[PATCH] D91828: [Sema/Attribute] Ignore noderef attribute in unevaluated context
Jann Horn via Phabricator via cfe-commits
cfe-commits at lists.llvm.org
Fri Nov 20 15:23:03 PST 2020
thejh updated this revision to Diff 306792.
thejh marked an inline comment as done.
thejh added a comment.
As requested by @aaron.ballman, added tests for edgecases where
sizeof()/typeid() can cause memory access.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D91828/new/
https://reviews.llvm.org/D91828
Files:
clang/lib/Sema/SemaExpr.cpp
clang/lib/Sema/SemaExprMember.cpp
clang/test/Frontend/noderef.c
clang/test/Frontend/noderef.cpp
Index: clang/test/Frontend/noderef.cpp
===================================================================
--- clang/test/Frontend/noderef.cpp
+++ clang/test/Frontend/noderef.cpp
@@ -6,6 +6,11 @@
#define NODEREF __attribute__((noderef))
+// Stub out types for 'typeid' to work.
+namespace std {
+class type_info {};
+} // namespace std
+
void Normal() {
int NODEREF i; // expected-warning{{'noderef' can only be used on an array or pointer type}}
int NODEREF *i_ptr; // expected-note 2 {{i_ptr declared here}}
@@ -102,6 +107,18 @@
return child->func(); // expected-warning{{dereferencing child; was declared with a 'noderef' type}}
}
+std::type_info TypeIdPolymorphic(NODEREF A *a) { // expected-note{{a declared here}}
+ return typeid(*a); // expected-warning{{dereferencing a; was declared with a 'noderef' type}}
+}
+
+class SimpleClass {
+ int a;
+};
+
+std::type_info TypeIdNonPolymorphic(NODEREF SimpleClass *simple) {
+ return typeid(*simple);
+}
+
template <class Ty>
class B {
Ty NODEREF *member;
Index: clang/test/Frontend/noderef.c
===================================================================
--- clang/test/Frontend/noderef.c
+++ clang/test/Frontend/noderef.c
@@ -57,12 +57,19 @@
p = &*(p + 1);
// Struct member access
- struct S NODEREF *s; // expected-note 2 {{s declared here}}
+ struct S NODEREF *s; // expected-note 3 {{s declared here}}
x = s->a; // expected-warning{{dereferencing s; was declared with a 'noderef' type}}
x = (*s).b; // expected-warning{{dereferencing s; was declared with a 'noderef' type}}
p = &s->a;
p = &(*s).b;
+ // Most things in sizeof() can't actually access memory
+ x = sizeof(s->a); // ok
+ x = sizeof(*s); // ok
+ x = sizeof(s[0]); // ok
+ x = sizeof(s->a + (s->b)); // ok
+ x = sizeof(int[++s->a]); // expected-warning{{dereferencing s; was declared with a 'noderef' type}}
+
// Nested struct access
struct S2 NODEREF *s2_noderef; // expected-note 5 {{s2_noderef declared here}}
p = s2_noderef->a; // ok since result is an array in a struct
Index: clang/lib/Sema/SemaExprMember.cpp
===================================================================
--- clang/lib/Sema/SemaExprMember.cpp
+++ clang/lib/Sema/SemaExprMember.cpp
@@ -1734,6 +1734,9 @@
}
void Sema::CheckMemberAccessOfNoDeref(const MemberExpr *E) {
+ if (isUnevaluatedContext())
+ return;
+
QualType ResultTy = E->getType();
// Do not warn on member accesses to arrays since this returns an array
Index: clang/lib/Sema/SemaExpr.cpp
===================================================================
--- clang/lib/Sema/SemaExpr.cpp
+++ clang/lib/Sema/SemaExpr.cpp
@@ -4751,6 +4751,9 @@
}
void Sema::CheckSubscriptAccessOfNoDeref(const ArraySubscriptExpr *E) {
+ if (isUnevaluatedContext())
+ return;
+
QualType ResultTy = E->getType();
ExpressionEvaluationContextRecord &LastRecord = ExprEvalContexts.back();
@@ -14666,7 +14669,8 @@
OpLoc, CanOverflow, CurFPFeatureOverrides());
if (Opc == UO_Deref && UO->getType()->hasAttr(attr::NoDeref) &&
- !isa<ArrayType>(UO->getType().getDesugaredType(Context)))
+ !isa<ArrayType>(UO->getType().getDesugaredType(Context)) &&
+ !isUnevaluatedContext())
ExprEvalContexts.back().PossibleDerefs.insert(UO);
// Convert the result back to a half vector.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: D91828.306792.patch
Type: text/x-patch
Size: 3450 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20201120/ddf494b3/attachment.bin>
More information about the cfe-commits
mailing list