From 930c05c32eac171ef1a94fabf80aecb4e6e2c840 Mon Sep 17 00:00:00 2001 From: Richard Smith Date: Wed, 10 Oct 2012 01:11:12 +0000 Subject: -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 --- lib/CodeGen/CodeGenFunction.cpp | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) (limited to 'lib/CodeGen/CodeGenFunction.cpp') diff --git a/lib/CodeGen/CodeGenFunction.cpp b/lib/CodeGen/CodeGenFunction.cpp index d7fcf9f8b2..9c0b1aa549 100644 --- a/lib/CodeGen/CodeGenFunction.cpp +++ b/lib/CodeGen/CodeGenFunction.cpp @@ -1043,6 +1043,7 @@ CodeGenFunction::getVLASize(const VariableArrayType *type) { 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 @@ void CodeGenFunction::EmitVariablyModifiedType(QualType type) { // 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); } } -- cgit v1.2.3-18-g5258