-fcatch-undefined-behavior: catch a VLA bound which evalutes to a non-positive value.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@165583 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CodeGenFunction.cpp b/lib/CodeGen/CodeGenFunction.cpp
index d7fcf9f..9c0b1aa 100644
--- a/lib/CodeGen/CodeGenFunction.cpp
+++ b/lib/CodeGen/CodeGenFunction.cpp
@@ -1043,6 +1043,7 @@
numElements = vlaSize;
} else {
// It's undefined behavior if this wraps around, so mark it that way.
+ // FIXME: Teach -fcatch-undefined-behavior to trap this.
numElements = Builder.CreateNUWMul(numElements, vlaSize);
}
} while ((type = getContext().getAsVariableArrayType(elementType)));
@@ -1120,9 +1121,25 @@
// e.g. with a typedef and a pointer to it.
llvm::Value *&entry = VLASizeMap[size];
if (!entry) {
+ llvm::Value *Size = EmitScalarExpr(size);
+
+ // C11 6.7.6.2p5:
+ // If the size is an expression that is not an integer constant
+ // expression [...] each time it is evaluated it shall have a value
+ // greater than zero.
+ if (CatchUndefined && size->getType()->isSignedIntegerType()) {
+ llvm::Value *Zero = llvm::Constant::getNullValue(Size->getType());
+ llvm::Constant *StaticArgs[] = {
+ EmitCheckSourceLocation(size->getLocStart()),
+ EmitCheckTypeDescriptor(size->getType())
+ };
+ EmitCheck(Builder.CreateICmpSGT(Size, Zero),
+ "vla_bound_not_positive", StaticArgs, Size);
+ }
+
// Always zexting here would be wrong if it weren't
// undefined behavior to have a negative bound.
- entry = Builder.CreateIntCast(EmitScalarExpr(size), SizeTy,
+ entry = Builder.CreateIntCast(Size, SizeTy,
/*signed*/ false);
}
}