtValue();
 
-    EmitAlignmentAssumption(PtrValue, Alignment, OffsetValue);
+    EmitAlignmentAssumption(PtrValue, Ptr, /*The expr loc is sufficient.*/ SourceLocation(),
+                            Alignment, OffsetValue);
     return RValue::get(PtrValue);
   }
   case Builtin::BI__assume:
   case Builtin::BI__builtin_assume: {
     if (E->getArg(0)->HasSideEffects(getContext()))
       return RValue::get(nullptr);
 
     Value *ArgValue = EmitScalarExpr(E->getArg(0));

lib/CodeGen/CGCall.cpp

case ABIArgInfo::Direct: {
                 !CGM.getCodeGenOpts().NullPointerIsValid)
               AI->addAttr(llvm::Attribute::NonNull);
           }
 
           const auto *AVAttr = PVD->getAttr<AlignValueAttr>();
           if (!AVAttr)
             if (const auto *TOTy = dyn_cast<TypedefType>(OTy))
               AVAttr = TOTy->getDecl()->getAttr<AlignValueAttr>();
-          if (AVAttr) {
+          if (AVAttr && !SanOpts.has(SanitizerKind::Alignment)) {
+            // If alignment-assumption sanitizer is enabled, we do *not* add
+            // alignment attribute here, but emit normal alignment assumption,
+            // so the UBSAN check could function.
             llvm::Value *AlignmentValue =
               EmitScalarExpr(AVAttr->getAlignment());
             llvm::ConstantInt *AlignmentCI =
               cast<llvm::ConstantInt>(AlignmentValue);
             unsigned Alignment = std::min((unsigned)AlignmentCI->getZExtValue(),
                                           +llvm::Value::MaximumAlignment);
             AI->addAttrs(llvm::AttrBuilder().addAlignmentAttr(Alignment));
           }
#endif
   if (Ret.isScalar() && TargetDecl) {
     if (const auto *AA = TargetDecl->getAttr<AssumeAlignedAttr>()) {
       llvm::Value *OffsetValue = nullptr;
       if (const auto *Offset = AA->getOffset())
         OffsetValue = EmitScalarExpr(Offset);
 
       llvm::Value *Alignment = EmitScalarExpr(AA->getAlignment());
       llvm::ConstantInt *AlignmentCI = cast<llvm::ConstantInt>(Alignment);
-      EmitAlignmentAssumption(Ret.getScalarVal(), AlignmentCI->getZExtValue(),
-                              OffsetValue);
+      EmitAlignmentAssumption(Ret.getScalarVal(), RetTy, Loc, AA->getLocation(),
+                              AlignmentCI->getZExtValue(), OffsetValue);
     } else if (const auto *AA = TargetDecl->getAttr<AllocAlignAttr>()) {
-      llvm::Value *ParamVal =
-          CallArgs[AA->getParamIndex().getLLVMIndex()].getRValue(
-              *this).getScalarVal();
-      EmitAlignmentAssumption(Ret.getScalarVal(), ParamVal);
+      llvm::Value *AlignmentVal = CallArgs[AA->getParamIndex().getLLVMIndex()]
+                                      .getRValue(*this)
+                                      .getScalarVal();
+      EmitAlignmentAssumption(Ret.getScalarVal(), RetTy, Loc, AA->getLocation(),
+                              AlignmentVal);
     }
   }
 
   return Ret;
 }
 
 CGCallee CGCallee::prepareConcreteCallee(CodeGenFunction &CGF) const {
   if (isVirtual()) {

lib/CodeGen/CGExprScalar.cpp

if (const auto *DRE = dyn_cast<DeclRefExpr>(E)) {
       const ValueDecl *VD = DRE->getDecl();
 
       if (VD->getType()->isReferenceType()) {
         if (const auto *TTy =
             dyn_cast<TypedefType>(VD->getType().getNonReferenceType()))
           AVAttr = TTy->getDecl()->getAttr<AlignValueAttr>();
       } else {
         // Assumptions for function parameters are emitted at the start of the
-        // function, so there is no need to repeat that here.
-        if (isa<ParmVarDecl>(VD))
+        // function, so there is no need to repeat that here,
+        // unless the alignment-assumption sanitizer is enabled,
+        // then we prefer the assumption over alignment attribute
+        // on IR function param.
+        if (isa<ParmVarDecl>(VD) && !CGF.SanOpts.has(SanitizerKind::Alignment))
           return;
 
         AVAttr = VD->getAttr<AlignValueAttr>();
       }
     }
 
     if (!AVAttr)
       if (const auto *TTy =
           dyn_cast<TypedefType>(E->getType()))
         AVAttr = TTy->getDecl()->getAttr<AlignValueAttr>();
 
     if (!AVAttr)
       return;
 
     Value *AlignmentValue = CGF.EmitScalarExpr(AVAttr->getAlignment());
     llvm::ConstantInt *AlignmentCI = cast<llvm::ConstantInt>(AlignmentValue);
-    CGF.EmitAlignmentAssumption(V, AlignmentCI->getZExtValue());
+    CGF.EmitAlignmentAssumption(V, E, AVAttr->getLocation(),
+                                AlignmentCI->getZExtValue());
   }
 
   /// EmitLoadOfLValue - Given an expression with complex type that represents a
   /// value l-value, this method emits the address of the l-value, then loads
   /// and returns the result.
   Value *EmitLoadOfLValue(const Expr *E) {
     Value *V = EmitLoadOfLValue(EmitCheckedLValue(E, CodeGenFunction::TCK_Load),
                                 E->getExprLoc());

lib/CodeGen/CGStmtOpenMP.cpp

for (const Expr *E : Clause->varlists()) {
                 .toCharUnitsFromBits(CGF.getContext().getOpenMPDefaultSimdAlign(
                     E->getType()->getPointeeType()))
                 .getQuantity();
       }
       assert((Alignment == 0 || llvm::isPowerOf2_32(Alignment)) &&
              "alignment is not power of 2");
       if (Alignment != 0) {
         llvm::Value *PtrValue = CGF.EmitScalarExpr(E);
-        CGF.EmitAlignmentAssumption(PtrValue, Alignment);
+        CGF.EmitAlignmentAssumption(PtrValue, E, {/*No second loc needed*/},
+                                    Alignment);
       }
     }
   }
 }
 
 void CodeGenFunction::EmitOMPPrivateLoopCounters(
     const OMPLoopDirective &S, CodeGenFunction::OMPPrivateScope &LoopScope) {
   if (!HaveInsertPoint())

lib/CodeGen/CodeGenFunction.h

#define LIST_SANITIZER_CHECKS                                                  \
   SANITIZER_CHECK(NullabilityReturn, nullability_return, 1)                    \
   SANITIZER_CHECK(NonnullArg, nonnull_arg, 0)                                  \
   SANITIZER_CHECK(NonnullReturn, nonnull_return, 1)                            \
   SANITIZER_CHECK(OutOfBounds, out_of_bounds, 0)                               \
   SANITIZER_CHECK(PointerOverflow, pointer_overflow, 0)                        \
   SANITIZER_CHECK(ShiftOutOfBounds, shift_out_of_bounds, 0)                    \
   SANITIZER_CHECK(SubOverflow, sub_overflow, 0)                                \
   SANITIZER_CHECK(TypeMismatch, type_mismatch, 1)                              \
+  SANITIZER_CHECK(AlignmentAssumption, alignment_assumption, 0)                \
   SANITIZER_CHECK(VLABoundNotPositive, vla_bound_not_positive, 0)
 
 enum SanitizerHandler {
 #define SANITIZER_CHECK(Enum, Name, Version) Enum,
   LIST_SANITIZER_CHECKS
 #undef SANITIZER_CHECK
 };
 

   void EmitBoundsCheck(const Expr *E, const Expr *Base, llvm::Value *Index,
                        QualType IndexType, bool Accessed);
 
   llvm::Value *EmitScalarPrePostIncDec(const UnaryOperator *E, LValue LV,
                                        bool isInc, bool isPre);
   ComplexPairTy EmitComplexPrePostIncDec(const UnaryOperator *E, LValue LV,
                                          bool isInc, bool isPre);
 
-  void EmitAlignmentAssumption(llvm::Value *PtrValue, unsigned Alignment,
-                               llvm::Value *OffsetValue = nullptr) {
-    Builder.CreateAlignmentAssumption(CGM.getDataLayout(), PtrValue, Alignment,
-                                      OffsetValue);
-  }
-
   /// Converts Location to a DebugLoc, if debug information is enabled.
   llvm::DebugLoc SourceLocToDebugLoc(SourceLocation Location);
 
 
   //===--------------------------------------------------------------------===//
   //                            Declaration Emission
   //===--------------------------------------------------------------------===//
 

   /// Pass the result to unprotectFromPeepholes to declare that
   /// protection is no longer required.
   ///
   /// There's no particular reason why this shouldn't apply to
   /// l-values, it's just that no existing peepholes work on pointers.
   PeepholeProtection protectFromPeepholes(RValue rvalue);
   void unprotectFromPeepholes(PeepholeProtection protection);
 
-  void EmitAlignmentAssumption(llvm::Value *PtrValue, llvm::Value *Alignment,
-                               llvm::Value *OffsetValue = nullptr) {
-    Builder.CreateAlignmentAssumption(CGM.getDataLayout(), PtrValue, Alignment,
-                                      OffsetValue);
-  }
+  void EmitAlignmentAssumptionCheck(llvm::Value *Ptr, QualType Ty,
+                                    SourceLocation Loc,
+                                    SourceLocation AssumptionLoc,
+                                    llvm::Value *Alignment,
+                                    llvm::Value *OffsetValue,
+                                    llvm::Value *TheCheck,
+                                    llvm::Instruction *Assumption);
+
+  void EmitAlignmentAssumption(llvm::Value *PtrValue, QualType Ty,
+                               SourceLocation Loc, SourceLocation AssumptionLoc,
+                               llvm::Value *Alignment,
+                               llvm::Value *OffsetValue = nullptr);
+
+  void EmitAlignmentAssumption(llvm::Value *PtrValue, QualType Ty,
+                               SourceLocation Loc, SourceLocation AssumptionLoc,
+                               unsigned Alignment,
+                               llvm::Value *OffsetValue = nullptr);
+
+  void EmitAlignmentAssumption(llvm::Value *PtrValue, const Expr *E,
+                               SourceLocation AssumptionLoc, unsigned Alignment,
+                               llvm::Value *OffsetValue = nullptr);
 
   //===--------------------------------------------------------------------===//
   //                             Statement Emission
   //===--------------------------------------------------------------------===//
 
   /// EmitStopPoint - Emit a debug stoppoint if we are emitting debug info.
   void EmitStopPoint(const Stmt *S);
 
   /// EmitStmt - Emit the code for the statement \arg S. It is legal to call
   /// this function even if there is no current insertion point.
   ///
   /// This function may clear the current insertion point; callers should use
   /// EnsureInsertPoint if they wish to subsequently generate code without first
   /// calling EmitBlock, EmitBranch, or EmitStmt.
   void EmitStmt(const Stmt *S, ArrayRef<const Attr *> Attrs = None);

lib/CodeGen/CodeGenFunction.cpp

 
 void CodeGenFunction::unprotectFromPeepholes(PeepholeProtection protection) {
   if (!protection.Inst) return;
 
   // In theory, we could try to duplicate the peepholes now, but whatever.
   protection.Inst->eraseFromParent();
 }
 
+void CodeGenFunction::EmitAlignmentAssumption(llvm::Value *PtrValue,
+                                              QualType Ty, SourceLocation Loc,
+                                              SourceLocation AssumptionLoc,
+                                              llvm::Value *Alignment,
+                                              llvm::Value *OffsetValue) {
+  llvm::Value *TheCheck;
+  llvm::Instruction *Assumption = Builder.CreateAlignmentAssumption(
+      CGM.getDataLayout(), PtrValue, Alignment, OffsetValue, &TheCheck);
+  if (SanOpts.has(SanitizerKind::Alignment)) {
+    EmitAlignmentAssumptionCheck(PtrValue, Ty, Loc, AssumptionLoc, Alignment,
+                                 OffsetValue, TheCheck, Assumption);
+  }
+}
+
+void CodeGenFunction::EmitAlignmentAssumption(llvm::Value *PtrValue,
+                                              QualType Ty, SourceLocation Loc,
+                                              SourceLocation AssumptionLoc,
+                                              unsigned Alignment,
+                                              llvm::Value *OffsetValue) {
+  llvm::Value *TheCheck;
+  llvm::Instruction *Assumption = Builder.CreateAlignmentAssumption(
+      CGM.getDataLayout(), PtrValue, Alignment, OffsetValue, &TheCheck);
+  if (SanOpts.has(SanitizerKind::Alignment)) {
+    llvm::Value *AlignmentVal = llvm::ConstantInt::get(IntPtrTy, Alignment);
+    EmitAlignmentAssumptionCheck(PtrValue, Ty, Loc, AssumptionLoc, AlignmentVal,
+                                 OffsetValue, TheCheck, Assumption);
+  }
+}
+
+void CodeGenFunction::EmitAlignmentAssumption(llvm::Value *PtrValue,
+                                              const Expr *E,
+                                              SourceLocation AssumptionLoc,
+                                              unsigned Alignment,
+                                              llvm::Value *OffsetValue) {
+  if (auto *CE = dyn_cast<CastExpr>(E))
+    E = CE->getSubExprAsWritten();
+  QualType Ty = E->getType();
+  SourceLocation Loc = E->getExprLoc();
+
+  EmitAlignmentAssumption(PtrValue, Ty, Loc, AssumptionLoc, Alignment,
+                          OffsetValue);
+}
+
 llvm::Value *CodeGenFunction::EmitAnnotationCall(llvm::Value *AnnotationFn,
                                                  llvm::Value *AnnotatedVal,
                                                  StringRef AnnotationStr,
                                                  SourceLocation Location) {
   llvm::Value *Args[4] = {
     AnnotatedVal,
     Builder.CreateBitCast(CGM.EmitAnnotationString(AnnotationStr), Int8PtrTy),
     Builder.CreateBitCast(CGM.EmitAnnotationUnit(Location), Int8PtrTy),
void CodeGenFunction::EmitMultiVersionResolver(
   Builder.SetInsertPoint(CurBlock);
   llvm::CallInst *TrapCall = EmitTrapCall(llvm::Intrinsic::trap);
   TrapCall->setDoesNotReturn();
   TrapCall->setDoesNotThrow();
   Builder.CreateUnreachable();
   Builder.ClearInsertionPoint();
 }
 
+// Loc - where the diagnostic will point, where in the source code this
+//  alignemnt has failed.
+// SecondaryLoc - if present (will be present if sufficiently different from
+//  Loc), the diagnostic will additionally point a "Note:" to this location.
+//  It should be the location where the __attribute__((assume_aligned))
+//  was written e.g.
+void CodeGenFunction::EmitAlignmentAssumptionCheck(
+    llvm::Value *Ptr, QualType Ty, SourceLocation Loc,
+    SourceLocation SecondaryLoc, llvm::Value *Alignment,
+    llvm::Value *OffsetValue, llvm::Value *TheCheck,
+    llvm::Instruction *Assumption) {
+  assert(Assumption && isa<llvm::CallInst>(Assumption) &&
+         cast<llvm::CallInst>(Assumption)->getCalledValue() ==
+             llvm::Intrinsic::getDeclaration(
+                 Builder.GetInsertBlock()->getParent()->getParent(),
+                 llvm::Intrinsic::assume) &&
+         "Assumption should be a call to llvm.assume().");
+  assert(&(Builder.GetInsertBlock()->back()) == Assumption &&
+         "Assumption should be the last instruction of the basic block, "
+         "since the basic block is still being generated.");
+
+  if (!SanOpts.has(SanitizerKind::Alignment))
+    return;
+
+  // Don't check pointers to volatile data. The behavior here is implementation-
+  // defined.
+  if (Ty->getPointeeType().isVolatileQualified())
+    return;
+
+  // We need to temorairly remove the assumption so we can insert the
+  // sanitizer check before it, else the check will be dropped by optimizations.
+  Assumption->removeFromParent();
+
+  {
+    SanitizerScope SanScope(this);
+
+    if (!OffsetValue)
+      OffsetValue = Builder.getInt1(0); // no offset.
+
+    llvm::Constant *StaticData[] = {EmitCheckSourceLocation(Loc),
+                                    EmitCheckSourceLocation(SecondaryLoc),
+                                    EmitCheckTypeDescriptor(Ty)};
+    llvm::Value *DynamicData[] = {EmitCheckValue(Ptr),
+                                  EmitCheckValue(Alignment),
+                                  EmitCheckValue(OffsetValue)};
+    EmitCheck({std::make_pair(TheCheck, SanitizerKind::Alignment)},
+              SanitizerHandler::AlignmentAssumption, StaticData, DynamicData);
+  }
+
+  // We are now in the (new, empty) "cont" basic block.
+  // Reintroduce the assumption.
+  Builder.Insert(Assumption);
+  // FIXME: Assumption still has it's original basic block as it's Parent.
+}
+
 llvm::DebugLoc CodeGenFunction::SourceLocToDebugLoc(SourceLocation Location) {
   if (CGDebugInfo *DI = getDebugInfo())
     return DI->SourceLocToDebugLoc(Location);
 
   return llvm::DebugLoc();
 }

test/CodeGen/catch-alignment-assumption-attribute-align_value-on-lvalue.cpp

+// RUN: %clang_cc1 -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s --check-prefixes=CHECK,CHECK-NOSANITIZE
+// RUN: %clang_cc1 -fsanitize=alignment -fno-sanitize-recover=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-ANYRECOVER,CHECK-SANITIZE-NORECOVER,CHECK-SANITIZE-UNREACHABLE
+// RUN: %clang_cc1 -fsanitize=alignment -fsanitize-recover=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-ANYRECOVER,CHECK-SANITIZE-RECOVER
+// RUN: %clang_cc1 -fsanitize=alignment -fsanitize-trap=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-TRAP,CHECK-SANITIZE-UNREACHABLE
+
+typedef char **__attribute__((align_value(0x80000000))) aligned_char;
+
+struct ac_struct {
+  // CHECK:  %[[STRUCT_AC_STRUCT:.*]] = type { i8** }
+  aligned_char a;
+};
+
+// CHECK-SANITIZE-ANYRECOVER: @[[ALIGNED_CHAR:.*]] = {{.*}} c"'aligned_char' (aka 'char **')\00" }
+// CHECK-SANITIZE-ANYRECOVER: @[[LINE_100_ALIGNMENT_ASSUMPTION:.*]] = {{.*}}, i32 100, i32 13 }, {{.*}}* @[[ALIGNED_CHAR]] }
+
+char **load_from_ac_struct(struct ac_struct *x) {
+  // CHECK:                           define i8** @{{.*}}(%[[STRUCT_AC_STRUCT]]* %[[X:.*]])
+  // CHECK-NEXT:                      [[ENTRY:.*]]:
+  // CHECK-NEXT:                        %[[STRUCT_AC_STRUCT_ADDR:.*]] = alloca %[[STRUCT_AC_STRUCT]]*, align 8
+  // CHECK-NEXT:                        store %[[STRUCT_AC_STRUCT]]* %[[X]], %[[STRUCT_AC_STRUCT]]** %[[STRUCT_AC_STRUCT_ADDR]], align 8
+  // CHECK-NEXT:                        %[[X_RELOADED:.*]] = load %[[STRUCT_AC_STRUCT]]*, %[[STRUCT_AC_STRUCT]]** %[[STRUCT_AC_STRUCT_ADDR]], align 8
+  // CHECK:                             %[[A_ADDR:.*]] = getelementptr inbounds %[[STRUCT_AC_STRUCT]], %[[STRUCT_AC_STRUCT]]* %[[X_RELOADED]], i32 0, i32 0
+  // CHECK:                             %[[A:.*]] = load i8**, i8*** %[[A_ADDR]], align 8
+  // CHECK-NEXT:                        %[[PTRINT:.*]] = ptrtoint i8** %[[A]] to i64
+  // CHECK-NEXT:                        %[[MASKEDPTR:.*]] = and i64 %[[PTRINT]], 2147483647
+  // CHECK-NEXT:                        %[[MASKCOND:.*]] = icmp eq i64 %[[MASKEDPTR]], 0
+  // CHECK-SANITIZE-NEXT:               %[[PTRINT_DUP:.*]] = ptrtoint i8** %[[A]] to i64, !nosanitize
+  // CHECK-SANITIZE-NEXT:               br i1 %[[MASKCOND]], label %[[CONT:.*]], label %[[HANDLER_ALIGNMENT_ASSUMPTION:[^,]+]],{{.*}} !nosanitize
+  // CHECK-SANITIZE:                  [[HANDLER_ALIGNMENT_ASSUMPTION]]:
+  // CHECK-SANITIZE-NORECOVER-NEXT:     call void @__ubsan_handle_alignment_assumption_abort(i8* bitcast ({ {{{.*}}}, {{{.*}}}, {{{.*}}}* }* @[[LINE_100_ALIGNMENT_ASSUMPTION]] to i8*), i64 %[[PTRINT_DUP]], i64 2147483648, i64 0){{.*}}, !nosanitize
+  // CHECK-SANITIZE-RECOVER-NEXT:       call void @__ubsan_handle_alignment_assumption(i8* bitcast ({ {{{.*}}}, {{{.*}}}, {{{.*}}}* }* @[[LINE_100_ALIGNMENT_ASSUMPTION]] to i8*), i64 %[[PTRINT_DUP]], i64 2147483648, i64 0){{.*}}, !nosanitize
+  // CHECK-SANITIZE-TRAP-NEXT:          call void @llvm.trap(){{.*}}, !nosanitize
+  // CHECK-SANITIZE-UNREACHABLE-NEXT:   unreachable, !nosanitize
+  // CHECK-SANITIZE:                  [[CONT]]:
+  // CHECK-NEXT:                        call void @llvm.assume(i1 %[[MASKCOND]])
+  // CHECK-NEXT:                        ret i8** %[[A]]
+  // CHECK-NEXT:                      }
+#line 100
+  return x->a;
+}

test/CodeGen/catch-alignment-assumption-attribute-align_value-on-paramvar.cpp

+// RUN: %clang_cc1 -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s --check-prefixes=CHECK,CHECK-NOSANITIZE
+// RUN: %clang_cc1 -fsanitize=alignment -fno-sanitize-recover=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-ANYRECOVER,CHECK-SANITIZE-NORECOVER,CHECK-SANITIZE-UNREACHABLE
+// RUN: %clang_cc1 -fsanitize=alignment -fsanitize-recover=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-ANYRECOVER,CHECK-SANITIZE-RECOVER
+// RUN: %clang_cc1 -fsanitize=alignment -fsanitize-trap=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-TRAP,CHECK-SANITIZE-UNREACHABLE
+
+// CHECK-SANITIZE-ANYRECOVER: @[[CHAR:.*]] = {{.*}} c"'char **'\00" }
+// CHECK-SANITIZE-ANYRECOVER: @[[LINE_100_ALIGNMENT_ASSUMPTION:.*]] = {{.*}}, i32 100, i32 10 }, {{.*}}* @[[CHAR]] }
+
+char **passthrough(__attribute__((align_value(0x80000000))) char **x) {
+  // CHECK-NOSANITIZE:                define i8** @{{.*}}(i8** align 536870912 %[[X:.*]])
+  // CHECK-SANITIZE:                  define i8** @{{.*}}(i8** %[[X:.*]])
+  // CHECK-NEXT:                      [[entry:.*]]:
+  // CHECK-NEXT:                        %[[X_ADDR:.*]] = alloca i8**, align 8
+  // CHECK-NEXT:                        store i8** %[[X]], i8*** %[[X_ADDR]], align 8
+  // CHECK-NEXT:                        %[[X_RELOADED:.*]] = load i8**, i8*** %[[X_ADDR]], align 8
+  // CHECK-SANITIZE-NEXT:               %[[PTRINT:.*]] = ptrtoint i8** %[[X_RELOADED]] to i64
+  // CHECK-SANITIZE-NEXT:               %[[MASKEDPTR:.*]] = and i64 %[[PTRINT]], 2147483647
+  // CHECK-SANITIZE-NEXT:               %[[MASKCOND:.*]] = icmp eq i64 %[[MASKEDPTR]], 0
+  // CHECK-SANITIZE-NEXT:               %[[PTRINT_DUP:.*]] = ptrtoint i8** %[[X_RELOADED]] to i64, !nosanitize
+  // CHECK-SANITIZE-NEXT:               br i1 %[[MASKCOND]], label %[[CONT:.*]], label %[[HANDLER_ALIGNMENT_ASSUMPTION:[^,]+]],{{.*}} !nosanitize
+  // CHECK-SANITIZE:                  [[HANDLER_ALIGNMENT_ASSUMPTION]]:
+  // CHECK-SANITIZE-NORECOVER-NEXT:     call void @__ubsan_handle_alignment_assumption_abort(i8* bitcast ({ {{{.*}}}, {{{.*}}}, {{{.*}}}* }* @[[LINE_100_ALIGNMENT_ASSUMPTION]] to i8*), i64 %[[PTRINT_DUP]], i64 2147483648, i64 0){{.*}}, !nosanitize
+  // CHECK-SANITIZE-RECOVER-NEXT:       call void @__ubsan_handle_alignment_assumption(i8* bitcast ({ {{{.*}}}, {{{.*}}}, {{{.*}}}* }* @[[LINE_100_ALIGNMENT_ASSUMPTION]] to i8*), i64 %[[PTRINT_DUP]], i64 2147483648, i64 0){{.*}}, !nosanitize
+  // CHECK-SANITIZE-TRAP-NEXT:          call void @llvm.trap(){{.*}}, !nosanitize
+  // CHECK-SANITIZE-UNREACHABLE-NEXT:   unreachable, !nosanitize
+  // CHECK-SANITIZE:                  [[CONT]]:
+  // CHECK-SANITIZE-NEXT:               call void @llvm.assume(i1 %[[MASKCOND]])
+  // CHECK-NEXT:                        ret i8** %[[X_RELOADED]]
+  // CHECK-NEXT:                      }
+#line 100
+  return x;
+}

test/CodeGen/catch-alignment-assumption-attribute-alloc_align-on-function-variable.cpp

+// RUN: %clang_cc1 -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s --check-prefixes=CHECK,CHECK-NOSANITIZE
+// RUN: %clang_cc1 -fsanitize=alignment -fno-sanitize-recover=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-ANYRECOVER,CHECK-SANITIZE-NORECOVER,CHECK-SANITIZE-UNREACHABLE
+// RUN: %clang_cc1 -fsanitize=alignment -fsanitize-recover=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-ANYRECOVER,CHECK-SANITIZE-RECOVER
+// RUN: %clang_cc1 -fsanitize=alignment -fsanitize-trap=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-TRAP,CHECK-SANITIZE-UNREACHABLE
+
+// CHECK-SANITIZE-ANYRECOVER: @[[CHAR:.*]] = {{.*}} c"'char **'\00" }
+// CHECK-SANITIZE-ANYRECOVER: @[[LINE_100_ALIGNMENT_ASSUMPTION:.*]] = {{.*}}, i32 100, i32 10 }, {{.*}}* @[[CHAR]] }
+
+char **__attribute__((alloc_align(2)))
+passthrough(char **x, unsigned long alignment) {
+  // CHECK:      define i8** @[[PASSTHROUGH:.*]](i8** %[[X:.*]], i64 %[[ALIGNMENT:.*]])
+  // CHECK-NEXT: entry:
+  // CHECK-NEXT:   %[[X_ADDR:.*]] = alloca i8**, align 8
+  // CHECK-NEXT:   %[[ALIGNMENT_ADDR:.*]] = alloca i64, align 8
+  // CHECK-NEXT:   store i8** %[[X]], i8*** %[[X_ADDR]], align 8
+  // CHECK-NEXT:   store i64 %[[ALIGNMENT]], i64* %[[ALIGNMENT_ADDR]], align 8
+  // CHECK-NEXT:   %[[X_RELOADED:.*]] = load i8**, i8*** %[[X_ADDR]], align 8
+  // CHECK-NEXT:   ret i8** %[[X_RELOADED]]
+  // CHECK-NEXT: }
+  return x;
+}
+
+char **caller(char **x, unsigned long alignment) {
+  // CHECK:                           define i8** @{{.*}}(i8** %[[X:.*]], i64 %[[ALIGNMENT:.*]])
+  // CHECK-NEXT:                      entry:
+  // CHECK-NEXT:                        %[[X_ADDR:.*]] = alloca i8**, align 8
+  // CHECK-NEXT:                        %[[ALIGNMENT_ADDR:.*]] = alloca i64, align 8
+  // CHECK-NEXT:                        store i8** %[[X]], i8*** %[[X_ADDR]], align 8
+  // CHECK-NEXT:                        store i64 %[[ALIGNMENT]], i64* %[[ALIGNMENT_ADDR]], align 8
+  // CHECK-NEXT:                        %[[X_RELOADED:.*]] = load i8**, i8*** %[[X_ADDR]], align 8
+  // CHECK-NEXT:                        %[[ALIGNMENT_RELOADED:.*]] = load i64, i64* %[[ALIGNMENT_ADDR]], align 8
+  // CHECK-NEXT:                        %[[X_RETURNED:.*]] = call i8** @[[PASSTHROUGH]](i8** %[[X_RELOADED]], i64 %[[ALIGNMENT_RELOADED]])
+  // CHECK-NEXT:                        %[[ISPOSITIVE:.*]] = icmp sgt i64 %[[ALIGNMENT_RELOADED]], 0
+  // CHECK-NEXT:                        %[[POSITIVEMASK:.*]] = sub i64 %[[ALIGNMENT_RELOADED]], 1
+  // CHECK-NEXT:                        %[[MASK:.*]] = select i1 %[[ISPOSITIVE]], i64 %[[POSITIVEMASK]], i64 0
+  // CHECK-NEXT:                        %[[PTRINT:.*]] = ptrtoint i8** %[[X_RETURNED]] to i64
+  // CHECK-NEXT:                        %[[MASKEDPTR:.*]] = and i64 %[[PTRINT]], %[[MASK]]
+  // CHECK-NEXT:                        %[[MASKCOND:.*]] = icmp eq i64 %[[MASKEDPTR]], 0
+  // CHECK-SANITIZE-NEXT:               %[[PTRINT_DUP:.*]] = ptrtoint i8** %[[X_RETURNED]] to i64, !nosanitize
+  // CHECK-SANITIZE-NEXT:               br i1 %[[MASKCOND]], label %[[CONT:.*]], label %[[HANDLER_ALIGNMENT_ASSUMPTION:[^,]+]],{{.*}} !nosanitize
+  // CHECK-SANITIZE:                  [[HANDLER_ALIGNMENT_ASSUMPTION]]:
+  // CHECK-SANITIZE-NORECOVER-NEXT:     call void @__ubsan_handle_alignment_assumption_abort(i8* bitcast ({ {{{.*}}}, {{{.*}}}, {{{.*}}}* }* @[[LINE_100_ALIGNMENT_ASSUMPTION]] to i8*), i64 %[[PTRINT_DUP]], i64 %[[ALIGNMENT_RELOADED]], i64 0){{.*}}, !nosanitize
+  // CHECK-SANITIZE-RECOVER-NEXT:       call void @__ubsan_handle_alignment_assumption(i8* bitcast ({ {{{.*}}}, {{{.*}}}, {{{.*}}}* }* @[[LINE_100_ALIGNMENT_ASSUMPTION]] to i8*), i64 %[[PTRINT_DUP]], i64 %[[ALIGNMENT_RELOADED]], i64 0){{.*}}, !nosanitize
+  // CHECK-SANITIZE-TRAP-NEXT:          call void @llvm.trap(){{.*}}, !nosanitize
+  // CHECK-SANITIZE-UNREACHABLE-NEXT:   unreachable, !nosanitize
+  // CHECK-SANITIZE:                  [[CONT]]:
+  // CHECK-NEXT:                        call void @llvm.assume(i1 %[[MASKCOND]])
+  // CHECK-NEXT:                        ret i8** %[[X_RETURNED]]
+  // CHECK-NEXT:                      }
+#line 100
+  return passthrough(x, alignment);
+}

test/CodeGen/catch-alignment-assumption-attribute-alloc_align-on-function.cpp

+// RUN: %clang_cc1 -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s --check-prefixes=CHECK,CHECK-NOSANITIZE
+// RUN: %clang_cc1 -fsanitize=alignment -fno-sanitize-recover=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-ANYRECOVER,CHECK-SANITIZE-NORECOVER,CHECK-SANITIZE-UNREACHABLE
+// RUN: %clang_cc1 -fsanitize=alignment -fsanitize-recover=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-ANYRECOVER,CHECK-SANITIZE-RECOVER
+// RUN: %clang_cc1 -fsanitize=alignment -fsanitize-trap=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-TRAP,CHECK-SANITIZE-UNREACHABLE
+
+// CHECK-SANITIZE-ANYRECOVER: @[[CHAR:.*]] = {{.*}} c"'char **'\00" }
+// CHECK-SANITIZE-ANYRECOVER: @[[LINE_100_ALIGNMENT_ASSUMPTION:.*]] = {{.*}}, i32 100, i32 10 }, {{.*}}* @[[CHAR]] }
+
+char **__attribute__((alloc_align(2)))
+passthrough(char **x, unsigned long alignment) {
+  // CHECK:      define i8** @[[PASSTHROUGH:.*]](i8** %[[X:.*]], i64 %[[ALIGNMENT:.*]])
+  // CHECK-NEXT: entry:
+  // CHECK-NEXT:   %[[X_ADDR:.*]] = alloca i8**, align 8
+  // CHECK-NEXT:   %[[ALIGNMENT_ADDR:.*]] = alloca i64, align 8
+  // CHECK-NEXT:   store i8** %[[X]], i8*** %[[X_ADDR]], align 8
+  // CHECK-NEXT:   store i64 %[[ALIGNMENT]], i64* %[[ALIGNMENT_ADDR]], align 8
+  // CHECK-NEXT:   %[[X_RELOADED:.*]] = load i8**, i8*** %[[X_ADDR]], align 8
+  // CHECK-NEXT:   ret i8** %[[X_RELOADED]]
+  // CHECK-NEXT: }
+  return x;
+}
+
+char **caller(char **x) {
+  // CHECK:                           define i8** @{{.*}}(i8** %[[X:.*]])
+  // CHECK-NEXT:                      entry:
+  // CHECK-NEXT:                        %[[X_ADDR:.*]] = alloca i8**, align 8
+  // CHECK-NEXT:                        store i8** %[[X]], i8*** %[[X_ADDR]], align 8
+  // CHECK-NEXT:                        %[[X_RELOADED:.*]] = load i8**, i8*** %[[X_ADDR]], align 8
+  // CHECK-NEXT:                        %[[X_RETURNED:.*]] = call i8** @[[PASSTHROUGH]](i8** %[[X_RELOADED]], i64 2147483648)
+  // CHECK-NEXT:                        %[[PTRINT:.*]] = ptrtoint i8** %[[X_RETURNED]] to i64
+  // CHECK-NEXT:                        %[[MASKEDPTR:.*]] = and i64 %[[PTRINT]], 2147483647
+  // CHECK-NEXT:                        %[[MASKCOND:.*]] = icmp eq i64 %[[MASKEDPTR]], 0
+  // CHECK-SANITIZE-NEXT:               %[[PTRINT_DUP:.*]] = ptrtoint i8** %[[X_RETURNED]] to i64, !nosanitize
+  // CHECK-SANITIZE-NEXT:               br i1 %[[MASKCOND]], label %[[CONT:.*]], label %[[HANDLER_ALIGNMENT_ASSUMPTION:[^,]+]],{{.*}} !nosanitize
+  // CHECK-SANITIZE:                  [[HANDLER_ALIGNMENT_ASSUMPTION]]:
+  // CHECK-SANITIZE-NORECOVER-NEXT:     call void @__ubsan_handle_alignment_assumption_abort(i8* bitcast ({ {{{.*}}}, {{{.*}}}, {{{.*}}}* }* @[[LINE_100_ALIGNMENT_ASSUMPTION]] to i8*), i64 %[[PTRINT_DUP]], i64 2147483648, i64 0){{.*}}, !nosanitize
+  // CHECK-SANITIZE-RECOVER-NEXT:       call void @__ubsan_handle_alignment_assumption(i8* bitcast ({ {{{.*}}}, {{{.*}}}, {{{.*}}}* }* @[[LINE_100_ALIGNMENT_ASSUMPTION]] to i8*), i64 %[[PTRINT_DUP]], i64 2147483648, i64 0){{.*}}, !nosanitize
+  // CHECK-SANITIZE-TRAP-NEXT:          call void @llvm.trap(){{.*}}, !nosanitize
+  // CHECK-SANITIZE-UNREACHABLE-NEXT:   unreachable, !nosanitize
+  // CHECK-SANITIZE:                  [[CONT]]:
+  // CHECK-NEXT:                        call void @llvm.assume(i1 %[[MASKCOND]])
+  // CHECK-NEXT:                        ret i8** %[[X_RETURNED]]
+  // CHECK-NEXT:                      }
+#line 100
+  return passthrough(x, 0x80000000);
+}

test/CodeGen/catch-alignment-assumption-attribute-assume_aligned-on-function-two-params.cpp

+// RUN: %clang_cc1 -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s --check-prefixes=CHECK,CHECK-NOSANITIZE
+// RUN: %clang_cc1 -fsanitize=alignment -fno-sanitize-recover=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-ANYRECOVER,CHECK-SANITIZE-NORECOVER,CHECK-SANITIZE-UNREACHABLE
+// RUN: %clang_cc1 -fsanitize=alignment -fsanitize-recover=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-ANYRECOVER,CHECK-SANITIZE-RECOVER
+// RUN: %clang_cc1 -fsanitize=alignment -fsanitize-trap=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-TRAP,CHECK-SANITIZE-UNREACHABLE
+
+// CHECK-SANITIZE-ANYRECOVER: @[[CHAR:.*]] = {{.*}} c"'char **'\00" }
+// CHECK-SANITIZE-ANYRECOVER: @[[LINE_100_ALIGNMENT_ASSUMPTION:.*]] = {{.*}}, i32 100, i32 10 }, {{.*}}* @[[CHAR]] }
+
+char **__attribute__((assume_aligned(0x80000000, 42))) passthrough(char **x) {
+  // CHECK:      define i8** @[[PASSTHROUGH:.*]](i8** %[[X:.*]])
+  // CHECK-NEXT: entry:
+  // CHECK-NEXT:   %[[X_ADDR:.*]] = alloca i8**, align 8
+  // CHECK-NEXT:   store i8** %[[X]], i8*** %[[X_ADDR]], align 8
+  // CHECK-NEXT:   %[[X_RELOADED:.*]] = load i8**, i8*** %[[X_ADDR]], align 8
+  // CHECK-NEXT:   ret i8** %[[X_RELOADED]]
+  // CHECK-NEXT: }
+  return x;
+}
+
+char **caller(char **x) {
+  // CHECK:                           define i8** @{{.*}}(i8** %[[X:.*]])
+  // CHECK-NEXT:                      entry:
+  // CHECK-NEXT:                        %[[X_ADDR:.*]] = alloca i8**, align 8
+  // CHECK-NEXT:                        store i8** %[[X]], i8*** %[[X_ADDR]], align 8
+  // CHECK-NEXT:                        %[[X_RELOADED:.*]] = load i8**, i8*** %[[X_ADDR]], align 8
+  // CHECK-NEXT:                        %[[X_RETURNED:.*]] = call i8** @[[PASSTHROUGH]](i8** %[[X_RELOADED]])
+  // CHECK-NEXT:                        %[[PTRINT:.*]] = ptrtoint i8** %[[X_RETURNED]] to i64
+  // CHECK-NEXT:                        %[[OFFSETPTR:.*]] = sub i64 %[[PTRINT]], 42
+  // CHECK-NEXT:                        %[[MASKEDPTR:.*]] = and i64 %[[OFFSETPTR]], 2147483647
+  // CHECK-NEXT:                        %[[MASKCOND:.*]] = icmp eq i64 %[[MASKEDPTR]], 0
+  // CHECK-SANITIZE-NEXT:               %[[PTRINT_DUP:.*]] = ptrtoint i8** %[[X_RETURNED]] to i64, !nosanitize
+  // CHECK-SANITIZE-NEXT:               br i1 %[[MASKCOND]], label %[[CONT:.*]], label %[[HANDLER_ALIGNMENT_ASSUMPTION:[^,]+]],{{.*}} !nosanitize
+  // CHECK-SANITIZE:                  [[HANDLER_ALIGNMENT_ASSUMPTION]]:
+  // CHECK-SANITIZE-NORECOVER-NEXT:     call void @__ubsan_handle_alignment_assumption_abort(i8* bitcast ({ {{{.*}}}, {{{.*}}}, {{{.*}}}* }* @[[LINE_100_ALIGNMENT_ASSUMPTION]] to i8*), i64 %[[PTRINT_DUP]], i64 2147483648, i64 42){{.*}}, !nosanitize
+  // CHECK-SANITIZE-RECOVER-NEXT:       call void @__ubsan_handle_alignment_assumption(i8* bitcast ({ {{{.*}}}, {{{.*}}}, {{{.*}}}* }* @[[LINE_100_ALIGNMENT_ASSUMPTION]] to i8*), i64 %[[PTRINT_DUP]], i64 2147483648, i64 42){{.*}}, !nosanitize
+  // CHECK-SANITIZE-TRAP-NEXT:          call void @llvm.trap(){{.*}}, !nosanitize
+  // CHECK-SANITIZE-UNREACHABLE-NEXT:   unreachable, !nosanitize
+  // CHECK-SANITIZE:                  [[CONT]]:
+  // CHECK-NEXT:                        call void @llvm.assume(i1 %[[MASKCOND]])
+  // CHECK-NEXT:                        ret i8** %[[X_RETURNED]]
+  // CHECK-NEXT:                      }
+#line 100
+  return passthrough(x);
+}

test/CodeGen/catch-alignment-assumption-attribute-assume_aligned-on-function.cpp

+// RUN: %clang_cc1 -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s --check-prefixes=CHECK,CHECK-NOSANITIZE
+// RUN: %clang_cc1 -fsanitize=alignment -fno-sanitize-recover=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-ANYRECOVER,CHECK-SANITIZE-NORECOVER,CHECK-SANITIZE-UNREACHABLE
+// RUN: %clang_cc1 -fsanitize=alignment -fsanitize-recover=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-ANYRECOVER,CHECK-SANITIZE-RECOVER
+// RUN: %clang_cc1 -fsanitize=alignment -fsanitize-trap=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-TRAP,CHECK-SANITIZE-UNREACHABLE
+
+// CHECK-SANITIZE-ANYRECOVER: @[[CHAR:.*]] = {{.*}} c"'char **'\00" }
+// CHECK-SANITIZE-ANYRECOVER: @[[LINE_100_ALIGNMENT_ASSUMPTION:.*]] = {{.*}}, i32 100, i32 10 }, {{.*}}* @[[CHAR]] }
+
+char **__attribute__((assume_aligned(0x80000000))) passthrough(char **x) {
+  // CHECK:      define i8** @[[PASSTHROUGH:.*]](i8** %[[X:.*]])
+  // CHECK-NEXT: entry:
+  // CHECK-NEXT:   %[[X_ADDR:.*]] = alloca i8**, align 8
+  // CHECK-NEXT:   store i8** %[[X]], i8*** %[[X_ADDR]], align 8
+  // CHECK-NEXT:   %[[X_RELOADED:.*]] = load i8**, i8*** %[[X_ADDR]], align 8
+  // CHECK-NEXT:   ret i8** %[[X_RELOADED]]
+  // CHECK-NEXT: }
+  return x;
+}
+
+char **caller(char **x) {
+  // CHECK:                           define i8** @{{.*}}(i8** %[[X]])
+  // CHECK-NEXT:                      entry:
+  // CHECK-NEXT:                        %[[X_ADDR]] = alloca i8**, align 8
+  // CHECK-NEXT:                        store i8** %[[X]], i8*** %[[X_ADDR]], align 8
+  // CHECK-NEXT:                        %[[X_RELOADED:.*]] = load i8**, i8*** %[[X_ADDR]], align 8
+  // CHECK-NEXT:                        %[[X_RETURNED:.*]] = call i8** @[[PASSTHROUGH]](i8** %[[X_RELOADED]])
+  // CHECK-NEXT:                        %[[PTRINT:.*]] = ptrtoint i8** %[[X_RETURNED]] to i64
+  // CHECK-NEXT:                        %[[MASKEDPTR:.*]] = and i64 %[[PTRINT]], 2147483647
+  // CHECK-NEXT:                        %[[MASKCOND:.*]] = icmp eq i64 %[[MASKEDPTR]], 0
+  // CHECK-SANITIZE-NEXT:               %[[PTRINT_DUP:.*]] = ptrtoint i8** %[[X_RETURNED]] to i64, !nosanitize
+  // CHECK-SANITIZE-NEXT:               br i1 %[[MASKCOND]], label %[[CONT:.*]], label %[[HANDLER_ALIGNMENT_ASSUMPTION:[^,]+]],{{.*}} !nosanitize
+  // CHECK-SANITIZE:                  [[HANDLER_ALIGNMENT_ASSUMPTION]]:
+  // CHECK-SANITIZE-NORECOVER-NEXT:     call void @__ubsan_handle_alignment_assumption_abort(i8* bitcast ({ {{{.*}}}, {{{.*}}}, {{{.*}}}* }* @[[LINE_100_ALIGNMENT_ASSUMPTION]] to i8*), i64 %[[PTRINT_DUP]], i64 2147483648, i64 0){{.*}}, !nosanitize
+  // CHECK-SANITIZE-RECOVER-NEXT:       call void @__ubsan_handle_alignment_assumption(i8* bitcast ({ {{{.*}}}, {{{.*}}}, {{{.*}}}* }* @[[LINE_100_ALIGNMENT_ASSUMPTION]] to i8*), i64 %[[PTRINT_DUP]], i64 2147483648, i64 0){{.*}}, !nosanitize
+  // CHECK-SANITIZE-TRAP-NEXT:          call void @llvm.trap(){{.*}}, !nosanitize
+  // CHECK-SANITIZE-UNREACHABLE-NEXT:   unreachable, !nosanitize
+  // CHECK-SANITIZE:                  [[CONT]]:
+  // CHECK-NEXT:                        call void @llvm.assume(i1 %[[MASKCOND]])
+  // CHECK-NEXT:                        ret i8** %[[X_RETURNED]]
+  // CHECK-NEXT:                      }
+#line 100
+  return passthrough(x);
+}

test/CodeGen/catch-alignment-assumption-blacklist.c

+// RUN: %clang_cc1 -fsanitize=alignment -fsanitize-recover=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK
+
+// CHECK-LABEL: @baseline
+void *baseline(void *x) {
+  // CHECK: call void @__ubsan_handle_alignment_assumption(
+  return __builtin_assume_aligned(x, 1);
+}
+
+// CHECK-LABEL: blacklist_0
+__attribute__((no_sanitize("undefined"))) void *blacklist_0(void *x) {
+  return __builtin_assume_aligned(x, 1);
+}
+
+// CHECK-LABEL: blacklist_1
+__attribute__((no_sanitize("alignment"))) void *blacklist_1(void *x) {
+  return __builtin_assume_aligned(x, 1);
+}
+
+// CHECK-LABEL: dont_ignore_volatile_ptrs
+void *dont_ignore_volatile_ptrs(void * volatile x) {
+  // CHECK: call void @__ubsan_handle_alignment_assumption(
+  return __builtin_assume_aligned(x, 1);
+}
+
+// CHECK-LABEL: ignore_volatiles
+void *ignore_volatiles(volatile void * x) {
+  return __builtin_assume_aligned(x, 1);
+}

test/CodeGen/catch-alignment-assumption-builtin_assume_aligned-three-params-variable.cpp

+// RUN: %clang_cc1 -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s --check-prefixes=CHECK,CHECK-NOSANITIZE
+// RUN: %clang_cc1 -fsanitize=alignment -fno-sanitize-recover=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-ANYRECOVER,CHECK-SANITIZE-NORECOVER,CHECK-SANITIZE-UNREACHABLE
+// RUN: %clang_cc1 -fsanitize=alignment -fsanitize-recover=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-ANYRECOVER,CHECK-SANITIZE-RECOVER
+// RUN: %clang_cc1 -fsanitize=alignment -fsanitize-trap=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-TRAP,CHECK-SANITIZE-UNREACHABLE
+
+// CHECK-SANITIZE-ANYRECOVER: @[[CHAR:.*]] = {{.*}} c"'char **'\00" }
+// CHECK-SANITIZE-ANYRECOVER: @[[LINE_100_ALIGNMENT_ASSUMPTION:.*]] = {{.*}}, i32 100, i32 35 }, {{.*}}* @[[CHAR]] }
+
+void *caller(char **x, unsigned long offset) {
+  // CHECK:                           define i8* @{{.*}}(i8** %[[X:.*]], i64 %[[OFFSET:.*]])
+  // CHECK-NEXT:                      entry:
+  // CHECK-NEXT:                        %[[X_ADDR:.*]] = alloca i8**, align 8
+  // CHECK-NEXT:                        %[[OFFSET_ADDR:.*]] = alloca i64, align 8
+  // CHECK-NEXT:                        store i8** %[[X]], i8*** %[[X_ADDR]], align 8
+  // CHECK-NEXT:                        store i64 %[[OFFSET]], i64* %[[OFFSET_ADDR]], align 8
+  // CHECK-NEXT:                        %[[X_RELOADED:.*]] = load i8**, i8*** %[[X_ADDR]], align 8
+  // CHECK-NEXT:                        %[[BITCAST:.*]] = bitcast i8** %[[X_RELOADED]] to i8*
+  // CHECK-NEXT:                        %[[OFFSET_RELOADED:.*]] = load i64, i64* %[[OFFSET_ADDR]], align 8
+  // CHECK-NEXT:                        %[[PTRINT:.*]] = ptrtoint i8* %[[BITCAST]] to i64
+  // CHECK-NEXT:                        %[[OFFSETPTR:.*]] = sub i64 %[[PTRINT]], %[[OFFSET_RELOADED]]
+  // CHECK-NEXT:                        %[[MASKEDPTR:.*]] = and i64 %[[OFFSETPTR]], 2147483647
+  // CHECK-NEXT:                        %[[MASKCOND:.*]] = icmp eq i64 %[[MASKEDPTR]], 0
+  // CHECK-SANITIZE-NEXT:               %[[PTRINT_DUP:.*]] = ptrtoint i8* %[[BITCAST]] to i64, !nosanitize
+  // CHECK-SANITIZE-NEXT:               br i1 %[[MASKCOND]], label %[[CONT:.*]], label %[[HANDLER_ALIGNMENT_ASSUMPTION:[^,]+]],{{.*}} !nosanitize
+  // CHECK-SANITIZE:                  [[HANDLER_ALIGNMENT_ASSUMPTION]]:
+  // CHECK-SANITIZE-NORECOVER-NEXT:     call void @__ubsan_handle_alignment_assumption_abort(i8* bitcast ({ {{{.*}}}, {{{.*}}}, {{{.*}}}* }* @[[LINE_100_ALIGNMENT_ASSUMPTION]] to i8*), i64 %[[PTRINT_DUP]], i64 2147483648, i64 %[[OFFSET_RELOADED]]){{.*}}, !nosanitize
+  // CHECK-SANITIZE-RECOVER-NEXT:       call void @__ubsan_handle_alignment_assumption(i8* bitcast ({ {{{.*}}}, {{{.*}}}, {{{.*}}}* }* @[[LINE_100_ALIGNMENT_ASSUMPTION]] to i8*), i64 %[[PTRINT_DUP]], i64 2147483648, i64 %[[OFFSET_RELOADED]]){{.*}}, !nosanitize
+  // CHECK-SANITIZE-TRAP-NEXT:          call void @llvm.trap(){{.*}}, !nosanitize
+  // CHECK-SANITIZE-UNREACHABLE-NEXT:   unreachable, !nosanitize
+  // CHECK-SANITIZE:                  [[CONT]]:
+  // CHECK-NEXT:                        call void @llvm.assume(i1 %[[MASKCOND]])
+  // CHECK-NEXT:                        ret i8* %[[BITCAST]]
+  // CHECK-NEXT:                      }
+#line 100
+  return __builtin_assume_aligned(x, 0x80000000, offset);
+}

test/CodeGen/catch-alignment-assumption-builtin_assume_aligned-three-params.cpp

+// RUN: %clang_cc1 -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s --check-prefixes=CHECK,CHECK-NOSANITIZE
+// RUN: %clang_cc1 -fsanitize=alignment -fno-sanitize-recover=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-ANYRECOVER,CHECK-SANITIZE-NORECOVER,CHECK-SANITIZE-UNREACHABLE
+// RUN: %clang_cc1 -fsanitize=alignment -fsanitize-recover=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-ANYRECOVER,CHECK-SANITIZE-RECOVER
+// RUN: %clang_cc1 -fsanitize=alignment -fsanitize-trap=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-TRAP,CHECK-SANITIZE-UNREACHABLE
+
+// CHECK-SANITIZE-ANYRECOVER: @[[CHAR:.*]] = {{.*}} c"'char **'\00" }
+// CHECK-SANITIZE-ANYRECOVER: @[[LINE_100_ALIGNMENT_ASSUMPTION:.*]] = {{.*}}, i32 100, i32 35 }, {{.*}}* @[[CHAR]] }
+
+void *caller(char **x) {
+  // CHECK:                           define i8* @{{.*}}(i8** %[[X:.*]])
+  // CHECK-NEXT:                      entry:
+  // CHECK-NEXT:                        %[[X_ADDR:.*]] = alloca i8**, align 8
+  // CHECK-NEXT:                        store i8** %[[X]], i8*** %[[X_ADDR]], align 8
+  // CHECK-NEXT:                        %[[X_RELOADED:.*]] = load i8**, i8*** %[[X_ADDR]], align 8
+  // CHECK-NEXT:                        %[[BITCAST:.*]] = bitcast i8** %[[X_RELOADED]] to i8*
+  // CHECK-NEXT:                        %[[PTRINT:.*]] = ptrtoint i8* %[[BITCAST]] to i64
+  // CHECK-NEXT:                        %[[OFFSETPTR:.*]] = sub i64 %[[PTRINT]], 42
+  // CHECK-NEXT:                        %[[MASKEDPTR:.*]] = and i64 %[[OFFSETPTR]], 2147483647
+  // CHECK-NEXT:                        %[[MASKCOND:.*]] = icmp eq i64 %[[MASKEDPTR]], 0
+  // CHECK-SANITIZE-NEXT:               %[[PTRINT_DUP:.*]] = ptrtoint i8* %[[BITCAST]] to i64, !nosanitize
+  // CHECK-SANITIZE-NEXT:               br i1 %[[MASKCOND]], label %[[CONT:.*]], label %[[HANDLER_ALIGNMENT_ASSUMPTION:[^,]+]],{{.*}} !nosanitize
+  // CHECK-SANITIZE:                  [[HANDLER_ALIGNMENT_ASSUMPTION]]:
+  // CHECK-SANITIZE-NORECOVER-NEXT:     call void @__ubsan_handle_alignment_assumption_abort(i8* bitcast ({ {{{.*}}}, {{{.*}}}, {{{.*}}}* }* @[[LINE_100_ALIGNMENT_ASSUMPTION]] to i8*), i64 %[[PTRINT_DUP]], i64 2147483648, i64 42){{.*}}, !nosanitize
+  // CHECK-SANITIZE-RECOVER-NEXT:       call void @__ubsan_handle_alignment_assumption(i8* bitcast ({ {{{.*}}}, {{{.*}}}, {{{.*}}}* }* @[[LINE_100_ALIGNMENT_ASSUMPTION]] to i8*), i64 %[[PTRINT_DUP]], i64 2147483648, i64 42){{.*}}, !nosanitize
+  // CHECK-SANITIZE-TRAP-NEXT:          call void @llvm.trap(){{.*}}, !nosanitize
+  // CHECK-SANITIZE-UNREACHABLE-NEXT:   unreachable, !nosanitize
+  // CHECK-SANITIZE:                  [[CONT]]:
+  // CHECK-NEXT:                        call void @llvm.assume(i1 %[[MASKCOND]])
+  // CHECK-NEXT:                        ret i8* %[[BITCAST]]
+  // CHECK-NEXT:                      }
+#line 100
+  return __builtin_assume_aligned(x, 0x80000000, 42);
+}

test/CodeGen/catch-alignment-assumption-builtin_assume_aligned-two-params.cpp

+// RUN: %clang_cc1 -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s --check-prefixes=CHECK,CHECK-NOSANITIZE
+// RUN: %clang_cc1 -fsanitize=alignment -fno-sanitize-recover=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-ANYRECOVER,CHECK-SANITIZE-NORECOVER,CHECK-SANITIZE-UNREACHABLE
+// RUN: %clang_cc1 -fsanitize=alignment -fsanitize-recover=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-ANYRECOVER,CHECK-SANITIZE-RECOVER
+// RUN: %clang_cc1 -fsanitize=alignment -fsanitize-trap=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-TRAP,CHECK-SANITIZE-UNREACHABLE
+
+// CHECK-SANITIZE-ANYRECOVER: @[[CHAR:.*]] = {{.*}} c"'char **'\00" }
+// CHECK-SANITIZE-ANYRECOVER: @[[LINE_100_ALIGNMENT_ASSUMPTION:.*]] = {{.*}}, i32 100, i32 35 }, {{.*}}* @[[CHAR]] }
+
+void *caller(char **x) {
+  // CHECK:                           define i8* @{{.*}}(i8** %[[X:.*]])
+  // CHECK-NEXT:                      entry:
+  // CHECK-NEXT:                        %[[X_ADDR:.*]] = alloca i8**, align 8
+  // CHECK-NEXT:                        store i8** %[[X]], i8*** %[[X_ADDR]], align 8
+  // CHECK-NEXT:                        %[[X_RELOADED:.*]] = load i8**, i8*** %[[X_ADDR]], align 8
+  // CHECK-NEXT:                        %[[BITCAST:.*]] = bitcast i8** %[[X_RELOADED]] to i8*
+  // CHECK-NEXT:                        %[[PTRINT:.*]] = ptrtoint i8* %[[BITCAST]] to i64
+  // CHECK-NEXT:                        %[[MASKEDPTR:.*]] = and i64 %[[PTRINT]], 2147483647
+  // CHECK-NEXT:                        %[[MASKCOND:.*]] = icmp eq i64 %[[MASKEDPTR]], 0
+  // CHECK-SANITIZE-NEXT:               %[[PTRINT_DUP:.*]] = ptrtoint i8* %[[BITCAST]] to i64, !nosanitize
+  // CHECK-SANITIZE-NEXT:               br i1 %[[MASKCOND]], label %[[CONT:.*]], label %[[HANDLER_ALIGNMENT_ASSUMPTION:[^,]+]],{{.*}} !nosanitize
+  // CHECK-SANITIZE:                  [[HANDLER_ALIGNMENT_ASSUMPTION]]:
+  // CHECK-SANITIZE-NORECOVER-NEXT:     call void @__ubsan_handle_alignment_assumption_abort(i8* bitcast ({ {{{.*}}}, {{{.*}}}, {{{.*}}}* }* @[[LINE_100_ALIGNMENT_ASSUMPTION]] to i8*), i64 %[[PTRINT_DUP]], i64 2147483648, i64 0){{.*}}, !nosanitize
+  // CHECK-SANITIZE-RECOVER-NEXT:       call void @__ubsan_handle_alignment_assumption(i8* bitcast ({ {{{.*}}}, {{{.*}}}, {{{.*}}}* }* @[[LINE_100_ALIGNMENT_ASSUMPTION]] to i8*), i64 %[[PTRINT_DUP]], i64 2147483648, i64 0){{.*}}, !nosanitize
+  // CHECK-SANITIZE-TRAP-NEXT:          call void @llvm.trap(){{.*}}, !nosanitize
+  // CHECK-SANITIZE-UNREACHABLE-NEXT:   unreachable, !nosanitize
+  // CHECK-SANITIZE:                  [[CONT]]:
+  // CHECK-NEXT:                        call void @llvm.assume(i1 %[[MASKCOND]])
+  // CHECK-NEXT:                        ret i8* %[[BITCAST]]
+  // CHECK-NEXT:                      }
+#line 100
+  return __builtin_assume_aligned(x, 0x80000000);
+}

test/CodeGen/catch-alignment-assumption-openmp.cpp

+// RUN: %clang_cc1 -fopenmp-simd -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s --check-prefixes=CHECK,CHECK-NOSANITIZE
+// RUN: %clang_cc1 -fopenmp-simd -fsanitize=alignment -fno-sanitize-recover=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-ANYRECOVER,CHECK-SANITIZE-NORECOVER,CHECK-SANITIZE-UNREACHABLE
+// RUN: %clang_cc1 -fopenmp-simd -fsanitize=alignment -fsanitize-recover=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-ANYRECOVER,CHECK-SANITIZE-RECOVER
+// RUN: %clang_cc1 -fopenmp-simd -fsanitize=alignment -fsanitize-trap=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-TRAP,CHECK-SANITIZE-UNREACHABLE
+
+// CHECK-SANITIZE-ANYRECOVER: @[[CHAR:.*]] = {{.*}} c"'char *'\00" }
+// CHECK-SANITIZE-ANYRECOVER: @[[LINE_100_ALIGNMENT_ASSUMPTION:.*]] = {{.*}}, i32 100, i32 30 }, {{.*}}* @[[CHAR]] }
+
+void func(char *data) {
+  // CHECK: define void @{{.*}}(i8* %[[DATA:.*]])
+  // CHECK-NEXT: [[ENTRY:.*]]:
+  // CHECK-NEXT:   %[[DATA_ADDR:.*]] = alloca i8*, align 8
+  // CHECK:   store i8* %[[DATA]], i8** %[[DATA_ADDR]], align 8
+  // CHECK:   %[[DATA_RELOADED:.*]] = load i8*, i8** %[[DATA_ADDR]], align 8
+  // CHECK-NEXT:   %[[PTRINT:.*]] = ptrtoint i8* %[[DATA_RELOADED]] to i64
+  // CHECK-NEXT:   %[[MASKEDPTR:.*]] = and i64 %[[PTRINT]], 1073741823
+  // CHECK-NEXT:   %[[MASKCOND:.*]] = icmp eq i64 %[[MASKEDPTR]], 0
+  // CHECK-SANITIZE-NEXT:               %[[PTRINT_DUP:.*]] = ptrtoint i8* %[[DATA_RELOADED]] to i64, !nosanitize
+  // CHECK-SANITIZE-NEXT:               br i1 %[[MASKCOND]], label %[[CONT:.*]], label %[[HANDLER_ALIGNMENT_ASSUMPTION:[^,]+]],{{.*}} !nosanitize
+  // CHECK-SANITIZE:                  [[HANDLER_ALIGNMENT_ASSUMPTION]]:
+  // CHECK-SANITIZE-NORECOVER-NEXT:     call void @__ubsan_handle_alignment_assumption_abort(i8* bitcast ({ {{{.*}}}, {{{.*}}}, {{{.*}}}* }* @[[LINE_100_ALIGNMENT_ASSUMPTION]] to i8*), i64 %[[PTRINT_DUP]], i64 1073741824, i64 0){{.*}}, !nosanitize
+  // CHECK-SANITIZE-RECOVER-NEXT:       call void @__ubsan_handle_alignment_assumption(i8* bitcast ({ {{{.*}}}, {{{.*}}}, {{{.*}}}* }* @[[LINE_100_ALIGNMENT_ASSUMPTION]] to i8*), i64 %[[PTRINT_DUP]], i64 1073741824, i64 0){{.*}}, !nosanitize
+  // CHECK-SANITIZE-TRAP-NEXT:          call void @llvm.trap(){{.*}}, !nosanitize
+  // CHECK-SANITIZE-UNREACHABLE-NEXT:   unreachable, !nosanitize
+  // CHECK-SANITIZE:                  [[CONT]]:
+  // CHECK-NEXT:                        call void @llvm.assume(i1 %[[MASKCOND]])
+
+#line 100
+#pragma omp for simd aligned(data : 0x40000000)
+  for (int x = 0; x < 1; x++)
+    data[x] = data[x];
+}