https://github.com/tbaederr created
https://github.com/llvm/llvm-project/pull/68888
Instead of (ab)using incomplete array types for this, add a 'Dummy' bit to
Descriptor. We need to be able to differentiate between the two when adding an
offset.
>From 03184302329bfd3e02cd97ccfa26613379d8767f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timm=20B=C3=A4der?= <tbae...@redhat.com>
Date: Thu, 12 Oct 2023 15:27:38 +0200
Subject: [PATCH] [clang][Interp] Add explicit dummy descriptors
Instead of (ab)using incomplete array types for this, add a 'Dummy' bit
to Descriptor. We need to be able to differentiate between the two when
adding an offset.
---
clang/lib/AST/Interp/Descriptor.cpp | 7 +++++++
clang/lib/AST/Interp/Descriptor.h | 6 ++++++
clang/lib/AST/Interp/Interp.cpp | 6 ++++++
clang/lib/AST/Interp/Interp.h | 20 ++++++++++++++------
clang/lib/AST/Interp/InterpBuiltin.cpp | 3 +++
clang/lib/AST/Interp/Pointer.h | 2 ++
clang/lib/AST/Interp/Program.cpp | 20 +++++++++++---------
clang/test/AST/Interp/c.c | 10 ++++++++++
8 files changed, 59 insertions(+), 15 deletions(-)
diff --git a/clang/lib/AST/Interp/Descriptor.cpp
b/clang/lib/AST/Interp/Descriptor.cpp
index 4ecb7466998e705..56e03a32abe5c34 100644
--- a/clang/lib/AST/Interp/Descriptor.cpp
+++ b/clang/lib/AST/Interp/Descriptor.cpp
@@ -284,6 +284,13 @@ Descriptor::Descriptor(const DeclTy &D, Record *R,
MetadataSize MD,
assert(Source && "Missing source");
}
+Descriptor::Descriptor(const DeclTy &D, MetadataSize MD)
+ : Source(D), ElemSize(1), Size(ElemSize), MDSize(MD.value_or(0)),
+ AllocSize(Size + MDSize), ElemRecord(nullptr), IsConst(true),
+ IsMutable(false), IsTemporary(false), IsDummy(true) {
+ assert(Source && "Missing source");
+}
+
QualType Descriptor::getType() const {
if (auto *E = asExpr())
return E->getType();
diff --git a/clang/lib/AST/Interp/Descriptor.h
b/clang/lib/AST/Interp/Descriptor.h
index 55a754c3505cce7..8de637a31a0ffff 100644
--- a/clang/lib/AST/Interp/Descriptor.h
+++ b/clang/lib/AST/Interp/Descriptor.h
@@ -109,6 +109,8 @@ struct Descriptor final {
const bool IsTemporary = false;
/// Flag indicating if the block is an array.
const bool IsArray = false;
+ /// Flag indicating if this is a dummy descriptor.
+ const bool IsDummy = false;
/// Storage management methods.
const BlockCtorFn CtorFn = nullptr;
@@ -137,6 +139,8 @@ struct Descriptor final {
Descriptor(const DeclTy &D, Record *R, MetadataSize MD, bool IsConst,
bool IsTemporary, bool IsMutable);
+ Descriptor(const DeclTy &D, MetadataSize MD);
+
QualType getType() const;
QualType getElemQualType() const;
SourceLocation getLocation() const;
@@ -190,6 +194,8 @@ struct Descriptor final {
bool isArray() const { return IsArray; }
/// Checks if the descriptor is of a record.
bool isRecord() const { return !IsArray && ElemRecord; }
+ /// Checks if this is a dummy descriptor.
+ bool isDummy() const { return IsDummy; }
};
/// Bitfield tracking the initialisation status of elements of primitive
arrays.
diff --git a/clang/lib/AST/Interp/Interp.cpp b/clang/lib/AST/Interp/Interp.cpp
index a4d6844ebe61722..1d14241106a63eb 100644
--- a/clang/lib/AST/Interp/Interp.cpp
+++ b/clang/lib/AST/Interp/Interp.cpp
@@ -186,6 +186,10 @@ bool CheckLive(InterpState &S, CodePtr OpPC, const Pointer
&Ptr,
return true;
}
+bool CheckDummy(InterpState &S, CodePtr OpPC, const Pointer &Ptr) {
+ return !Ptr.isDummy();
+}
+
bool CheckNull(InterpState &S, CodePtr OpPC, const Pointer &Ptr,
CheckSubobjectKind CSK) {
if (!Ptr.isZero())
@@ -268,6 +272,8 @@ bool CheckInitialized(InterpState &S, CodePtr OpPC, const
Pointer &Ptr,
}
bool CheckLoad(InterpState &S, CodePtr OpPC, const Pointer &Ptr) {
+ if (!CheckDummy(S, OpPC, Ptr))
+ return false;
if (!CheckLive(S, OpPC, Ptr, AK_Read))
return false;
if (!CheckExtern(S, OpPC, Ptr))
diff --git a/clang/lib/AST/Interp/Interp.h b/clang/lib/AST/Interp/Interp.h
index 1ad3b8bfc7711d3..4d2cd9dc2ae8c1d 100644
--- a/clang/lib/AST/Interp/Interp.h
+++ b/clang/lib/AST/Interp/Interp.h
@@ -55,6 +55,10 @@ bool CheckArray(InterpState &S, CodePtr OpPC, const Pointer
&Ptr);
/// Checks if a pointer is live and accessible.
bool CheckLive(InterpState &S, CodePtr OpPC, const Pointer &Ptr,
AccessKinds AK);
+
+/// Checks if a pointer is a dummy pointer.
+bool CheckDummy(InterpState &S, CodePtr OpPC, const Pointer &Ptr);
+
/// Checks if a pointer is null.
bool CheckNull(InterpState &S, CodePtr OpPC, const Pointer &Ptr,
CheckSubobjectKind CSK);
@@ -1423,8 +1427,9 @@ bool OffsetHelper(InterpState &S, CodePtr OpPC, const T
&Offset,
// Compute the largest index into the array.
unsigned MaxIndex = Ptr.getNumElems();
+ bool Invalid = false;
// Helper to report an invalid offset, computed as APSInt.
- auto InvalidOffset = [&]() {
+ auto DiagInvalidOffset = [&]() -> void {
const unsigned Bits = Offset.bitWidth();
APSInt APOffset(Offset.toAPSInt().extend(Bits + 2), false);
APSInt APIndex(Index.toAPSInt().extend(Bits + 2), false);
@@ -1434,28 +1439,31 @@ bool OffsetHelper(InterpState &S, CodePtr OpPC, const T
&Offset,
<< NewIndex
<< /*array*/ static_cast<int>(!Ptr.inArray())
<< static_cast<unsigned>(MaxIndex);
- return false;
+ Invalid = true;
};
unsigned MaxOffset = MaxIndex - Ptr.getIndex();
if constexpr (Op == ArithOp::Add) {
// If the new offset would be negative, bail out.
if (Offset.isNegative() && (Offset.isMin() || -Offset > Index))
- return InvalidOffset();
+ DiagInvalidOffset();
// If the new offset would be out of bounds, bail out.
if (Offset.isPositive() && Offset > MaxOffset)
- return InvalidOffset();
+ DiagInvalidOffset();
} else {
// If the new offset would be negative, bail out.
if (Offset.isPositive() && Index < Offset)
- return InvalidOffset();
+ DiagInvalidOffset();
// If the new offset would be out of bounds, bail out.
if (Offset.isNegative() && (Offset.isMin() || -Offset > MaxOffset))
- return InvalidOffset();
+ DiagInvalidOffset();
}
+ if (Invalid && !Ptr.isDummy())
+ return false;
+
// Offset is valid - compute it on unsigned.
int64_t WideIndex = static_cast<int64_t>(Index);
int64_t WideOffset = static_cast<int64_t>(Offset);
diff --git a/clang/lib/AST/Interp/InterpBuiltin.cpp
b/clang/lib/AST/Interp/InterpBuiltin.cpp
index 7552c1b88cff60c..e329794cb79243d 100644
--- a/clang/lib/AST/Interp/InterpBuiltin.cpp
+++ b/clang/lib/AST/Interp/InterpBuiltin.cpp
@@ -152,6 +152,9 @@ static bool interp__builtin_strlen(InterpState &S, CodePtr
OpPC,
if (!CheckLive(S, OpPC, StrPtr, AK_Read))
return false;
+ if (!CheckDummy(S, OpPC, StrPtr))
+ return false;
+
assert(StrPtr.getFieldDesc()->isPrimitiveArray());
size_t Len = 0;
diff --git a/clang/lib/AST/Interp/Pointer.h b/clang/lib/AST/Interp/Pointer.h
index d5279e757f04764..52c44915c4a3775 100644
--- a/clang/lib/AST/Interp/Pointer.h
+++ b/clang/lib/AST/Interp/Pointer.h
@@ -313,6 +313,8 @@ class Pointer {
bool isActive() const { return Base == 0 || getInlineDesc()->IsActive; }
/// Checks if a structure is a base class.
bool isBaseClass() const { return isField() && getInlineDesc()->IsBase; }
+ /// Checks if the pointer pointers to a dummy value.
+ bool isDummy() const { return getDeclDesc()->isDummy(); }
/// Checks if an object or a subfield is mutable.
bool isConst() const {
diff --git a/clang/lib/AST/Interp/Program.cpp b/clang/lib/AST/Interp/Program.cpp
index 65e170881e313d7..c6d19afd7d2219d 100644
--- a/clang/lib/AST/Interp/Program.cpp
+++ b/clang/lib/AST/Interp/Program.cpp
@@ -144,16 +144,18 @@ std::optional<unsigned> Program::getOrCreateDummy(const
ValueDecl *PD) {
It != DummyParams.end())
return It->second;
- // Create a pointer to an incomplete array of the specified elements.
- QualType ElemTy = PD->getType();
- QualType Ty =
- Ctx.getASTContext().getIncompleteArrayType(ElemTy, ArrayType::Normal, 0);
+ // Create dummy descriptor.
+ Descriptor *Desc = allocateDescriptor(PD, std::nullopt);
+ // Allocate a block for storage.
+ unsigned I = Globals.size();
- if (auto Idx = createGlobal(PD, Ty, /*isStatic=*/true, /*isExtern=*/true)) {
- DummyParams[PD] = *Idx;
- return Idx;
- }
- return std::nullopt;
+ auto *G = new (Allocator, Desc->getAllocSize())
+ Global(getCurrentDecl(), Desc, /*IsStatic=*/true, /*IsExtern=*/false);
+ G->block()->invokeCtor();
+
+ Globals.push_back(G);
+ DummyParams[PD] = I;
+ return I;
}
std::optional<unsigned> Program::createGlobal(const ValueDecl *VD,
diff --git a/clang/test/AST/Interp/c.c b/clang/test/AST/Interp/c.c
index 974ca72702f7dd0..ae6001aa3b4eee8 100644
--- a/clang/test/AST/Interp/c.c
+++ b/clang/test/AST/Interp/c.c
@@ -47,3 +47,13 @@ _Static_assert(&a != 0, ""); // ref-warning {{always true}} \
// expected-warning {{always true}} \
// pedantic-expected-warning {{always true}} \
// pedantic-expected-warning {{is a GNU
extension}}
+_Static_assert((&c + 1) != 0, ""); // pedantic-ref-warning {{is a GNU
extension}} \
+ // pedantic-expected-warning {{is a GNU
extension}}
+_Static_assert((&a + 100) != 0, ""); // pedantic-ref-warning {{is a GNU
extension}} \
+ // pedantic-ref-note {{100 of non-array}}
\
+ // pedantic-expected-note {{100 of
non-array}} \
+ // pedantic-expected-warning {{is a GNU
extension}}
+_Static_assert((&a - 100) != 0, ""); // pedantic-ref-warning {{is a GNU
extension}} \
+ // pedantic-expected-warning {{is a GNU
extension}} \
+ // pedantic-ref-note {{-100 of
non-array}} \
+ // pedantic-expected-note {{-100 of
non-array}}
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