Fix a bunch of really nasty bugs in how we compute alignment for reference lvalues. PR11376.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@144745 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 28 insertions, 14 deletions

diff --git a/lib/CodeGen/CGExpr.cpp b/lib/CodeGen/CGExpr.cpp
index 0b6195dc79..a35bb5f711 100644
--- a/lib/CodeGen/CGExpr.cpp
+++ b/lib/CodeGen/CGExpr.cpp
@@ -1319,14 +1319,19 @@ static LValue EmitGlobalVarDeclLValue(CodeGenFunction &CGF,
          "Var decl must have external storage or be a file var decl!");
 
   llvm::Value *V = CGF.CGM.GetAddrOfGlobalVar(VD);
-  if (VD->getType()->isReferenceType())
-    V = CGF.Builder.CreateLoad(V);
-  
-  V = EmitBitCastOfLValueToProperType(CGF, V,
-                                CGF.getTypes().ConvertTypeForMem(E->getType()));
-
+  llvm::Type *RealVarTy = CGF.getTypes().ConvertTypeForMem(VD->getType());
+  V = EmitBitCastOfLValueToProperType(CGF, V, RealVarTy);
   unsigned Alignment = CGF.getContext().getDeclAlign(VD).getQuantity();
-  LValue LV = CGF.MakeAddrLValue(V, E->getType(), Alignment);
+  QualType T = E->getType();
+  LValue LV;
+  if (VD->getType()->isReferenceType()) {
+    llvm::LoadInst *LI = CGF.Builder.CreateLoad(V);
+    LI->setAlignment(Alignment);
+    V = LI;
+    LV = CGF.MakeNaturalAlignAddrLValue(V, T);
+  } else {
+    LV = CGF.MakeAddrLValue(V, E->getType(), Alignment);
+  }
   setObjCGCLValueClass(CGF.getContext(), E, LV);
   return LV;
 }
@@ -1353,6 +1358,7 @@ static LValue EmitFunctionDeclLValue(CodeGenFunction &CGF,
 LValue CodeGenFunction::EmitDeclRefLValue(const DeclRefExpr *E) {
   const NamedDecl *ND = E->getDecl();
   unsigned Alignment = getContext().getDeclAlign(ND).getQuantity();
+  QualType T = E->getType();
 
   if (ND->hasAttr<WeakRefAttr>()) {
     const ValueDecl *VD = cast<ValueDecl>(ND);
@@ -1377,14 +1383,17 @@ LValue CodeGenFunction::EmitDeclRefLValue(const DeclRefExpr *E) {
 
     if (VD->hasAttr<BlocksAttr>())
       V = BuildBlockByrefAddress(V, VD);
-    
-    if (VD->getType()->isReferenceType())
-      V = Builder.CreateLoad(V);
 
-    V = EmitBitCastOfLValueToProperType(*this, V,
-                                    getTypes().ConvertTypeForMem(E->getType()));
+    LValue LV;
+    if (VD->getType()->isReferenceType()) {
+      llvm::LoadInst *LI = Builder.CreateLoad(V);
+      LI->setAlignment(Alignment);
+      V = LI;
+      LV = MakeNaturalAlignAddrLValue(V, T);
+    } else {
+      LV = MakeAddrLValue(V, T, Alignment);
+    }
 
-    LValue LV = MakeAddrLValue(V, E->getType(), Alignment);
     if (NonGCable) {
       LV.getQuals().removeObjCGCAttr();
       LV.setNonGC(true);
@@ -1843,6 +1852,7 @@ LValue CodeGenFunction::EmitLValueForField(llvm::Value *baseAddr,
 
   const RecordDecl *rec = field->getParent();
   QualType type = field->getType();
+  unsigned alignment = getContext().getDeclAlign(field).getQuantity();
 
   bool mayAlias = rec->hasAttr<MayAliasAttr>();
 
@@ -1859,6 +1869,7 @@ LValue CodeGenFunction::EmitLValueForField(llvm::Value *baseAddr,
     if (const ReferenceType *refType = type->getAs<ReferenceType>()) {
       llvm::LoadInst *load = Builder.CreateLoad(addr, "ref");
       if (cvr & Qualifiers::Volatile) load->setVolatile(true);
+      load->setAlignment(alignment);
 
       if (CGM.shouldUseTBAA()) {
         llvm::MDNode *tbaa;
@@ -1872,6 +1883,10 @@ LValue CodeGenFunction::EmitLValueForField(llvm::Value *baseAddr,
       addr = load;
       mayAlias = false;
       type = refType->getPointeeType();
+      if (type->isIncompleteType())
+        alignment = 0;
+      else
+        alignment = getContext().getTypeAlignInChars(type).getQuantity();
       cvr = 0; // qualifiers don't recursively apply to referencee
     }
   }
@@ -1887,7 +1902,6 @@ LValue CodeGenFunction::EmitLValueForField(llvm::Value *baseAddr,
   if (field->hasAttr<AnnotateAttr>())
     addr = EmitFieldAnnotations(field, addr);
 
-  unsigned alignment = getContext().getDeclAlign(field).getQuantity();
   LValue LV = MakeAddrLValue(addr, type, alignment);
   LV.getQuals().addCVRQualifiers(cvr);