Author: scott-0 Date: Wed Jun 10 10:18:23 2015 New Revision: 239476 URL: http://llvm.org/viewvc/llvm-project?rev=239476&view=rev Log: some StmtExprs do not have side-effects
Differential Revision: http://reviews.llvm.org/D10211 Added: cfe/trunk/test/Sema/stmtexprs.c (with props) Modified: cfe/trunk/include/clang/AST/EvaluatedExprVisitor.h cfe/trunk/lib/AST/Expr.cpp Modified: cfe/trunk/include/clang/AST/EvaluatedExprVisitor.h URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/AST/EvaluatedExprVisitor.h?rev=239476&r1=239475&r2=239476&view=diff ============================================================================== --- cfe/trunk/include/clang/AST/EvaluatedExprVisitor.h (original) +++ cfe/trunk/include/clang/AST/EvaluatedExprVisitor.h Wed Jun 10 10:18:23 2015 @@ -28,6 +28,7 @@ class ASTContext; /// 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: Modified: cfe/trunk/lib/AST/Expr.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/Expr.cpp?rev=239476&r1=239475&r2=239476&view=diff ============================================================================== --- cfe/trunk/lib/AST/Expr.cpp (original) +++ cfe/trunk/lib/AST/Expr.cpp Wed Jun 10 10:18:23 2015 @@ -2887,6 +2887,28 @@ bool Expr::isConstantInitializer(ASTCont 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 IncludePossible) + : Inherited(Context), + IncludePossibleEffects(IncludePossible), HasSideEffects(false) { } + + bool hasSideEffects() const { return HasSideEffects; } + + void VisitExpr(const Expr *E) { + if (!HasSideEffects && + E->HasSideEffects(Context, IncludePossibleEffects)) + HasSideEffects = true; + } + }; +} + bool Expr::HasSideEffects(const ASTContext &Ctx, bool IncludePossibleEffects) const { // In circumstances where we care about definite side effects instead of @@ -2974,7 +2996,6 @@ bool Expr::HasSideEffects(const ASTConte case CompoundAssignOperatorClass: case VAArgExprClass: case AtomicExprClass: - case StmtExprClass: case CXXThrowExprClass: case CXXNewExprClass: case CXXDeleteExprClass: @@ -2982,6 +3003,13 @@ bool Expr::HasSideEffects(const ASTConte // These always have a side-effect. return true; + case StmtExprClass: { + // StmtExprs have a side-effect if any substatement does. + SideEffectFinder Finder(Ctx, IncludePossibleEffects); + Finder.Visit(cast<StmtExpr>(this)->getSubStmt()); + return Finder.hasSideEffects(); + } + case ParenExprClass: case ArraySubscriptExprClass: case MemberExprClass: Added: cfe/trunk/test/Sema/stmtexprs.c URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/stmtexprs.c?rev=239476&view=auto ============================================================================== --- cfe/trunk/test/Sema/stmtexprs.c (added) +++ cfe/trunk/test/Sema/stmtexprs.c Wed Jun 10 10:18:23 2015 @@ -0,0 +1,9 @@ +// RUN: %clang_cc1 %s -verify -pedantic -fsyntax-only -Wno-gnu-statement-expression + +int stmtexpr_fn(); +void stmtexprs(int i) { + __builtin_assume( ({ 1; }) ); // no warning about "side effects" + __builtin_assume( ({ if (i) { (void)0; }; 42; }) ); // no warning about "side effects" + // expected-warning@+1 {{the argument to '__builtin_assume' has side effects that will be discarded}} + __builtin_assume( ({ if (i) ({ stmtexpr_fn(); }); 1; }) ); +} Propchange: cfe/trunk/test/Sema/stmtexprs.c ------------------------------------------------------------------------------ svn:eol-style = native Propchange: cfe/trunk/test/Sema/stmtexprs.c ------------------------------------------------------------------------------ svn:keywords = Rev Date Author URL Id _______________________________________________ cfe-commits mailing list [email protected] http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
