Re: Rquest for timings
Thank you for your suprising timings, Jerry. All timings done with gdc 0.30 using dmd 2.055 and gcc 4.6.2. I built with both D and C++ enabled so the back end would be the same. Is your system a 64 bit one? So, the upshot seems like DMD and GDC generate similar code for this test. This is an uncommon thing, expecially on 32 bit systems. And both D compilers generate slightly faster code than the C++ version, therefore the D front end is doing a slightly better optimization job, or your first version is slightly more efficient code. D1 code is often a bit slower than similar C++ code, but in this case I think D2 has allowed to specify more semantics that has produced a faster program. The static foreach I have used that D2 code is not just looking more clean compared to the those C++0x template tricks, but also the assembly output is better. And the first D2 program is not even the fastest possible: that second D2 program today is slow, but it contains some more semantics that hopefuly someday will allow the second version of the program to be faster than the first one, and about as fast as that Fortran version. This code that currently doesn't compile (no vector ^^, no vector sqrt, no good sum function): immutable double[NPAIR] distance = sqrt(sum(r[] ^^ 2, dim=0)); Is currently implemented like this: double[NPAIR] distance = void; foreach (i; Iota!(0, NPAIR)) distance[i] = sqrt(r[i][0] ^^ 2 + r[i][1] ^^ 2 + r[i][2] ^^ 2); Here those square roots are parallelizable, the compiler is allowed to use a SSE2 sqrtpd instruction to performs those 10 sqrt(double) with 5 instructions. With the ymm register of AVX the instruction VSQRTPD (intrinsic _mm256_sqrt_pd in lesser languages) does 4 double squares at a time. But maybe its starting location needs to be aligned to 16 bytes (not currently supported syntax): align(16) immutable double[NPAIR] distance = sqrt(sum(r[] ^^ 2, dim=0)); Bye, bearophile
Re: Rquest for timings
Maybe Jerry could test my edits and check for timing... About ^^: have you tried to benchmark 1/(x ^^ n) vs x ^^ -n ? (with n0) On my setup second version is very very slow. == Quotato dall`articolo bearophile (bearophileh...@lycos.com) Andrea Fontana Wrote: Yes, really :-) Timings taken with DMD 2.056+, 32 bit Vista OS. Bye, bearophile
Re: Rquest for timings
Andrea Fontana: About ^^: have you tried to benchmark 1/(x ^^ n) vs x ^^ -n ? (with n0) On my setup second version is very very slow. Take a look at the produced assembly code :-) Maybe x ^^ n is rewritten with a simple code, while ^^-n calls the pow function. Bye, bearophile
Re: auto
Did you know that auto is not auto in the way auto behalfs. it's just a
placeholder so the compiler can determine that a variable follows. but
you can use any other keyword for type interfering, too.
void main()
{
const a = FunctionThatReturnsSomething();
static b = 5.0;
scope c = hey;
}
Strong size_t
Tried to create a stronger version of size_t which will not interoperate with int and long http://codepad.org/47OB3nJi But for some reason can't compare struct to int using opEquals and opCmp. How to fix it? And should it? One can write `v==intp(42)` or `vintp(43)`.
Re: Strong size_t
On Sat, 26 Nov 2011 17:22:58 +0100, Kagamin s...@here.lot wrote:
Tried to create a stronger version of size_t which will not interoperate
with int and long
http://codepad.org/47OB3nJi
But for some reason can't compare struct to int using opEquals and
opCmp. How to fix it? And should it? One can write `v==intp(42)` or
`vintp(43)`.
Have you tried to overload opEquals and opCmp for ints? That seems to
work just fine for me:
bool opEquals(int v) const { return value == v; }
int opCmp(int v) const
{
return valuev?1:valuev?-1:0;
}
Just add those to the intp struct.
Re: Strong size_t
Simen Kjærås Wrote:
On Sat, 26 Nov 2011 17:22:58 +0100, Kagamin s...@here.lot wrote:
Tried to create a stronger version of size_t which will not interoperate
with int and long
http://codepad.org/47OB3nJi
But for some reason can't compare struct to int using opEquals and
opCmp. How to fix it? And should it? One can write `v==intp(42)` or
`vintp(43)`.
Have you tried to overload opEquals and opCmp for ints? That seems to
work just fine for me:
bool opEquals(int v) const { return value == v; }
int opCmp(int v) const
{
return valuev?1:valuev?-1:0;
}
Just add those to the intp struct.
It writes
Error: function strongintp.intp.opEquals type signature should be const
bool(ref const(intp)) not const bool(ref const const(short) v)
Hmm... may be my compiler version is old and this was fixed...
Re: Strong size_t
On Sat, 26 Nov 2011 11:45:26 -0500, Kagamin s...@here.lot wrote:
Simen Kjærås Wrote:
On Sat, 26 Nov 2011 17:22:58 +0100, Kagamin s...@here.lot wrote:
Tried to create a stronger version of size_t which will not
interoperate
with int and long
http://codepad.org/47OB3nJi
But for some reason can't compare struct to int using opEquals and
opCmp. How to fix it? And should it? One can write `v==intp(42)` or
`vintp(43)`.
Have you tried to overload opEquals and opCmp for ints? That seems to
work just fine for me:
bool opEquals(int v) const { return value == v; }
int opCmp(int v) const
{
return valuev?1:valuev?-1:0;
}
Just add those to the intp struct.
It writes
Error: function strongintp.intp.opEquals type signature should be const
bool(ref const(intp)) not const bool(ref const const(short) v)
Hmm... may be my compiler version is old and this was fixed...
According to bugzilla, yes.
http://d.puremagic.com/issues/show_bug.cgi?id=3659
-Steve
