Comments on the suggestion to use infinite precision math for wide int.

[Kenneth Zadeck]

On 04/08/2013 10:12 AM, Robert Dewar wrote:
> On 4/8/2013 9:58 AM, Kenneth Zadeck wrote:
>
>> yes but the relevant question for the not officially static integer
>> constants is "in what precision are those operations to be performed
>> in?    I assume that you choose gcc types for these operations and you
>> expect the math to be done within that type, i.e. exactly the way you
>> expect the machine to perform.
>
> As I explained in an earlier message, *within* a single expression, we
> are free to use higher precision, and we provide modes that allow this
> up to and including the usea of infinite precision. That applies not
> just to constant expressions but to all expressions.
>>
>
My confusion is what you mean by "we"?   Do you mean "we" the writer of 
the program, "we" the person invoking the compiler by the use command 
line options or "we", your company's implementation of ada?

My interpretation of your first email was that it was possible for the 
programmer to do something equivalent to adding attributes surrounding a 
block in the program to control the precision and overflow detection of 
the expressions in the block.   And if this is so, then by the time the 
expression is seen by the middle end of gcc, those attributes will have 
been converted into tree code will evaluate the code in a well defined 
way by both the optimization passes and the target machine.

Kenny