Reasons to use asm?

Re: Reasons to use asm?

Quote:

Originally Posted by NoteMe

But hell yeah, C++ have thought me a lot about structure, maintenance, coding paterns, and pros and cons about how to lay out your code, that VB never thought me.

That was the point of my compliment!

It appears you have arrived at the inner knowledge of the way things "compute" through C++ - we did it through machine code...

Same goal reached - different paths.

Structure, laying out code - that low level stuff you appreciate and acknowlege does not seem to be available to the programmers I've interviewed/hired/used in the past 3 years.

Re: Reasons to use asm?

Quote:

Originally Posted by szlamany

"Giving someone a big head" means giving them a compliment - one that is well deserved, but so well deserved it's better not said!

Banging it is something you appear to be doing in your little animated jpg - that was just a silly joke.

I meant nothing but respect for your level of knowledge. :)

I can't see a joke even if someone smacks me in the head with it outside the ChitChat forum...:)

Quote:

Originally Posted by szlamany

I already knew what lines of code were required to be "duplicated" and I also knew that VB was not going to detect duplicate code or function usage and in-line it in the machine code executable.

I didn't need a profiler - and never need a profiler - to show me what's going on.

But for an average person, you won't see that just because you took an ASM course or what ever. That is something that is much easier to get through teaching more languages (languages that is actualy useful), and learning the languages WELL, not just touch them, as most VB users do that post on this forum.

If you know C++ well, you know that wrapping something into a class will make the your machine look up one extra address in memory without knowing anything about ASM. And you also know that if the class is inherited, there is no way for the compiler to know where this address is at compile time. It requires a vTable, so the address can be found at run time. And that will slow down the function you talked about even more. And the worst thing is that it can no longer be inlined either.

But my point is that you don't know much more about that by teaching some ASM. You get that from experience over a longer period, and reading.

But now I feel we are touching an other topic here. Because people that say they know C++ and don't know what a vTable is, they are most of then self taught. And that is an other problem. They lose a lot of the inner work, because they teach them what they want in stead of things they should have known. And that you will be taught on a collage or at a uni. And reminds me about the old stories I have read about self taught VB programmers coming to an interview, and the guy that is interviewing asks him about algorithms, and the guy doesn't even know what an algorithm is because he has just taught himself the VB skills he wanted.

Well back on track again. At my Uni (the one I am soon finished at) we had a computer course that was about how a computer works and what parts there is in a computer and so on. And they taught us ASM. The teachers and the school board liked the course. Then I became the second in command (or what the PIIIP it is called....guess I have been in the army too long..:)) in the school board for physics and CS at my Uni and presented them with an other plan that changed the C++ course and the computer course that I just talked about. And they liked it. It no longer contains ASM coding. They will be taught about the registers and so on, but the rest will be about other PC parts as it was. And then they will use this in the C++ course.

So after the new semester new students at our Uni will no longer be taught ASM, but I am pretty sure they will understand the plot just as well.

Quote:

Originally Posted by szlamany

C&D (my 4 year old twins needed to sign their initials!)

You are just too cute to be a computer geek...:D

Quote:

Originally Posted by szlamany

It appears you have arrived at the inner knowledge of the way things "compute" through C++ - we did it through machine code...

Same goal reached - different paths.

Well I guess we some how, in an odd way agree then....hmmm....:D

Quote:

Originally Posted by szlamany

Structure, laying out code - that low level stuff you appreciate and acknowlege does not seem to be available to the programmers I've interviewed/hired/used in the past 3 years.

I hope you have just interviewed self taught programmers the last 3 years. If not, then I will rule out USA (if that is where you are coming from) for my master degree. That's for sure.

You should try too look for employees in an other country..:D

Re: Reasons to use asm?

Quote:

Originally Posted by NoteMe

But last time I checked it made pretty much faster code. And C++ also has the ability to use other instructionsets that you can't use in VB.

The way visual basic works internally is much different from C++. That is why you see a speed difference, because microsoft made visual basic very simple. Visual basic is a very object based langauge, everything from array variables to the functions you rely on are all OLE objects. A good example of this is to look at the internals of an array. One thing you will find that all visual basic arrays are actually OLE_SAFEARRAY structures. When you call LEN(String) for example, you don't actually perform any calculations on the variable, it reads a memory address. That is why you will never write a better len function then the one visual basic provides. In fact calling len multiple times in visual basic on a large string would more then likely be faster then doing the same in C++ using strlen.

In C++, you have the ability to work with the strings and arrays in the same fasion as visual basic. You will also make the same sacrafices in speed that microsoft made with their design of vb. MFC is a good example of sacrafice in the name of simplicity. Just like visual basic, if you use MFC, you wouldn't have the ability to make much use of directx graphics because the method is too slow. In a nutshell, the more high level layers you add onto a language, the slower it will become.

Re: Reasons to use asm?

Quote:

Originally Posted by NoteMe

It is not all about how much machine code the compiler uses. Different techniques for a job makes differnte ASM output after compiled in C++.

And why would Intel and Codeplay use sooo much money to make fast compilers, if the compiler doesn't do a lot of stuff with the code before it makes the machine code so it can be faster. No one would use US$26500 on a compiler if it wasn't faster then the free compilers out there.

ØØ

Compiler design is one of the hardest software programming projects in existance. That's why it's so expensive =/

Re: Reasons to use asm?

Quote:

Originally Posted by NoteMe

Well let me try to rephrase it again then. Make a thread in the game section and say that "speed doesn't really matter"....this should be fun...:D

Speed is not the only design goal. That's important to remember!

Re: Reasons to use asm?

Quote:

Originally Posted by NoteMe

Now over to the last of the big compilers on the selling market. Intels C/C++ compiler. It sells like ****. But on this example you can see that it is nearly making 100% longer code then the VectorC compiler. And it is not that optimized at all. Unless you have a P4 processor that is. But still the VectorC output will beat it to deth.

Code:

_RotateVectors: sub esp,52 call _SetRotation mov byte ptr [_DrawFlag],1 xor al,al mov [_SOAFlag],al mov [_IntFlag],al xor eax,eax fld dword ptr [_CameraRotation] fstp dword ptr 24[esp] fld dword ptr [.bss+1650036] fld dword ptr [.bss+1650040] fld dword ptr [.bss+1650044] fld dword ptr [.bss+1650048] fld dword ptr [.bss+1650052] fld dword ptr [.bss+1650056] fld dword ptr [.bss+1650060] fld dword ptr [.bss+1650064] fstp dword ptr 28[esp] fstp dword ptr 32[esp] fxch st(3) fstp dword ptr 44[esp] fxch st(3) fstp dword ptr 40[esp] fxch st(3) fstp dword ptr 36[esp] L2: xor ecx,ecx xor edx,edx jmp short L0 mov esi,esi lea edi,0[edi] L1: fstp dword ptr .bss+800024[edx] L0: fld dword ptr _Points[edx] fld dword ptr .bss+36[edx] fld dword ptr .bss+40[edx] fld st(2) fmul dword ptr 24[esp] fld st(2) fmul dword ptr 36[esp] faddp st(1),st fld st(1) fmul dword ptr 40[esp] faddp st(1),st fstp dword ptr _TPoints[edx] fld st(2) fmul dword ptr 44[esp] fld st(2) fmul st,st(7) faddp st(1),st fld st(1) fmul st,st(6) faddp st(1),st fstp dword ptr .bss+800036[edx] fxch st(2) fmul st,st(3) fxch st(1) fmul dword ptr 32[esp] faddp st(1),st fxch st(1) fmul dword ptr 28[esp] faddp st(1),st mov byte ptr _Flags[ecx],1 add edx,16 inc ecx cmp ecx,50000 jl short L1 fstp dword ptr .bss+800024[edx] inc eax cmp eax,4 jl long L2 fstp st fstp st fstp st add esp,52 ret lea esi,0[esi] _SetRotation: sub esp,124 fld qword ptr [$2$3_2il0floatpacket$1] fadd dword ptr [_Rotx] fstp dword ptr 96[esp] fld dword ptr 96[esp] fst dword ptr [_Rotx] fld qword ptr [$2$3_2il0floatpacket$3] fadd dword ptr [_Roty] fstp dword ptr 96[esp] fld dword ptr 96[esp] fst dword ptr [_Roty] fxch st(1) fsincos fstp dword ptr 96[esp] fld dword ptr 96[esp] fxch st(1) fstp dword ptr 96[esp] fld dword ptr 96[esp] fxch st(2) fsincos fchs fstp dword ptr 96[esp] fld dword ptr 96[esp] fxch st(1) fstp dword ptr 96[esp] fld dword ptr 96[esp] fxch st(2) fst dword ptr 24[esp] fld dword ptr [$2$3_2il0floatpacket$5] fst dword ptr 28[esp] fld st(4) fchs fstp dword ptr 96[esp] fld dword ptr 96[esp] fst dword ptr 32[esp] fxch st(1) fst dword ptr 36[esp] fld dword ptr [$2$3_2il0floatpacket$7] fst dword ptr 40[esp] fxch st(1) fst dword ptr 44[esp] fxch st(6) fst dword ptr 48[esp] fxch st(6) fst dword ptr 52[esp] fxch st(3) fst dword ptr 56[esp] fxch st(1) fst dword ptr 60[esp] fxch st(3) fst dword ptr 64[esp] fst dword ptr 68[esp] fst dword ptr 72[esp] fxch st(4) fst dword ptr 76[esp] fld st(5) fchs fstp dword ptr 80[esp] fxch st(4) fst dword ptr 84[esp] fxch st(5) fstp dword ptr 88[esp] fxch st(3) fstp dword ptr 92[esp] fld dword ptr 24[esp] xor eax,eax fstp qword ptr 104[esp] fstp st(1) fxch st(1) fstp qword ptr 112[esp] jmp short L3 lea esi,0[esi] lea edi,0[edi] L4: fstp dword ptr .bss+1650028[eax] L3: fld dword ptr 60[esp][eax] fld dword ptr 64[esp][eax] fld dword ptr 68[esp][eax] fld qword ptr 104[esp] fmul st,st(3) fld st(5) fmul st,st(3) faddp st(1),st fld st(6) fmul st,st(2) faddp st(1),st fstp dword ptr _CameraRotation[eax] fld st(4) fmul st,st(3) fld dword ptr [$2$3_2il0floatpacket$7] fmul st,st(3) faddp st(1),st fld st(5) fmul st,st(2) faddp st(1),st fstp dword ptr .bss+1650036[eax] fxch st(2) fmul st,st(3) fxch st(1) fmul st,st(4) faddp st(1),st fxch st(1) fmul qword ptr 112[esp] faddp st(1),st add eax,12 cmp eax,36 jl short L4 fstp dword ptr .bss+1650028[eax] fstp st fstp st fstp st add esp,124 ret mov esi,esi

Hold it there partner =P

Just because the code is longer in asm does not mean that it will run slower.

Re: Reasons to use asm?

Quote:

Originally Posted by NoteMe

No, you don't have to know anything about ASM, to grab a C++ compiler and beat VB with it hands down even without trying that much. And that is my point.

Maven said:

Hell yeah, but machine code is not just machine code. As long as VB makes crappy machine code as it does, it will never be comparable with VB. The output is alfa omega, but you don't have to care about it at all.

Learning ASM helps you understand what is going on, but I can't see it help you much in making fast C++ code, because it is more about knowing your compiler, and what it likes then anything else.

ØØ

It's not the machine code that makes visual basic so slow, it's the high level layers that go with it. If you added the same layers to C++, you would get the same slowdown.

You have to know you're compiler optimization settings and what they are to make full befinit out of a compiler. That my friend is not all there is to making fast programs. Have you ever heard of parallel processing? Did you know that intel has out of order execution and do you know how that effects speed of a program? Do you know what a register dependcy is and what it does? Have you ever heard of a cache miss or know anything at all about the system cache and how it effects code? Do you know anything at all about branch misspredictions and how that effects the speed of the code? Do you know what TLB priming is and what it does? Do you know why loop unrolling effects code or that multiplication is faster then division? How about data and code alignment and how that effects speed? Do you know why running two loops out of sync could create a speed boast?

Also I would like to point out Intel's v-tune code profiler. You're not going to understand much of that output unless you have a background in ASM.

Re: Reasons to use asm?

I almost hit the close button then thought I would add more:

It's a well known fact that different compilers generate different asm output for the very same reason that my hand optimized asm is going to be different from what a compiler will generate. The speed of one compiler will change from processor to processor. That is something that has been known in computer science since high level languages.

That is the reason complexity theory is the defacto standard way for analyzing algrorithms.

Re: Reasons to use asm?

Quote:

Originally Posted by Maven

The way visual basic works internally is much different from C++. That is why you see a speed difference, because microsoft made visual basic very simple. Visual basic is a very object based langauge, everything from array variables to the functions you rely on are all OLE objects. A good example of this is to look at the internals of an array. One thing you will find that all visual basic arrays are actually OLE_SAFEARRAY structures. When you call LEN(String) for example, you don't actually perform any calculations on the variable, it reads a memory address. That is why you will never write a better len function then the one visual basic provides. In fact calling len multiple times in visual basic on a large string would more then likely be faster then doing the same in C++ using strlen.

In C++, you have the ability to work with the strings and arrays in the same fasion as visual basic. You will also make the same sacrafices in speed that microsoft made with their design of vb. MFC is a good example of sacrafice in the name of simplicity. Just like visual basic, if you use MFC, you wouldn't have the ability to make much use of directx graphics because the method is too slow. In a nutshell, the more high level layers you add onto a language, the slower it will become.

And your point was?

And BTW, no one would use MFC for speed intensive apps anyway. To be honest, I can't see why anyone uses MFC at all.

Re: Reasons to use asm?

Quote:

Originally Posted by Maven

Compiler design is one of the hardest software programming projects in existance. That's why it's so expensive =/

But that doesn't explain why one compiler can be free and one cost a whole years of payments...;)

The reason my friend is because one of them just works, and one of them is making HIGLY optimized code...;)

Re: Reasons to use asm?

Quote:

Originally Posted by Maven

Speed is not the only design goal. That's important to remember!

Never said so...;)...but in some applications, you could just as well not make the game at all, if it isn't fast...;)

Re: Reasons to use asm?

Quote:

Originally Posted by Maven

Hold it there partner =P

Just because the code is longer in asm does not mean that it will run slower.

Never said so. But it is pretty importent. Often if you have an app in C++, and you compile it "for fast code" it will actualy run slower then if you compile it "for small code". Some of the reasons I can see you have listed in your next post.

But since the code I pasted is both smaller and vectorized, THAT means that it is faster...;)

Re: Reasons to use asm?

Quote:

Originally Posted by Maven

It's not the machine code that makes visual basic so slow, it's the high level layers that go with it. If you added the same layers to C++, you would get the same slowdown.

It's both actualy. Even if it didn't add the same layers to VB, it would still be slower because of the output of the VB compiler. VB was never ment for speed. It is a RAD language.

Quote:

Originally Posted by Maven

Have you ever heard of parallel processing?

Yes

Quote:

Originally Posted by Maven

Did you know that intel has out of order execution and do you know how that effects speed of a program?

Yes

Quote:

Originally Posted by Maven

Do you know what a register dependcy is and what it does?

Yes

Quote:

Originally Posted by Maven

Have you ever heard of a cache miss or know anything at all about the system cache and how it effects code?

Yes

Quote:

Originally Posted by Maven

Do you know anything at all about branch misspredictions and how that effects the speed of the code?

Yes

Quote:

Originally Posted by Maven

Do you know what TLB priming is and what it does?

Yes

Quote:

Originally Posted by Maven

Do you know why loop unrolling effects code or that multiplication is faster then division?

Yes

Quote:

Originally Posted by Maven

How about data and code alignment and how that effects speed?

Yes

Quote:

Originally Posted by Maven

Do you know why running two loops out of sync could create a speed boast?

Yes

All these things we students learn at school today...;)...and none of them thought through ASM at all.

Did you have any more questions...;)

Quote:

Originally Posted by Maven

Also I would like to point out Intel's v-tune code profiler. You're not going to understand much of that output unless you have a background in ASM.

Well, Intel's v-tune code profiler isn't the best anyway. I have never liked a profiler that is made from any HW vendor anyway.

Re: Reasons to use asm?

Quote:

Originally Posted by Maven

I almost hit the close button then thought I would add more:

It's a well known fact that different compilers generate different asm output for the very same reason that my hand optimized asm is going to be different from what a compiler will generate. The speed of one compiler will change from processor to processor. That is something that has been known in computer science since high level languages.

That is the reason complexity theory is the defacto standard way for analyzing algrorithms.

That is true. But vecotrized asm will always kill non vectorized output something that VB does.

And even Intels C/C++ compiler fails to make it most of the time.

Re: Reasons to use asm?

Quote:

Originally Posted by NoteMe

And your point was?

And BTW, no one would use MFC for speed intensive apps anyway. To be honest, I can't see why anyone uses MFC at all.

I was explaining that cpp isn't always faster, it depends on the decisions made during the design.

Unless you're programming something that requires intensive graphics processing, MFC is a good choice. Speed is not the only design goal.

Re: Reasons to use asm?

Quote:

Originally Posted by NoteMe

But that doesn't explain why one compiler can be free and one cost a whole years of payments...;)

The reason my friend is because one of them just works, and one of them is making HIGLY optimized code...;)

"Compiler design is one of the hardest software programming projects in existance. That's why it's so expensive =/"

I think that explained it correctly myself. How much simpler can one get?

Re: Reasons to use asm?

Quote:

Originally Posted by NoteMe

It's both actualy. Even if it didn't add the same layers to VB, it would still be slower because of the output of the VB compiler. VB was never ment for speed. It is a RAD language.

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

All these things we students learn at school today...;)...and none of them thought through ASM at all.

Did you have any more questions...;)

Well, Intel's v-tune code profiler isn't the best anyway. I have never liked a profiler that is made from any HW vendor anyway.

Explain a few of those to me then. =P

Re: Reasons to use asm?

oh man this topics gotten to hot for me...

Re: Reasons to use asm?

Ok - I've just been through a thread that debated two ways to do things.

The goal was to find the number of days in the month of a given date.

First up the solutions given had basically taking the YEAR() and MONTH() of the date and adding a month and subtracting a day. This is a pretty standard trick - I've used it in T-SQL many, many times - but T-SQL is a fourth generation (at least) language...

At any rate, I suggested using a logic/If/math method in code - basically an array having the number of days in a month and some logic to determine if it's a leap year - you could imagine...

I'm not sure what easy maintainable code would have dictated - or what complexity theory would have dictated.

Here's the post if you are interested...

Post with comparison of timing

And the whole thread, if you want to read what got us to this point.

The thread itself...

Re: Reasons to use asm?

What an interesting thread.

For what it's worth, I think ASM is worth learning because it gives you a much deeper and more tangible understanding of what the CPU is doing. You can really feel the processor's anatomy and appreciate how much work it has to do to accomplish even the simplest thing.

I doubt that any compiler will be able to write code as well as a human doing ASM by hand. And its a challenge too, it expands the intellect, and best of all it makes most other languaes look flabby and slooooooow (and easy).

I like to write code that performs as fast as it can for any given language, ASM happens to appeal to that side of me. I'll be using ASM mostly for spot-tuning my C# programs.

Re: Reasons to use asm?

Quote:

Originally Posted by wossname

What an interesting thread.

For what it's worth, I think ASM is worth learning because it gives you a much deeper and more tangible understanding of what the CPU is doing. You can really feel the processor's anatomy and appreciate how much work it has to do to accomplish even the simplest thing.

I doubt that any compiler will be able to write code as well as a human doing ASM by hand. And its a challenge too, it expands the intellect, and best of all it makes most other languaes look flabby and slooooooow (and easy).

I like to write code that performs as fast as it can for any given language, ASM happens to appeal to that side of me. I'll be using ASM mostly for spot-tuning my C# programs.

It certainly does not expand the intellect. It is simply another tool for getting the machine to do what you want it to do.

There are many people on this forums who have been using ASM for years; writing support DLL's, for instance.

This smells of some sort of elitist cr@p.

Re: Reasons to use asm?

Quote:

Originally Posted by yrwyddfa

It certainly does not expand the intellect. It is simply another tool for getting the machine to do what you want it to do.

There are many people on this forums who have been using ASM for years; writing support DLL's, for instance.

This smells of some sort of elitist cr@p.

Did I say something to make you angry? I have nothing against high level languages and I like ASM so I don't see why you are getting all upset.

Nobody is being elitist.

Re: Reasons to use asm?

Quote:

Originally Posted by wossname

Did I say something to make you angry? I have nothing against high level languages and I like ASM so I don't see why you are getting all upset.

Nobody is being elitist.

Oh, let's just be elitist and only let people in the club who have more then one "standard vowel" in their names :D

Re: Reasons to use asm?

Quote:

Originally Posted by szlamany

Oh, let's just be elitist and only let people in the club who have more then one "standard vowel" in their names :D

I agree.'a' counts for two vowels, though.

Re: Reasons to use asm?

Quote:

Originally Posted by wossname

Did I say something to make you angry? I have nothing against high level languages and I like ASM so I don't see why you are getting all upset.

Nobody is being elitist.

I'm always angry. The wife needs to learn how to stop burning my toast in the morning.

Re: Reasons to use asm?

Quote:

Originally Posted by NoteMe

Now over to the last of the big compilers on the selling market. Intels C/C++ compiler. It sells like ****. But on this example you can see that it is nearly making 100% longer code then the VectorC compiler. And it is not that optimized at all. Unless you have a P4 processor that is. But still the VectorC output will beat it to deth.

Noteme...just wondering...did you set the Intel compiler to compile for P4 and SSE/SSE2 architecture ? If you didn't it wouldn't produce SSE/SSE2 code.

btw...those you took from the VectorC website...they were using MSVC 6 and Intel Compiler 5
It is now coming MS VC 2005 .NET and currently is Intel Compiler 9.

Im not saying Vector C is bad as I have nevre tried it nor have tested it. But the source codes you are showing us are of really old versions of the other compilers. MSVC 6 came out before SSE2 was released i think(SSE maybe only just) and Intel Compiler 5 is old....very old 4 versions ago.

I believe they will all produce similar code now. Probably MS being the worst.

Re: Reasons to use asm?

Quote:

Originally Posted by NoteMe

If you want the MAX out of your compiler, you have to know what kind of coding style you should apply to let the compiler optimice it to the max. You don't have that opertunity at all in VB, because you only have one big bloated dumb compiler, that is just happy if it can make working code.

Sorry for bringing up an old thread but I agree with "one big bloated compiler" - not for VB6, of course - I love it's simplicity and non-fanciness - but for todays compilers such as Delphi 2005 and Visual Studio.NET. Way too bloated and color-fancy. I don't know about you but I prefer the olden-style compilers like Delphi 6-7 and Visual Studio 6. No bull**** and fancy colors - just nice and simple.

Thus, bloatedness and fancy colors = the reason I refuse to upgrade languages. Stupid? maybe. Get used to it? No. I can't stand looking at it, let-alone using it.

/rant

Re: Reasons to use asm?

Ummmm......we aren't talking about IDE or the libraries that go with languages.... we're talking about code generation! :P