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-rw-r--r--clang/include/clang/AST/Expr.h3
-rw-r--r--clang/lib/AST/ExprConstant.cpp181
-rw-r--r--clang/test/SemaCXX/constant-expression-cxx11.cpp53
3 files changed, 225 insertions, 12 deletions
diff --git a/clang/include/clang/AST/Expr.h b/clang/include/clang/AST/Expr.h
index ad686187c49..b484a42b042 100644
--- a/clang/include/clang/AST/Expr.h
+++ b/clang/include/clang/AST/Expr.h
@@ -1959,6 +1959,9 @@ public:
Expr **getArgs() {
return reinterpret_cast<Expr **>(SubExprs+getNumPreArgs()+PREARGS_START);
}
+ const Expr *const *getArgs() const {
+ return const_cast<CallExpr*>(this)->getArgs();
+ }
/// getArg - Return the specified argument.
Expr *getArg(unsigned Arg) {
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index d59d79ec69b..89bcacf2bba 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -43,12 +43,23 @@ using llvm::APFloat;
/// evaluate the expression regardless of what the RHS is, but C only allows
/// certain things in certain situations.
namespace {
+ struct CallStackFrame;
+
struct EvalInfo {
const ASTContext &Ctx;
/// EvalStatus - Contains information about the evaluation.
Expr::EvalStatus &EvalStatus;
+ /// CurrentCall - The top of the constexpr call stack.
+ const CallStackFrame *CurrentCall;
+
+ /// NumCalls - The number of calls we've evaluated so far.
+ unsigned NumCalls;
+
+ /// CallStackDepth - The number of calls in the call stack right now.
+ unsigned CallStackDepth;
+
typedef llvm::DenseMap<const OpaqueValueExpr*, APValue> MapTy;
MapTy OpaqueValues;
const APValue *getOpaqueValue(const OpaqueValueExpr *e) const {
@@ -58,11 +69,40 @@ namespace {
}
EvalInfo(const ASTContext &C, Expr::EvalStatus &S)
- : Ctx(C), EvalStatus(S) {}
+ : Ctx(C), EvalStatus(S), CurrentCall(0), NumCalls(0), CallStackDepth(0) {}
const LangOptions &getLangOpts() { return Ctx.getLangOptions(); }
};
+ /// A stack frame in the constexpr call stack.
+ struct CallStackFrame {
+ EvalInfo &Info;
+
+ /// Parent - The caller of this stack frame.
+ const CallStackFrame *Caller;
+
+ /// ParmBindings - Parameter bindings for this function call, indexed by
+ /// parameters' function scope indices.
+ const APValue *Arguments;
+
+ /// CallIndex - The index of the current call. This is used to match lvalues
+ /// referring to parameters up with the corresponding stack frame, and to
+ /// detect when the parameter is no longer in scope.
+ unsigned CallIndex;
+
+ CallStackFrame(EvalInfo &Info, const APValue *Arguments)
+ : Info(Info), Caller(Info.CurrentCall), Arguments(Arguments),
+ CallIndex(Info.NumCalls++) {
+ Info.CurrentCall = this;
+ ++Info.CallStackDepth;
+ }
+ ~CallStackFrame() {
+ assert(Info.CurrentCall == this && "calls retired out of order");
+ --Info.CallStackDepth;
+ Info.CurrentCall = Caller;
+ }
+ };
+
struct ComplexValue {
private:
bool IsInt;
@@ -269,11 +309,17 @@ static APFloat HandleIntToFloatCast(QualType DestType, QualType SrcType,
}
/// Try to evaluate the initializer for a variable declaration.
-static APValue *EvaluateVarDeclInit(EvalInfo &Info, const VarDecl *VD) {
- // FIXME: If this is a parameter to an active constexpr function call, perform
- // substitution now.
- if (isa<ParmVarDecl>(VD))
+static const APValue *EvaluateVarDeclInit(EvalInfo &Info, const VarDecl *VD) {
+ // If this is a parameter to an active constexpr function call, perform
+ // argument substitution.
+ if (const ParmVarDecl *PVD = dyn_cast<ParmVarDecl>(VD)) {
+ // FIXME This assumes that all parameters must be parameters of the current
+ // call. Add the CallIndex to the LValue representation and use that to
+ // check.
+ if (Info.CurrentCall)
+ return &Info.CurrentCall->Arguments[PVD->getFunctionScopeIndex()];
return 0;
+ }
const Expr *Init = VD->getAnyInitializer();
if (!Init)
@@ -341,22 +387,28 @@ bool HandleLValueToRValueConversion(EvalInfo &Info, QualType Type,
if (D) {
// In C++98, const, non-volatile integers initialized with ICEs are ICEs.
// In C++11, constexpr, non-volatile variables initialized with constant
- // expressions are constant expressions too.
+ // expressions are constant expressions too. Inside constexpr functions,
+ // parameters are constant expressions even if they're non-const.
// In C, such things can also be folded, although they are not ICEs.
//
// FIXME: Allow folding any const variable of literal type initialized with
// a constant expression. For now, we only allow variables with integral and
// floating types to be folded.
+ // FIXME: volatile-qualified ParmVarDecls need special handling. A literal
+ // interpretation of C++11 suggests that volatile parameters are OK if
+ // they're never read (there's no prohibition against constructing volatile
+ // objects in constant expressions), but lvalue-to-rvalue conversions on
+ // them are not permitted.
const VarDecl *VD = dyn_cast<VarDecl>(D);
- if (!VD || !IsConstNonVolatile(VD->getType()) ||
- (!Type->isIntegralOrEnumerationType() && !Type->isRealFloatingType()))
+ if (!VD || !(IsConstNonVolatile(VD->getType()) || isa<ParmVarDecl>(VD)) ||
+ !(Type->isIntegralOrEnumerationType() || Type->isRealFloatingType()))
return false;
- APValue *V = EvaluateVarDeclInit(Info, VD);
+ const APValue *V = EvaluateVarDeclInit(Info, VD);
if (!V || V->isUninit())
return false;
- if (!VD->getAnyInitializer()->isLValue()) {
+ if (isa<ParmVarDecl>(VD) || !VD->getAnyInitializer()->isLValue()) {
RVal = *V;
return true;
}
@@ -386,6 +438,64 @@ bool HandleLValueToRValueConversion(EvalInfo &Info, QualType Type,
}
namespace {
+enum EvalStmtResult {
+ /// Evaluation failed.
+ ESR_Failed,
+ /// Hit a 'return' statement.
+ ESR_Returned,
+ /// Evaluation succeeded.
+ ESR_Succeeded
+};
+}
+
+// Evaluate a statement.
+static EvalStmtResult EvaluateStmt(APValue &Result, EvalInfo &Info,
+ const Stmt *S) {
+ switch (S->getStmtClass()) {
+ default:
+ return ESR_Failed;
+
+ case Stmt::NullStmtClass:
+ case Stmt::DeclStmtClass:
+ return ESR_Succeeded;
+
+ case Stmt::ReturnStmtClass:
+ if (Evaluate(Result, Info, cast<ReturnStmt>(S)->getRetValue()))
+ return ESR_Returned;
+ return ESR_Failed;
+
+ case Stmt::CompoundStmtClass: {
+ const CompoundStmt *CS = cast<CompoundStmt>(S);
+ for (CompoundStmt::const_body_iterator BI = CS->body_begin(),
+ BE = CS->body_end(); BI != BE; ++BI) {
+ EvalStmtResult ESR = EvaluateStmt(Result, Info, *BI);
+ if (ESR != ESR_Succeeded)
+ return ESR;
+ }
+ return ESR_Succeeded;
+ }
+ }
+}
+
+/// Evaluate a function call.
+static bool HandleFunctionCall(ArrayRef<const Expr*> Args, const Stmt *Body,
+ EvalInfo &Info, APValue &Result) {
+ // FIXME: Implement a proper call limit, along with a command-line flag.
+ if (Info.NumCalls >= 1000000 || Info.CallStackDepth >= 512)
+ return false;
+
+ SmallVector<APValue, 16> ArgValues(Args.size());
+ // FIXME: Deal with default arguments and 'this'.
+ for (ArrayRef<const Expr*>::iterator I = Args.begin(), E = Args.end();
+ I != E; ++I)
+ if (!Evaluate(ArgValues[I - Args.begin()], Info, *I))
+ return false;
+
+ CallStackFrame Frame(Info, ArgValues.data());
+ return EvaluateStmt(Result, Info, Body) == ESR_Returned;
+}
+
+namespace {
class HasSideEffect
: public ConstStmtVisitor<HasSideEffect, bool> {
const ASTContext &Ctx;
@@ -568,6 +678,47 @@ public:
return DerivedSuccess(*value, E);
}
+ RetTy VisitCallExpr(const CallExpr *E) {
+ const Expr *Callee = E->getCallee();
+ QualType CalleeType = Callee->getType();
+
+ // FIXME: Handle the case where Callee is a (parenthesized) MemberExpr for a
+ // non-static member function.
+ if (CalleeType->isSpecificBuiltinType(BuiltinType::BoundMember))
+ return DerivedError(E);
+
+ if (!CalleeType->isFunctionType() && !CalleeType->isFunctionPointerType())
+ return DerivedError(E);
+
+ APValue Call;
+ if (!Evaluate(Call, Info, Callee) || !Call.isLValue() ||
+ !Call.getLValueBase() || !Call.getLValueOffset().isZero())
+ return DerivedError(Callee);
+
+ const FunctionDecl *FD = 0;
+ if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Call.getLValueBase()))
+ FD = dyn_cast<FunctionDecl>(DRE->getDecl());
+ else if (const MemberExpr *ME = dyn_cast<MemberExpr>(Call.getLValueBase()))
+ FD = dyn_cast<FunctionDecl>(ME->getMemberDecl());
+ if (!FD)
+ return DerivedError(Callee);
+
+ // Don't call function pointers which have been cast to some other type.
+ if (!Info.Ctx.hasSameType(CalleeType->getPointeeType(), FD->getType()))
+ return DerivedError(E);
+
+ const FunctionDecl *Definition;
+ Stmt *Body = FD->getBody(Definition);
+ APValue Result;
+ llvm::ArrayRef<const Expr*> Args(E->getArgs(), E->getNumArgs());
+
+ if (Body && Definition->isConstexpr() && !Definition->isInvalidDecl() &&
+ HandleFunctionCall(Args, Body, Info, Result))
+ return DerivedSuccess(Result, E);
+
+ return DerivedError(E);
+ }
+
RetTy VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) {
return StmtVisitorTy::Visit(E->getInitializer());
}
@@ -716,7 +867,7 @@ bool LValueExprEvaluator::VisitVarDecl(const Expr *E, const VarDecl *VD) {
if (!VD->getType()->isReferenceType())
return Success(E);
- APValue *V = EvaluateVarDeclInit(Info, VD);
+ const APValue *V = EvaluateVarDeclInit(Info, VD);
if (V && !V->isUninit())
return Success(*V, E);
@@ -738,6 +889,14 @@ bool LValueExprEvaluator::VisitMemberExpr(const MemberExpr *E) {
return VisitVarDecl(E, VD);
}
+ // Handle static member functions.
+ if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(E->getMemberDecl())) {
+ if (MD->isStatic()) {
+ VisitIgnoredValue(E->getBase());
+ return Success(E);
+ }
+ }
+
QualType Ty;
if (E->isArrow()) {
if (!EvaluatePointer(E->getBase(), Result, Info))
diff --git a/clang/test/SemaCXX/constant-expression-cxx11.cpp b/clang/test/SemaCXX/constant-expression-cxx11.cpp
index fdab2838937..4ecc53c61b8 100644
--- a/clang/test/SemaCXX/constant-expression-cxx11.cpp
+++ b/clang/test/SemaCXX/constant-expression-cxx11.cpp
@@ -1,6 +1,17 @@
// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 %s
-template<typename T> constexpr T id(const T &t) { return t; }
+// FIXME: support const T& parameters here.
+//template<typename T> constexpr T id(const T &t) { return t; }
+template<typename T> constexpr T id(T t) { return t; }
+// FIXME: support templates here.
+//template<typename T> constexpr T min(const T &a, const T &b) {
+// return a < b ? a : b;
+//}
+//template<typename T> constexpr T max(const T &a, const T &b) {
+// return a < b ? b : a;
+//}
+constexpr int min(int a, int b) { return a < b ? a : b; }
+constexpr int max(int a, int b) { return a < b ? b : a; }
struct MemberZero {
constexpr int zero() { return 0; }
@@ -40,3 +51,43 @@ namespace MemberEnum {
constexpr bool b = wme.A == 42;
int n[b];
}
+
+namespace Recursion {
+ constexpr int fib(int n) { return n > 1 ? fib(n-1) + fib(n-2) : n; }
+ // FIXME: this isn't an ICE yet.
+ using check_fib = int[fib(11)];
+ using check_fib = int[89];
+
+ constexpr int gcd_inner(int a, int b) {
+ return b == 0 ? a : gcd_inner(b, a % b);
+ }
+ constexpr int gcd(int a, int b) {
+ return gcd_inner(max(a, b), min(a, b));
+ }
+
+ // FIXME: this isn't an ICE yet.
+ using check_gcd = int[gcd(1749237, 5628959)];
+ using check_gcd = int[7];
+}
+
+namespace FunctionCast {
+ // When folding, we allow functions to be cast to different types. Such
+ // cast functions cannot be called, even if they're constexpr.
+ constexpr int f() { return 1; }
+ typedef double (*DoubleFn)();
+ typedef int (*IntFn)();
+ int a[(int)DoubleFn(f)()]; // expected-error {{variable length array}}
+ int b[(int)IntFn(f)()]; // ok
+}
+
+namespace StaticMemberFunction {
+ struct S {
+ static constexpr int k = 42;
+ static constexpr int f(int n) { return n * k + 2; }
+ } s;
+ // FIXME: this isn't an ICE yet.
+ using check_static_call = int[S::f(19)];
+ constexpr int n = s.f(19);
+ using check_static_call = int[s.f(19)];
+ using check_static_call = int[800];
+}
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