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Re: Alpha vs. new ABI
Jeff Sturm wrote:
> Looks like C++ and the runtime are basically working both for static and
> dynamically allocated arrays. But the Java expression `i[n]' seems to get the
> array offset wrong. And compiling from bytecode yields yet another variation:
I think I understand what is happening. Please let me know if I'm off track.
The element offset is computed in build_java_arrayaccess accordingly:
arith = fold (build (PLUS_EXPR, int_type_node,
fold (build (MULT_EXPR, int_type_node,
and java_array_data_offset searches for the `data' member. If successful, it
returns the offset of data, else the size of the entire array header:
tree data_fld = TREE_CHAIN (TREE_CHAIN (TYPE_FIELDS (array_type)));
if (data_fld == NULL_TREE)
return size_in_bytes (array_type);
return byte_position (data_fld);
I'm finding that data_fld == NULL_TREE _each_ time this method is called. This
looks very wrong to me... the size of array_type is always a multiple of its
largest member, which is _not_ necessarily the same as the offset of its last
member, due to padding.
Back in build_java_array_type (where we started), I'm finding the `length'
argument is frequently -1, so arfld is not initialized (why?) and
build_java_arrayaccess runs amok.