common tree nodes question

[Aldy Hernandez <aldyh at redhat dot com>]

as yall might recall, for dwarf, vectors are treated as a structure
containing an array.  so:

	vector int foo;

will really be passed to gdb as:

	struct {
		int xxx[4];
	} foo;

elena pointed out that type of the base type for the array elements (xxx)
comes out with unknown:

 <1><b7>: Abbrev Number: 4 (DW_TAG_base_type)
     DW_AT_name        : __unknown__    
     DW_AT_byte_size   : 4      
     DW_AT_encoding    : 5      (signed)


i debuged this and found out that base_type_die() cannot find a
TYPE_NAME() for the SImode, consequently putting an __unknown__ for
it's name.

the culprit is build_common_tree_nodes():

  intQI_type_node = make_signed_type (GET_MODE_BITSIZE (QImode));
  intHI_type_node = make_signed_type (GET_MODE_BITSIZE (HImode));
  etc

which doesn't define the TYPE_NAME field, just makes the raw types.

what's the right solution here?

i could change build_common_tree_nodes to stick the appropriate
TYPE_NAME, but i don't think i can do that.  for example,
SI might not be an "int", QI might not be "char", etc etc for
some weird architecture.

comments?