Fix bug in constant evaluation exposed by 176.gcc.
- Evaluation of , operator used bogus assumption that LHS could be
evaluated as an integral expression even though its type is
unspecified.
This change is making isICE very permissive of the LHS in non-evaluated
contexts because it is not clear what predicate we would use to reject
code here. The standard didn't offer me any guidance; opinions?
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@59196 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/ExprConstant.cpp b/lib/AST/ExprConstant.cpp
index d6a4094..f5477f3 100644
--- a/lib/AST/ExprConstant.cpp
+++ b/lib/AST/ExprConstant.cpp
@@ -376,6 +376,7 @@
}
bool VisitDeclRefExpr(const DeclRefExpr *E);
bool VisitCallExpr(const CallExpr *E);
+ bool VisitBinOpComma(const BinaryOperator *E);
bool VisitBinaryOperator(const BinaryOperator *E);
bool VisitUnaryOperator(const UnaryOperator *E);
@@ -480,7 +481,37 @@
}
}
+bool IntExprEvaluator::VisitBinOpComma(const BinaryOperator *E) {
+ llvm::APSInt RHS(32);
+
+ // Require that we be able to evaluate the LHS.
+ if (!E->getLHS()->isEvaluatable(Info.Ctx))
+ return false;
+
+ bool OldEval = Info.isEvaluated;
+ if (!EvaluateInteger(E->getRHS(), RHS, Info))
+ return false;
+ Info.isEvaluated = OldEval;
+
+ // Result of the comma is just the result of the RHS.
+ Result = RHS;
+
+ // C99 6.6p3: "shall not contain assignment, ..., or comma operators,
+ // *except* when they are contained within a subexpression that is not
+ // evaluated". Note that Assignment can never happen due to constraints
+ // on the LHS subexpr, so we don't need to check it here.
+ if (!Info.isEvaluated)
+ return true;
+
+ // If the value is evaluated, we can accept it as an extension.
+ return Extension(E->getOperatorLoc(), diag::ext_comma_in_constant_expr);
+}
+
bool IntExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
+ // Comma operator requires special handling.
+ if (E->getOpcode() == BinaryOperator::Comma)
+ return VisitBinOpComma(E);
+
// The LHS of a constant expr is always evaluated and needed.
llvm::APSInt RHS(32);
if (!Visit(E->getLHS())) {
@@ -585,22 +616,7 @@
Result = Result != 0 || RHS != 0;
Result.zextOrTrunc(getIntTypeSizeInBits(E->getType()));
break;
-
-
- case BinaryOperator::Comma:
- // Result of the comma is just the result of the RHS.
- Result = RHS;
-
- // C99 6.6p3: "shall not contain assignment, ..., or comma operators,
- // *except* when they are contained within a subexpression that is not
- // evaluated". Note that Assignment can never happen due to constraints
- // on the LHS subexpr, so we don't need to check it here.
- if (!Info.isEvaluated)
- return true;
-
- // If the value is evaluated, we can accept it as an extension.
- return Extension(E->getOperatorLoc(), diag::ext_comma_in_constant_expr);
- }
+}
Result.setIsUnsigned(E->getType()->isUnsignedIntegerType());
return true;