[clang] [clang][bytecode] Diagnose volatile writes (PR #160350)
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Tue Sep 23 10:46:56 PDT 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang
Author: Timm Baeder (tbaederr)
<details>
<summary>Changes</summary>
---
Full diff: https://github.com/llvm/llvm-project/pull/160350.diff
7 Files Affected:
- (modified) clang/lib/AST/ByteCode/Compiler.cpp (+9-4)
- (modified) clang/lib/AST/ByteCode/Compiler.h (+1)
- (modified) clang/lib/AST/ByteCode/Interp.cpp (+2)
- (modified) clang/lib/AST/ByteCode/Interp.h (+13)
- (modified) clang/lib/AST/ByteCode/Opcodes.td (+1)
- (modified) clang/test/AST/ByteCode/cxx23.cpp (+42)
- (modified) clang/test/AST/ByteCode/invalid.cpp (+1-1)
``````````diff
diff --git a/clang/lib/AST/ByteCode/Compiler.cpp b/clang/lib/AST/ByteCode/Compiler.cpp
index b4da99957ee88..a81107289d91d 100644
--- a/clang/lib/AST/ByteCode/Compiler.cpp
+++ b/clang/lib/AST/ByteCode/Compiler.cpp
@@ -4452,6 +4452,9 @@ bool Compiler<Emitter>::visitAssignment(const Expr *LHS, const Expr *RHS,
if (!this->visit(LHS))
return false;
+ if (LHS->getType().isVolatileQualified())
+ return this->emitInvalidStore(LHS->getType().getTypePtr(), E);
+
// We don't support assignments in C.
if (!Ctx.getLangOpts().CPlusPlus && !this->emitInvalid(E))
return false;
@@ -4560,13 +4563,14 @@ bool Compiler<Emitter>::emitConst(const APSInt &Value, const Expr *E) {
template <class Emitter>
unsigned Compiler<Emitter>::allocateLocalPrimitive(
- DeclTy &&Src, PrimType Ty, bool IsConst, const ValueDecl *ExtendingDecl,
- ScopeKind SC, bool IsConstexprUnknown) {
+ DeclTy &&Src, PrimType Ty, bool IsConst, bool IsVolatile,
+ const ValueDecl *ExtendingDecl, ScopeKind SC, bool IsConstexprUnknown) {
// FIXME: There are cases where Src.is<Expr*>() is wrong, e.g.
// (int){12} in C. Consider using Expr::isTemporaryObject() instead
// or isa<MaterializeTemporaryExpr>().
Descriptor *D = P.createDescriptor(Src, Ty, nullptr, Descriptor::InlineDescMD,
- IsConst, isa<const Expr *>(Src));
+ IsConst, isa<const Expr *>(Src),
+ /*IsMutable=*/false, IsVolatile);
D->IsConstexprUnknown = IsConstexprUnknown;
Scope::Local Local = this->createLocal(D);
if (auto *VD = dyn_cast_if_present<ValueDecl>(Src.dyn_cast<const Decl *>()))
@@ -4874,7 +4878,8 @@ Compiler<Emitter>::visitVarDecl(const VarDecl *VD, const Expr *Init,
if (VarT) {
unsigned Offset = this->allocateLocalPrimitive(
- VD, *VarT, VD->getType().isConstQualified(), nullptr, ScopeKind::Block,
+ VD, *VarT, VD->getType().isConstQualified(),
+ VD->getType().isVolatileQualified(), nullptr, ScopeKind::Block,
IsConstexprUnknown);
if (Init) {
// If this is a toplevel declaration, create a scope for the
diff --git a/clang/lib/AST/ByteCode/Compiler.h b/clang/lib/AST/ByteCode/Compiler.h
index 09599b3547888..5c46f75af4da3 100644
--- a/clang/lib/AST/ByteCode/Compiler.h
+++ b/clang/lib/AST/ByteCode/Compiler.h
@@ -327,6 +327,7 @@ class Compiler : public ConstStmtVisitor<Compiler<Emitter>, bool>,
/// Creates a local primitive value.
unsigned allocateLocalPrimitive(DeclTy &&Decl, PrimType Ty, bool IsConst,
+ bool IsVolatile = false,
const ValueDecl *ExtendingDecl = nullptr,
ScopeKind SC = ScopeKind::Block,
bool IsConstexprUnknown = false);
diff --git a/clang/lib/AST/ByteCode/Interp.cpp b/clang/lib/AST/ByteCode/Interp.cpp
index 0f322f6ed42ac..6a737c1c5e550 100644
--- a/clang/lib/AST/ByteCode/Interp.cpp
+++ b/clang/lib/AST/ByteCode/Interp.cpp
@@ -889,6 +889,8 @@ bool CheckStore(InterpState &S, CodePtr OpPC, const Pointer &Ptr) {
return false;
if (!CheckConst(S, OpPC, Ptr))
return false;
+ if (!CheckVolatile(S, OpPC, Ptr, AK_Assign))
+ return false;
if (!S.inConstantContext() && isConstexprUnknown(Ptr))
return false;
return true;
diff --git a/clang/lib/AST/ByteCode/Interp.h b/clang/lib/AST/ByteCode/Interp.h
index b3b4b998439cc..d98ae8853147e 100644
--- a/clang/lib/AST/ByteCode/Interp.h
+++ b/clang/lib/AST/ByteCode/Interp.h
@@ -3344,6 +3344,19 @@ inline bool InvalidCast(InterpState &S, CodePtr OpPC, CastKind Kind,
return false;
}
+inline bool InvalidStore(InterpState &S, CodePtr OpPC, const Type *T) {
+
+ if (S.getLangOpts().CPlusPlus) {
+ QualType VolatileType = QualType(T, 0).withVolatile();
+ S.FFDiag(S.Current->getSource(OpPC),
+ diag::note_constexpr_access_volatile_type)
+ << AK_Assign << VolatileType;
+ } else {
+ S.FFDiag(S.Current->getSource(OpPC));
+ }
+ return false;
+}
+
inline bool InvalidDeclRef(InterpState &S, CodePtr OpPC, const DeclRefExpr *DR,
bool InitializerFailed) {
assert(DR);
diff --git a/clang/lib/AST/ByteCode/Opcodes.td b/clang/lib/AST/ByteCode/Opcodes.td
index 7af2df5318106..532c4448e6f40 100644
--- a/clang/lib/AST/ByteCode/Opcodes.td
+++ b/clang/lib/AST/ByteCode/Opcodes.td
@@ -797,6 +797,7 @@ def SideEffect : Opcode {}
def InvalidCast : Opcode {
let Args = [ArgCastKind, ArgBool];
}
+def InvalidStore : Opcode { let Args = [ArgTypePtr]; }
def CheckPseudoDtor : Opcode {}
def InvalidDeclRef : Opcode {
diff --git a/clang/test/AST/ByteCode/cxx23.cpp b/clang/test/AST/ByteCode/cxx23.cpp
index 72c751d627a44..0cc6e3b25fcef 100644
--- a/clang/test/AST/ByteCode/cxx23.cpp
+++ b/clang/test/AST/ByteCode/cxx23.cpp
@@ -393,6 +393,48 @@ namespace UnionMemberCallDiags {
static_assert(g()); // all-error {{not an integral constant expression}} \
// all-note {{in call to}}
}
+#endif
+
+namespace VolatileWrites {
+ constexpr void test1() {// all20-error {{never produces a constant expression}}
+ int k;
+ volatile int &m = k;
+ m = 10; // all20-note {{assignment to volatile-qualified type 'volatile int'}}
+ }
+
+ constexpr void test2() { // all20-error {{never produces a constant expression}}
+ volatile int k = 12;
+
+ k = 13; // all20-note {{assignment to volatile-qualified type 'volatile int'}}
+ }
+
+ constexpr void test3() { // all20-error {{never produces a constant expression}}
+ volatile int k = 12; // all20-note {{volatile object declared here}}
+
+ *((int *)&k) = 13; // all20-note {{assignment to volatile object 'k' is not allowed in a constant expression}}
+ }
+
+
+ constexpr void test4() { // all20-error {{never produces a constant expression}}
+ int k = 12; // all20-note {{volatile object declared here}}
+
+ *((volatile int *)&k) = 13; // all20-note {{assignment to volatile-qualified type 'volatile int' is not allowed in a constant expression}}
+ }
+
+
+#if __cplusplus >= 202302L
+ struct S {
+ volatile int k;
+ };
+ constexpr int test5() {
+ S s;
+ s.k = 12; // all-note {{assignment to volatile-qualified type 'volatile int' is not}}
+
+ return 0;
+ }
+ static_assert(test5() == 0); // all-error{{not an integral constant expression}} \
+ // all-note {{in call to}}
#endif
+}
diff --git a/clang/test/AST/ByteCode/invalid.cpp b/clang/test/AST/ByteCode/invalid.cpp
index affb40eada870..00db27419e36b 100644
--- a/clang/test/AST/ByteCode/invalid.cpp
+++ b/clang/test/AST/ByteCode/invalid.cpp
@@ -1,5 +1,5 @@
// RUN: %clang_cc1 -fcxx-exceptions -std=c++20 -fexperimental-new-constant-interpreter -verify=expected,both %s
-// RUN: %clang_cc1 -fcxx-exceptions -std=c++20 -verify=ref,both %s
+// RUN: %clang_cc1 -fcxx-exceptions -std=c++20 -verify=ref,both %s
namespace Throw {
``````````
</details>
https://github.com/llvm/llvm-project/pull/160350
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