[clang] [Clang][counted_by] Add support for 'counted_by' on struct pointers (PR #127116)

Bill Wendling via cfe-commits cfe-commits at lists.llvm.org
Thu Feb 13 11:42:16 PST 2025


https://github.com/bwendling created https://github.com/llvm/llvm-project/pull/127116

The 'counted_by' attribute is now available for structs. It generates code for sanity checks as well as __builtin_dynamic_object_size() calculations. For example:

  struct annotated_ptr {
    int count;
    char *buf __counted_by(count);
  };

'counted_by' cannot be applied to a pointer to an incomplete type. So this is invalid:

  struct foo;
  struct annotated_ptr {
    int count;
    struct foo *buf __counted_by(count); /* invalid */
  };

The 'count' field member may occur after the pointer. If it does, use the '-fexperimental-late-parse-attributes' flag (which will hopefully be made the default in future Clang versions).

>From b5b9b158e7e379f2d430584e3ccf519677bf27a3 Mon Sep 17 00:00:00 2001
From: Bill Wendling <morbo at google.com>
Date: Fri, 10 Jan 2025 17:13:30 -0800
Subject: [PATCH] [Clang][counted_by] Add support for 'counted_by' on struct
 pointers

The 'counted_by' attribute is now available for structs. It generates
code for sanity checks as well as __builtin_dynamic_object_size()
calculations. For example:

  struct annotated_ptr {
    int count;
    char *buf __counted_by(count);
  };

'counted_by' cannot be applied to a pointer to an incomplete type. So
this is invalid:

  struct foo;
  struct annotated_ptr {
    int count;
    struct foo *buf __counted_by(count); /* invalid */
  };

The 'count' field member may occur after the pointer. If it does, use
the '-fexperimental-late-parse-attributes' flag (which will hopefully be
made the default in future Clang versions).

Signed-off-by: Bill Wendling <morbo at google.com>
---
 clang/lib/CodeGen/CGBuiltin.cpp               | 259 ++++++++++++++----
 clang/lib/CodeGen/CGExpr.cpp                  | 130 ++++++---
 clang/lib/CodeGen/CodeGenFunction.h           |  19 +-
 .../CodeGen/attr-counted-by-for-pointers.c    | 216 +++++++++++++++
 4 files changed, 519 insertions(+), 105 deletions(-)
 create mode 100644 clang/test/CodeGen/attr-counted-by-for-pointers.c

diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index 361e4c4bf2e2e..f7ff244a519d0 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -1061,7 +1061,7 @@ class StructFieldAccess
   bool AddrOfSeen = false;
 
 public:
-  const ArraySubscriptExpr *ASE = nullptr;
+  const Expr *ArrayIndex = nullptr;
 
   const Expr *VisitMemberExpr(const MemberExpr *E) {
     if (AddrOfSeen && E->getType()->isArrayType())
@@ -1071,12 +1071,12 @@ class StructFieldAccess
   }
 
   const Expr *VisitArraySubscriptExpr(const ArraySubscriptExpr *E) {
-    if (ASE)
+    if (ArrayIndex)
       // We don't support multiple subscripts.
       return nullptr;
 
     AddrOfSeen = false; // '&ptr->array[idx]' is okay.
-    ASE = E;
+    ArrayIndex = E->getIdx();
     return Visit(E->getBase());
   }
   const Expr *VisitCastExpr(const CastExpr *E) {
@@ -1168,12 +1168,10 @@ GetFieldOffset(ASTContext &Ctx, const RecordDecl *RD, const FieldDecl *FD) {
   return std::nullopt;
 }
 
-llvm::Value *
-CodeGenFunction::emitCountedByMemberSize(const Expr *E, llvm::Value *EmittedE,
-                                         unsigned Type,
-                                         llvm::IntegerType *ResType) {
-  ASTContext &Ctx = getContext();
-
+llvm::Value *CodeGenFunction::emitCountedBySize(const Expr *E,
+                                                llvm::Value *EmittedE,
+                                                unsigned Type,
+                                                llvm::IntegerType *ResType) {
   // Note: If the whole struct is specificed in the __bdos (i.e. Visitor
   // returns a DeclRefExpr). The calculation of the whole size of the structure
   // with a flexible array member can be done in two ways:
@@ -1192,14 +1190,161 @@ CodeGenFunction::emitCountedByMemberSize(const Expr *E, llvm::Value *EmittedE,
   // GCC does for consistency's sake.
 
   StructFieldAccess Visitor;
-  const MemberExpr *ME = dyn_cast_if_present<MemberExpr>(Visitor.Visit(E));
+  E = Visitor.Visit(E);
+  if (!E)
+    return nullptr;
+
+  const Expr *Idx = Visitor.ArrayIndex;
+  if (Idx) {
+    if (Idx->HasSideEffects(getContext()))
+      // We can't have side-effects.
+      return getDefaultBuiltinObjectSizeResult(Type, ResType);
+
+    if (const auto *IL = dyn_cast<IntegerLiteral>(Idx)) {
+      int64_t Val = IL->getValue().getSExtValue();
+      if (Val < 0)
+        return getDefaultBuiltinObjectSizeResult(Type, ResType);
+
+      // The index is 0, so we don't need to take it into account.
+      if (Val == 0)
+        Idx = nullptr;
+    }
+  }
+
+  if (const auto *ME = dyn_cast<MemberExpr>(E))
+    // This is either a flexible array member or a pointer into a struct with a
+    // flexible array member.
+    return emitCountedByMemberSize(ME, Idx, EmittedE, Type, ResType);
+
+  if (const auto *ICE = dyn_cast<ImplicitCastExpr>(E);
+      ICE && ICE->getCastKind() == CK_LValueToRValue)
+    // This may be a pointer.
+    return emitCountedByPointerSize(ICE, Idx, EmittedE, Type, ResType);
+
+  return nullptr;
+}
+
+llvm::Value *CodeGenFunction::emitCountedByPointerSize(
+    const ImplicitCastExpr *E, const Expr *Idx, llvm::Value *EmittedE,
+    unsigned Type, llvm::IntegerType *ResType) {
+  assert(E->getCastKind() == CK_LValueToRValue &&
+         "must be an LValue to RValue cast");
+
+  const MemberExpr *ME = dyn_cast<MemberExpr>(E->getSubExpr());
   if (!ME)
     return nullptr;
 
+  const auto *ArrayBaseFD = dyn_cast<FieldDecl>(ME->getMemberDecl());
+  if (!ArrayBaseFD || !ArrayBaseFD->getType()->isPointerType() ||
+      !ArrayBaseFD->getType()->isCountAttributedType())
+    return nullptr;
+
+  // Get the 'count' FieldDecl.
+  const FieldDecl *CountFD = ArrayBaseFD->findCountedByField();
+  if (!CountFD)
+    // Can't find the field referenced by the "counted_by" attribute.
+    return nullptr;
+
+  // Calculate the array's object size using these formulae. (Note: if the
+  // calculation is negative, we return 0.):
+  //
+  //      struct p;
+  //      struct s {
+  //          /* ... */
+  //          struct p **array __attribute__((counted_by(count)));
+  //          int count;
+  //      };
+  //
+  // 1) 'ptr->array':
+  //
+  //    count = ptr->count;
+  //
+  //    array_base_size = sizeof (*ptr->array);
+  //    array_size = count * array_base_size;
+  //
+  //    result = array_size;
+  //
+  //    cmp = (result >= 0)
+  //    return cmp ? result : 0;
+  //
+  // 2) '&ptr->array[idx]':
+  //
+  //    count = ptr->count;
+  //    index = idx;
+  //
+  //    array_base_size = sizeof (*ptr->array_base_size);
+  //    array_size = count * array_base_size;
+  //
+  //    index_size = index * array_base_size;
+  //
+  //    result = array_size - index_size;
+  //
+  //    cmp = (result >= 0)
+  //    if (index)
+  //        cmp  = (cmp && index > 0)
+  //    return cmp ? result : 0;
+
+  bool IsSigned = CountFD->getType()->isSignedIntegerType();
+
+  //  count = ptr->count;
+  Value *Count = EmitLoadOfCountedByField(ME, ArrayBaseFD, CountFD);
+  if (!Count)
+    return nullptr;
+  Count = Builder.CreateIntCast(Count, ResType, IsSigned, "count");
+
+  //  index = ptr->index;
+  Value *Index = nullptr;
+  if (Idx) {
+    bool IdxSigned = Idx->getType()->isSignedIntegerType();
+    Index = EmitScalarExpr(Idx);
+    Index = Builder.CreateIntCast(Index, ResType, IdxSigned, "index");
+  }
+
+  //  array_base_size = sizeof (*ptr->array);
+  ASTContext &Ctx = getContext();
+  QualType ArrayBaseTy = ArrayBaseFD->getType()->getPointeeType();
+  CharUnits BaseSize = Ctx.getTypeSizeInChars(ArrayBaseTy);
+  auto *ArrayBaseSize =
+      llvm::ConstantInt::get(ResType, BaseSize.getQuantity(), IsSigned);
+
+  //  array_size = count * array_base_size;
+  Value *ArraySize = Builder.CreateMul(Count, ArrayBaseSize, "array_size",
+                                       !IsSigned, IsSigned);
+
+  // Option (1) 'ptr->array'
+  //   result = array_size
+  Value *Res = ArraySize;
+
+  if (Idx) { // Option (2) '&ptr->array[idx]'
+    //  index_size = index * array_base_size;
+    Value *IndexSize = Builder.CreateMul(ArrayBaseSize, Index, "index_size",
+                                         !IsSigned, IsSigned);
+
+    //  result = result - index_size;
+    Res = Builder.CreateSub(Res, IndexSize, "result", !IsSigned, IsSigned);
+  }
+
+  //  cmp = (array_size >= 0)
+  Value *Cmp = Builder.CreateIsNotNeg(Res);
+  if (Idx)
+    //  cmp = (cmp && index >= 0)
+    Cmp = Builder.CreateAnd(Builder.CreateIsNotNeg(Index), Cmp);
+
+  //  return cmp ? result : 0
+  return Builder.CreateSelect(Cmp, Res, ConstantInt::get(ResType, 0, IsSigned));
+}
+
+llvm::Value *
+CodeGenFunction::emitCountedByMemberSize(const MemberExpr *ME, const Expr *Idx,
+                                         llvm::Value *EmittedE, unsigned Type,
+                                         llvm::IntegerType *ResType) {
   const auto *FD = dyn_cast<FieldDecl>(ME->getMemberDecl());
   if (!FD)
     return nullptr;
 
+  // Find the flexible array member and check that it has the __counted_by
+  // attribute.
+  ASTContext &Ctx = getContext();
   const RecordDecl *RD = FD->getDeclContext()->getOuterLexicalRecordContext();
   const FieldDecl *FlexibleArrayMemberFD = nullptr;
 
@@ -1214,32 +1359,14 @@ CodeGenFunction::emitCountedByMemberSize(const Expr *E, llvm::Value *EmittedE,
       !FlexibleArrayMemberFD->getType()->isCountAttributedType())
     return nullptr;
 
+  // Get the 'count' FieldDecl.
   const FieldDecl *CountFD = FlexibleArrayMemberFD->findCountedByField();
   if (!CountFD)
     // Can't find the field referenced by the "counted_by" attribute.
     return nullptr;
 
-  const Expr *Idx = nullptr;
-  if (Visitor.ASE) {
-    Idx = Visitor.ASE->getIdx();
-
-    if (Idx->HasSideEffects(Ctx))
-      // We can't have side-effects.
-      return getDefaultBuiltinObjectSizeResult(Type, ResType);
-
-    if (const auto *IL = dyn_cast<IntegerLiteral>(Idx)) {
-      int64_t Val = IL->getValue().getSExtValue();
-      if (Val < 0)
-        return getDefaultBuiltinObjectSizeResult(Type, ResType);
-
-      // The index is 0, so we don't need to take it into account.
-      if (Val == 0)
-        Idx = nullptr;
-    }
-  }
-
-  // Calculate the flexible array member's object size using these formulae
-  // (note: if the calculation is negative, we return 0.):
+  // Calculate the flexible array member's object size using these formulae.
+  // (Note: if the calculation is negative, we return 0.):
   //
   //      struct p;
   //      struct s {
@@ -1256,9 +1383,11 @@ CodeGenFunction::emitCountedByMemberSize(const Expr *E, llvm::Value *EmittedE,
   //    flexible_array_member_size =
   //            count * flexible_array_member_base_size;
   //
-  //    if (flexible_array_member_size < 0)
-  //        return 0;
-  //    return flexible_array_member_size;
+  //    result = flexible_array_member_size;
+  //
+  //    cmp = (result >= 0)
+  //
+  //    return cmp ? result : 0;
   //
   // 2) '&ptr->array[idx]':
   //
@@ -1271,9 +1400,13 @@ CodeGenFunction::emitCountedByMemberSize(const Expr *E, llvm::Value *EmittedE,
   //
   //    index_size = index * flexible_array_member_base_size;
   //
-  //    if (flexible_array_member_size < 0 || index < 0)
-  //        return 0;
-  //    return flexible_array_member_size - index_size;
+  //    result = flexible_array_member_size - index_size;
+  //
+  //    cmp = (result >= 0)
+  //    if (index != 0)
+  //        cmp = (cmp && index >= 0)
+  //
+  //    return cmp ? result : 0;
   //
   // 3) '&ptr->field':
   //
@@ -1287,9 +1420,11 @@ CodeGenFunction::emitCountedByMemberSize(const Expr *E, llvm::Value *EmittedE,
   //    field_offset = offsetof (struct s, field);
   //    offset_diff = sizeof_struct - field_offset;
   //
-  //    if (flexible_array_member_size < 0)
-  //        return 0;
-  //    return offset_diff + flexible_array_member_size;
+  //    result = offset_diff + flexible_array_member_size;
+  //
+  //    cmp = (result >= 0)
+  //
+  //    return cmp ? result : 0;
   //
   // 4) '&ptr->field_array[idx]':
   //
@@ -1307,21 +1442,24 @@ CodeGenFunction::emitCountedByMemberSize(const Expr *E, llvm::Value *EmittedE,
   //
   //    offset_diff = sizeof_struct - field_offset;
   //
-  //    if (flexible_array_member_size < 0 || index < 0)
-  //        return 0;
-  //    return offset_diff + flexible_array_member_size;
+  //    result = offset_diff + flexible_array_member_size;
+  //
+  //    cmp = (result >= 0)
+  //    if (index != 0)
+  //        cmp = (cmp && index >= 0)
+  //
+  //    return cmp ? result : 0;
 
-  QualType CountTy = CountFD->getType();
-  bool IsSigned = CountTy->isSignedIntegerType();
+  bool IsSigned = CountFD->getType()->isSignedIntegerType();
 
   QualType FlexibleArrayMemberTy = FlexibleArrayMemberFD->getType();
   QualType FieldTy = FD->getType();
 
   // Explicit cast because otherwise the CharWidth will promote an i32's into
-  // u64's leading to overflows..
+  // u64's leading to overflows.
   int64_t CharWidth = static_cast<int64_t>(CGM.getContext().getCharWidth());
 
-  //  size_t field_offset = offsetof (struct s, field);
+  //  field_offset = offsetof (struct s, field);
   Value *FieldOffset = nullptr;
   if (FlexibleArrayMemberFD != FD) {
     std::optional<int64_t> Offset = GetFieldOffset(Ctx, RD, FD);
@@ -1331,13 +1469,13 @@ CodeGenFunction::emitCountedByMemberSize(const Expr *E, llvm::Value *EmittedE,
         llvm::ConstantInt::get(ResType, *Offset / CharWidth, IsSigned);
   }
 
-  //  size_t count = (size_t) ptr->count;
+  //  count = ptr->count;
   Value *Count = EmitLoadOfCountedByField(ME, FlexibleArrayMemberFD, CountFD);
   if (!Count)
     return nullptr;
   Count = Builder.CreateIntCast(Count, ResType, IsSigned, "count");
 
-  //  size_t index = (size_t) ptr->index;
+  //  index = ptr->index;
   Value *Index = nullptr;
   if (Idx) {
     bool IdxSigned = Idx->getType()->isSignedIntegerType();
@@ -1345,13 +1483,13 @@ CodeGenFunction::emitCountedByMemberSize(const Expr *E, llvm::Value *EmittedE,
     Index = Builder.CreateIntCast(Index, ResType, IdxSigned, "index");
   }
 
-  //  size_t flexible_array_member_base_size = sizeof (*ptr->array);
+  //  flexible_array_member_base_size = sizeof (*ptr->array);
   const ArrayType *ArrayTy = Ctx.getAsArrayType(FlexibleArrayMemberTy);
   CharUnits BaseSize = Ctx.getTypeSizeInChars(ArrayTy->getElementType());
   auto *FlexibleArrayMemberBaseSize =
       llvm::ConstantInt::get(ResType, BaseSize.getQuantity(), IsSigned);
 
-  //  size_t flexible_array_member_size =
+  //  flexible_array_member_size =
   //          count * flexible_array_member_base_size;
   Value *FlexibleArrayMemberSize =
       Builder.CreateMul(Count, FlexibleArrayMemberBaseSize,
@@ -1360,19 +1498,19 @@ CodeGenFunction::emitCountedByMemberSize(const Expr *E, llvm::Value *EmittedE,
   Value *Res = nullptr;
   if (FlexibleArrayMemberFD == FD) {
     if (Idx) { // Option (2) '&ptr->array[idx]'
-      //  size_t index_size = index * flexible_array_member_base_size;
+      //  index_size = index * flexible_array_member_base_size;
       Value *IndexSize = Builder.CreateMul(FlexibleArrayMemberBaseSize, Index,
                                            "index_size", !IsSigned, IsSigned);
 
-      //  return flexible_array_member_size - index_size;
+      //  result = flexible_array_member_size - index_size;
       Res = Builder.CreateSub(FlexibleArrayMemberSize, IndexSize, "result",
                               !IsSigned, IsSigned);
     } else { // Option (1) 'ptr->array'
-      //  return flexible_array_member_size;
+      //  result = flexible_array_member_size;
       Res = FlexibleArrayMemberSize;
     }
   } else {
-    //  size_t sizeof_struct = sizeof (struct s);
+    //  sizeof_struct = sizeof (struct s);
     llvm::StructType *StructTy = getTypes().getCGRecordLayout(RD).getLLVMType();
     const llvm::DataLayout &Layout = CGM.getDataLayout();
     TypeSize Size = Layout.getTypeSizeInBits(StructTy);
@@ -1380,7 +1518,7 @@ CodeGenFunction::emitCountedByMemberSize(const Expr *E, llvm::Value *EmittedE,
         llvm::ConstantInt::get(ResType, Size.getKnownMinValue() / CharWidth);
 
     if (Idx) { // Option (4) '&ptr->field_array[idx]'
-      //  size_t field_base_size = sizeof (*ptr->field_array);
+      //  field_base_size = sizeof (*ptr->field_array);
       const ArrayType *ArrayTy = Ctx.getAsArrayType(FieldTy);
       CharUnits BaseSize = Ctx.getTypeSizeInChars(ArrayTy->getElementType());
       auto *FieldBaseSize =
@@ -1393,18 +1531,21 @@ CodeGenFunction::emitCountedByMemberSize(const Expr *E, llvm::Value *EmittedE,
     }
     // Option (3) '&ptr->field', and Option (4) continuation.
 
-    //  size_t offset_diff = flexible_array_member_offset - field_offset;
+    //  offset_diff = flexible_array_member_offset - field_offset;
     Value *OffsetDiff = Builder.CreateSub(SizeofStruct, FieldOffset,
                                           "offset_diff", !IsSigned, IsSigned);
 
-    //  return offset_diff + flexible_array_member_size;
+    //  result = offset_diff + flexible_array_member_size;
     Res = Builder.CreateAdd(FlexibleArrayMemberSize, OffsetDiff, "result");
   }
 
+  //  cmp = (array_size >= 0)
   Value *Cmp = Builder.CreateIsNotNeg(Res);
   if (Idx)
+    //  cmp = (cmp && index >= 0)
     Cmp = Builder.CreateAnd(Builder.CreateIsNotNeg(Index), Cmp);
 
+  //  return cmp ? result : 0
   return Builder.CreateSelect(Cmp, Res, ConstantInt::get(ResType, 0, IsSigned));
 }
 
@@ -1453,7 +1594,7 @@ CodeGenFunction::emitBuiltinObjectSize(const Expr *E, unsigned Type,
   if (IsDynamic)
     // Emit special code for a flexible array member with the "counted_by"
     // attribute.
-    if (Value *V = emitCountedByMemberSize(E, Ptr, Type, ResType))
+    if (Value *V = emitCountedBySize(E, Ptr, Type, ResType))
       return V;
 
   Function *F =
diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index 2bbc0791c6587..876eb06772273 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -4248,6 +4248,52 @@ static std::optional<int64_t> getOffsetDifferenceInBits(CodeGenFunction &CGF,
   return std::make_optional<int64_t>(FD1Offset - FD2Offset);
 }
 
+/// EmitCountedByBoundsChecking - If the array being accessed has a "counted_by"
+/// attribute, generate bounds checking code. The "count" field is at the top
+/// level of the struct or in an anonymous struct, that's also at the top level.
+/// Future expansions may allow the "count" to reside at any place in the
+/// struct, but the value of "counted_by" will be a "simple" path to the count,
+/// i.e. "a.b.count", so we shouldn't need the full force of EmitLValue or
+/// similar to emit the correct GEP.
+void CodeGenFunction::EmitCountedByBoundsChecking(
+    const Expr *E, llvm::Value *Idx, Address Addr, QualType IdxTy,
+    QualType ArrayTy, bool Accessed, bool FlexibleArray) {
+  const auto *ME = dyn_cast<MemberExpr>(E->IgnoreImpCasts());
+  if (!ME || !ME->getMemberDecl()->getType()->isCountAttributedType())
+    return;
+
+  const LangOptions::StrictFlexArraysLevelKind StrictFlexArraysLevel =
+      getLangOpts().getStrictFlexArraysLevel();
+  if (FlexibleArray &&
+      !ME->isFlexibleArrayMemberLike(getContext(), StrictFlexArraysLevel))
+    return;
+
+  const FieldDecl *FD = cast<FieldDecl>(ME->getMemberDecl());
+  const FieldDecl *CountFD = FD->findCountedByField();
+  if (!CountFD)
+    return;
+
+  if (std::optional<int64_t> Diff = getOffsetDifferenceInBits(*this, CountFD, FD)) {
+    // FIXME: The 'static_cast' is necessary, otherwise the result turns into a
+    // uint64_t, which messes things up if we have a negative offset difference.
+    Diff = *Diff / static_cast<int64_t>(CGM.getContext().getCharWidth());
+
+    // Create a GEP with the byte offset between the counted object and the
+    // count and use that to load the count value.
+    Addr = Builder.CreatePointerBitCastOrAddrSpaceCast(Addr, Int8PtrTy, Int8Ty);
+
+    llvm::Type *CountTy = ConvertType(CountFD->getType());
+    llvm::Value *Res = Builder.CreateInBoundsGEP(
+        Int8Ty, Addr.emitRawPointer(*this),
+        Builder.getInt32(*Diff), ".counted_by.gep");
+    Res = Builder.CreateAlignedLoad(CountTy, Res, getIntAlign(),
+                                    ".counted_by.load");
+
+    // Now emit the bounds checking.
+    EmitBoundsCheckImpl(E, Res, Idx, IdxTy, ArrayTy, Accessed);
+  }
+}
+
 LValue CodeGenFunction::EmitArraySubscriptExpr(const ArraySubscriptExpr *E,
                                                bool Accessed) {
   // The index must always be an integer, which is not an aggregate.  Emit it
@@ -4374,46 +4420,10 @@ LValue CodeGenFunction::EmitArraySubscriptExpr(const ArraySubscriptExpr *E,
       ArrayLV = EmitLValue(Array);
     auto *Idx = EmitIdxAfterBase(/*Promote*/true);
 
-    if (SanOpts.has(SanitizerKind::ArrayBounds)) {
-      // If the array being accessed has a "counted_by" attribute, generate
-      // bounds checking code. The "count" field is at the top level of the
-      // struct or in an anonymous struct, that's also at the top level. Future
-      // expansions may allow the "count" to reside at any place in the struct,
-      // but the value of "counted_by" will be a "simple" path to the count,
-      // i.e. "a.b.count", so we shouldn't need the full force of EmitLValue or
-      // similar to emit the correct GEP.
-      const LangOptions::StrictFlexArraysLevelKind StrictFlexArraysLevel =
-          getLangOpts().getStrictFlexArraysLevel();
-
-      if (const auto *ME = dyn_cast<MemberExpr>(Array);
-          ME &&
-          ME->isFlexibleArrayMemberLike(getContext(), StrictFlexArraysLevel) &&
-          ME->getMemberDecl()->getType()->isCountAttributedType()) {
-        const FieldDecl *FAMDecl = cast<FieldDecl>(ME->getMemberDecl());
-        if (const FieldDecl *CountFD = FAMDecl->findCountedByField()) {
-          if (std::optional<int64_t> Diff =
-                  getOffsetDifferenceInBits(*this, CountFD, FAMDecl)) {
-            CharUnits OffsetDiff = CGM.getContext().toCharUnitsFromBits(*Diff);
-
-            // Create a GEP with a byte offset between the FAM and count and
-            // use that to load the count value.
-            Addr = Builder.CreatePointerBitCastOrAddrSpaceCast(
-                ArrayLV.getAddress(), Int8PtrTy, Int8Ty);
-
-            llvm::Type *CountTy = ConvertType(CountFD->getType());
-            llvm::Value *Res = Builder.CreateInBoundsGEP(
-                Int8Ty, Addr.emitRawPointer(*this),
-                Builder.getInt32(OffsetDiff.getQuantity()), ".counted_by.gep");
-            Res = Builder.CreateAlignedLoad(CountTy, Res, getIntAlign(),
-                                            ".counted_by.load");
-
-            // Now emit the bounds checking.
-            EmitBoundsCheckImpl(E, Res, Idx, E->getIdx()->getType(),
-                                Array->getType(), Accessed);
-          }
-        }
-      }
-    }
+    if (SanOpts.has(SanitizerKind::ArrayBounds))
+      EmitCountedByBoundsChecking(Array, Idx, ArrayLV.getAddress(),
+                                  E->getIdx()->getType(), Array->getType(),
+                                  Accessed, /*FlexibleArray=*/true);
 
     // Propagate the alignment from the array itself to the result.
     QualType arrayType = Array->getType();
@@ -4425,12 +4435,44 @@ LValue CodeGenFunction::EmitArraySubscriptExpr(const ArraySubscriptExpr *E,
     EltTBAAInfo = CGM.getTBAAInfoForSubobject(ArrayLV, E->getType());
   } else {
     // The base must be a pointer; emit it with an estimate of its alignment.
-    Addr = EmitPointerWithAlignment(E->getBase(), &EltBaseInfo, &EltTBAAInfo);
+    Address BaseAddr =
+        EmitPointerWithAlignment(E->getBase(), &EltBaseInfo, &EltTBAAInfo);
     auto *Idx = EmitIdxAfterBase(/*Promote*/true);
     QualType ptrType = E->getBase()->getType();
-    Addr = emitArraySubscriptGEP(
-        *this, Addr, Idx, E->getType(), !getLangOpts().PointerOverflowDefined,
-        SignedIndices, E->getExprLoc(), &ptrType, E->getBase());
+    Addr = emitArraySubscriptGEP(*this, BaseAddr, Idx, E->getType(),
+                                 !getLangOpts().PointerOverflowDefined,
+                                 SignedIndices, E->getExprLoc(), &ptrType,
+                                 E->getBase());
+
+    if (SanOpts.has(SanitizerKind::ArrayBounds)) {
+      // FIXME: There *has* to be a better way to get the base GEP than
+      // crawling back through the LoadInst.
+      const Expr *Base = E->getBase();
+      while (true) {
+        if (const auto *CE = dyn_cast<CastExpr>(Base)) {
+          if (CE->getCastKind() == CK_LValueToRValue)
+            break;
+          Base = CE->getSubExpr();
+        } else if (const auto *PE = dyn_cast<ParenExpr>(Base)) {
+          Base = PE->getSubExpr();
+        } else {
+          break;
+        }
+      }
+
+      if (const auto *CE = dyn_cast<CastExpr>(Base);
+          CE && CE->getCastKind() == CK_LValueToRValue) {
+        // FIXME: This is a bit fragile. See if we can strengthen it a bit
+        // better.
+        if (const auto *ME = dyn_cast<MemberExpr>(CE->getSubExpr());
+            ME && ME->getMemberDecl()->getType()->isCountAttributedType()) {
+          LValue LV = EmitCheckedLValue(Base, TCK_MemberAccess);
+          EmitCountedByBoundsChecking(E->getBase(), Idx, LV.getAddress(),
+                                      E->getIdx()->getType(), ptrType, Accessed,
+                                      /*FlexibleArray=*/false);
+        }
+      }
+    }
   }
 
   LValue LV = MakeAddrLValue(Addr, E->getType(), EltBaseInfo, EltTBAAInfo);
diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index 64cd8a3ac55e2..1efe21b70783d 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -3313,6 +3313,13 @@ class CodeGenFunction : public CodeGenTypeCache {
   llvm::Value *EmitLoadOfCountedByField(const Expr *Base, const FieldDecl *FD,
                                         const FieldDecl *CountDecl);
 
+  // Emit bounds checking for flexible array and pointer members with the
+  // counted_by attribute.
+  void EmitCountedByBoundsChecking(const Expr *E, llvm::Value *Idx,
+                                   Address Addr, QualType IdxTy,
+                                   QualType ArrayTy, bool Accessed,
+                                   bool FlexibleArray);
+
   llvm::Value *EmitScalarPrePostIncDec(const UnaryOperator *E, LValue LV,
                                        bool isInc, bool isPre);
   ComplexPairTy EmitComplexPrePostIncDec(const UnaryOperator *E, LValue LV,
@@ -5332,10 +5339,18 @@ class CodeGenFunction : public CodeGenTypeCache {
                                      llvm::IntegerType *ResType,
                                      llvm::Value *EmittedE, bool IsDynamic);
 
-  llvm::Value *emitCountedByMemberSize(const Expr *E, llvm::Value *EmittedE,
-                                       unsigned Type,
+  llvm::Value *emitCountedBySize(const Expr *E, llvm::Value *EmittedE,
+                                 unsigned Type, llvm::IntegerType *ResType);
+
+  llvm::Value *emitCountedByMemberSize(const MemberExpr *E, const Expr *Idx,
+                                       llvm::Value *EmittedE, unsigned Type,
                                        llvm::IntegerType *ResType);
 
+  llvm::Value *emitCountedByPointerSize(const ImplicitCastExpr *E,
+                                        const Expr *Idx, llvm::Value *EmittedE,
+                                        unsigned Type,
+                                        llvm::IntegerType *ResType);
+
   void emitZeroOrPatternForAutoVarInit(QualType type, const VarDecl &D,
                                        Address Loc);
 
diff --git a/clang/test/CodeGen/attr-counted-by-for-pointers.c b/clang/test/CodeGen/attr-counted-by-for-pointers.c
new file mode 100644
index 0000000000000..dc40721806a61
--- /dev/null
+++ b/clang/test/CodeGen/attr-counted-by-for-pointers.c
@@ -0,0 +1,216 @@
+// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py UTC_ARGS: --version 3
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -O2 -DCOUNTED_BY -Wall -fsanitize=array-bounds,object-size,local-bounds -fstrict-flex-arrays=3 -fexperimental-late-parse-attributes -emit-llvm -o - %s | FileCheck --check-prefix=SANITIZE-WITH-ATTR %s
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -O2 -DCOUNTED_BY -Wall -fstrict-flex-arrays=3 -fexperimental-late-parse-attributes -emit-llvm -o - %s | FileCheck --check-prefix=NO-SANITIZE-WITH-ATTR %s
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -O2 -Wall -fsanitize=array-bounds,object-size,local-bounds -fstrict-flex-arrays=3 -fexperimental-late-parse-attributes -emit-llvm -o - %s | FileCheck --check-prefix=SANITIZE-WITHOUT-ATTR %s
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -O2 -Wall -fstrict-flex-arrays=3 -fexperimental-late-parse-attributes -emit-llvm -o - %s | FileCheck --check-prefix=NO-SANITIZE-WITHOUT-ATTR %s
+
+#if !__has_attribute(counted_by)
+#error "has attribute broken"
+#endif
+
+#ifdef COUNTED_BY
+#define __counted_by(member)   __attribute__((__counted_by__(member)))
+#else
+#define __counted_by(member)
+#endif
+
+#define __bdos(P)              __builtin_dynamic_object_size(P, 0)
+
+typedef long unsigned int size_t;
+
+struct foo { size_t field; };
+struct annotated_ptr {
+  unsigned long flags;
+  struct foo **buf __counted_by(ptr_count);
+  int ptr_count;
+};
+
+// SANITIZE-WITH-ATTR-LABEL: define dso_local void @test1(
+// SANITIZE-WITH-ATTR-SAME: ptr noundef [[P:%.*]], i32 noundef [[INDEX:%.*]], ptr noundef [[VALUE:%.*]]) local_unnamed_addr #[[ATTR0:[0-9]+]] {
+// SANITIZE-WITH-ATTR-NEXT:  entry:
+// SANITIZE-WITH-ATTR-NEXT:    [[IDXPROM:%.*]] = sext i32 [[INDEX]] to i64
+// SANITIZE-WITH-ATTR-NEXT:    [[DOTCOUNTED_BY_GEP:%.*]] = getelementptr inbounds nuw i8, ptr [[P]], i64 16
+// SANITIZE-WITH-ATTR-NEXT:    [[DOTCOUNTED_BY_LOAD:%.*]] = load i32, ptr [[DOTCOUNTED_BY_GEP]], align 4
+// SANITIZE-WITH-ATTR-NEXT:    [[TMP0:%.*]] = zext i32 [[DOTCOUNTED_BY_LOAD]] to i64, !nosanitize [[META2:![0-9]+]]
+// SANITIZE-WITH-ATTR-NEXT:    [[TMP1:%.*]] = icmp ult i64 [[IDXPROM]], [[TMP0]], !nosanitize [[META2]]
+// SANITIZE-WITH-ATTR-NEXT:    br i1 [[TMP1]], label [[CONT10:%.*]], label [[HANDLER_OUT_OF_BOUNDS:%.*]], !prof [[PROF3:![0-9]+]], !nosanitize [[META2]]
+// SANITIZE-WITH-ATTR:       handler.out_of_bounds:
+// SANITIZE-WITH-ATTR-NEXT:    tail call void @__ubsan_handle_out_of_bounds_abort(ptr nonnull @[[GLOB2:[0-9]+]], i64 [[IDXPROM]]) #[[ATTR3:[0-9]+]], !nosanitize [[META2]]
+// SANITIZE-WITH-ATTR-NEXT:    unreachable, !nosanitize [[META2]]
+// SANITIZE-WITH-ATTR:       cont10:
+// SANITIZE-WITH-ATTR-NEXT:    [[BUF:%.*]] = getelementptr inbounds nuw i8, ptr [[P]], i64 8
+// SANITIZE-WITH-ATTR-NEXT:    [[TMP2:%.*]] = load ptr, ptr [[BUF]], align 8, !tbaa [[TBAA4:![0-9]+]]
+// SANITIZE-WITH-ATTR-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds ptr, ptr [[TMP2]], i64 [[IDXPROM]]
+// SANITIZE-WITH-ATTR-NEXT:    store ptr [[VALUE]], ptr [[ARRAYIDX]], align 8, !tbaa [[TBAA12:![0-9]+]]
+// SANITIZE-WITH-ATTR-NEXT:    ret void
+//
+// NO-SANITIZE-WITH-ATTR-LABEL: define dso_local void @test1(
+// NO-SANITIZE-WITH-ATTR-SAME: ptr noundef readonly captures(none) [[P:%.*]], i32 noundef [[INDEX:%.*]], ptr noundef [[VALUE:%.*]]) local_unnamed_addr #[[ATTR0:[0-9]+]] {
+// NO-SANITIZE-WITH-ATTR-NEXT:  entry:
+// NO-SANITIZE-WITH-ATTR-NEXT:    [[BUF:%.*]] = getelementptr inbounds nuw i8, ptr [[P]], i64 8
+// NO-SANITIZE-WITH-ATTR-NEXT:    [[TMP0:%.*]] = load ptr, ptr [[BUF]], align 8, !tbaa [[TBAA2:![0-9]+]]
+// NO-SANITIZE-WITH-ATTR-NEXT:    [[IDXPROM:%.*]] = sext i32 [[INDEX]] to i64
+// NO-SANITIZE-WITH-ATTR-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds ptr, ptr [[TMP0]], i64 [[IDXPROM]]
+// NO-SANITIZE-WITH-ATTR-NEXT:    store ptr [[VALUE]], ptr [[ARRAYIDX]], align 8, !tbaa [[TBAA10:![0-9]+]]
+// NO-SANITIZE-WITH-ATTR-NEXT:    ret void
+//
+// SANITIZE-WITHOUT-ATTR-LABEL: define dso_local void @test1(
+// SANITIZE-WITHOUT-ATTR-SAME: ptr noundef [[P:%.*]], i32 noundef [[INDEX:%.*]], ptr noundef [[VALUE:%.*]]) local_unnamed_addr #[[ATTR0:[0-9]+]] {
+// SANITIZE-WITHOUT-ATTR-NEXT:  entry:
+// SANITIZE-WITHOUT-ATTR-NEXT:    [[BUF:%.*]] = getelementptr inbounds nuw i8, ptr [[P]], i64 8
+// SANITIZE-WITHOUT-ATTR-NEXT:    [[TMP0:%.*]] = load ptr, ptr [[BUF]], align 8, !tbaa [[TBAA2:![0-9]+]]
+// SANITIZE-WITHOUT-ATTR-NEXT:    [[IDXPROM:%.*]] = sext i32 [[INDEX]] to i64
+// SANITIZE-WITHOUT-ATTR-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds ptr, ptr [[TMP0]], i64 [[IDXPROM]]
+// SANITIZE-WITHOUT-ATTR-NEXT:    store ptr [[VALUE]], ptr [[ARRAYIDX]], align 8, !tbaa [[TBAA10:![0-9]+]]
+// SANITIZE-WITHOUT-ATTR-NEXT:    ret void
+//
+// NO-SANITIZE-WITHOUT-ATTR-LABEL: define dso_local void @test1(
+// NO-SANITIZE-WITHOUT-ATTR-SAME: ptr noundef readonly captures(none) [[P:%.*]], i32 noundef [[INDEX:%.*]], ptr noundef [[VALUE:%.*]]) local_unnamed_addr #[[ATTR0:[0-9]+]] {
+// NO-SANITIZE-WITHOUT-ATTR-NEXT:  entry:
+// NO-SANITIZE-WITHOUT-ATTR-NEXT:    [[BUF:%.*]] = getelementptr inbounds nuw i8, ptr [[P]], i64 8
+// NO-SANITIZE-WITHOUT-ATTR-NEXT:    [[TMP0:%.*]] = load ptr, ptr [[BUF]], align 8, !tbaa [[TBAA2:![0-9]+]]
+// NO-SANITIZE-WITHOUT-ATTR-NEXT:    [[IDXPROM:%.*]] = sext i32 [[INDEX]] to i64
+// NO-SANITIZE-WITHOUT-ATTR-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds ptr, ptr [[TMP0]], i64 [[IDXPROM]]
+// NO-SANITIZE-WITHOUT-ATTR-NEXT:    store ptr [[VALUE]], ptr [[ARRAYIDX]], align 8, !tbaa [[TBAA10:![0-9]+]]
+// NO-SANITIZE-WITHOUT-ATTR-NEXT:    ret void
+//
+void test1(struct annotated_ptr *p, int index, struct foo *value) {
+  p->buf[index] = value;
+}
+
+// SANITIZE-WITH-ATTR-LABEL: define dso_local void @test2(
+// SANITIZE-WITH-ATTR-SAME: ptr noundef [[P:%.*]], i32 noundef [[INDEX:%.*]], ptr noundef [[VALUE:%.*]]) local_unnamed_addr #[[ATTR0]] {
+// SANITIZE-WITH-ATTR-NEXT:  entry:
+// SANITIZE-WITH-ATTR-NEXT:    [[IDXPROM:%.*]] = sext i32 [[INDEX]] to i64
+// SANITIZE-WITH-ATTR-NEXT:    [[DOTCOUNTED_BY_GEP:%.*]] = getelementptr inbounds nuw i8, ptr [[P]], i64 16
+// SANITIZE-WITH-ATTR-NEXT:    [[DOTCOUNTED_BY_LOAD:%.*]] = load i32, ptr [[DOTCOUNTED_BY_GEP]], align 4
+// SANITIZE-WITH-ATTR-NEXT:    [[TMP0:%.*]] = zext i32 [[DOTCOUNTED_BY_LOAD]] to i64, !nosanitize [[META2]]
+// SANITIZE-WITH-ATTR-NEXT:    [[DOTNOT:%.*]] = icmp ugt i64 [[IDXPROM]], [[TMP0]], !nosanitize [[META2]]
+// SANITIZE-WITH-ATTR-NEXT:    br i1 [[DOTNOT]], label [[HANDLER_OUT_OF_BOUNDS:%.*]], label [[CONT10:%.*]], !prof [[PROF14:![0-9]+]], !nosanitize [[META2]]
+// SANITIZE-WITH-ATTR:       handler.out_of_bounds:
+// SANITIZE-WITH-ATTR-NEXT:    tail call void @__ubsan_handle_out_of_bounds_abort(ptr nonnull @[[GLOB3:[0-9]+]], i64 [[IDXPROM]]) #[[ATTR3]], !nosanitize [[META2]]
+// SANITIZE-WITH-ATTR-NEXT:    unreachable, !nosanitize [[META2]]
+// SANITIZE-WITH-ATTR:       cont10:
+// SANITIZE-WITH-ATTR-NEXT:    [[BUF:%.*]] = getelementptr inbounds nuw i8, ptr [[P]], i64 8
+// SANITIZE-WITH-ATTR-NEXT:    [[TMP1:%.*]] = load ptr, ptr [[BUF]], align 8, !tbaa [[TBAA4]]
+// SANITIZE-WITH-ATTR-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds ptr, ptr [[TMP1]], i64 [[IDXPROM]]
+// SANITIZE-WITH-ATTR-NEXT:    store ptr [[VALUE]], ptr [[ARRAYIDX]], align 8, !tbaa [[TBAA12]]
+// SANITIZE-WITH-ATTR-NEXT:    ret void
+//
+// NO-SANITIZE-WITH-ATTR-LABEL: define dso_local void @test2(
+// NO-SANITIZE-WITH-ATTR-SAME: ptr noundef readonly captures(none) [[P:%.*]], i32 noundef [[INDEX:%.*]], ptr noundef [[VALUE:%.*]]) local_unnamed_addr #[[ATTR0]] {
+// NO-SANITIZE-WITH-ATTR-NEXT:  entry:
+// NO-SANITIZE-WITH-ATTR-NEXT:    [[BUF:%.*]] = getelementptr inbounds nuw i8, ptr [[P]], i64 8
+// NO-SANITIZE-WITH-ATTR-NEXT:    [[TMP0:%.*]] = load ptr, ptr [[BUF]], align 8, !tbaa [[TBAA2]]
+// NO-SANITIZE-WITH-ATTR-NEXT:    [[IDXPROM:%.*]] = sext i32 [[INDEX]] to i64
+// NO-SANITIZE-WITH-ATTR-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds ptr, ptr [[TMP0]], i64 [[IDXPROM]]
+// NO-SANITIZE-WITH-ATTR-NEXT:    store ptr [[VALUE]], ptr [[ARRAYIDX]], align 8, !tbaa [[TBAA10]]
+// NO-SANITIZE-WITH-ATTR-NEXT:    ret void
+//
+// SANITIZE-WITHOUT-ATTR-LABEL: define dso_local void @test2(
+// SANITIZE-WITHOUT-ATTR-SAME: ptr noundef [[P:%.*]], i32 noundef [[INDEX:%.*]], ptr noundef [[VALUE:%.*]]) local_unnamed_addr #[[ATTR0]] {
+// SANITIZE-WITHOUT-ATTR-NEXT:  entry:
+// SANITIZE-WITHOUT-ATTR-NEXT:    [[BUF:%.*]] = getelementptr inbounds nuw i8, ptr [[P]], i64 8
+// SANITIZE-WITHOUT-ATTR-NEXT:    [[TMP0:%.*]] = load ptr, ptr [[BUF]], align 8, !tbaa [[TBAA2]]
+// SANITIZE-WITHOUT-ATTR-NEXT:    [[IDXPROM:%.*]] = sext i32 [[INDEX]] to i64
+// SANITIZE-WITHOUT-ATTR-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds ptr, ptr [[TMP0]], i64 [[IDXPROM]]
+// SANITIZE-WITHOUT-ATTR-NEXT:    store ptr [[VALUE]], ptr [[ARRAYIDX]], align 8, !tbaa [[TBAA10]]
+// SANITIZE-WITHOUT-ATTR-NEXT:    ret void
+//
+// NO-SANITIZE-WITHOUT-ATTR-LABEL: define dso_local void @test2(
+// NO-SANITIZE-WITHOUT-ATTR-SAME: ptr noundef readonly captures(none) [[P:%.*]], i32 noundef [[INDEX:%.*]], ptr noundef [[VALUE:%.*]]) local_unnamed_addr #[[ATTR0]] {
+// NO-SANITIZE-WITHOUT-ATTR-NEXT:  entry:
+// NO-SANITIZE-WITHOUT-ATTR-NEXT:    [[BUF:%.*]] = getelementptr inbounds nuw i8, ptr [[P]], i64 8
+// NO-SANITIZE-WITHOUT-ATTR-NEXT:    [[TMP0:%.*]] = load ptr, ptr [[BUF]], align 8, !tbaa [[TBAA2]]
+// NO-SANITIZE-WITHOUT-ATTR-NEXT:    [[IDXPROM:%.*]] = sext i32 [[INDEX]] to i64
+// NO-SANITIZE-WITHOUT-ATTR-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds ptr, ptr [[TMP0]], i64 [[IDXPROM]]
+// NO-SANITIZE-WITHOUT-ATTR-NEXT:    store ptr [[VALUE]], ptr [[ARRAYIDX]], align 8, !tbaa [[TBAA10]]
+// NO-SANITIZE-WITHOUT-ATTR-NEXT:    ret void
+//
+void test2(struct annotated_ptr *p, int index, struct foo *value) {
+  *&*&*&p->buf[index] = value;
+}
+
+// SANITIZE-WITH-ATTR-LABEL: define dso_local range(i64 -17179869184, 17179869177) i64 @test3(
+// SANITIZE-WITH-ATTR-SAME: ptr noundef [[P:%.*]], i32 noundef [[INDEX:%.*]]) local_unnamed_addr #[[ATTR0]] {
+// SANITIZE-WITH-ATTR-NEXT:  entry:
+// SANITIZE-WITH-ATTR-NEXT:    [[COUNTED_BY_GEP:%.*]] = getelementptr inbounds nuw i8, ptr [[P]], i64 16
+// SANITIZE-WITH-ATTR-NEXT:    [[COUNTED_BY_LOAD:%.*]] = load i32, ptr [[COUNTED_BY_GEP]], align 4
+// SANITIZE-WITH-ATTR-NEXT:    [[COUNT:%.*]] = sext i32 [[COUNTED_BY_LOAD]] to i64
+// SANITIZE-WITH-ATTR-NEXT:    [[ARRAY_SIZE:%.*]] = shl nsw i64 [[COUNT]], 3
+// SANITIZE-WITH-ATTR-NEXT:    [[TMP0:%.*]] = icmp sgt i32 [[COUNTED_BY_LOAD]], -1
+// SANITIZE-WITH-ATTR-NEXT:    [[TMP1:%.*]] = select i1 [[TMP0]], i64 [[ARRAY_SIZE]], i64 0
+// SANITIZE-WITH-ATTR-NEXT:    ret i64 [[TMP1]]
+//
+// NO-SANITIZE-WITH-ATTR-LABEL: define dso_local range(i64 -17179869184, 17179869177) i64 @test3(
+// NO-SANITIZE-WITH-ATTR-SAME: ptr noundef readonly captures(none) [[P:%.*]], i32 noundef [[INDEX:%.*]]) local_unnamed_addr #[[ATTR1:[0-9]+]] {
+// NO-SANITIZE-WITH-ATTR-NEXT:  entry:
+// NO-SANITIZE-WITH-ATTR-NEXT:    [[COUNTED_BY_GEP:%.*]] = getelementptr inbounds nuw i8, ptr [[P]], i64 16
+// NO-SANITIZE-WITH-ATTR-NEXT:    [[COUNTED_BY_LOAD:%.*]] = load i32, ptr [[COUNTED_BY_GEP]], align 4
+// NO-SANITIZE-WITH-ATTR-NEXT:    [[COUNT:%.*]] = sext i32 [[COUNTED_BY_LOAD]] to i64
+// NO-SANITIZE-WITH-ATTR-NEXT:    [[ARRAY_SIZE:%.*]] = shl nsw i64 [[COUNT]], 3
+// NO-SANITIZE-WITH-ATTR-NEXT:    [[TMP0:%.*]] = icmp sgt i32 [[COUNTED_BY_LOAD]], -1
+// NO-SANITIZE-WITH-ATTR-NEXT:    [[TMP1:%.*]] = select i1 [[TMP0]], i64 [[ARRAY_SIZE]], i64 0
+// NO-SANITIZE-WITH-ATTR-NEXT:    ret i64 [[TMP1]]
+//
+// SANITIZE-WITHOUT-ATTR-LABEL: define dso_local i64 @test3(
+// SANITIZE-WITHOUT-ATTR-SAME: ptr noundef [[P:%.*]], i32 noundef [[INDEX:%.*]]) local_unnamed_addr #[[ATTR0]] {
+// SANITIZE-WITHOUT-ATTR-NEXT:  entry:
+// SANITIZE-WITHOUT-ATTR-NEXT:    ret i64 -1
+//
+// NO-SANITIZE-WITHOUT-ATTR-LABEL: define dso_local i64 @test3(
+// NO-SANITIZE-WITHOUT-ATTR-SAME: ptr noundef readonly captures(none) [[P:%.*]], i32 noundef [[INDEX:%.*]]) local_unnamed_addr #[[ATTR1:[0-9]+]] {
+// NO-SANITIZE-WITHOUT-ATTR-NEXT:  entry:
+// NO-SANITIZE-WITHOUT-ATTR-NEXT:    ret i64 -1
+//
+size_t test3(struct annotated_ptr *p, int index) {
+  return __bdos(p->buf);
+}
+
+// SANITIZE-WITH-ATTR-LABEL: define dso_local range(i64 0, 17179869177) i64 @test4(
+// SANITIZE-WITH-ATTR-SAME: ptr noundef [[P:%.*]], i32 noundef [[INDEX:%.*]]) local_unnamed_addr #[[ATTR0]] {
+// SANITIZE-WITH-ATTR-NEXT:  entry:
+// SANITIZE-WITH-ATTR-NEXT:    [[IDXPROM:%.*]] = sext i32 [[INDEX]] to i64
+// SANITIZE-WITH-ATTR-NEXT:    [[DOTCOUNTED_BY_GEP:%.*]] = getelementptr inbounds nuw i8, ptr [[P]], i64 16
+// SANITIZE-WITH-ATTR-NEXT:    [[DOTCOUNTED_BY_LOAD:%.*]] = load i32, ptr [[DOTCOUNTED_BY_GEP]], align 4
+// SANITIZE-WITH-ATTR-NEXT:    [[TMP0:%.*]] = zext i32 [[DOTCOUNTED_BY_LOAD]] to i64, !nosanitize [[META2]]
+// SANITIZE-WITH-ATTR-NEXT:    [[DOTNOT:%.*]] = icmp ugt i64 [[IDXPROM]], [[TMP0]], !nosanitize [[META2]]
+// SANITIZE-WITH-ATTR-NEXT:    br i1 [[DOTNOT]], label [[HANDLER_OUT_OF_BOUNDS:%.*]], label [[CONT8:%.*]], !prof [[PROF14]], !nosanitize [[META2]]
+// SANITIZE-WITH-ATTR:       handler.out_of_bounds:
+// SANITIZE-WITH-ATTR-NEXT:    tail call void @__ubsan_handle_out_of_bounds_abort(ptr nonnull @[[GLOB4:[0-9]+]], i64 [[IDXPROM]]) #[[ATTR3]], !nosanitize [[META2]]
+// SANITIZE-WITH-ATTR-NEXT:    unreachable, !nosanitize [[META2]]
+// SANITIZE-WITH-ATTR:       cont8:
+// SANITIZE-WITH-ATTR-NEXT:    [[COUNT:%.*]] = sext i32 [[DOTCOUNTED_BY_LOAD]] to i64
+// SANITIZE-WITH-ATTR-NEXT:    [[TMP1:%.*]] = sub nsw i64 [[COUNT]], [[IDXPROM]]
+// SANITIZE-WITH-ATTR-NEXT:    [[TMP2:%.*]] = tail call i64 @llvm.smax.i64(i64 [[TMP1]], i64 0)
+// SANITIZE-WITH-ATTR-NEXT:    [[TMP3:%.*]] = shl nuw nsw i64 [[TMP2]], 3
+// SANITIZE-WITH-ATTR-NEXT:    ret i64 [[TMP3]]
+//
+// NO-SANITIZE-WITH-ATTR-LABEL: define dso_local range(i64 -34359738360, 34359738361) i64 @test4(
+// NO-SANITIZE-WITH-ATTR-SAME: ptr noundef readonly captures(none) [[P:%.*]], i32 noundef [[INDEX:%.*]]) local_unnamed_addr #[[ATTR1]] {
+// NO-SANITIZE-WITH-ATTR-NEXT:  entry:
+// NO-SANITIZE-WITH-ATTR-NEXT:    [[IDXPROM:%.*]] = sext i32 [[INDEX]] to i64
+// NO-SANITIZE-WITH-ATTR-NEXT:    [[COUNTED_BY_GEP:%.*]] = getelementptr inbounds nuw i8, ptr [[P]], i64 16
+// NO-SANITIZE-WITH-ATTR-NEXT:    [[COUNTED_BY_LOAD:%.*]] = load i32, ptr [[COUNTED_BY_GEP]], align 4
+// NO-SANITIZE-WITH-ATTR-NEXT:    [[COUNT:%.*]] = sext i32 [[COUNTED_BY_LOAD]] to i64
+// NO-SANITIZE-WITH-ATTR-NEXT:    [[TMP0:%.*]] = sub nsw i64 [[COUNT]], [[IDXPROM]]
+// NO-SANITIZE-WITH-ATTR-NEXT:    [[RESULT:%.*]] = shl nsw i64 [[TMP0]], 3
+// NO-SANITIZE-WITH-ATTR-NEXT:    [[TMP1:%.*]] = icmp sgt i64 [[TMP0]], -1
+// NO-SANITIZE-WITH-ATTR-NEXT:    [[TMP2:%.*]] = icmp sgt i32 [[INDEX]], -1
+// NO-SANITIZE-WITH-ATTR-NEXT:    [[TMP3:%.*]] = and i1 [[TMP2]], [[TMP1]]
+// NO-SANITIZE-WITH-ATTR-NEXT:    [[TMP4:%.*]] = select i1 [[TMP3]], i64 [[RESULT]], i64 0
+// NO-SANITIZE-WITH-ATTR-NEXT:    ret i64 [[TMP4]]
+//
+// SANITIZE-WITHOUT-ATTR-LABEL: define dso_local i64 @test4(
+// SANITIZE-WITHOUT-ATTR-SAME: ptr noundef [[P:%.*]], i32 noundef [[INDEX:%.*]]) local_unnamed_addr #[[ATTR0]] {
+// SANITIZE-WITHOUT-ATTR-NEXT:  entry:
+// SANITIZE-WITHOUT-ATTR-NEXT:    ret i64 -1
+//
+// NO-SANITIZE-WITHOUT-ATTR-LABEL: define dso_local i64 @test4(
+// NO-SANITIZE-WITHOUT-ATTR-SAME: ptr noundef readonly captures(none) [[P:%.*]], i32 noundef [[INDEX:%.*]]) local_unnamed_addr #[[ATTR1]] {
+// NO-SANITIZE-WITHOUT-ATTR-NEXT:  entry:
+// NO-SANITIZE-WITHOUT-ATTR-NEXT:    ret i64 -1
+//
+size_t test4(struct annotated_ptr *p, int index) {
+  return __bdos(&p->buf[index]);
+}



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