Author: rsmith
Date: Thu Aug 27 21:43:42 2015
New Revision: 246263
URL: http://llvm.org/viewvc/llvm-project?rev=246263&view=rev
Log:
PR24597: Fix in-place evaluation of call expressions to provide a proper "this"
pointer to an RVO construction of a returned object.
Modified:
cfe/trunk/lib/AST/ExprConstant.cpp
cfe/trunk/test/PCH/cxx1y-default-initializer.cpp
cfe/trunk/test/SemaCXX/constant-expression-cxx11.cpp
Modified: cfe/trunk/lib/AST/ExprConstant.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ExprConstant.cpp?rev=246263&r1=246262&r2=246263&view=diff
==============================================================================
--- cfe/trunk/lib/AST/ExprConstant.cpp (original)
+++ cfe/trunk/lib/AST/ExprConstant.cpp Thu Aug 27 21:43:42 2015
@@ -3248,12 +3248,21 @@ static bool EvaluateCond(EvalInfo &Info,
return EvaluateAsBooleanCondition(Cond, Result, Info);
}
-static EvalStmtResult EvaluateStmt(APValue &Result, EvalInfo &Info,
+/// \brief A location where the result (returned value) of evaluating a
+/// statement should be stored.
+struct StmtResult {
+ /// The APValue that should be filled in with the returned value.
+ APValue &Value;
+ /// The location containing the result, if any (used to support RVO).
+ const LValue *Slot;
+};
+
+static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info,
const Stmt *S,
const SwitchCase *SC = nullptr);
/// Evaluate the body of a loop, and translate the result as appropriate.
-static EvalStmtResult EvaluateLoopBody(APValue &Result, EvalInfo &Info,
+static EvalStmtResult EvaluateLoopBody(StmtResult &Result, EvalInfo &Info,
const Stmt *Body,
const SwitchCase *Case = nullptr) {
BlockScopeRAII Scope(Info);
@@ -3272,7 +3281,7 @@ static EvalStmtResult EvaluateLoopBody(A
}
/// Evaluate a switch statement.
-static EvalStmtResult EvaluateSwitch(APValue &Result, EvalInfo &Info,
+static EvalStmtResult EvaluateSwitch(StmtResult &Result, EvalInfo &Info,
const SwitchStmt *SS) {
BlockScopeRAII Scope(Info);
@@ -3329,7 +3338,7 @@ static EvalStmtResult EvaluateSwitch(APV
}
// Evaluate a statement.
-static EvalStmtResult EvaluateStmt(APValue &Result, EvalInfo &Info,
+static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info,
const Stmt *S, const SwitchCase *Case) {
if (!Info.nextStep(S))
return ESR_Failed;
@@ -3435,7 +3444,10 @@ static EvalStmtResult EvaluateStmt(APVal
case Stmt::ReturnStmtClass: {
const Expr *RetExpr = cast<ReturnStmt>(S)->getRetValue();
FullExpressionRAII Scope(Info);
- if (RetExpr && !Evaluate(Result, Info, RetExpr))
+ if (RetExpr &&
+ !(Result.Slot
+ ? EvaluateInPlace(Result.Value, Info, *Result.Slot, RetExpr)
+ : Evaluate(Result.Value, Info, RetExpr)))
return ESR_Failed;
return ESR_Returned;
}
@@ -3705,7 +3717,8 @@ static bool EvaluateArgs(ArrayRef<const
static bool HandleFunctionCall(SourceLocation CallLoc,
const FunctionDecl *Callee, const LValue *This,
ArrayRef<const Expr*> Args, const Stmt *Body,
- EvalInfo &Info, APValue &Result) {
+ EvalInfo &Info, APValue &Result,
+ const LValue *ResultSlot) {
ArgVector ArgValues(Args.size());
if (!EvaluateArgs(Args, ArgValues, Info))
return false;
@@ -3740,7 +3753,8 @@ static bool HandleFunctionCall(SourceLoc
return true;
}
- EvalStmtResult ESR = EvaluateStmt(Result, Info, Body);
+ StmtResult Ret = {Result, ResultSlot};
+ EvalStmtResult ESR = EvaluateStmt(Ret, Info, Body);
if (ESR == ESR_Succeeded) {
if (Callee->getReturnType()->isVoidType())
return true;
@@ -3769,6 +3783,11 @@ static bool HandleConstructorCall(Source
CallStackFrame Frame(Info, CallLoc, Definition, &This, ArgValues.data());
+ // FIXME: Creating an APValue just to hold a nonexistent return value is
+ // wasteful.
+ APValue RetVal;
+ StmtResult Ret = {RetVal, nullptr};
+
// If it's a delegating constructor, just delegate.
if (Definition->isDelegatingConstructor()) {
CXXConstructorDecl::init_const_iterator I = Definition->init_begin();
@@ -3777,7 +3796,7 @@ static bool HandleConstructorCall(Source
if (!EvaluateInPlace(Result, Info, This, (*I)->getInit()))
return false;
}
- return EvaluateStmt(Result, Info, Definition->getBody()) != ESR_Failed;
+ return EvaluateStmt(Ret, Info, Definition->getBody()) != ESR_Failed;
}
// For a trivial copy or move constructor, perform an APValue copy. This is
@@ -3885,7 +3904,7 @@ static bool HandleConstructorCall(Source
}
return Success &&
- EvaluateStmt(Result, Info, Definition->getBody()) != ESR_Failed;
+ EvaluateStmt(Ret, Info, Definition->getBody()) != ESR_Failed;
}
//===----------------------------------------------------------------------===//
@@ -3897,11 +3916,12 @@ template <class Derived>
class ExprEvaluatorBase
: public ConstStmtVisitor<Derived, bool> {
private:
+ Derived &getDerived() { return static_cast<Derived&>(*this); }
bool DerivedSuccess(const APValue &V, const Expr *E) {
- return static_cast<Derived*>(this)->Success(V, E);
+ return getDerived().Success(V, E);
}
bool DerivedZeroInitialization(const Expr *E) {
- return static_cast<Derived*>(this)->ZeroInitialization(E);
+ return getDerived().ZeroInitialization(E);
}
// Check whether a conditional operator with a non-constant condition is a
@@ -4082,6 +4102,14 @@ public:
}
bool VisitCallExpr(const CallExpr *E) {
+ APValue Result;
+ if (!handleCallExpr(E, Result, nullptr))
+ return false;
+ return DerivedSuccess(Result, E);
+ }
+
+ bool handleCallExpr(const CallExpr *E, APValue &Result,
+ const LValue *ResultSlot) {
const Expr *Callee = E->getCallee()->IgnoreParens();
QualType CalleeType = Callee->getType();
@@ -4156,14 +4184,13 @@ public:
const FunctionDecl *Definition = nullptr;
Stmt *Body = FD->getBody(Definition);
- APValue Result;
if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition) ||
- !HandleFunctionCall(E->getExprLoc(), Definition, This, Args, Body,
- Info, Result))
+ !HandleFunctionCall(E->getExprLoc(), Definition, This, Args, Body,
Info,
+ Result, ResultSlot))
return false;
- return DerivedSuccess(Result, E);
+ return true;
}
bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) {
@@ -4288,7 +4315,8 @@ public:
}
APValue ReturnValue;
- EvalStmtResult ESR = EvaluateStmt(ReturnValue, Info, *BI);
+ StmtResult Result = { ReturnValue, nullptr };
+ EvalStmtResult ESR = EvaluateStmt(Result, Info, *BI);
if (ESR != ESR_Succeeded) {
// FIXME: If the statement-expression terminated due to 'return',
// 'break', or 'continue', it would be nice to propagate that to
@@ -5143,6 +5171,9 @@ namespace {
}
bool ZeroInitialization(const Expr *E);
+ bool VisitCallExpr(const CallExpr *E) {
+ return handleCallExpr(E, Result, &This);
+ }
bool VisitCastExpr(const CastExpr *E);
bool VisitInitListExpr(const InitListExpr *E);
bool VisitCXXConstructExpr(const CXXConstructExpr *E);
@@ -5705,6 +5736,9 @@ namespace {
return EvaluateInPlace(Result.getArrayFiller(), Info, Subobject, &VIE);
}
+ bool VisitCallExpr(const CallExpr *E) {
+ return handleCallExpr(E, Result, &This);
+ }
bool VisitInitListExpr(const InitListExpr *E);
bool VisitCXXConstructExpr(const CXXConstructExpr *E);
bool VisitCXXConstructExpr(const CXXConstructExpr *E,
@@ -9224,7 +9258,7 @@ bool Expr::isPotentialConstantExpr(const
HandleConstructorCall(Loc, This, Args, CD, Info, Scratch);
} else
HandleFunctionCall(Loc, FD, (MD && MD->isInstance()) ? &This : nullptr,
- Args, FD->getBody(), Info, Scratch);
+ Args, FD->getBody(), Info, Scratch, nullptr);
return Diags.empty();
}
Modified: cfe/trunk/test/PCH/cxx1y-default-initializer.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/test/PCH/cxx1y-default-initializer.cpp?rev=246263&r1=246262&r2=246263&view=diff
==============================================================================
--- cfe/trunk/test/PCH/cxx1y-default-initializer.cpp (original)
+++ cfe/trunk/test/PCH/cxx1y-default-initializer.cpp Thu Aug 27 21:43:42 2015
@@ -1,3 +1,4 @@
+// RUN: %clang_cc1 -pedantic -std=c++1y %s -o %t
// RUN: %clang_cc1 -pedantic -std=c++1y -emit-pch %s -o %t
// RUN: %clang_cc1 -pedantic -std=c++1y -include-pch %t -verify %s
Modified: cfe/trunk/test/SemaCXX/constant-expression-cxx11.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/constant-expression-cxx11.cpp?rev=246263&r1=246262&r2=246263&view=diff
==============================================================================
--- cfe/trunk/test/SemaCXX/constant-expression-cxx11.cpp (original)
+++ cfe/trunk/test/SemaCXX/constant-expression-cxx11.cpp Thu Aug 27 21:43:42
2015
@@ -1994,3 +1994,15 @@ namespace PR17938 {
static constexpr auto z = f(Z());
}
+
+namespace PR24597 {
+ struct A {
+ int x, *p;
+ constexpr A() : x(0), p(&x) {}
+ constexpr A(const A &a) : x(a.x), p(&x) {}
+ };
+ constexpr A f() { return A(); }
+ constexpr A g() { return f(); }
+ constexpr int a = *f().p;
+ constexpr int b = *g().p;
+}
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