r301721 - ObjCBoxedExpr can't be evaluated by the constant expression evaluator.

[Nick Lewycky via cfe-commits]

Author: nicholas
Date: Fri Apr 28 19:07:27 2017
New Revision: 301721

URL: http://llvm.org/viewvc/llvm-project?rev=301721&view=rev
Log:
ObjCBoxedExpr can't be evaluated by the constant expression evaluator.

A boxed expression evaluates its subexpr and then calls an objc method to transform it into another value with pointer type. The objc method can never be constexpr and therefore this expression can never be evaluated. Fixes a miscompile boxing expressions with side-effects.

Also make ObjCBoxedExpr handling a normal part of the expression evaluator instead of being the only case besides full-expression where we check for integer overflow.

Added:
    cfe/trunk/test/CodeGenObjCXX/boxing.mm
Modified:
    cfe/trunk/lib/AST/ExprConstant.cpp
    cfe/trunk/lib/Sema/SemaChecking.cpp
    cfe/trunk/lib/Sema/SemaExprObjC.cpp

Modified: cfe/trunk/lib/AST/ExprConstant.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ExprConstant.cpp?rev=301721&r1=301720&r2=301721&view=diff
==============================================================================
--- cfe/trunk/lib/AST/ExprConstant.cpp (original)
+++ cfe/trunk/lib/AST/ExprConstant.cpp Fri Apr 28 19:07:27 2017
@@ -5481,8 +5481,11 @@ public:
   bool VisitUnaryAddrOf(const UnaryOperator *E);
   bool VisitObjCStringLiteral(const ObjCStringLiteral *E)
       { return Success(E); }
-  bool VisitObjCBoxedExpr(const ObjCBoxedExpr *E)
-      { return Success(E); }
+  bool VisitObjCBoxedExpr(const ObjCBoxedExpr *E) {
+    if (Info.noteFailure())
+      EvaluateIgnoredValue(Info, E->getSubExpr());
+    return Error(E);
+  }
   bool VisitAddrLabelExpr(const AddrLabelExpr *E)
       { return Success(E); }
   bool VisitCallExpr(const CallExpr *E);

Modified: cfe/trunk/lib/Sema/SemaChecking.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaChecking.cpp?rev=301721&r1=301720&r2=301721&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaChecking.cpp (original)
+++ cfe/trunk/lib/Sema/SemaChecking.cpp Fri Apr 28 19:07:27 2017
@@ -9882,6 +9882,9 @@ void Sema::CheckForIntOverflow (Expr *E)
 
     if (auto InitList = dyn_cast<InitListExpr>(E))
       Exprs.append(InitList->inits().begin(), InitList->inits().end());
+
+    if (isa<ObjCBoxedExpr>(E))
+      E->IgnoreParenCasts()->EvaluateForOverflow(Context);
   } while (!Exprs.empty());
 }
 

Modified: cfe/trunk/lib/Sema/SemaExprObjC.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExprObjC.cpp?rev=301721&r1=301720&r2=301721&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaExprObjC.cpp (original)
+++ cfe/trunk/lib/Sema/SemaExprObjC.cpp Fri Apr 28 19:07:27 2017
@@ -595,7 +595,6 @@ ExprResult Sema::BuildObjCBoxedExpr(Sour
         break;
       }
     }
-    CheckForIntOverflow(ValueExpr);
     // FIXME:  Do I need to do anything special with BoolTy expressions?
     
     // Look for the appropriate method within NSNumber.

Added: cfe/trunk/test/CodeGenObjCXX/boxing.mm
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenObjCXX/boxing.mm?rev=301721&view=auto
==============================================================================
--- cfe/trunk/test/CodeGenObjCXX/boxing.mm (added)
+++ cfe/trunk/test/CodeGenObjCXX/boxing.mm Fri Apr 28 19:07:27 2017
@@ -0,0 +1,12 @@
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -emit-llvm -o - %s | FileCheck %s
+
+ at interface NSNumber
++ (id)numberWithInt:(int)n;
+ at end
+
+int n = 1;
+int m = (@(n++), 0);
+
+// CHECK: define {{.*}} @__cxx_global_var_init()
+// CHECK: load i32, i32* @n
+// CHECK: store i32 %{{.*}}, i32* @n