constexpr: Treat INT_MIN % -1 as undefined behavior in C++11. Technically, it
isn't, but this is just a (reported) defect in the wording.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@149448 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/ExprConstant.cpp b/lib/AST/ExprConstant.cpp
index 5a385e6..15ab15c 100644
--- a/lib/AST/ExprConstant.cpp
+++ b/lib/AST/ExprConstant.cpp
@@ -4431,17 +4431,15 @@
case BO_Xor: return Success(LHS ^ RHS, E);
case BO_Or: return Success(LHS | RHS, E);
case BO_Div:
- if (RHS == 0)
- return Error(E, diag::note_expr_divide_by_zero);
- // Check for overflow case: INT_MIN / -1.
- if (RHS.isNegative() && RHS.isAllOnesValue() &&
- LHS.isSigned() && LHS.isMinSignedValue())
- HandleOverflow(Info, E, -LHS.extend(LHS.getBitWidth() + 1), E->getType());
- return Success(LHS / RHS, E);
case BO_Rem:
if (RHS == 0)
return Error(E, diag::note_expr_divide_by_zero);
- return Success(LHS % RHS, E);
+ // Check for overflow case: INT_MIN / -1 or INT_MIN % -1. The latter is not
+ // actually undefined behavior in C++11 due to a language defect.
+ if (RHS.isNegative() && RHS.isAllOnesValue() &&
+ LHS.isSigned() && LHS.isMinSignedValue())
+ HandleOverflow(Info, E, -LHS.extend(LHS.getBitWidth() + 1), E->getType());
+ return Success(E->getOpcode() == BO_Rem ? LHS % RHS : LHS / RHS, E);
case BO_Shl: {
// During constant-folding, a negative shift is an opposite shift. Such a
// shift is not a constant expression.