Re: function-at-a-time processing in C

[Per Bothner <per at bothner dot com>]

Benjamin Chelf <chelf@codesourcery.com> writes:

> + DEFTREECODE (EXPR_STMT, "expr_stmt", 'e', 1)
> + DEFTREECODE (COMPOUND_STMT, "compound_stmt", 'e', 1)
> + DEFTREECODE (DECL_STMT, "decl_stmt", 'e', 1)
> + DEFTREECODE (IF_STMT, "if_stmt", 'e', 3)
> + DEFTREECODE (FOR_STMT, "for_stmt", 'e', 4)
> + DEFTREECODE (WHILE_STMT, "while_stmt", 'e', 2)
> + DEFTREECODE (DO_STMT, "do_stmt", 'e', 2)

This has serious problems.

First, where is the documentation?  Yes, I can figure these out
from my knowledge of C, but I still want documentation.

Second, why is there an IF_STMT?  What does it do that COND_EXPR
doesn't do?

Third, why are there separate FOR_STMT, WHILE_STMT, DO_STMT?
They are all variants of each other.  In fact, they are all special
cases of LOOP_EXPR.  Using separate tree codes means useless extra code,
and more difficulty writing optimizers.

> + /* A SCOPE_STMT marks the beginning or end of a scope.  If
> +    SCOPE_BEGIN_P holds, then this is the start of a scope.  If
> +    SCOPE_END_P holds, then this is the end of a scope.  If
> +    SCOPE_NULLIFIED_P holds then there turned out to be no variables in
> +    this scope.  The SCOPE_STMT_BLOCK is the BLOCK containing the
> +    variables declared in this scope.  */
> + DEFTREECODE (SCOPE_STMT, "scope_stmt", 'e', 1)

This is strange way to represent a scope.

> + DEFTREECODE (CASE_LABEL, "case_label", 'e', 2)

What are the two operands?

A final problem is that Java (when using the source code parser)
also represents methods as trees.  Java should use the same tree
nodes as C/C++.  That means java/java-tree.def should be partially
merged with tree.def - though that is primarily the job of the
Java people.
-- 
	--Per Bothner
per@bothner.com   http://www.bothner.com/~per/