| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 2183.1 | need more info | DECC::OUELLETTE | mudseason into blackfly season | Mon May 12 1997 20:38 | 17 |
| The short answer is that the difference must lie in the different Fortran
and C frontends. A lot may depend upon the version of the C or C++
compiler; which version is getting complaints? We know we have problems
with some codes and our current version of our C++ compiler. Preliminary
results with preliminary versions of what will be the V6.0 C++ compiler are
much better on code that needs to instantiate templates.
We too are very conserned about compile time speed, but do they *really*
spend *all* day compiling, or do they eventually need to run their code?
And what does their C and C++ code look like? Is their problematic code
C++ only or do they have problem with C also (this would be news to us and
we'd like to see sample code).
We'd need a whole lot more information to diagnose a compile time problem
definitively. We've done such work before and can do it again.
Roland.
|
| 2183.2 | Will get more info. | DV780::ENGQUIST | Eric Engquist | Tue May 13 1997 00:42 | 4 |
| I will have to check and see. I didn't load the compilers. The
system is a 433au running Digital Unix 4.0C. I will get back to your
on this.
|
| 2183.3 | need MUCH more info :-) | DECC::MDAVIS | Mark Davis - compiler maniac | Tue May 13 1997 10:52 | 43 |
| >> They love comp[i]ling,
So they must REALLY love our c++, since we let them spend more TIME
compiling...
1. what is the compiler version. Is it just c++ that is slow, or
c too?
2. what are the compiler options used, e.g., is debugging turned on;
what opt level? (Sun does their debugging info differently than
we do.)
3. Is the "compile time" cpu time or elapsed time; and is it time to
run the compiler, or to compile AND link?
4. Does the c++ code use lots of templates? Auto template instantiation
requires several rounds of: compile the .cxx files, trial link looking
for unresolved references, compile files from cxx_repository to
instantiate templates, trial link, etc.
5. c++ programs typically have zillions of tiny routines - each one is
passed all the way through GEM before the next one (this is a slight lie,
but close enough). In contrast, Fortran programs usually have a few, LARGE
routines. GEM's structure is designed to crunch on a large mouthful of
program, not on miniscule snacks.
6. If you compile using "-source_listing -show statistics" you will get
something like:
COMPILATION STATISTICS
CPU time: 0.01 seconds
Elapsed time: 0.06 seconds
Pagefaults: 0
I/O Count: 6
Source lines: 3
18000 lines per CPU minute.
It would be interesting to compare the "lines per minute" with the
fortran compiles (f77 -V ).
Mark Davis
c/c++ team
|
| 2183.4 | DEC C V5.2 on Digital UNIX V4.0C, latest DEC C++ | DECC::SULLIVAN | Jeff Sullivan | Tue May 13 1997 13:22 | 15 |
| The default C compiler for Digital UNIX V4.0C is DEC C V5.2, with GEM BL31
backend. We'd be interested in both compile- and run-time bottlenecks, if you
can provide details. There is a field test version of DEC C V5.6, with GEM BL33
available via the web at http://www.zk3.dec.com/decc/decc-kitinfo.html. It is
ecpected that the later GEM backend should produce better run-time performance.
The final version of this compiler is expected to be delivered on V4.0D.
The latest SSB DEC C++ compiler for Digital UNIX V4.0C is V5.5 and is found on
the layered product CD. A field test version of V5.6 is available (DEC C++
T5.6-006, FT2), which contains some enhancements over V5.5; including compress
object files. See TURRIS::C_PLUS_PLUS Note 3546 or
http://www.zk3.dec.com/decc/decc-kitinfo.html if you are interested in the field
test DEC C++ compiler.
-Jeff
|
| 2183.5 | | DECCXL::OUELLETTE | mudseason into blackfly season | Tue May 13 1997 14:18 | 5 |
| There has been lots of work since DEC C V5.2.
Several fairly major C compile time performance problems have been
solved since then. Trying the field test V5.6 would be interesting
as would trying whatever cc.alt is on Digital UNIX V4.0C (It's newer
than the default cc compiler -- DEC C V5.3, V5.4 or V5.5 (I don't know which)).
|
| 2183.6 | Thanks foir the answers | DV780::ENGQUIST | Eric Engquist | Wed May 14 1997 23:45 | 6 |
| Thanks for your answers. The customer did not feel that we were
slow, it just wasn't the magintude of the fortran compiles.
They were using C++ version 5.5. They did purchase about 10
of the au series, but because adobe is saying the next version
of framemaker would not run on dux, they are buying 60 SUNs. However
we did impress them enought that we did get a foot in the door.
|