http://d.puremagic.com/issues/show_bug.cgi?id=10779

           Summary: cartesianProduct leads to heavy code bloat
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Phobos
        AssignedTo: nobody@puremagic.com
        ReportedBy: tobias@pankrath.net


--- Comment #0 from Tobias Pankrath <tobias@pankrath.net> 2013-08-08 07:53:48 PDT ---
http://dpaste.dzfl.pl/45240ef6

The program compiled with DMD64 D Compiler v2.063.2 has a size of 37MiB. It drops to 1,5MiB if you delete the usage of cartesianProduct.

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bearophile_hugs@eml.cc changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bearophile_hugs@eml.cc


--- Comment #1 from bearophile_hugs@eml.cc 2013-08-08 08:13:44 PDT ---
(In reply to comment #0)
> http://dpaste.dzfl.pl/45240ef6
> 
> The program compiled with DMD64 D Compiler v2.063.2 has a size of 37MiB. It drops to 1,5MiB if you delete the usage of cartesianProduct.

The code on dpaste:


import std.conv, std.algorithm, std.range, std.stdio, std.string, std.file,
std.csv;
import std.getopt, std.path, std.bitmanip, std.exception;

Parameter[] macParameter;
Parameter[] registerParameter;
Parameter[] immediateParameter;

struct AsmTemplate
{
    string template_;
    string result;
    string arguments;
}

struct Parameter
{
    enum Type { Register, Immediate, Mac, None};
    Type type;
    uint val;
}

struct Test {
    string template_;
    Parameter[] params;
}

void generateTests(OR)(AsmTemplate ins, ref OR sink)
{
    // params is a list of argument ranges with varying length, originally
    // optained through a functioncall. We pad it,
    // with some empty elements so we can use it in cartProd
    auto params = [immediateParameter, registerParameter, macParameter, [],
[]];
    foreach(tup; cartesianProduct(params[0], params[1], params[2], params[3],
                                   params[4]))
    {
        auto t = Test(ins.template_, [tup[0], tup[1], tup[2], tup[3], tup[4]]);
    }
}

void main()
{
    auto app = appender!(Test[]);
    AsmTemplate asm_;
    asm_.generateTests(app);
}




Probably cartesianProduct should be rewritten from scratch, in a lower level way.

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--- Comment #2 from hsteoh@quickfur.ath.cx 2013-08-10 09:40:38 PDT ---
You are right, cartesianProduct uses a lot of templates internally. It's worse with cartesianProduct of >2 arguments, it uses an exponential number of templates. I'll have to rewrite it from scratch to not use existing range templates. :-(  So much for dogfooding...

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--- Comment #3 from hsteoh@quickfur.ath.cx 2013-08-10 13:30:04 PDT ---
Related: #10693

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--- Comment #4 from hsteoh@quickfur.ath.cx 2013-08-10 13:30:42 PDT ---
Sigh, let's see if we can get the link: issue #10693

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