Re: [PATCH]: Trying to make list nodes smaller, but the C++ FE keepsbeating me down

[Daniel Berlin <dberlin at dberlin dot org>]

On Sun, 15 May 2005, Mike Stump wrote:

> On Saturday, May 14, 2005, at 08:41  PM, Daniel Berlin wrote:
> > It removes the TREE_TYPE field from TREE_LIST,
>
> This is just hard.  Better to not use TREE_LIST, which is a TREE, which is 
> defined to have a type,

Stop here.

We have other trees that don't have types :)

STATEMENT_LIST, etc.

We should be able to get rid of all of them without making htem 
"not-trees".


> and instead retype it to be a LIST, and then fixup 
> all the code so that it uses the hard type instead.  After converting all the 
> code, I suspect TREE_LIST could just go away entirely.

We can't easily, because it's in CALL_EXPR, and a *lot* of places expect 
all operands of a call expr to be a tree, including the list.
Sad, but true.  This would be very hard to change, because we have 
recursive calls that call themselves on TREE_OPERAND (CALL_EXPR, 1) and 
take a tree as a parameter.

If we can't do TREE_LIST, i'm thinking of making a
struct tree_minimal that is the base for "struct tree_common", and only 
contains the "chain" field (IE no type or flags).

Then STATEMENT_LIST and friends could use struct tree_minimal.
We could also have an ARGUMENT_LIST that is tree_minimal and only consists 
of TREE_VALUE, not TREE_PURPOSE.

The second of these will require about half the work of making 
TREE_OPERAND (CALL_EXPR, 1) not a tree :).


IE

struct tree_argument_list
{
	struct tree_minimal minimal;
	tree value;
};