Article: MAQSIP-RT: An HPC Benchmark
By: Ian Ollmann (iano.delete@this.apple.com), July 6, 2010 2:07 pm
Room: Moderated Discussions
Max (max@a.com) on 7/1/10 wrote:
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>
>C is pretty uncontroversial these days. It's hard to even get an argument started
>since everyone has made their peace with it.
True.
I used to have that opinion, too. However, lately I've been working on a open standards based C language derivative and it's becoming increasingly clear just how creaky C is as we work through all the different ways that it has to be fixed to get different platforms to return the same answer and perform decently. The fundamental problem with C in my book falls into three major areas:
1) Weak support for threading. The timing of operations is at times over-described or under-described.
2) No SIMD vector support / failure to standardize types early on -- how big is an int anyway? A double? What is the bit pattern for these things? (I group these together because many algorithms for vectors require fixed data representations.)
3) Most of all -- The language is conversion-happy. Following basic hardware models of 50 years ago, it tries to convert everything to a core hardware type, do the work, and convert back. All the conversions are a problem, because they make it difficult to precisely describe an algorithm -- what you see is not what you get. E.g. short << 16, forces a conversion to int (of what size?) before the shift occurs, so if you right shift again later, those bits might be there or might not.
There is at least some excuse for item 2. C has to handle the widest diversity of devices out there. However, in general, modern processors handle most of this stuff now, and there is increasingly less and less good reason to keep around those that don't. Modern processors are usually multicore. Many ISAs now have special instructions for different integer and floating point encodings. They have SIMD vector units. If C were developed today, it would probably not look the way it does, because many of the core assumptions about the appearance of the underlying device no longer hold.
To be clear, I'm not asking for garbage collection, OOP, or saccharine Javaness to be added to C. That is what Java is for. I just want a WYSIWYG programming language that is portable between multiple ISAs.
---------------------------
>
>C is pretty uncontroversial these days. It's hard to even get an argument started
>since everyone has made their peace with it.
True.
I used to have that opinion, too. However, lately I've been working on a open standards based C language derivative and it's becoming increasingly clear just how creaky C is as we work through all the different ways that it has to be fixed to get different platforms to return the same answer and perform decently. The fundamental problem with C in my book falls into three major areas:
1) Weak support for threading. The timing of operations is at times over-described or under-described.
2) No SIMD vector support / failure to standardize types early on -- how big is an int anyway? A double? What is the bit pattern for these things? (I group these together because many algorithms for vectors require fixed data representations.)
3) Most of all -- The language is conversion-happy. Following basic hardware models of 50 years ago, it tries to convert everything to a core hardware type, do the work, and convert back. All the conversions are a problem, because they make it difficult to precisely describe an algorithm -- what you see is not what you get. E.g. short << 16, forces a conversion to int (of what size?) before the shift occurs, so if you right shift again later, those bits might be there or might not.
There is at least some excuse for item 2. C has to handle the widest diversity of devices out there. However, in general, modern processors handle most of this stuff now, and there is increasingly less and less good reason to keep around those that don't. Modern processors are usually multicore. Many ISAs now have special instructions for different integer and floating point encodings. They have SIMD vector units. If C were developed today, it would probably not look the way it does, because many of the core assumptions about the appearance of the underlying device no longer hold.
To be clear, I'm not asking for garbage collection, OOP, or saccharine Javaness to be added to C. That is what Java is for. I just want a WYSIWYG programming language that is portable between multiple ISAs.
Topic | Posted By | Date |
---|---|---|
New article online: MAQSIP RT | David Kanter | 2010/06/21 10:57 AM |
Why no GCC? | Rohit | 2010/06/22 08:25 PM |
Why no GCC? | David Kanter | 2010/06/22 11:45 PM |
sun 's cc better than GCC? | Rohit | 2010/06/23 04:04 AM |
sun 's cc better than GCC? | anon | 2010/06/23 06:49 AM |
Where is the GCC optimization effort directed? | Mark Roulo | 2010/06/23 09:42 AM |
GCC is very ugly bad everywhere in 64 bits | Vincent Diepeveen | 2010/06/23 01:49 PM |
even for 64-bit arch? | anon | 2010/06/23 01:59 PM |
GCC is very ugly bad everywhere in 64 bits | ajensen | 2010/06/23 10:03 PM |
GCC is very ugly bad everywhere in 64 bits | Gabriele Svelto | 2010/06/24 01:33 AM |
GCC is very ugly bad everywhere in 64 bits | ajensen | 2010/06/24 04:32 AM |
GCC is very ugly bad everywhere in 64 bits | Gabriele Svelto | 2010/06/24 06:18 AM |
GCC is very ugly bad everywhere in 64 bits | ajensen | 2010/06/24 08:50 AM |
Why GCC is big and complicated (my guess) | Mark Roulo | 2010/06/24 11:17 AM |
Why GCC is big and complicated (my guess) | Gabriele Svelto | 2010/06/28 03:00 AM |
GCC is very ugly bad everywhere in 64 bits | Bernd Schmidt | 2010/06/24 04:46 AM |
GCC is very ugly bad everywhere in 64 bits | ajensen | 2010/06/24 08:43 AM |
GCC is very ugly bad everywhere in 64 bits | Vincent Diepeveen | 2010/06/26 01:12 PM |
GCC is very ugly bad everywhere in 64 bits | Rob Thorpe | 2010/06/24 06:47 AM |
GCC is very ugly bad everywhere in 64 bits | Anon | 2010/06/24 04:23 PM |
Where is the GCC optimization effort directed? | Gabriele Svelto | 2010/06/23 09:45 PM |
Where is the GCC optimization effort directed? | ? | 2010/06/24 12:48 AM |
Where is the GCC optimization effort directed? | Gabriele Svelto | 2010/06/24 01:29 AM |
Where is the GCC optimization effort directed? | ? | 2010/06/24 02:13 AM |
Where is the GCC optimization effort directed? | Andi Kleen | 2010/06/24 02:15 AM |
Where is the GCC optimization effort directed? | ? | 2010/06/24 03:08 AM |
Where is the GCC optimization effort directed? | Gabriele Svelto | 2010/06/24 02:54 AM |
Where is the GCC optimization effort directed? | ? | 2010/06/24 03:15 AM |
Where is the GCC optimization effort directed? | Gabriele Svelto | 2010/06/24 06:22 AM |
Where is the GCC optimization effort directed? | Rohit | 2010/06/24 02:04 AM |
Placebo effect | ? | 2010/06/24 05:37 AM |
Placebo effect | Rohit | 2010/06/24 07:45 AM |
Placebo effect | Vincent Diepeveen | 2010/06/26 01:50 PM |
Compile time | Mark Roulo | 2010/06/26 04:28 PM |
Compile time | Richard Cownie | 2010/06/27 03:44 AM |
Compile time | Mark Roulo | 2010/06/27 09:12 AM |
Compile time | Mark Roulo | 2010/06/27 09:21 AM |
Compile time | EduardoS | 2010/06/27 10:37 AM |
Compile time | Richard Cownie | 2010/06/27 03:07 PM |
Compile time & efficiency | ? | 2010/06/27 11:03 PM |
Compile time & efficiency | Mark Christiansen | 2010/06/28 05:08 AM |
Compile time & efficiency | Linus Torvalds | 2010/06/28 06:48 AM |
kernel programming language | John Simon | 2010/06/29 05:46 PM |
Compile time & efficiency | Richard Cownie | 2010/06/28 08:29 AM |
Compile time & efficiency | Linus Torvalds | 2010/06/28 10:17 AM |
Compile time & efficiency | Richard Cownie | 2010/06/28 01:16 PM |
Compile time & efficiency | Richard Cownie | 2010/06/28 05:23 PM |
Compile time & efficiency | Mark Roulo | 2010/06/29 07:31 AM |
Compile time & efficiency | Richard Cownie | 2010/06/29 10:48 AM |
Compile time & efficiency | rwessel | 2010/06/29 11:28 AM |
C is a crappy | dev | 2010/06/29 06:12 PM |
C is a crappy, but only when you push it out of it's niche | Rohit | 2010/06/30 01:11 AM |
C is a crappy | anon | 2010/06/30 01:17 AM |
C is a crappy | dev | 2010/06/30 06:59 AM |
C is a crappy | Max | 2010/07/01 03:30 AM |
C is a crappy | Michael S | 2010/07/01 06:00 AM |
C is a crappy | Konrad Schwarz | 2010/07/01 07:02 AM |
C is a crappy | Michael S | 2010/07/01 07:50 AM |
C isn't so crappy | anon | 2010/07/01 09:11 AM |
C isn't so crappy | Mikael Tillenius | 2010/07/01 10:39 AM |
C is a crappy | Konrad Schwarz | 2010/07/01 10:22 AM |
C is a crappy | Max | 2010/07/02 07:44 AM |
C is a crappy | rwessel | 2010/07/02 11:33 AM |
C is a crappy | anon | 2010/07/02 12:17 PM |
C is a crappy | Max | 2010/07/02 01:56 PM |
C is a crappy | Max | 2010/07/02 02:13 PM |
C is a crappy | rwessel | 2010/07/02 02:32 PM |
C is a crappy | Max | 2010/07/02 03:19 PM |
C is a crappy | Gabriele Svelto | 2010/07/05 04:25 AM |
C is a crappy | gallier2 | 2010/07/01 11:14 PM |
C is a crappy | Ian Ollmann | 2010/07/06 02:07 PM |
Portability | Max | 2010/07/06 02:37 PM |
C is a crappy | hobold | 2010/07/07 01:31 AM |
C is a crappy | Ian Ollmann | 2010/07/07 04:18 PM |
failure to standardize types | Carlie Coats | 2010/07/07 03:11 AM |
C is a crappy | Konrad Schwarz | 2010/07/07 07:34 AM |
C is a crappy | Ian Ollmann | 2010/07/07 04:29 PM |
C is a crappy NOT | Konrad Schwarz | 2010/07/07 11:29 PM |
C is a crappy | anon | 2010/07/01 09:40 PM |
C type safety | ? | 2010/07/02 12:10 AM |
C type safety | anon | 2010/07/02 10:02 PM |
C is a crappy | dev | 2010/07/03 03:51 PM |
C is a crappy | anon | 2010/07/03 06:02 PM |
C is a crappy | dev | 2010/07/05 06:27 AM |
C is a crappy | ? | 2010/07/05 08:05 AM |
C is a crappy | anonymous | 2010/07/07 07:32 AM |
C is a crappy | ? | 2010/07/07 09:48 PM |
C is a crappy | Anon | 2010/07/07 11:53 PM |
C is a crappy and a crappie is a fish | anonymous | 2010/07/03 06:24 PM |
Compile time & efficiency | Michael S | 2010/06/29 02:18 AM |
Compile time & efficiency | rwessel | 2010/06/29 11:20 AM |
Compile time & efficiency | someone | 2010/06/30 10:03 AM |
Compile time & efficiency | Jouni Osmala | 2010/07/02 04:29 AM |
Compile time & efficiency | Max | 2010/06/28 04:05 PM |
Compile time & efficiency | EduardoS | 2010/06/28 04:11 PM |
Compile time & efficiency | Michael S | 2010/06/29 02:33 AM |
Compile time | Foo_ | 2010/06/28 08:03 AM |
sun 's cc better than GCC? | Silent | 2010/06/23 05:19 PM |
sun 's cc better than GCC? | Foo_ | 2010/06/23 06:06 PM |
sun 's cc better than GCC? | Andi Kleen | 2010/06/24 01:49 AM |
sun 's versus gcc | Vincent Diepeveen | 2010/06/23 02:07 PM |
Why no GCC? | Carlie Coats | 2010/06/23 04:11 AM |