r303957 - Create valid LValue to represent null pointers in constant exprs
Tim Northover via cfe-commits
cfe-commits at lists.llvm.org
Thu May 25 19:16:00 PDT 2017
Author: tnorthover
Date: Thu May 25 21:16:00 2017
New Revision: 303957
URL: http://llvm.org/viewvc/llvm-project?rev=303957&view=rev
Log:
Create valid LValue to represent null pointers in constant exprs
We were leaving the SubobjectDesignator in a surprising situation, where
it was allegedly valid but didn't actually refer to a type. This caused
a crash later on.
This patch fills out the SubobjectDesignator with the pointee type (as
happens in other evaluations of constant pointers) so that we don't
crash later.
Added:
cfe/trunk/test/SemaCXX/null-cast.cpp
Modified:
cfe/trunk/lib/AST/ExprConstant.cpp
Modified: cfe/trunk/lib/AST/ExprConstant.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ExprConstant.cpp?rev=303957&r1=303956&r2=303957&view=diff
==============================================================================
--- cfe/trunk/lib/AST/ExprConstant.cpp (original)
+++ cfe/trunk/lib/AST/ExprConstant.cpp Thu May 25 21:16:00 2017
@@ -1230,8 +1230,7 @@ namespace {
IsNullPtr = V.isNullPointer();
}
- void set(APValue::LValueBase B, unsigned I = 0, bool BInvalid = false,
- bool IsNullPtr_ = false, uint64_t Offset_ = 0) {
+ void set(APValue::LValueBase B, unsigned I = 0, bool BInvalid = false) {
#ifndef NDEBUG
// We only allow a few types of invalid bases. Enforce that here.
if (BInvalid) {
@@ -1242,11 +1241,20 @@ namespace {
#endif
Base = B;
- Offset = CharUnits::fromQuantity(Offset_);
+ Offset = CharUnits::fromQuantity(0);
InvalidBase = BInvalid;
CallIndex = I;
Designator = SubobjectDesignator(getType(B));
- IsNullPtr = IsNullPtr_;
+ IsNullPtr = false;
+ }
+
+ void setNull(QualType PointerTy, uint64_t TargetVal) {
+ Base = (Expr *)nullptr;
+ Offset = CharUnits::fromQuantity(TargetVal);
+ InvalidBase = false;
+ CallIndex = 0;
+ Designator = SubobjectDesignator(PointerTy->getPointeeType());
+ IsNullPtr = true;
}
void setInvalid(APValue::LValueBase B, unsigned I = 0) {
@@ -5494,8 +5502,8 @@ public:
return true;
}
bool ZeroInitialization(const Expr *E) {
- auto Offset = Info.Ctx.getTargetNullPointerValue(E->getType());
- Result.set((Expr*)nullptr, 0, false, true, Offset);
+ auto TargetVal = Info.Ctx.getTargetNullPointerValue(E->getType());
+ Result.setNull(E->getType(), TargetVal);
return true;
}
Added: cfe/trunk/test/SemaCXX/null-cast.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/null-cast.cpp?rev=303957&view=auto
==============================================================================
--- cfe/trunk/test/SemaCXX/null-cast.cpp (added)
+++ cfe/trunk/test/SemaCXX/null-cast.cpp Thu May 25 21:16:00 2017
@@ -0,0 +1,8 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+struct A {};
+struct B : virtual A {};
+
+void foo() {
+ (void)static_cast<A&>(*(B *)0); // expected-warning {{binding dereferenced null pointer to reference has undefined behavior}}
+}
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