r254699 - Don't assert if evaluation of an expression that we're syntactically required

[Richard Smith via cfe-commits]

Author: rsmith
Date: Thu Dec  3 21:00:44 2015
New Revision: 254699

URL: http://llvm.org/viewvc/llvm-project?rev=254699&view=rev
Log:
Don't assert if evaluation of an expression that we're syntactically required
to treat as an ICE results in undefined behavior. Instead, return the "natural"
result of the operation (signed wraparound / inf / nan).

Modified:
    cfe/trunk/lib/AST/ExprConstant.cpp
    cfe/trunk/test/SemaCXX/constant-expression.cpp

Modified: cfe/trunk/lib/AST/ExprConstant.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ExprConstant.cpp?rev=254699&r1=254698&r2=254699&view=diff
==============================================================================
--- cfe/trunk/lib/AST/ExprConstant.cpp (original)
+++ cfe/trunk/lib/AST/ExprConstant.cpp Thu Dec  3 21:00:44 2015
@@ -9408,7 +9408,11 @@ bool Expr::isIntegerConstantExpr(llvm::A
 
   if (!isIntegerConstantExpr(Ctx, Loc))
     return false;
-  if (!EvaluateAsInt(Value, Ctx))
+  // The only possible side-effects here are due to UB discovered in the
+  // evaluation (for instance, INT_MAX + 1). In such a case, we are still
+  // required to treat the expression as an ICE, so we produce the folded
+  // value.
+  if (!EvaluateAsInt(Value, Ctx, SE_AllowSideEffects))
     llvm_unreachable("ICE cannot be evaluated!");
   return true;
 }

Modified: cfe/trunk/test/SemaCXX/constant-expression.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/constant-expression.cpp?rev=254699&r1=254698&r2=254699&view=diff
==============================================================================
--- cfe/trunk/test/SemaCXX/constant-expression.cpp (original)
+++ cfe/trunk/test/SemaCXX/constant-expression.cpp Thu Dec  3 21:00:44 2015
@@ -141,3 +141,5 @@ namespace rdar16064952 {
    unsigned w = ({int a = b.val[sizeof(0)]; 0; }); // expected-warning {{use of GNU statement expression extension}}
   }
 }
+
+char PR17381_ice = 1000000 * 1000000; // expected-warning {{overflow}} expected-warning {{changes value}}