Emit an error if an array is too large. We're slightly more strict

than GCC 4.2 here when building 32-bit (where GCC will allow
allocation of an array for which we can't get a valid past-the-end
pointer), and emulate its odd behavior in 64-bit where it only allows
63 bits worth of storage in the array. The former is a correctness
issue; the latter is harmless in practice (you wouldn't be able to use
such an array anyway) and helps us pass a GCC DejaGNU test.

Fixes <rdar://problem/8212293>.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@111338 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/clang/AST/Type.h b/include/clang/AST/Type.h
index 7a522f42fa33f530c9fecabe6d09bbcb07a0b341..4a9f10a8707e34d124cea2cbd01bc8338723d718 100644 (file)
--- a/include/clang/AST/Type.h
+++ b/include/clang/AST/Type.h
@@ -1458,6 +1458,17 @@ public:
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
+  
+  /// \brief Determine the number of bits required to address a member of
+  // an array with the given element type and number of elements.
+  static unsigned getNumAddressingBits(ASTContext &Context,
+                                       QualType ElementType,
+                                       const llvm::APInt &NumElements);
+  
+  /// \brief Determine the maximum number of active bits that an array's size
+  /// can require, which limits the maximum size of the array.
+  static unsigned getMaxSizeBits(ASTContext &Context);
+  
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, getElementType(), getSize(),
             getSizeModifier(), getIndexTypeCVRQualifiers());

diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index f20c19924640c2d6321e908c7835e578a74ebee7..b333a833b0030ad3196eb11c6e4c56af09f10fa2 100644 (file)
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -1797,6 +1797,8 @@ def err_typecheck_field_variable_size : Error<
   "extension will never be supported">;
 def err_vm_func_decl : Error<
   "function declaration cannot have variably modified type">;
+def err_array_too_large : Error<
+  "array is too large (%0 elements)">;
 
 def err_typecheck_negative_array_size : Error<"array size is negative">;
 def warn_typecheck_function_qualifiers : Warning<

diff --git a/lib/AST/Type.cpp b/lib/AST/Type.cpp
index 31af6fb6619d98b887aa3478bdbf9f8cb4362a8f..4ab463699c8f6738f621c6025d4e791ea9ce95bf 100644 (file)
--- a/lib/AST/Type.cpp
+++ b/lib/AST/Type.cpp
@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "clang/AST/ASTContext.h"
+#include "clang/AST/CharUnits.h"
 #include "clang/AST/Type.h"
 #include "clang/AST/DeclCXX.h"
 #include "clang/AST/DeclObjC.h"
@@ -21,6 +22,7 @@
 #include "clang/Basic/Specifiers.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/raw_ostream.h"
+#include <algorithm>
 using namespace clang;
 
 bool QualType::isConstant(QualType T, ASTContext &Ctx) {
@@ -35,6 +37,32 @@ bool QualType::isConstant(QualType T, ASTContext &Ctx) {
 
 Type::~Type() { }
 
+unsigned ConstantArrayType::getNumAddressingBits(ASTContext &Context,
+                                                 QualType ElementType,
+                                               const llvm::APInt &NumElements) {
+  llvm::APSInt SizeExtended(NumElements, true);
+  unsigned SizeTypeBits = Context.getTypeSize(Context.getSizeType());
+  SizeExtended.extend(std::max(SizeTypeBits, SizeExtended.getBitWidth()) * 2);
+
+  uint64_t ElementSize
+    = Context.getTypeSizeInChars(ElementType).getQuantity();
+  llvm::APSInt TotalSize(llvm::APInt(SizeExtended.getBitWidth(), ElementSize));
+  TotalSize *= SizeExtended;  
+  
+  return TotalSize.getActiveBits();
+}
+
+unsigned ConstantArrayType::getMaxSizeBits(ASTContext &Context) {
+  unsigned Bits = Context.getTypeSize(Context.getSizeType());
+  
+  // GCC appears to only allow 63 bits worth of address space when compiling
+  // for 64-bit, so we do the same.
+  if (Bits == 64)
+    --Bits;
+  
+  return Bits;
+}
+
 void DependentSizedArrayType::Profile(llvm::FoldingSetNodeID &ID,
                                       ASTContext &Context,
                                       QualType ET,

diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 550dcb8aeb7168bdbe899d63aa93648622cc6480..dfbc7e1559b64c3d04c33314c7dc03fed5e599d1 100644 (file)
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -2364,20 +2364,26 @@ Sema::HandleDeclarator(Scope *S, Declarator &D,
 /// be errors (for GCC compatibility).
 static QualType TryToFixInvalidVariablyModifiedType(QualType T,
                                                     ASTContext &Context,
-                                                    bool &SizeIsNegative) {
+                                                    bool &SizeIsNegative,
+                                                    llvm::APSInt &Oversized) {
   // This method tries to turn a variable array into a constant
   // array even when the size isn't an ICE.  This is necessary
   // for compatibility with code that depends on gcc's buggy
   // constant expression folding, like struct {char x[(int)(char*)2];}
   SizeIsNegative = false;
-
+  Oversized = 0;
+  
+  if (T->isDependentType())
+    return QualType();
+  
   QualifierCollector Qs;
   const Type *Ty = Qs.strip(T);
 
   if (const PointerType* PTy = dyn_cast<PointerType>(Ty)) {
     QualType Pointee = PTy->getPointeeType();
     QualType FixedType =
-        TryToFixInvalidVariablyModifiedType(Pointee, Context, SizeIsNegative);
+        TryToFixInvalidVariablyModifiedType(Pointee, Context, SizeIsNegative,
+                                            Oversized);
     if (FixedType.isNull()) return FixedType;
     FixedType = Context.getPointerType(FixedType);
     return Qs.apply(FixedType);
@@ -2396,15 +2402,24 @@ static QualType TryToFixInvalidVariablyModifiedType(QualType T,
       !EvalResult.Val.isInt())
     return QualType();
 
+  // Check whether the array size is negative.
   llvm::APSInt &Res = EvalResult.Val.getInt();
-  if (Res >= llvm::APSInt(Res.getBitWidth(), Res.isUnsigned())) {
-    // TODO: preserve the size expression in declarator info
-    return Context.getConstantArrayType(VLATy->getElementType(),
-                                        Res, ArrayType::Normal, 0);
+  if (Res.isSigned() && Res.isNegative()) {
+    SizeIsNegative = true;
+    return QualType();
   }
 
-  SizeIsNegative = true;
-  return QualType();
+  // Check whether the array is too large to be addressed.
+  unsigned ActiveSizeBits
+    = ConstantArrayType::getNumAddressingBits(Context, VLATy->getElementType(),
+                                              Res);
+  if (ActiveSizeBits > ConstantArrayType::getMaxSizeBits(Context)) {
+    Oversized = Res;
+    return QualType();
+  }
+  
+  return Context.getConstantArrayType(VLATy->getElementType(),
+                                      Res, ArrayType::Normal, 0);
 }
 
 /// \brief Register the given locally-scoped external C declaration so
@@ -2501,8 +2516,10 @@ Sema::ActOnTypedefDeclarator(Scope* S, Declarator& D, DeclContext* DC,
 
     if (S->getFnParent() == 0) {
       bool SizeIsNegative;
+      llvm::APSInt Oversized;
       QualType FixedTy =
-          TryToFixInvalidVariablyModifiedType(T, Context, SizeIsNegative);
+          TryToFixInvalidVariablyModifiedType(T, Context, SizeIsNegative,
+                                              Oversized);
       if (!FixedTy.isNull()) {
         Diag(D.getIdentifierLoc(), diag::warn_illegal_constant_array_size);
         NewTD->setTypeSourceInfo(Context.getTrivialTypeSourceInfo(FixedTy));
@@ -2511,6 +2528,9 @@ Sema::ActOnTypedefDeclarator(Scope* S, Declarator& D, DeclContext* DC,
           Diag(D.getIdentifierLoc(), diag::err_typecheck_negative_array_size);
         else if (T->isVariableArrayType())
           Diag(D.getIdentifierLoc(), diag::err_vla_decl_in_file_scope);
+        else if (Oversized.getBoolValue())
+          Diag(D.getIdentifierLoc(), diag::err_array_too_large)
+            << Oversized.toString(10);
         else
           Diag(D.getIdentifierLoc(), diag::err_vm_decl_in_file_scope);
         NewTD->setInvalidDecl();
@@ -2931,8 +2951,10 @@ void Sema::CheckVariableDeclaration(VarDecl *NewVD,
   if ((isVM && NewVD->hasLinkage()) ||
       (T->isVariableArrayType() && NewVD->hasGlobalStorage())) {
     bool SizeIsNegative;
+    llvm::APSInt Oversized;
     QualType FixedTy =
-        TryToFixInvalidVariablyModifiedType(T, Context, SizeIsNegative);
+        TryToFixInvalidVariablyModifiedType(T, Context, SizeIsNegative,
+                                            Oversized);
 
     if (FixedTy.isNull() && T->isVariableArrayType()) {
       const VariableArrayType *VAT = Context.getAsVariableArrayType(T);
@@ -5965,14 +5987,19 @@ FieldDecl *Sema::CheckFieldDecl(DeclarationName Name, QualType T,
   // than a variably modified type.
   if (!InvalidDecl && T->isVariablyModifiedType()) {
     bool SizeIsNegative;
+    llvm::APSInt Oversized;
     QualType FixedTy = TryToFixInvalidVariablyModifiedType(T, Context,
-                                                           SizeIsNegative);
+                                                           SizeIsNegative,
+                                                           Oversized);
     if (!FixedTy.isNull()) {
       Diag(Loc, diag::warn_illegal_constant_array_size);
       T = FixedTy;
     } else {
       if (SizeIsNegative)
         Diag(Loc, diag::err_typecheck_negative_array_size);
+      else if (Oversized.getBoolValue())
+        Diag(Loc, diag::err_array_too_large)
+          << Oversized.toString(10);
       else
         Diag(Loc, diag::err_typecheck_field_variable_size);
       InvalidDecl = true;

diff --git a/lib/Sema/SemaExprCXX.cpp b/lib/Sema/SemaExprCXX.cpp
index 35e679f53e778a3abc6a7d7a13bd3a451f9b9515..5e46090c0588f7274d1b6113ed325c808078378f 100644 (file)
--- a/lib/Sema/SemaExprCXX.cpp
+++ b/lib/Sema/SemaExprCXX.cpp
@@ -716,8 +716,20 @@ Sema::BuildCXXNew(SourceLocation StartLoc, bool UseGlobal,
                         llvm::APInt::getNullValue(Value.getBitWidth()), 
                                  Value.isUnsigned()))
           return ExprError(Diag(ArraySize->getSourceRange().getBegin(),
-                           diag::err_typecheck_negative_array_size)
+                                diag::err_typecheck_negative_array_size)
             << ArraySize->getSourceRange());
+        
+        if (!AllocType->isDependentType()) {
+          unsigned ActiveSizeBits
+            = ConstantArrayType::getNumAddressingBits(Context, AllocType, Value);
+          if (ActiveSizeBits > ConstantArrayType::getMaxSizeBits(Context)) {
+            Diag(ArraySize->getSourceRange().getBegin(), 
+                 diag::err_array_too_large)
+              << Value.toString(10)
+              << ArraySize->getSourceRange();
+            return ExprError();
+          }
+        }
       } else if (TypeIdParens.isValid()) {
         // Can't have dynamic array size when the type-id is in parentheses.
         Diag(ArraySize->getLocStart(), diag::ext_new_paren_array_nonconst)

diff --git a/lib/Sema/SemaType.cpp b/lib/Sema/SemaType.cpp
index 6df16bd300b190ae215d35f49e5e7f89138404c5..accd7e63ed866c285fc85cea0fb14ba19268d13e 100644 (file)
--- a/lib/Sema/SemaType.cpp
+++ b/lib/Sema/SemaType.cpp
@@ -677,7 +677,7 @@ QualType Sema::BuildArrayType(QualType T, ArrayType::ArraySizeModifier ASM,
       << ArraySize->getType() << ArraySize->getSourceRange();
     return QualType();
   }
-  llvm::APSInt ConstVal(32);
+  llvm::APSInt ConstVal(Context.getTypeSize(Context.getSizeType()));
   if (!ArraySize) {
     if (ASM == ArrayType::Star)
       T = Context.getVariableArrayType(T, 0, ASM, Quals, Brackets);
@@ -707,7 +707,17 @@ QualType Sema::BuildArrayType(QualType T, ArrayType::ArraySizeModifier ASM,
            isSFINAEContext()? diag::err_typecheck_zero_array_size
                             : diag::ext_typecheck_zero_array_size)
         << ArraySize->getSourceRange();
+    } else if (!T->isDependentType() && !T->isVariablyModifiedType() && 
+               !T->isIncompleteType()) {
+      // Is the array too large?      
+      unsigned ActiveSizeBits
+        = ConstantArrayType::getNumAddressingBits(Context, T, ConstVal);
+      if (ActiveSizeBits > ConstantArrayType::getMaxSizeBits(Context))
+        Diag(ArraySize->getLocStart(), diag::err_array_too_large)
+          << ConstVal.toString(10)
+          << ArraySize->getSourceRange();
     }
+    
     T = Context.getConstantArrayType(T, ConstVal, ASM, Quals);
   }
   // If this is not C99, extwarn about VLA's and C99 array size modifiers.

diff --git a/test/Sema/array-size-64.c b/test/Sema/array-size-64.c
new file mode 100644 (file)
index 0000000..f22e8e7
--- /dev/null
+++ b/test/Sema/array-size-64.c
@@ -0,0 +1,7 @@
+// RUN: %clang_cc1 -triple x86_64-apple-darwin -verify %s
+
+void f() {
+  int a[2147483647U][2147483647U]; // expected-error{{array is too large}}
+  int b[1073741825U - 1U][2147483647U];
+  int c[18446744073709551615U/sizeof(int)/2];
+}

diff --git a/test/Sema/array-size.c b/test/Sema/array-size.c
new file mode 100644 (file)
index 0000000..7580e3e
--- /dev/null
+++ b/test/Sema/array-size.c
@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 -triple i686-apple-darwin -verify %s
+
+void f() {
+  int x0[1073741824]; // expected-error{{array is too large}}
+  int x1[1073741824 + 1]; // expected-error{{array is too large}}
+  int x2[(unsigned)1073741824]; // expected-error{{array is too large}}
+  int x3[(unsigned)1073741824 + 1]; // expected-error{{array is too large}}
+  int x4[1073741824 - 1];
+}
+