One of the reasons I keep dropping hints about #perlffi , #pdl and #openmp is that one can literally have five multithreading frameworks in the same #perl application of a master process: 1) PDL, and FFI intefacing with 2) #Fortran coarrays, 3) Fortran openmp, 4) #c openmp and 5) #cplusplus #openmp. All these frameworks can share memory addresses for array and vector objects, and #perl aided by #PerlAlien makes the authoring of the high-level code a pleasure ! https://hgpu.org/?p=29403

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Optimizing the Weather Research and Forecasting Model with OpenMP Offload and Codee

Currently, the Weather Research and Forecasting model (WRF) utilizes shared memory (OpenMP) and distributed memory (MPI) parallelisms. To take advantage of GPU resources on the Perlmutter supercomp…

^hgpu.org

Direct (non-LinkedIn-shortened) link: https://catonmat.net/ftp/perl1line.txt

I’m also pleased that its author ranked Perl as one of his top 5 best #programming languages: https://catonmat.net/5-best-programming-languages
1. #C / #Clang
2. #PHP
3. #Perl
4. #GoLang
5. #JavaScript (but only version 1 circa 1995 plus #jQuery)

His 5 worst? https://catonmat.net/5-worst-programming-languages
1. #Haskell
2. #Rust / #RustLang
3. #CPlusPlus
4. #Python
5. modern #JavaScript

“My only metric... is time to get things done and ship to customers.”

Top 5 Best Programming Languages

This is the reverse post of my highly popular Top 5 Worst Programming Languages post. My only metric for a good programming language is time to get things done and ship to customers. I don't care about anything else.

^catonmat.net

To demonstrate the power of C++, I have reimplemented the algorithm in a single file using the built-in metaprogramming capabilities of C++. No more manual source generation; no more Python!

#[url=https://infosec.exchange/tags/include]include[/url] <stdio.h><br>#[url=https://infosec.exchange/tags/include]include[/url] <stdint.h><br>#[url=https://infosec.exchange/tags/include]include[/url] <stdlib.h><br>#[url=https://infosec.exchange/tags/include]include[/url] <limits><br><br>using T = uint8_t;<br><br>namespace {<br>    template<T><br>    void do_check(T, const char *, const char *);<br><br>    template<><br>    void do_check<0>(T n, const char *msg_yes, const char *) {<br>        if (n == 0) {<br>            puts(msg_yes);<br>        }<br>    }<br><br>    template<T limit><br>    void do_check(T n, const char *msg_yes, const char *msg_no) {<br>        do_check<limit - 1>(n, msg_no, msg_yes);<br>        if (n == limit) {<br>            puts(msg_yes);<br>        }<br>    }<br>}<br><br>static void check(T n) {<br>    do_check<std::numeric_limits<T>::max()>(n, "odd", "even");<br>}<br><br>int main(int, char **argv) {<br>    check(atoi(argv[1]));<br>}<br>

To generate the comparisons, we use template metaprogramming. However, there are no template loops. C++ templates can be classified as an esoteric purely functional programming language, so we have to use pattern matching and recursion.

The do_check<N> template generates comparisons up to N. Our base case is do_check<0>, which compares to 0 and does nothing else. The general (inductive) case calls do_check<N - 1> and then compares to N.

It is interesting to look at the generated code. G++ translates the algorithm faithfully, if slightly chaotically (look at the order of labels and comparisons in the source; it jumps all over the place). Clang, on the other hand, implements one of the optimizations suggested by @gkemp. It fills a big array with messages (messages[256] = { "even", "odd", "even", "odd", ... }) and then outputs messages[n] (there is only a single call to puts in the generated assembler code).

This covers numbers from 0 to 255 (the range of uint8_t). We can extend the range by switching to using T = uint16_t, although doing so naively runs into the following error:

x.cc:21:28: fatal error: template instantiation depth exceeds maximum of 900 (use ‘-ftemplate-depth=’ to increase the maximum)<br>

I haven't dared try T = uint32_t yet.

#CPlusPlus #templates

Compiler Explorer - C++

using T = uint8_t; namespace { template void do_check(T, const char *, const char *); template<> void do_check<0>(T n, const char *msg_yes, const char *) { if (n == 0) { puts(msg_yes); } } tem…

^godbolt.org

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