On Tue, 19 Mar 2019 at 13:07, Robin Dapp <rd...@linux.ibm.com> wrote:
>
> Hi,
>
> > Alignment is written to TypeInfo, I don't think it should ever be
> > zero. That would mean that it isn't being generated by the compiler,
> > or read by the library correctly, so something else is amiss.
>
> it took me a while to see that in libphobos/libdruntime/object.d
>
> override @property size_t talign() nothrow pure const {return m_align;}
>
> returns a size_t but m_align is a uint. The type info seems to be
> stored in memory by the compiler and writes a GCC "sizetype". When
> using it, we only emit a 4-byte read which loads the first half of the
> stored 8 bytes. This will work on a little-endian machine but fail on
> big endian.
>
> I'd hope it is safe to change m_align's type to size_t since, as far as
> I can tell, the compiler will always write 8 bytes and the memory layout
> will not be changed by that.
>
So, when the initializer value type is larger than the field, it
truncates rather than rounds?
This would mean that StructFlags and ClassFlags will also both have a
wrong value as well.
> Does this [1] look reasonable?
>
If there's a compiler/library discrepancy, the compiler should be
adjusted to write out the value at the correct size.
I think the following below should do it.
--
Iain
--- a/gcc/d/typeinfo.cc
+++ b/gcc/d/typeinfo.cc
@@ -830,7 +830,7 @@ public:
flags |= ClassFlags::noPointers;
Lhaspointers:
- this->layout_field (size_int (flags));
+ this->layout_field (build_integer_cst (flags, d_uint_type));
/* void *deallocator; */
tree ddtor = (cd->aggDelete)
@@ -886,7 +886,7 @@ public:
if (cd->isCOMinterface ())
flags |= ClassFlags::isCOMclass;
- this->layout_field (size_int (flags));
+ this->layout_field (build_integer_cst (flags, d_uint_type));
/* void *deallocator;
OffsetTypeInfo[] m_offTi; (not implemented)
@@ -1019,7 +1019,7 @@ public:
StructFlags::Type m_flags = 0;
if (ti->hasPointers ())
m_flags |= StructFlags::hasPointers;
- this->layout_field (size_int (m_flags));
+ this->layout_field (build_integer_cst (m_flags, d_uint_type));
/* void function(void*) xdtor; */
tree dtor = (sd->dtor) ? build_address (get_symbol_decl (sd->dtor))
@@ -1033,7 +1033,7 @@ public:
this->layout_field (null_pointer_node);
/* uint m_align; */
- this->layout_field (size_int (ti->alignsize ()));
+ this->layout_field (build_integer_cst (ti->alignsize (), d_uint_type));
if (global.params.is64bit)
{
@@ -1488,9 +1488,8 @@ create_typeinfo (Type *type, Module *mod)
make_internal_typeinfo (tk, ident,
array_type_node, array_type_node,
ptr_type_node, ptr_type_node,
- ptr_type_node, ptr_type_node,
- size_type_node, ptr_type_node,
- ptr_type_node, size_type_node,
+ ptr_type_node, ptr_type_node, d_uint_type,
+ ptr_type_node, ptr_type_node, d_uint_type,
ptr_type_node, argtype, argtype, NULL);
}
t->vtinfo = TypeInfoStructDeclaration::create (t);
