commit 60b70388e43d146d968a1cc0705b30cb2d7263fe
author Richard Smith <richard-llvm@metafoo.co.uk> Tue Aug 07 05:18:29 2012 +0000
committer Richard Smith <richard-llvm@metafoo.co.uk> Tue Aug 07 05:18:29 2012 +0000
tree 96916a0f31a3802667ed5f67716ae4d3bcdfbf90
parent acac844992d9b28d30f2801711bd92f353ada084

Update documentation of HasSideEffects to match its callers' expectations, and
update implementation to match. An elidable, non-trivial constructor call is a
side-effect under this definition, but wasn't under the old one, because we are
not required to evaluate it even though it may have an effect.

Also rationalize checking for volatile reads: just look for lvalue-to-rvalue
conversions on volatile glvalues, and ignore whether a DeclRefExpr etc is for
a volatile variable.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@161393 91177308-0d34-0410-b5e6-96231b3b80d8

lib/AST/Expr.cpp

diff --git a/lib/AST/Expr.cpp b/lib/AST/Expr.cpp
index faba404..9df850d 100644
--- a/lib/AST/Expr.cpp
+++ b/lib/AST/Expr.cpp
@@ -2643,6 +2643,8 @@
   case SubstNonTypeTemplateParmPackExprClass:
     llvm_unreachable("shouldn't see dependent / unresolved nodes here");
 
+  case DeclRefExprClass:
+  case ObjCIvarRefExprClass:
   case PredefinedExprClass:
   case IntegerLiteralClass:
   case FloatingLiteralClass:
@@ -2696,16 +2698,10 @@
   case MemberExprClass:
   case ConditionalOperatorClass:
   case BinaryConditionalOperatorClass:
-  case ImplicitCastExprClass:
-  case CStyleCastExprClass:
   case CompoundLiteralExprClass:
   case ExtVectorElementExprClass:
   case DesignatedInitExprClass:
   case ParenListExprClass:
-  case CXXStaticCastExprClass:
-  case CXXReinterpretCastExprClass:
-  case CXXConstCastExprClass:
-  case CXXFunctionalCastExprClass:
   case CXXPseudoDestructorExprClass:
   case SubstNonTypeTemplateParmExprClass:
   case MaterializeTemporaryExprClass:
@@ -2714,24 +2710,16 @@
     // These have a side-effect if any subexpression does.
     break;
 
-  case UnaryOperatorClass: {
-    const UnaryOperator *UO = cast<UnaryOperator>(this);
-    if (UO->isIncrementDecrementOp())
-      return true;
-    if (UO->getOpcode() == UO_Deref && UO->getType().isVolatileQualified())
+  case UnaryOperatorClass:
+    if (cast<UnaryOperator>(this)->isIncrementDecrementOp())
       return true;
     break;
-  }
 
   case BinaryOperatorClass:
     if (cast<BinaryOperator>(this)->isAssignmentOp())
       return true;
     break;
 
-  case DeclRefExprClass:
-  case ObjCIvarRefExprClass:
-    return getType().isVolatileQualified();
-
   case InitListExprClass:
     // FIXME: The children for an InitListExpr doesn't include the array filler.
     if (const Expr *E = cast<InitListExpr>(this)->getArrayFiller())
@@ -2755,7 +2743,17 @@
     if (DCE->getTypeAsWritten()->isReferenceType() &&
         DCE->getCastKind() == CK_Dynamic)
       return true;
-    // Also has side-effects if the subexpression does.
+  } // Fall through.
+  case ImplicitCastExprClass:
+  case CStyleCastExprClass:
+  case CXXStaticCastExprClass:
+  case CXXReinterpretCastExprClass:
+  case CXXConstCastExprClass:
+  case CXXFunctionalCastExprClass: {
+    const CastExpr *CE = cast<CastExpr>(this);
+    if (CE->getCastKind() == CK_LValueToRValue &&
+        CE->getSubExpr()->getType().isVolatileQualified())
+      return true;
     break;
   }
 
@@ -2779,10 +2777,10 @@
   case CXXConstructExprClass:
   case CXXTemporaryObjectExprClass: {
     const CXXConstructExpr *CE = cast<CXXConstructExpr>(this);
-    if (!CE->isElidable() && !CE->getConstructor()->isTrivial())
+    if (!CE->getConstructor()->isTrivial())
       return true;
-    // An elidable or trivial constructor does not add any side-effects of its
-    // own. Just look at its arguments.
+    // A trivial constructor does not add any side-effects of its own. Just look
+    // at its arguments.
     break;
   }