------- Additional Comments From schlie at comcast dot net 2005-03-01 01:02 ------- Subject: Re: static initialization .data redundantly copied to ram prior to use.
> ------- Additional Comments From bjoern dot m dot haase at web dot de > I think the key problem is, that C language permits you to pass pointers to > your static const data structures to other functions. Possibly functions that > are not located within the same source file. While functions whithin the > source file that defines the const data structures could in principle know > that these data should be located in program memory and that they should be > accessed by using lpm instructions, I do not see how to pass this knowledge to > externally defined functions. Only solution in my opinion would be to define > different classes of pointers. - Understood, however would seem to correspondingly require a new type and/or attribute be defined and visible from the parser through to type checking and rtl template matching; So wonder if it's sufficient to use the existing "static const" attributes to designate program-memory mapped data (which is what it is) and thereby assume that only references to "static const" are prog-mem references, and correspondingly require functions which access such data directly to explicitly identify their arguments accordingly, as otherwise the reference will be presumed to reference data-memory. However any "static const" may first be copied to a data-memory variable and then passed as reference as desired to utilize functions with more generalized arguments, and then freed, or whatever. Hopefully such attributes are already visible at the tree/rtl/template level so that memory operand templates may identify (static const *) types, and utilize program vs data memory loads as appropriate; as otherwise, it's not real clear that this has much a chance of being accomplished; and would be a shame to otherwise waist RAM on static const data already stored and accessible the program-memory. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20243
