A move away from CLN?

[Richard B. Kreckel]

On Tue, 31 Jul 2001, I wrote:
> Talking about KAI's C++ compiler, I just tested it.
[...]

Talking about Intel's Reference Compiler, I just tested the
x86-edition, version 5.0beta for Linux on the CLN/GiNaC system.  It
detected a few minor glitches in the GiNaC code that went undetected
by all GCC versions and by KAI and Portland Group.  Those are being
fixed in our CVS tree.

The Intel compiler is really good w.r.t. ISO standard conformance.  With
the usual two preprocessor settings it compiled vanilla CLN-1.1.2
statically and passed all the checks.  Then it came to GiNaC's timings and
there the Intel compiler showed it is *not* doing a good job. Maybe if one
tunes the whole system for Pentium-IV or such the picture will change.  
Maybe switching on Intel's global optimizations would help, too.  I
couldn't do that because the compiler chose to segfault every time I
tried.  :-(

Without more ado, here are the timings in seconds (static, stripped
binaries) on a P-III 800:

commutative expansion and substitution (a.k.a. Denny Fliegner's test)
     size   GCC 3       Intel-C++ 5       Ratio
       50   0.08        0.11              1.38
      100   0.35        0.50              1.42
      200   1.57        2.19              1.39
Laurent series expansion of Gamma function
    order   GCC 3       Intel-C++ 5       Ratio
       15   0.27        0.38              1.41
       20   1.219       1.74              1.42
       25   4.879       6.73              1.38
determinant of univariate symbolic Vandermonde matrices
      dim   GCC 3       Intel-C++ 5       Ratio
     6x 6   0.006       0.010             1.67
     8x 8   0.11        0.15              1.36
    10x10   1.01        1.52              1.50
determinant of polyvariate symbolic Toeplitz matrices
      dim   GCC 3       Intel-C++ 5       Ratio
     6x 6   0.065       0.08              1.23
     7x 7   0.30        0.39              1.30
     8x 8   1.32        1.66              1.26
Lewis-Wester test A (divide factorials)
            GCC 3       Intel-C++ 5       Ratio
            0.11        0.56              5.09
Lewis-Wester test B (sum of rational numbers)
            GCC 3       Intel-C++ 5       Ratio
            0.010       0.026             2.60
Lewis-Wester test C (gcd of big integers)
            GCC 3       Intel-C++ 5       Ratio
            0.149       0.71              4.76
Lewis-Wester test D (normalized sum of rational fcns)
            GCC 3       Intel-C++ 5       Ratio
            0.309       0.72              2.32
Lewis-Wester test E (normalized sum of rational fcns)
            GCC 3       Intel-C++ 5       Ratio
            0.25        0.43              1.72
Lewis-Wester test F (gcd of 2-var polys)
            GCC 3       Intel-C++ 5       Ratio
            0.032       0.05              1.56
Lewis-Wester test G (gcd of 3-var polys)
            GCC 3       Intel-C++ 5       Ratio
            1.08        2.39              2.21
Lewis-Wester test H (det of 80x80 Hilbert)
            GCC 3       Intel-C++ 5       Ratio
            4.509       7.09              1.57
Lewis-Wester test I (invert rank 40 Hilbert)
            GCC 3       Intel-C++ 5       Ratio
            1.30        1.98              1.52
Lewis-Wester test J (check rank 40 Hilbert)
            GCC 3       Intel-C++ 5       Ratio
            0.74        1.07              1.45
Lewis-Wester test K (invert rank 70 Hilbert)
            GCC 3       Intel-C++ 5       Ratio
            8.81        13.67             1.55
Lewis-Wester test L (check rank 70 Hilbert)
            GCC 3       Intel-C++ 5       Ratio
            4.35        6.55              1.51
Lewis-Wester test M1 (26x26 sparse, det)
            GCC 3       Intel-C++ 5       Ratio
            0.17        0.24              1.41
Lewis-Wester test N (poly at rational fcns)
            GCC 3       Intel-C++ 5       Ratio
            483.47      512.52            1.06
Lewis-Wester test P (det of sparse rank 101)
            GCC 3       Intel-C++ 5       Ratio
            0.59        0.73              1.24
Lewis-Wester test P' (det of less sparse rank 101)
            GCC 3       Intel-C++ 5       Ratio
            2.76        4.03              1.46
computation of an antipode in Yukawa theory
            GCC 3       Intel-C++ 5       Ratio
            59.78       75.21             1.25

One could argue that this result is restricted to x86 and the situation
looks different on real RISC machines.  However, after trying some simple
template-heavy tests with Sun's WorkShop 5.0 for UltraSparc we realized
that GCC-3.0 performs better on real C++ code, even on that platform.

I hope this helps debunk the two myths that GCC does not perform
well and that CLN/GiNaC is not portable.

Happy heavy hacking
                -richy.
-- 
Richard Kreckel
<Richard.Kreckel at Uni-Mainz.DE>
<http://wwwthep.physik.uni-mainz.de/~kreckel/>