[RFC] Add DECL_CHAIN and some other *_CHAIN

[Andrew Pinski]

On Dec 27, 2005, at 3:24 PM, Mike Stump wrote:

> On Dec 26, 2005, at 10:22 PM, Andrew Pinski wrote:
>> What do people think about this patch, it is very mechanical.
>
> A couple of thoughts, first, timings for C++ (once converted) at -O0 
> as chain influences time more than most, and I suspect we'd want all 
> languages bootstrapped and tested before any mid end backend code goes 
> in, just to be sure a front end isn't misusing any part of the tree 
> and it sure would be nice if the complier had hard types for those 
> places that used something like DECL_CHAIN to ensure it was a decl, 
> but, failing that, I'd hope that you could ensure that the 
> documentation reflects the new assert.  For example, take 
> DECL_ARGUMENTS:
>
>   tree arguments;       /* Also used for DECL_FIELD_OFFSET */
>
> /* In FUNCTION_DECL, a chain of ..._DECL nodes.
>    VAR_DECL and PARM_DECL reserve the arguments slot for 
> language-specific
>    uses.  */
> #define DECL_ARGUMENTS(NODE) (DECL_CHECK (NODE)->decl.arguments)
>
> here, we don't have hard typing, but, we do have documentation which, 
> if people followed and if complete would make the conversion of this 
> one reasonably safe (ignoring non-C fonrtends).
>
> Once you convert C++, you'd find:

What version are you looking at, 4.0.x?
Well that is too old since Daniel Berlin has already changed the 
comment and the
accessor:

/* The DECL_TEMPLATE_PARMS are a list.  The TREE_PURPOSE of each node
    is a INT_CST whose TREE_INT_CST_LOW indicates the level of the
    template parameters, with 1 being the outermost set of template
    parameters.  The TREE_VALUE is a vector, whose elements are the
    template parameters at each level.  Each element in the vector is a
    TREE_LIST, whose TREE_VALUE is a PARM_DECL (if the parameter is a
    non-type parameter), or a TYPE_DECL (if the parameter is a type
    parameter).  The TREE_PURPOSE is the default value, if any.  The
    TEMPLATE_PARM_INDEX for the parameter is available as the
    DECL_INITIAL (for a PARM_DECL) or as the TREE_TYPE (for a
    TYPE_DECL).  */
#define DECL_TEMPLATE_PARMS(NODE)       DECL_NON_COMMON_CHECK 
(NODE)->decl_non_common.arguments

-- Pinski