Expand array bounds checking to work in the presence of unary & and *,

and to work with pointer arithmetic in addition to array indexing.

The new pointer arithmetic porition of the array bounds checking can be
turned on by -Warray-bounds-pointer-arithmetic (and is off by default).


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@136046 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 17 insertions, 0 deletions

diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 4a9b4bcfdf..bb7e3d8669 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -268,6 +268,7 @@ ExprResult Sema::DefaultFunctionArrayConversion(Expr *E) {
     E = ImpCastExprToType(E, Context.getPointerType(Ty),
                           CK_FunctionToPointerDecay).take();
   else if (Ty->isArrayType()) {
+    CheckArrayAccess(E);
     // In C90 mode, arrays only promote to pointers if the array expression is
     // an lvalue.  The relevant legalese is C90 6.2.2.1p3: "an lvalue that has
     // type 'array of type' is converted to an expression that has type 'pointer
@@ -310,6 +311,7 @@ ExprResult Sema::DefaultLvalueConversion(Expr *E) {
   //   A glvalue of a non-function, non-array type T can be
   //   converted to a prvalue.
   if (!E->isGLValue()) return Owned(E);
+
   QualType T = E->getType();
   assert(!T.isNull() && "r-value conversion on typeless expression?");
 
@@ -385,6 +387,14 @@ ExprResult Sema::UsualUnaryConversions(Expr *E) {
   QualType Ty = E->getType();
   assert(!Ty.isNull() && "UsualUnaryConversions - missing type");
   
+  if (Ty->isPointerType() || Ty->isArrayType()) {
+    Expr *subE = E->IgnoreParenImpCasts();
+    while (UnaryOperator *UO = dyn_cast<UnaryOperator>(subE)) {
+      subE = UO->getSubExpr()->IgnoreParenImpCasts();
+    }
+    if (subE) CheckArrayAccess(subE);
+  }
+
   // Try to perform integral promotions if the object has a theoretically
   // promotable type.
   if (Ty->isIntegralOrUnscopedEnumerationType()) {
@@ -5812,6 +5822,8 @@ QualType Sema::CheckAdditionOperands( // C99 6.5.6
         return QualType();
       }
 
+      CheckArrayAccess(PExp, IExp);
+
       if (CompLHSTy) {
         QualType LHSTy = Context.isPromotableBitField(lex.get());
         if (LHSTy.isNull()) {
@@ -5866,6 +5878,11 @@ QualType Sema::CheckSubtractionOperands(ExprResult &lex, ExprResult &rex,
       if (!checkArithmeticOpPointerOperand(*this, Loc, lex.get()))
         return QualType();
 
+      Expr *IExpr = rex.get()->IgnoreParenCasts();
+      UnaryOperator negRex(IExpr, UO_Minus, IExpr->getType(), VK_RValue,
+                           OK_Ordinary, IExpr->getExprLoc());
+      CheckArrayAccess(lex.get()->IgnoreParenCasts(), &negRex);
+
       if (CompLHSTy) *CompLHSTy = lex.get()->getType();
       return lex.get()->getType();
     }