Fix a problem Eli ran into where we now reject incomplete arrays of

uncompleted struct types.  We now do what llvm-gcc does and compile
them into [i8 x 0].  If the type is later completed, we make sure that
it is appropriately cast.

We compile the terrible example to something like this now:

%struct.A = type { i32, i32, i32 }

@g = external global [0 x i8]

define void @_Z1fv() nounwind {
entry:
  call void @_Z3fooP1A(%struct.A* bitcast ([0 x i8]* @g to %struct.A*))
  ret void
}

declare void @_Z3fooP1A(%struct.A*)

define %struct.A* @_Z2f2v() nounwind {
entry:
  ret %struct.A* getelementptr inbounds ([0 x %struct.A]* bitcast ([0 x i8]* @g to [0 x %struct.A]*), i32 0, i64 1)
}





git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@134972 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 8 insertions, 3 deletions

diff --git a/lib/CodeGen/CodeGenTypes.cpp b/lib/CodeGen/CodeGenTypes.cpp
index 64348ea7d1..8efe9e1eea 100644
--- a/lib/CodeGen/CodeGenTypes.cpp
+++ b/lib/CodeGen/CodeGenTypes.cpp
@@ -92,7 +92,6 @@ llvm::Type *CodeGenTypes::ConvertTypeForMem(QualType T){
   // Otherwise, return an integer of the target-specified size.
   return llvm::IntegerType::get(getLLVMContext(),
                                 (unsigned)Context.getTypeSize(T));
-
 }
 
 /// isFuncTypeArgumentConvertible - Return true if the specified type in a 
@@ -318,8 +317,14 @@ llvm::Type *CodeGenTypes::ConvertType(QualType T) {
     const IncompleteArrayType *A = cast<IncompleteArrayType>(Ty);
     assert(A->getIndexTypeCVRQualifiers() == 0 &&
            "FIXME: We only handle trivial array types so far!");
-    // int X[] -> [0 x int]
-    ResultType = llvm::ArrayType::get(ConvertTypeForMem(A->getElementType()),0);
+    // int X[] -> [0 x int], unless the element type is not sized.  If it is
+    // unsized (e.g. an incomplete struct) just use [0 x i8].
+    ResultType = ConvertTypeForMem(A->getElementType());
+    if (!ResultType->isSized()) {
+      SkippedLayout = true;
+      ResultType = llvm::Type::getInt8Ty(getLLVMContext());
+    }
+    ResultType = llvm::ArrayType::get(ResultType, 0);
     break;
   }
   case Type::ConstantArray: {