Re: Efficiency of code generated by Ada compilers

["Yannick Duchêne (Hibou57)" <yannick_duchene@yahoo.fr>]

Le Wed, 11 Aug 2010 00:50:40 +0200, <anon@att.net> a écrit:
> While the main expression are equal. The code generation by Ada compilers
> versus C or C++ is less efficient do to a number of factors.
>
>   1. Elaboration:     Ada compilers can generate run-time elaboration
>                       routines that must be executed before starting
>                       the main users program. C/C++ compilers do not
>                       perform any run-time elaboration, which cause
>                       the execution and code generation to be more
>                       efficient but cause the less program to be less
>                       reliable.
>
>   2. Run-Time Checks: The Ada compiler generates inline run-time checks
>                       which the C/C++ compiler do not.  Using the pragma
>                       "suppress" statement can eliminate most checks. The
>                       absent of these checks makes C/C++ less reliable.

Yes. You have the choice (with the former)

>             pragma Suppress ( All_Checks, ON => <name 1>,
>                                                ...
>                                            ON => <name n> ) ;
>              --  removes all checks on that set of names only.
>              --  Names may be an object such as an array or routine
>              --  Also, the "ON =>" symbols are optional

Interesting point. Is that GNAT or other compiler specific ? I do not this  
variant in the reference.

In “11.5 Suppressing Checks”:
> 3/2    The forms of checking pragmas are of a pragma Suppress is as  
> follows:4/2    pragma Suppress(identifier [, [On =>] name]);
> 4.1/2  pragma Unsuppress(identifier);

Standard or not, this seems nice. This may be better for centralized  
management of runtime-checks.

-- 
There is even better than a pragma Assert: a SPARK --# check.
--# check C and WhoKnowWhat and YouKnowWho;
--# assert Ada;
--  i.e. forget about previous premises which leads to conclusion
--  and start with new conclusion as premise.