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A ConstantExpr class represents a full expression that's in a
context where a constant expression is required. This class reflects
the path the evaluator took to reach the expression rather than
the syntactic context in which the expression occurs.
In the future, the class will be expanded to cache the result of
the evaluated expression so that it's not needlessly re-evaluated.
Repository:
rC Clang
https://reviews.llvm.org/D53475
Files:
include/clang/AST/Expr.h
include/clang/AST/RecursiveASTVisitor.h
include/clang/AST/StmtDataCollectors.td
include/clang/Basic/StmtNodes.td
include/clang/Serialization/ASTBitCodes.h
lib/AST/Expr.cpp
lib/AST/ExprClassification.cpp
lib/AST/ExprConstant.cpp
lib/AST/ItaniumMangle.cpp
lib/AST/StmtPrinter.cpp
lib/AST/StmtProfile.cpp
lib/Sema/SemaExceptionSpec.cpp
lib/Sema/TreeTransform.h
lib/Serialization/ASTReaderStmt.cpp
lib/Serialization/ASTWriterStmt.cpp
lib/StaticAnalyzer/Core/ExprEngine.cpp
tools/libclang/CXCursor.cpp
Index: tools/libclang/CXCursor.cpp
===================================================================
--- tools/libclang/CXCursor.cpp
+++ tools/libclang/CXCursor.cpp
@@ -343,6 +343,10 @@
K = CXCursor_CharacterLiteral;
break;
+ case Stmt::ConstantExprClass:
+ return MakeCXCursor(cast<ConstantExpr>(S)->getSubExpr(),
+ Parent, TU, RegionOfInterest);
+
case Stmt::ParenExprClass:
K = CXCursor_ParenExpr;
break;
Index: lib/StaticAnalyzer/Core/ExprEngine.cpp
===================================================================
--- lib/StaticAnalyzer/Core/ExprEngine.cpp
+++ lib/StaticAnalyzer/Core/ExprEngine.cpp
@@ -1267,6 +1267,9 @@
case Stmt::ObjCPropertyRefExprClass:
llvm_unreachable("These are handled by PseudoObjectExpr");
+ case Expr::ConstantExprClass:
+ return Visit(cast<ConstantExpr>(S)->getSubExpr(), Pred, DstTop);
+
case Stmt::GNUNullExprClass: {
// GNU __null is a pointer-width integer, not an actual pointer.
ProgramStateRef state = Pred->getState();
Index: lib/Serialization/ASTWriterStmt.cpp
===================================================================
--- lib/Serialization/ASTWriterStmt.cpp
+++ lib/Serialization/ASTWriterStmt.cpp
@@ -386,6 +386,12 @@
Record.push_back(E->getObjectKind());
}
+void ASTStmtWriter::VisitConstantExpr(ConstantExpr *E) {
+ VisitExpr(E);
+ Record.AddStmt(E->getSubExpr());
+ Code = serialization::EXPR_CONSTANT;
+}
+
void ASTStmtWriter::VisitPredefinedExpr(PredefinedExpr *E) {
VisitExpr(E);
Record.AddSourceLocation(E->getLocation());
Index: lib/Serialization/ASTReaderStmt.cpp
===================================================================
--- lib/Serialization/ASTReaderStmt.cpp
+++ lib/Serialization/ASTReaderStmt.cpp
@@ -491,6 +491,11 @@
"Incorrect expression field count");
}
+void ASTStmtReader::VisitConstantExpr(ConstantExpr *E) {
+ VisitExpr(E);
+ E->setSubExpr(Record.readSubExpr());
+}
+
void ASTStmtReader::VisitPredefinedExpr(PredefinedExpr *E) {
VisitExpr(E);
E->setLocation(ReadSourceLocation());
@@ -2335,6 +2340,10 @@
Record[ASTStmtReader::NumStmtFields]);
break;
+ case EXPR_CONSTANT:
+ S = new (Context) ConstantExpr(Empty);
+ break;
+
case EXPR_PREDEFINED:
S = new (Context) PredefinedExpr(Empty);
break;
Index: lib/Sema/TreeTransform.h
===================================================================
--- lib/Sema/TreeTransform.h
+++ lib/Sema/TreeTransform.h
@@ -8914,6 +8914,12 @@
//===----------------------------------------------------------------------===//
// Expression transformation
//===----------------------------------------------------------------------===//
+template<typename Derived>
+ExprResult
+TreeTransform<Derived>::TransformConstantExpr(ConstantExpr *E) {
+ return TransformExpr(E->getSubExpr());
+}
+
template<typename Derived>
ExprResult
TreeTransform<Derived>::TransformPredefinedExpr(PredefinedExpr *E) {
Index: lib/Sema/SemaExceptionSpec.cpp
===================================================================
--- lib/Sema/SemaExceptionSpec.cpp
+++ lib/Sema/SemaExceptionSpec.cpp
@@ -1051,6 +1051,9 @@
// [Can throw] if in a potentially-evaluated context the expression would
// contain:
switch (E->getStmtClass()) {
+ case Expr::ConstantExprClass:
+ return canThrow(cast<ConstantExpr>(E)->getSubExpr());
+
case Expr::CXXThrowExprClass:
// - a potentially evaluated throw-expression
return CT_Can;
Index: lib/AST/StmtProfile.cpp
===================================================================
--- lib/AST/StmtProfile.cpp
+++ lib/AST/StmtProfile.cpp
@@ -996,6 +996,11 @@
VisitStmt(S);
}
+void StmtProfiler::VisitConstantExpr(const ConstantExpr *S) {
+ VisitExpr(S);
+ VisitExpr(S->getSubExpr());
+}
+
void StmtProfiler::VisitDeclRefExpr(const DeclRefExpr *S) {
VisitExpr(S);
if (!Canonical)
Index: lib/AST/StmtPrinter.cpp
===================================================================
--- lib/AST/StmtPrinter.cpp
+++ lib/AST/StmtPrinter.cpp
@@ -906,6 +906,10 @@
// Expr printing methods.
//===----------------------------------------------------------------------===//
+void StmtPrinter::VisitConstantExpr(ConstantExpr *Node) {
+ VisitExpr(Node->getSubExpr());
+}
+
void StmtPrinter::VisitDeclRefExpr(DeclRefExpr *Node) {
if (const auto *OCED = dyn_cast<OMPCapturedExprDecl>(Node->getDecl())) {
OCED->getInit()->IgnoreImpCasts()->printPretty(OS, nullptr, Policy);
Index: lib/AST/ItaniumMangle.cpp
===================================================================
--- lib/AST/ItaniumMangle.cpp
+++ lib/AST/ItaniumMangle.cpp
@@ -3524,6 +3524,10 @@
case Expr::CXXInheritedCtorInitExprClass:
llvm_unreachable("unexpected statement kind");
+ case Expr::ConstantExprClass:
+ E = cast<ConstantExpr>(E)->getSubExpr();
+ goto recurse;
+
// FIXME: invent manglings for all these.
case Expr::BlockExprClass:
case Expr::ChooseExprClass:
Index: lib/AST/ExprConstant.cpp
===================================================================
--- lib/AST/ExprConstant.cpp
+++ lib/AST/ExprConstant.cpp
@@ -11038,6 +11038,9 @@
return
CheckICE(cast<SubstNonTypeTemplateParmExpr>(E)->getReplacement(), Ctx);
+ case Expr::ConstantExprClass:
+ return CheckICE(cast<ConstantExpr>(E)->getSubExpr(), Ctx);
+
case Expr::ParenExprClass:
return CheckICE(cast<ParenExpr>(E)->getSubExpr(), Ctx);
case Expr::GenericSelectionExprClass:
Index: lib/AST/ExprClassification.cpp
===================================================================
--- lib/AST/ExprClassification.cpp
+++ lib/AST/ExprClassification.cpp
@@ -194,6 +194,9 @@
case Expr::DesignatedInitUpdateExprClass:
return Cl::CL_PRValue;
+ case Expr::ConstantExprClass:
+ return ClassifyInternal(Ctx, cast<ConstantExpr>(E)->getSubExpr());
+
// Next come the complicated cases.
case Expr::SubstNonTypeTemplateParmExprClass:
return ClassifyInternal(Ctx,
Index: lib/AST/Expr.cpp
===================================================================
--- lib/AST/Expr.cpp
+++ lib/AST/Expr.cpp
@@ -3096,6 +3096,10 @@
// These never have a side-effect.
return false;
+ case ConstantExprClass:
+ return cast<ConstantExpr>(this)->getSubExpr()->HasSideEffects(
+ Ctx, IncludePossibleEffects);
+
case CallExprClass:
case CXXOperatorCallExprClass:
case CXXMemberCallExprClass:
Index: include/clang/Serialization/ASTBitCodes.h
===================================================================
--- include/clang/Serialization/ASTBitCodes.h
+++ include/clang/Serialization/ASTBitCodes.h
@@ -1616,6 +1616,9 @@
/// A MS-style AsmStmt record.
STMT_MSASM,
+ /// A constant expression context.
+ EXPR_CONSTANT,
+
/// A PredefinedExpr record.
EXPR_PREDEFINED,
Index: include/clang/Basic/StmtNodes.td
===================================================================
--- include/clang/Basic/StmtNodes.td
+++ include/clang/Basic/StmtNodes.td
@@ -93,6 +93,9 @@
def GenericSelectionExpr : DStmt<Expr>;
def PseudoObjectExpr : DStmt<Expr>;
+// Wrapper expressions
+def ConstantExpr : DStmt<Expr>;
+
// Atomic expressions
def AtomicExpr : DStmt<Expr>;
Index: include/clang/AST/StmtDataCollectors.td
===================================================================
--- include/clang/AST/StmtDataCollectors.td
+++ include/clang/AST/StmtDataCollectors.td
@@ -14,6 +14,13 @@
}];
}
+//--- Wrappers -----------------------------------------------------------//
+class ConstantExpr {
+ code Code = [{
+ addData(S->getType());
+ }];
+}
+
//--- Builtin functionality ----------------------------------------------//
class ArrayTypeTraitExpr {
code Code = [{
Index: include/clang/AST/RecursiveASTVisitor.h
===================================================================
--- include/clang/AST/RecursiveASTVisitor.h
+++ include/clang/AST/RecursiveASTVisitor.h
@@ -2199,6 +2199,10 @@
DEF_TRAVERSE_STMT(SwitchStmt, {})
DEF_TRAVERSE_STMT(WhileStmt, {})
+DEF_TRAVERSE_STMT(ConstantExpr, {
+ TRY_TO(TraverseStmt(S->getSubExpr()));
+})
+
DEF_TRAVERSE_STMT(CXXDependentScopeMemberExpr, {
TRY_TO(TraverseNestedNameSpecifierLoc(S->getQualifierLoc()));
TRY_TO(TraverseDeclarationNameInfo(S->getMemberNameInfo()));
Index: include/clang/AST/Expr.h
===================================================================
--- include/clang/AST/Expr.h
+++ include/clang/AST/Expr.h
@@ -867,6 +867,46 @@
}
};
+//===----------------------------------------------------------------------===//
+// Wrapper Expressions.
+//===----------------------------------------------------------------------===//
+
+/// ConstantExpr - An expression that occurs in a constant context.
+class ConstantExpr : public Expr {
+ Stmt *Val;
+public:
+ ConstantExpr(Expr *val)
+ : Expr(ConstantExprClass, val->getType(),
+ val->getValueKind(), val->getObjectKind(),
+ val->isTypeDependent(), val->isValueDependent(),
+ val->isInstantiationDependent(),
+ val->containsUnexpandedParameterPack()),
+ Val(val) {}
+
+ /// Build an empty constant expression wrapper.
+ explicit ConstantExpr(EmptyShell Empty)
+ : Expr(ConstantExprClass, Empty) {}
+
+ const Expr *getSubExpr() const { return cast<Expr>(Val); }
+ Expr *getSubExpr() { return cast<Expr>(Val); }
+ void setSubExpr(Expr *E) { Val = E; }
+
+ SourceLocation getBeginLoc() const LLVM_READONLY {
+ return Val->getBeginLoc();
+ }
+ SourceLocation getEndLoc() const LLVM_READONLY {
+ return Val->getEndLoc();
+ }
+
+ static bool classof(const Stmt *T) {
+ return T->getStmtClass() == ConstantExprClass;
+ }
+
+ // Iterators
+ child_range children() { return Val->children(); }
+ const_child_range children() const { return Val->children(); }
+};
+
//===----------------------------------------------------------------------===//
// Primary Expressions.
//===----------------------------------------------------------------------===//
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