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//===--- InterpState.cpp - Interpreter for the constexpr VM -----*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "Interp.h"
#include <limits>
#include <vector>
#include "Function.h"
#include "InterpFrame.h"
#include "InterpStack.h"
#include "Opcode.h"
#include "PrimType.h"
#include "Program.h"
#include "State.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/ASTDiagnostic.h"
#include "clang/AST/CXXInheritance.h"
#include "clang/AST/Expr.h"
#include "clang/AST/ExprCXX.h"
#include "llvm/ADT/APSInt.h"
using namespace clang;
using namespace clang::interp;
//===----------------------------------------------------------------------===//
// Ret
//===----------------------------------------------------------------------===//
template <PrimType Name, class T = typename PrimConv<Name>::T>
static bool Ret(InterpState &S, CodePtr &PC, APValue &Result) {
S.CallStackDepth--;
const T &Ret = S.Stk.pop<T>();
assert(S.Current->getFrameOffset() == S.Stk.size() && "Invalid frame");
if (!S.checkingPotentialConstantExpression())
S.Current->popArgs();
if (InterpFrame *Caller = S.Current->Caller) {
PC = S.Current->getRetPC();
delete S.Current;
S.Current = Caller;
S.Stk.push<T>(Ret);
} else {
delete S.Current;
S.Current = nullptr;
if (!ReturnValue<T>(Ret, Result))
return false;
}
return true;
}
static bool RetVoid(InterpState &S, CodePtr &PC, APValue &Result) {
S.CallStackDepth--;
assert(S.Current->getFrameOffset() == S.Stk.size() && "Invalid frame");
if (!S.checkingPotentialConstantExpression())
S.Current->popArgs();
if (InterpFrame *Caller = S.Current->Caller) {
PC = S.Current->getRetPC();
delete S.Current;
S.Current = Caller;
} else {
delete S.Current;
S.Current = nullptr;
}
return true;
}
static bool RetValue(InterpState &S, CodePtr &Pt, APValue &Result) {
llvm::report_fatal_error("Interpreter cannot return values");
}
//===----------------------------------------------------------------------===//
// Jmp, Jt, Jf
//===----------------------------------------------------------------------===//
static bool Jmp(InterpState &S, CodePtr &PC, int32_t Offset) {
PC += Offset;
return true;
}
static bool Jt(InterpState &S, CodePtr &PC, int32_t Offset) {
if (S.Stk.pop<bool>()) {
PC += Offset;
}
return true;
}
static bool Jf(InterpState &S, CodePtr &PC, int32_t Offset) {
if (!S.Stk.pop<bool>()) {
PC += Offset;
}
return true;
}
static bool CheckInitialized(InterpState &S, CodePtr OpPC, const Pointer &Ptr,
AccessKinds AK) {
if (Ptr.isInitialized())
return true;
if (!S.checkingPotentialConstantExpression()) {
const SourceInfo &Loc = S.Current->getSource(OpPC);
S.FFDiag(Loc, diag::note_constexpr_access_uninit) << AK << false;
}
return false;
}
static bool CheckActive(InterpState &S, CodePtr OpPC, const Pointer &Ptr,
AccessKinds AK) {
if (Ptr.isActive())
return true;
// Get the inactive field descriptor.
const FieldDecl *InactiveField = Ptr.getField();
// Walk up the pointer chain to find the union which is not active.
Pointer U = Ptr.getBase();
while (!U.isActive()) {
U = U.getBase();
}
// Find the active field of the union.
Record *R = U.getRecord();
assert(R && R->isUnion() && "Not a union");
const FieldDecl *ActiveField = nullptr;
for (unsigned I = 0, N = R->getNumFields(); I < N; ++I) {
const Pointer &Field = U.atField(R->getField(I)->Offset);
if (Field.isActive()) {
ActiveField = Field.getField();
break;
}
}
const SourceInfo &Loc = S.Current->getSource(OpPC);
S.FFDiag(Loc, diag::note_constexpr_access_inactive_union_member)
<< AK << InactiveField << !ActiveField << ActiveField;
return false;
}
static bool CheckTemporary(InterpState &S, CodePtr OpPC, const Pointer &Ptr,
AccessKinds AK) {
if (auto ID = Ptr.getDeclID()) {
if (!Ptr.isStaticTemporary())
return true;
if (Ptr.getDeclDesc()->getType().isConstQualified())
return true;
if (S.P.getCurrentDecl() == ID)
return true;
const SourceInfo &E = S.Current->getSource(OpPC);
S.FFDiag(E, diag::note_constexpr_access_static_temporary, 1) << AK;
S.Note(Ptr.getDeclLoc(), diag::note_constexpr_temporary_here);
return false;
}
return true;
}
static bool CheckGlobal(InterpState &S, CodePtr OpPC, const Pointer &Ptr) {
if (auto ID = Ptr.getDeclID()) {
if (!Ptr.isStatic())
return true;
if (S.P.getCurrentDecl() == ID)
return true;
S.FFDiag(S.Current->getLocation(OpPC), diag::note_constexpr_modify_global);
return false;
}
return true;
}
namespace clang {
namespace interp {
bool CheckExtern(InterpState &S, CodePtr OpPC, const Pointer &Ptr) {
if (!Ptr.isExtern())
return true;
if (!S.checkingPotentialConstantExpression()) {
auto *VD = Ptr.getDeclDesc()->asValueDecl();
const SourceInfo &Loc = S.Current->getSource(OpPC);
S.FFDiag(Loc, diag::note_constexpr_ltor_non_constexpr, 1) << VD;
S.Note(VD->getLocation(), diag::note_declared_at);
}
return false;
}
bool CheckArray(InterpState &S, CodePtr OpPC, const Pointer &Ptr) {
if (!Ptr.isUnknownSizeArray())
return true;
const SourceInfo &E = S.Current->getSource(OpPC);
S.FFDiag(E, diag::note_constexpr_unsized_array_indexed);
return false;
}
bool CheckLive(InterpState &S, CodePtr OpPC, const Pointer &Ptr,
AccessKinds AK) {
const auto &Src = S.Current->getSource(OpPC);
if (Ptr.isZero()) {
if (Ptr.isField())
S.FFDiag(Src, diag::note_constexpr_null_subobject) << CSK_Field;
else
S.FFDiag(Src, diag::note_constexpr_access_null) << AK;
return false;
}
if (!Ptr.isLive()) {
bool IsTemp = Ptr.isTemporary();
S.FFDiag(Src, diag::note_constexpr_lifetime_ended, 1) << AK << !IsTemp;
if (IsTemp)
S.Note(Ptr.getDeclLoc(), diag::note_constexpr_temporary_here);
else
S.Note(Ptr.getDeclLoc(), diag::note_declared_at);
return false;
}
return true;
}
bool CheckNull(InterpState &S, CodePtr OpPC, const Pointer &Ptr,
CheckSubobjectKind CSK) {
if (!Ptr.isZero())
return true;
const SourceInfo &Loc = S.Current->getSource(OpPC);
S.FFDiag(Loc, diag::note_constexpr_null_subobject) << CSK;
return false;
}
bool CheckRange(InterpState &S, CodePtr OpPC, const Pointer &Ptr,
AccessKinds AK) {
if (!Ptr.isOnePastEnd())
return true;
const SourceInfo &Loc = S.Current->getSource(OpPC);
S.FFDiag(Loc, diag::note_constexpr_access_past_end) << AK;
return false;
}
bool CheckRange(InterpState &S, CodePtr OpPC, const Pointer &Ptr,
CheckSubobjectKind CSK) {
if (!Ptr.isElementPastEnd())
return true;
const SourceInfo &Loc = S.Current->getSource(OpPC);
S.FFDiag(Loc, diag::note_constexpr_past_end_subobject) << CSK;
return false;
}
bool CheckConst(InterpState &S, CodePtr OpPC, const Pointer &Ptr) {
assert(Ptr.isLive() && "Pointer is not live");
if (!Ptr.isConst()) {
return true;
}
const QualType Ty = Ptr.getType();
const SourceInfo &Loc = S.Current->getSource(OpPC);
S.FFDiag(Loc, diag::note_constexpr_modify_const_type) << Ty;
return false;
}
bool CheckMutable(InterpState &S, CodePtr OpPC, const Pointer &Ptr) {
assert(Ptr.isLive() && "Pointer is not live");
if (!Ptr.isMutable()) {
return true;
}
const SourceInfo &Loc = S.Current->getSource(OpPC);
const FieldDecl *Field = Ptr.getField();
S.FFDiag(Loc, diag::note_constexpr_access_mutable, 1) << AK_Read << Field;
S.Note(Field->getLocation(), diag::note_declared_at);
return false;
}
bool CheckLoad(InterpState &S, CodePtr OpPC, const Pointer &Ptr) {
if (!CheckLive(S, OpPC, Ptr, AK_Read))
return false;
if (!CheckExtern(S, OpPC, Ptr))
return false;
if (!CheckRange(S, OpPC, Ptr, AK_Read))
return false;
if (!CheckInitialized(S, OpPC, Ptr, AK_Read))
return false;
if (!CheckActive(S, OpPC, Ptr, AK_Read))
return false;
if (!CheckTemporary(S, OpPC, Ptr, AK_Read))
return false;
if (!CheckMutable(S, OpPC, Ptr))
return false;
return true;
}
bool CheckStore(InterpState &S, CodePtr OpPC, const Pointer &Ptr) {
if (!CheckLive(S, OpPC, Ptr, AK_Assign))
return false;
if (!CheckExtern(S, OpPC, Ptr))
return false;
if (!CheckRange(S, OpPC, Ptr, AK_Assign))
return false;
if (!CheckGlobal(S, OpPC, Ptr))
return false;
if (!CheckConst(S, OpPC, Ptr))
return false;
return true;
}
bool CheckInvoke(InterpState &S, CodePtr OpPC, const Pointer &Ptr) {
if (!CheckLive(S, OpPC, Ptr, AK_MemberCall))
return false;
if (!CheckExtern(S, OpPC, Ptr))
return false;
if (!CheckRange(S, OpPC, Ptr, AK_MemberCall))
return false;
return true;
}
bool CheckInit(InterpState &S, CodePtr OpPC, const Pointer &Ptr) {
if (!CheckLive(S, OpPC, Ptr, AK_Assign))
return false;
if (!CheckRange(S, OpPC, Ptr, AK_Assign))
return false;
return true;
}
bool CheckCallable(InterpState &S, CodePtr OpPC, Function *F) {
const SourceLocation &Loc = S.Current->getLocation(OpPC);
if (F->isVirtual()) {
if (!S.getLangOpts().CPlusPlus20) {
S.CCEDiag(Loc, diag::note_constexpr_virtual_call);
return false;
}
}
if (!F->isConstexpr()) {
if (S.getLangOpts().CPlusPlus11) {
const FunctionDecl *DiagDecl = F->getDecl();
// If this function is not constexpr because it is an inherited
// non-constexpr constructor, diagnose that directly.
auto *CD = dyn_cast<CXXConstructorDecl>(DiagDecl);
if (CD && CD->isInheritingConstructor()) {
auto *Inherited = CD->getInheritedConstructor().getConstructor();
if (!Inherited->isConstexpr())
DiagDecl = CD = Inherited;
}
// FIXME: If DiagDecl is an implicitly-declared special member function
// or an inheriting constructor, we should be much more explicit about why
// it's not constexpr.
if (CD && CD->isInheritingConstructor())
S.FFDiag(Loc, diag::note_constexpr_invalid_inhctor, 1)
<< CD->getInheritedConstructor().getConstructor()->getParent();
else
S.FFDiag(Loc, diag::note_constexpr_invalid_function, 1)
<< DiagDecl->isConstexpr() << (bool)CD << DiagDecl;
S.Note(DiagDecl->getLocation(), diag::note_declared_at);
} else {
S.FFDiag(Loc, diag::note_invalid_subexpr_in_const_expr);
}
return false;
}
return true;
}
bool CheckThis(InterpState &S, CodePtr OpPC, const Pointer &This) {
if (!This.isZero())
return true;
const SourceInfo &Loc = S.Current->getSource(OpPC);
bool IsImplicit = false;
if (auto *E = dyn_cast_or_null<CXXThisExpr>(Loc.asExpr()))
IsImplicit = E->isImplicit();
if (S.getLangOpts().CPlusPlus11)
S.FFDiag(Loc, diag::note_constexpr_this) << IsImplicit;
else
S.FFDiag(Loc);
return false;
}
bool CheckPure(InterpState &S, CodePtr OpPC, const CXXMethodDecl *MD) {
if (!MD->isPure())
return true;
const SourceInfo &E = S.Current->getSource(OpPC);
S.FFDiag(E, diag::note_constexpr_pure_virtual_call, 1) << MD;
S.Note(MD->getLocation(), diag::note_declared_at);
return false;
}
bool Interpret(InterpState &S, APValue &Result) {
assert(!S.Current->isRoot());
CodePtr PC = S.Current->getPC();
// Empty program.
if (!PC)
return true;
for (;;) {
auto Op = PC.read<Opcode>();
CodePtr OpPC = PC;
switch (Op) {
#define GET_INTERP
#include "Opcodes.inc"
#undef GET_INTERP
}
}
}
} // namespace interp
} // namespace clang