how many temp registers do we have?

[Peter Chen]

[Peter Goodman]

That is hardware dependent, so there is no "right" answer. See this for more details: http://www.eecg.toronto.edu/~jzhu/csc467/readings/ARB_Fragment_Program.pdf

I suggest coming up with a strategy that allows you to re-use temp registers.

Best Regards,

Peter Goodman,
http://www.petergoodman.me
65 High Park Ave.,
Toronto, Ontario
M6P 2R7

On Sat, Dec 1, 2012 at 8:04 PM, Peter Chen <peter.fe...@gmail.com> wrote:

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[Peter Chen]

would marks be deducted if i assume infinity? :D

[Peter Goodman]

No, marks will not be deducted.

I think the way I will test things is to make an interpreter for ARB fragment assembly. Test cases would then depend on the values in the result variables at the end of interpretation. I would run all programs through that interpreter, which itself would not have any bounds on temp registers.

I do think it would be a good exercise for you to figure out how to re-use registers though ;-)

Best Regards,

Peter Goodman,
http://www.petergoodman.me
65 High Park Ave.,
Toronto, Ontario
M6P 2R7

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[Peter Chen]

sure....can i have another week of extensions....

[Peter Goodman]

No. Re-using temp registers should not take you one week. Here is a simple example of an approach that might work:

1. For each non-constant variable type t, maintain two counters: allocated_t and needed_t.
   
2. Create an AST visitor that, for each top-level expression in a statement, does the following:
1. Set allocated_t = 0 for all t before visiting any expressions in the statement.
2. For each sub-expression of type t, increment allocated_t. If allocated_t > needed_t then increment needed_t.
3. For each type t, initialize needed_t temporary registers at the beginning of your program.
4. When doing codegen, use allocated_t in a similar way to decide which temporary register to use to store an intermediate result of type t.

Best Regards,

Peter Goodman,
http://www.petergoodman.me
65 High Park Ave.,
Toronto, Ontario
M6P 2R7

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