[CodeGen] Ignore OpaqueValueExprs that are unique references to their

source expressions when iterating over a PseudoObjectExpr's semantic
subexpression list.

Previously the loop in emitPseudoObjectExpr would emit the IR for each
OpaqueValueExpr that was in a PseudoObjectExpr's semantic-form
expression list and use the result when the OpaqueValueExpr later
appeared in other expressions. This caused an assertion failure when
AggExprEmitter tried to copy the result of an OpaqueValueExpr and the
copied type didn't have trivial copy/move constructors or assignment
operators.

This patch adds flag IsUnique to OpaqueValueExpr which indicates it is a
unique reference to its source expression (it is not used in multiple
places). The loop in emitPseudoObjectExpr ignores OpaqueValueExprs that
are unique and CodeGen visitors simply traverse the source expressions
of such OpaqueValueExprs.

rdar://problem/34363596

Differential Revision: https://reviews.llvm.org/D39562

llvm-svn: 327939

1 files changed, 39 insertions, 28 deletions

diff --git a/clang/lib/Sema/SemaPseudoObject.cpp b/clang/lib/Sema/SemaPseudoObject.cpp
index 8a671b14872..a267670cc9b 100644
--- a/clang/lib/Sema/SemaPseudoObject.cpp
+++ b/clang/lib/Sema/SemaPseudoObject.cpp
@@ -190,11 +190,12 @@ namespace {
     Sema &S;
     unsigned ResultIndex;
     SourceLocation GenericLoc;
+    bool IsUnique;
     SmallVector<Expr *, 4> Semantics;
 
-    PseudoOpBuilder(Sema &S, SourceLocation genericLoc)
+    PseudoOpBuilder(Sema &S, SourceLocation genericLoc, bool IsUnique)
       : S(S), ResultIndex(PseudoObjectExpr::NoResult),
-        GenericLoc(genericLoc) {}
+        GenericLoc(genericLoc), IsUnique(IsUnique) {}
 
     virtual ~PseudoOpBuilder() {}
 
@@ -208,6 +209,9 @@ namespace {
       assert(ResultIndex == PseudoObjectExpr::NoResult);
       ResultIndex = Semantics.size();
       Semantics.push_back(resultExpr);
+      // An OVE is not unique if it is used as the result expression.
+      if (auto *OVE = dyn_cast<OpaqueValueExpr>(Semantics.back()))
+        OVE->setIsUnique(false);
     }
 
     ExprResult buildRValueOperation(Expr *op);
@@ -227,6 +231,9 @@ namespace {
     void setResultToLastSemantic() {
       assert(ResultIndex == PseudoObjectExpr::NoResult);
       ResultIndex = Semantics.size() - 1;
+      // An OVE is not unique if it is used as the result expression.
+      if (auto *OVE = dyn_cast<OpaqueValueExpr>(Semantics.back()))
+        OVE->setIsUnique(false);
     }
 
     /// Return true if assignments have a non-void result.
@@ -274,10 +281,10 @@ namespace {
     Selector GetterSelector;
 
   public:
-    ObjCPropertyOpBuilder(Sema &S, ObjCPropertyRefExpr *refExpr) :
-      PseudoOpBuilder(S, refExpr->getLocation()), RefExpr(refExpr),
-      SyntacticRefExpr(nullptr), InstanceReceiver(nullptr), Getter(nullptr),
-      Setter(nullptr) {
+    ObjCPropertyOpBuilder(Sema &S, ObjCPropertyRefExpr *refExpr, bool IsUnique)
+        : PseudoOpBuilder(S, refExpr->getLocation(), IsUnique),
+          RefExpr(refExpr), SyntacticRefExpr(nullptr),
+          InstanceReceiver(nullptr), Getter(nullptr), Setter(nullptr) {
     }
 
     ExprResult buildRValueOperation(Expr *op);
@@ -314,11 +321,10 @@ namespace {
    Selector AtIndexSetterSelector;
   
  public:
-    ObjCSubscriptOpBuilder(Sema &S, ObjCSubscriptRefExpr *refExpr) :
-      PseudoOpBuilder(S, refExpr->getSourceRange().getBegin()), 
-      RefExpr(refExpr),
-      InstanceBase(nullptr), InstanceKey(nullptr),
-      AtIndexGetter(nullptr), AtIndexSetter(nullptr) {}
+   ObjCSubscriptOpBuilder(Sema &S, ObjCSubscriptRefExpr *refExpr, bool IsUnique)
+       : PseudoOpBuilder(S, refExpr->getSourceRange().getBegin(), IsUnique),
+         RefExpr(refExpr), InstanceBase(nullptr), InstanceKey(nullptr),
+         AtIndexGetter(nullptr), AtIndexSetter(nullptr) {}
 
    ExprResult buildRValueOperation(Expr *op);
    ExprResult buildAssignmentOperation(Scope *Sc,
@@ -342,11 +348,11 @@ namespace {
    MSPropertyRefExpr *getBaseMSProperty(MSPropertySubscriptExpr *E);
 
  public:
-   MSPropertyOpBuilder(Sema &S, MSPropertyRefExpr *refExpr) :
-     PseudoOpBuilder(S, refExpr->getSourceRange().getBegin()),
-     RefExpr(refExpr), InstanceBase(nullptr) {}
-   MSPropertyOpBuilder(Sema &S, MSPropertySubscriptExpr *refExpr)
-       : PseudoOpBuilder(S, refExpr->getSourceRange().getBegin()),
+   MSPropertyOpBuilder(Sema &S, MSPropertyRefExpr *refExpr, bool IsUnique)
+       : PseudoOpBuilder(S, refExpr->getSourceRange().getBegin(), IsUnique),
+         RefExpr(refExpr), InstanceBase(nullptr) {}
+   MSPropertyOpBuilder(Sema &S, MSPropertySubscriptExpr *refExpr, bool IsUnique)
+       : PseudoOpBuilder(S, refExpr->getSourceRange().getBegin(), IsUnique),
          InstanceBase(nullptr) {
      RefExpr = getBaseMSProperty(refExpr);
    }
@@ -365,7 +371,9 @@ OpaqueValueExpr *PseudoOpBuilder::capture(Expr *e) {
     new (S.Context) OpaqueValueExpr(GenericLoc, e->getType(),
                                     e->getValueKind(), e->getObjectKind(),
                                     e);
-  
+  if (IsUnique)
+    captured->setIsUnique(true);
+
   // Make sure we bind that in the semantics.
   addSemanticExpr(captured);
   return captured;
@@ -397,6 +405,8 @@ OpaqueValueExpr *PseudoOpBuilder::captureValueAsResult(Expr *e) {
     if (e == Semantics[index]) break;
   }
   ResultIndex = index;
+  // An OVE is not unique if it is used as the result expression.
+  cast<OpaqueValueExpr>(e)->setIsUnique(false);
   return cast<OpaqueValueExpr>(e);
 }
 
@@ -1528,20 +1538,20 @@ ExprResult Sema::checkPseudoObjectRValue(Expr *E) {
   Expr *opaqueRef = E->IgnoreParens();
   if (ObjCPropertyRefExpr *refExpr
         = dyn_cast<ObjCPropertyRefExpr>(opaqueRef)) {
-    ObjCPropertyOpBuilder builder(*this, refExpr);
+    ObjCPropertyOpBuilder builder(*this, refExpr, true);
     return builder.buildRValueOperation(E);
   }
   else if (ObjCSubscriptRefExpr *refExpr
            = dyn_cast<ObjCSubscriptRefExpr>(opaqueRef)) {
-    ObjCSubscriptOpBuilder builder(*this, refExpr);
+    ObjCSubscriptOpBuilder builder(*this, refExpr, true);
     return builder.buildRValueOperation(E);
   } else if (MSPropertyRefExpr *refExpr
              = dyn_cast<MSPropertyRefExpr>(opaqueRef)) {
-    MSPropertyOpBuilder builder(*this, refExpr);
+    MSPropertyOpBuilder builder(*this, refExpr, true);
     return builder.buildRValueOperation(E);
   } else if (MSPropertySubscriptExpr *RefExpr =
                  dyn_cast<MSPropertySubscriptExpr>(opaqueRef)) {
-    MSPropertyOpBuilder Builder(*this, RefExpr);
+    MSPropertyOpBuilder Builder(*this, RefExpr, true);
     return Builder.buildRValueOperation(E);
   } else {
     llvm_unreachable("unknown pseudo-object kind!");
@@ -1560,18 +1570,18 @@ ExprResult Sema::checkPseudoObjectIncDec(Scope *Sc, SourceLocation opcLoc,
   Expr *opaqueRef = op->IgnoreParens();
   if (ObjCPropertyRefExpr *refExpr
         = dyn_cast<ObjCPropertyRefExpr>(opaqueRef)) {
-    ObjCPropertyOpBuilder builder(*this, refExpr);
+    ObjCPropertyOpBuilder builder(*this, refExpr, false);
     return builder.buildIncDecOperation(Sc, opcLoc, opcode, op);
   } else if (isa<ObjCSubscriptRefExpr>(opaqueRef)) {
     Diag(opcLoc, diag::err_illegal_container_subscripting_op);
     return ExprError();
   } else if (MSPropertyRefExpr *refExpr
              = dyn_cast<MSPropertyRefExpr>(opaqueRef)) {
-    MSPropertyOpBuilder builder(*this, refExpr);
+    MSPropertyOpBuilder builder(*this, refExpr, false);
     return builder.buildIncDecOperation(Sc, opcLoc, opcode, op);
   } else if (MSPropertySubscriptExpr *RefExpr
              = dyn_cast<MSPropertySubscriptExpr>(opaqueRef)) {
-    MSPropertyOpBuilder Builder(*this, RefExpr);
+    MSPropertyOpBuilder Builder(*this, RefExpr, false);
     return Builder.buildIncDecOperation(Sc, opcLoc, opcode, op);
   } else {
     llvm_unreachable("unknown pseudo-object kind!");
@@ -1594,22 +1604,23 @@ ExprResult Sema::checkPseudoObjectAssignment(Scope *S, SourceLocation opcLoc,
     RHS = result.get();
   }
 
+  bool IsSimpleAssign = opcode == BO_Assign;
   Expr *opaqueRef = LHS->IgnoreParens();
   if (ObjCPropertyRefExpr *refExpr
         = dyn_cast<ObjCPropertyRefExpr>(opaqueRef)) {
-    ObjCPropertyOpBuilder builder(*this, refExpr);
+    ObjCPropertyOpBuilder builder(*this, refExpr, IsSimpleAssign);
     return builder.buildAssignmentOperation(S, opcLoc, opcode, LHS, RHS);
   } else if (ObjCSubscriptRefExpr *refExpr
              = dyn_cast<ObjCSubscriptRefExpr>(opaqueRef)) {
-    ObjCSubscriptOpBuilder builder(*this, refExpr);
+    ObjCSubscriptOpBuilder builder(*this, refExpr, IsSimpleAssign);
     return builder.buildAssignmentOperation(S, opcLoc, opcode, LHS, RHS);
   } else if (MSPropertyRefExpr *refExpr
              = dyn_cast<MSPropertyRefExpr>(opaqueRef)) {
-      MSPropertyOpBuilder builder(*this, refExpr);
+      MSPropertyOpBuilder builder(*this, refExpr, IsSimpleAssign);
       return builder.buildAssignmentOperation(S, opcLoc, opcode, LHS, RHS);
   } else if (MSPropertySubscriptExpr *RefExpr
              = dyn_cast<MSPropertySubscriptExpr>(opaqueRef)) {
-      MSPropertyOpBuilder Builder(*this, RefExpr);
+      MSPropertyOpBuilder Builder(*this, RefExpr, IsSimpleAssign);
       return Builder.buildAssignmentOperation(S, opcLoc, opcode, LHS, RHS);
   } else {
     llvm_unreachable("unknown pseudo-object kind!");