Re: [X10-core] major change to C++ codegeneration: elimination of x10aux::ref

[Josh M. <jos...@an...>]

Hi Dave,

this definitely improves the readability of the generated code. For our 
codes, there will be some changes required to definitions of native 
methods but this looks like only a few minutes' work.

I compared compile times for ANU-Chem packages on two computers: my ANU 
desktop which is a Core2 Q9550@2.83GHz with GCC 4.4.3, and my home 
computer which is a Pentium D (much slower) with GCC 4.6.3.   Example 
times are below: compile times have reduced slightly on the home 
computer but strangely seem to have actually increased on my ANU desktop.

I have no idea why this is.  You mentioned that the number of header 
files included has previously been the major issue, so maybe ref<T> 
wasn't the main problem after all...

Cheers,

Josh

Uni: GCC 4.4.3 before
anu-chem Total time: 1 minute 8 seconds
fmm Total time: 1 minute 45 seconds
fmm-lib Total time: 1 minute 48 seconds
anum Total time: 34 seconds

Uni: GCC 4.4.3 after
anu-chem Total time: 1 minute 19 seconds
fmm Total time: 1 minute 42 seconds
fmm-lib Total time: 2 minutes 14 seconds
anum Total time: 32 seconds


home: GCC 4.6.3 before
anu-chem Total time: 3 minutes 14 seconds
fmm      Total time: 5 minutes 45 seconds
fmm-lib  Total time: 6 minutes 13 seconds
anum     Total time: 1 minute 24 seconds

home: GCC 4.6.3 after
anu-chem Total time: 3 minutes 0 seconds
fmm      Total time: 5 minutes 24 seconds
fmm-lib  Total time: 5 minutes 52 seconds
anum     Total time: 1 minute 7 seconds

On 01/09/12 00:49, David P Grove wrote:
>
> I've just committed the major change in C++ code generation that I've 
> been contemplating doing for months and have talked to several of you 
> about....x10aux::ref is no more.
>
> If you don't know what x10aux::ref is, you can safely ignore the rest 
> of this email.  Modulo any @Native declarations that I failed to 
> update this change should be completely invisible to the X10 programmer.
>
> If you write @Native annotations (or native C++ code that needs to 
> interact with the X10 object model), then read on...
>
> The heart of the change is that a C++ type that used to be written 
> ref<T> is now written as T*
>
> For example:
>  ref<Array<ref<String> > becomes Array<String*>*
>  ref(Array<int> > becomes Array<int>*
>
> Benefits:
>  (1) Less template instantiation, faster C++ compilation and
>        more readable/standard C++ types (and symbol names)
>  (2) We can now actually use C++'s catch blocks properly instead of
>      generating our own dynamic type tests inside of a single catch.
>
> Drawbacks (?):
>  (1) No silent conversion from one pointer type to an arbitrary other 
> pointer type.
>      The C++ code generator (and the programmer writing native code)
>      needs to be more aware of how the X10 and C++ object model
>      are related to each other and inject reinterpret_casts where needed.
>       This makes some things more verbose, but based on the thousands 
> of lines
>       of code I was modifying yesterday, I think this is actually an 
> improvement
>       because the places where something interesting is happening 
> become explicit.
>
> --dave
>
>
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