5 files changed, 67 insertions, 44 deletions

diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index 93ca6011e16..5f8f34e9bcc 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -1339,6 +1339,25 @@ CodeGenFunction::tryEmitAsConstant(DeclRefExpr *refExpr) {
   return ConstantEmission::forValue(C);
 }
 
+static DeclRefExpr *tryToConvertMemberExprToDeclRefExpr(CodeGenFunction &CGF,
+                                                        const MemberExpr *ME) {
+  if (auto *VD = dyn_cast<VarDecl>(ME->getMemberDecl())) {
+    // Try to emit static variable member expressions as DREs.
+    return DeclRefExpr::Create(
+        CGF.getContext(), NestedNameSpecifierLoc(), SourceLocation(), VD,
+        /*RefersToEnclosingVariableOrCapture=*/false, ME->getExprLoc(),
+        ME->getType(), ME->getValueKind());
+  }
+  return nullptr;
+}
+
+CodeGenFunction::ConstantEmission
+CodeGenFunction::tryEmitAsConstant(const MemberExpr *ME) {
+  if (DeclRefExpr *DRE = tryToConvertMemberExprToDeclRefExpr(*this, ME))
+    return tryEmitAsConstant(DRE);
+  return ConstantEmission();
+}
+
 llvm::Value *CodeGenFunction::EmitLoadOfScalar(LValue lvalue,
                                                SourceLocation Loc) {
   return EmitLoadOfScalar(lvalue.getAddress(), lvalue.isVolatile(),
@@ -3540,6 +3559,11 @@ EmitExtVectorElementExpr(const ExtVectorElementExpr *E) {
 }
 
 LValue CodeGenFunction::EmitMemberExpr(const MemberExpr *E) {
+  if (DeclRefExpr *DRE = tryToConvertMemberExprToDeclRefExpr(*this, E)) {
+    EmitIgnoredExpr(E->getBase());
+    return EmitDeclRefLValue(DRE);
+  }
+
   Expr *BaseExpr = E->getBase();
   // If this is s.x, emit s as an lvalue.  If it is s->x, emit s as a scalar.
   LValue BaseLV;
@@ -3566,9 +3590,6 @@ LValue CodeGenFunction::EmitMemberExpr(const MemberExpr *E) {
     return LV;
   }
 
-  if (auto *VD = dyn_cast<VarDecl>(ND))
-    return EmitGlobalVarDeclLValue(*this, E, VD);
-
   if (const auto *FD = dyn_cast<FunctionDecl>(ND))
     return EmitFunctionDeclLValue(*this, E, FD);
 
diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index a05a088f091..1ab8433864c 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -124,24 +124,7 @@ public:
   }
 
   // l-values.
-  void VisitDeclRefExpr(DeclRefExpr *E) {
-    // For aggregates, we should always be able to emit the variable
-    // as an l-value unless it's a reference.  This is due to the fact
-    // that we can't actually ever see a normal l2r conversion on an
-    // aggregate in C++, and in C there's no language standard
-    // actively preventing us from listing variables in the captures
-    // list of a block.
-    if (E->getDecl()->getType()->isReferenceType()) {
-      if (CodeGenFunction::ConstantEmission result
-            = CGF.tryEmitAsConstant(E)) {
-        EmitFinalDestCopy(E->getType(), result.getReferenceLValue(CGF, E));
-        return;
-      }
-    }
-
-    EmitAggLoadOfLValue(E);
-  }
-
+  void VisitDeclRefExpr(DeclRefExpr *E) { EmitAggLoadOfLValue(E); }
   void VisitMemberExpr(MemberExpr *ME) { EmitAggLoadOfLValue(ME); }
   void VisitUnaryDeref(UnaryOperator *E) { EmitAggLoadOfLValue(E); }
   void VisitStringLiteral(StringLiteral *E) { EmitAggLoadOfLValue(E); }
diff --git a/clang/lib/CodeGen/CGExprComplex.cpp b/clang/lib/CodeGen/CGExprComplex.cpp
index 980972370dc..f019e3586e3 100644
--- a/clang/lib/CodeGen/CGExprComplex.cpp
+++ b/clang/lib/CodeGen/CGExprComplex.cpp
@@ -120,18 +120,22 @@ public:
     return Visit(E->getSubExpr());
   }
 
+  ComplexPairTy emitConstant(const CodeGenFunction::ConstantEmission &Constant,
+                             Expr *E) {
+    assert(Constant && "not a constant");
+    if (Constant.isReference())
+      return EmitLoadOfLValue(Constant.getReferenceLValue(CGF, E),
+                              E->getExprLoc());
+
+    llvm::Constant *pair = Constant.getValue();
+    return ComplexPairTy(pair->getAggregateElement(0U),
+                         pair->getAggregateElement(1U));
+  }
 
   // l-values.
   ComplexPairTy VisitDeclRefExpr(DeclRefExpr *E) {
-    if (CodeGenFunction::ConstantEmission result = CGF.tryEmitAsConstant(E)) {
-      if (result.isReference())
-        return EmitLoadOfLValue(result.getReferenceLValue(CGF, E),
-                                E->getExprLoc());
-
-      llvm::Constant *pair = result.getValue();
-      return ComplexPairTy(pair->getAggregateElement(0U),
-                           pair->getAggregateElement(1U));
-    }
+    if (CodeGenFunction::ConstantEmission Constant = CGF.tryEmitAsConstant(E))
+      return emitConstant(Constant, E);
     return EmitLoadOfLValue(E);
   }
   ComplexPairTy VisitObjCIvarRefExpr(ObjCIvarRefExpr *E) {
@@ -141,7 +145,14 @@ public:
     return CGF.EmitObjCMessageExpr(E).getComplexVal();
   }
   ComplexPairTy VisitArraySubscriptExpr(Expr *E) { return EmitLoadOfLValue(E); }
-  ComplexPairTy VisitMemberExpr(const Expr *E) { return EmitLoadOfLValue(E); }
+  ComplexPairTy VisitMemberExpr(MemberExpr *ME) {
+    if (CodeGenFunction::ConstantEmission Constant =
+            CGF.tryEmitAsConstant(ME)) {
+      CGF.EmitIgnoredExpr(ME->getBase());
+      return emitConstant(Constant, ME);
+    }
+    return EmitLoadOfLValue(ME);
+  }
   ComplexPairTy VisitOpaqueValueExpr(OpaqueValueExpr *E) {
     if (E->isGLValue())
       return EmitLoadOfLValue(CGF.getOpaqueLValueMapping(E), E->getExprLoc());
diff --git a/clang/lib/CodeGen/CGExprScalar.cpp b/clang/lib/CodeGen/CGExprScalar.cpp
index 1170b014ec7..46a01a3bb8b 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -428,14 +428,19 @@ public:
     return CGF.getOpaqueRValueMapping(E).getScalarVal();
   }
 
+  Value *emitConstant(const CodeGenFunction::ConstantEmission &Constant,
+                      Expr *E) {
+    assert(Constant && "not a constant");
+    if (Constant.isReference())
+      return EmitLoadOfLValue(Constant.getReferenceLValue(CGF, E),
+                              E->getExprLoc());
+    return Constant.getValue();
+  }
+
   // l-values.
   Value *VisitDeclRefExpr(DeclRefExpr *E) {
-    if (CodeGenFunction::ConstantEmission result = CGF.tryEmitAsConstant(E)) {
-      if (result.isReference())
-        return EmitLoadOfLValue(result.getReferenceLValue(CGF, E),
-                                E->getExprLoc());
-      return result.getValue();
-    }
+    if (CodeGenFunction::ConstantEmission Constant = CGF.tryEmitAsConstant(E))
+      return emitConstant(Constant, E);
     return EmitLoadOfLValue(E);
   }
 
@@ -1299,13 +1304,15 @@ Value *ScalarExprEmitter::VisitConvertVectorExpr(ConvertVectorExpr *E) {
 }
 
 Value *ScalarExprEmitter::VisitMemberExpr(MemberExpr *E) {
-  llvm::APSInt Value;
-  if (E->EvaluateAsInt(Value, CGF.getContext(), Expr::SE_AllowSideEffects)) {
-    if (E->isArrow())
-      CGF.EmitScalarExpr(E->getBase());
-    else
-      EmitLValue(E->getBase());
-    return Builder.getInt(Value);
+  if (CodeGenFunction::ConstantEmission Constant = CGF.tryEmitAsConstant(E)) {
+    CGF.EmitIgnoredExpr(E->getBase());
+    return emitConstant(Constant, E);
+  } else {
+    llvm::APSInt Value;
+    if (E->EvaluateAsInt(Value, CGF.getContext(), Expr::SE_AllowSideEffects)) {
+      CGF.EmitIgnoredExpr(E->getBase());
+      return Builder.getInt(Value);
+    }
   }
 
   return EmitLoadOfLValue(E);
diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index e334c315b8e..28253ff9852 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -3161,6 +3161,7 @@ public:
   };
 
   ConstantEmission tryEmitAsConstant(DeclRefExpr *refExpr);
+  ConstantEmission tryEmitAsConstant(const MemberExpr *ME);
 
   RValue EmitPseudoObjectRValue(const PseudoObjectExpr *e,
                                 AggValueSlot slot = AggValueSlot::ignored());