Refine Expr::HasSideEffects to correct identify StmtExprs that do not have
side-effects.
[Depends on http://reviews.llvm.org/D10210.]
http://reviews.llvm.org/D10211
Files:
include/clang/AST/EvaluatedExprVisitor.h
lib/AST/Expr.cpp
test/Sema/exprs.c
Index: include/clang/AST/EvaluatedExprVisitor.h
===================================================================
--- include/clang/AST/EvaluatedExprVisitor.h
+++ include/clang/AST/EvaluatedExprVisitor.h
@@ -28,6 +28,7 @@
/// of its potentially-evaluated subexpressions, recursively.
template<template <typename> class Ptr, typename ImplClass>
class EvaluatedExprVisitorBase : public StmtVisitorBase<Ptr, ImplClass, void> {
+protected:
const ASTContext &Context;
public:
Index: lib/AST/Expr.cpp
===================================================================
--- lib/AST/Expr.cpp
+++ lib/AST/Expr.cpp
@@ -2881,6 +2881,32 @@
return false;
}
+namespace {
+ /// \brief Look for any side effects within a Stmt.
+ class SideEffectFinder : public ConstEvaluatedExprVisitor<SideEffectFinder>
+ {
+ typedef ConstEvaluatedExprVisitor<SideEffectFinder> Inherited;
+ const bool IncludePossibleEffects;
+ bool HasSideEffects;
+
+ public:
+ explicit SideEffectFinder(const ASTContext &Context, bool
IncludePossibleEffects_)
+ : Inherited(Context),
+ IncludePossibleEffects(IncludePossibleEffects_), HasSideEffects(false)
{ }
+
+ bool getHasSideEffects() const { return HasSideEffects; }
+
+ void VisitExpr(const Expr *E) {
+ if (!E->HasSideEffects(Context, IncludePossibleEffects)) {
+ Inherited::VisitStmt(E);
+ return;
+ }
+
+ HasSideEffects = true;
+ }
+ };
+}
+
bool Expr::HasSideEffects(const ASTContext &Ctx,
bool IncludePossibleEffects) const {
// In circumstances where we care about definite side effects instead of
@@ -2967,14 +2993,20 @@
case CompoundAssignOperatorClass:
case VAArgExprClass:
case AtomicExprClass:
- case StmtExprClass:
case CXXThrowExprClass:
case CXXNewExprClass:
case CXXDeleteExprClass:
case ExprWithCleanupsClass:
// These always have a side-effect.
return true;
+ case StmtExprClass: {
+ // StmtExprs have a side-efect if any substatement does.
+ SideEffectFinder Finder(Ctx, IncludePossibleEffects);
+ Finder.Visit(cast<StmtExpr>(this)->getSubStmt());
+ return Finder.getHasSideEffects();
+ }
+
case ParenExprClass:
case ArraySubscriptExprClass:
case MemberExprClass:
Index: test/Sema/exprs.c
===================================================================
--- test/Sema/exprs.c
+++ test/Sema/exprs.c
@@ -251,3 +251,14 @@
if (&test22)
(void) 0;
}
+
+int stmtexpr_fn();
+void stmtexprs(int i) {
+ // No "side effects" warnig for the first two:
+ __builtin_assume( ({ 1; }) ); // expected-warning {{use of GNU statement
expression extension}}
+ __builtin_assume( ({ if (i) { (void)0; }; 42; }) ); // expected-warning
{{use of GNU statement expression extension}}
+ __builtin_assume( ({ if (i) ({ // expected-warning {{use of GNU statement
expression extension}} \
+ // expected-warning {{use of GNU statement
expression extension}} \
+ // expected-warning {{the argument to
'__builtin_assume' has side effects that will be discarded}}
+ stmtexpr_fn(); }); 1; }) );
+}
EMAIL PREFERENCES
http://reviews.llvm.org/settings/panel/emailpreferences/
Index: include/clang/AST/EvaluatedExprVisitor.h
===================================================================
--- include/clang/AST/EvaluatedExprVisitor.h
+++ include/clang/AST/EvaluatedExprVisitor.h
@@ -28,6 +28,7 @@
/// of its potentially-evaluated subexpressions, recursively.
template<template <typename> class Ptr, typename ImplClass>
class EvaluatedExprVisitorBase : public StmtVisitorBase<Ptr, ImplClass, void> {
+protected:
const ASTContext &Context;
public:
Index: lib/AST/Expr.cpp
===================================================================
--- lib/AST/Expr.cpp
+++ lib/AST/Expr.cpp
@@ -2881,6 +2881,32 @@
return false;
}
+namespace {
+ /// \brief Look for any side effects within a Stmt.
+ class SideEffectFinder : public ConstEvaluatedExprVisitor<SideEffectFinder>
+ {
+ typedef ConstEvaluatedExprVisitor<SideEffectFinder> Inherited;
+ const bool IncludePossibleEffects;
+ bool HasSideEffects;
+
+ public:
+ explicit SideEffectFinder(const ASTContext &Context, bool IncludePossibleEffects_)
+ : Inherited(Context),
+ IncludePossibleEffects(IncludePossibleEffects_), HasSideEffects(false) { }
+
+ bool getHasSideEffects() const { return HasSideEffects; }
+
+ void VisitExpr(const Expr *E) {
+ if (!E->HasSideEffects(Context, IncludePossibleEffects)) {
+ Inherited::VisitStmt(E);
+ return;
+ }
+
+ HasSideEffects = true;
+ }
+ };
+}
+
bool Expr::HasSideEffects(const ASTContext &Ctx,
bool IncludePossibleEffects) const {
// In circumstances where we care about definite side effects instead of
@@ -2967,14 +2993,20 @@
case CompoundAssignOperatorClass:
case VAArgExprClass:
case AtomicExprClass:
- case StmtExprClass:
case CXXThrowExprClass:
case CXXNewExprClass:
case CXXDeleteExprClass:
case ExprWithCleanupsClass:
// These always have a side-effect.
return true;
+ case StmtExprClass: {
+ // StmtExprs have a side-efect if any substatement does.
+ SideEffectFinder Finder(Ctx, IncludePossibleEffects);
+ Finder.Visit(cast<StmtExpr>(this)->getSubStmt());
+ return Finder.getHasSideEffects();
+ }
+
case ParenExprClass:
case ArraySubscriptExprClass:
case MemberExprClass:
Index: test/Sema/exprs.c
===================================================================
--- test/Sema/exprs.c
+++ test/Sema/exprs.c
@@ -251,3 +251,14 @@
if (&test22)
(void) 0;
}
+
+int stmtexpr_fn();
+void stmtexprs(int i) {
+ // No "side effects" warnig for the first two:
+ __builtin_assume( ({ 1; }) ); // expected-warning {{use of GNU statement expression extension}}
+ __builtin_assume( ({ if (i) { (void)0; }; 42; }) ); // expected-warning {{use of GNU statement expression extension}}
+ __builtin_assume( ({ if (i) ({ // expected-warning {{use of GNU statement expression extension}} \
+ // expected-warning {{use of GNU statement expression extension}} \
+ // expected-warning {{the argument to '__builtin_assume' has side effects that will be discarded}}
+ stmtexpr_fn(); }); 1; }) );
+}
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