flat assembler
Message board for the users of flat assembler.
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macomics 21 Jan 2025, 11:15
This is not a question about our salary. Ask Intel/AMD.
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revolution 21 Jan 2025, 12:11
The annual tradition of Roman asking why an instruction doesn't exist?
![]() In the previous 5 years, there are 5 other questions: https://board.flatassembler.net/topic.php?p=218283#218283 https://board.flatassembler.net/topic.php?p=217153#217153 https://board.flatassembler.net/topic.php?p=217235#217235 https://board.flatassembler.net/topic.php?p=214294#214294 https://board.flatassembler.net/topic.php?p=212863#212863 The answer is always the same, ask Intel/AMD. |
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Ali.Z 21 Jan 2025, 19:22
perhaps one day he will work at intel and implement these instructions as undocumented for his own use.
_________________ Asm For Wise Humans |
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Roman 22 Jan 2025, 06:07
And not exist cmove dl,al.
Crazy things. Code: mov ax,dx add ax,0x0707 cmp dl,0x39 ;for hex text number. cmova dl,al cmp dh,0x39 cmova dh,ah |
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Furs 22 Jan 2025, 17:37
Roman wrote: And not exist cmove dl,al. |
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revolution 23 Jan 2025, 06:07
If one wanted to speculate, then I assume that Intel/AMD have certainly considered such instructions.
Creating new encodings for new instructions doesn't appear to be a problem. As evidenced by all the new instruction being added on a regular basis. Perhaps the "real" reason is that the existing batch of HLL compilers wouldn't be able to make good use of such instructions, thus making them "useless" for most people? And the few people that could find them useful (i.e. asm coders) are an insignificant portion of the whole? Compare to ARM, where almost all of the 32-bit instructions can be predicated upon a condition. But in the 64-bit encodings almost none of the instructions can be predicated. I have no doubt it was studied and discovered that "wasted" predicate bits could be better used for other purposes (e.g. more registers). At least as far as HLLs go. Manual assembly could make much better use of them, but since "no one" programs raw assembly anymore, then the manufacturers don't consider it a high priority. Anyhow, just speculation. For a definitive answer, ask Intel/AMD. ![]() |
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Roman 23 Jan 2025, 13:34
I thinking Intel might be created 30 user asm instructions.
And mechanism(several Special asm commands) to upload microcode to this instructions. And any programer could created owned asm command. Last edited by Roman on 23 Jan 2025, 13:40; edited 1 time in total |
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revolution 23 Jan 2025, 13:38
Anything microcoded would be "slow", so you probably won't like it. Better to just use those highly optimised "fast" native instructions.
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Roman 23 Jan 2025, 13:50
Quote: "fast" native instructions This instructions Hardware and not be modified? Like as microcode. |
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Furs 23 Jan 2025, 15:35
revolution wrote: Creating new encodings for new instructions doesn't appear to be a problem. As evidenced by all the new instruction being added on a regular basis. In this case you can easily do it by re-arranging the code with other instructions so what's the point in bloating up the encoding for no benefit (actually less instruction cache so likely worse)? |
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revolution 24 Jan 2025, 04:36
Furs wrote: In this case you can easily do it by re-arranging the code with other instructions so what's the point in bloating up the encoding for no benefit (actually less instruction cache so likely worse)? |
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Roman 24 Jan 2025, 12:11
I don't think so.
For example exist asm commands like dpps dot product and fpu load 1.0 fld1 and very powerful command nop. No problem write code without this instructions. Intel/amd beter created cross product one asm Sse instruction more good than dpps. Intel created several Avx512 good instructions, but for busines sector. In avx2 this instructions not exist. This suggests that Intel is more interested in making money than helping a simple programmer or user. |
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macomics 24 Jan 2025, 16:03
Roman wrote: very powerful command nop. reg 90h = 10010000b = xchg eax, eax = nop 91h = 10010001b = xchg eax, ecx ... |
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revolution 24 Jan 2025, 16:07
macomics wrote: 90h = 10010000b = xchg eax, eax = nop. |
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Furs 24 Jan 2025, 17:34
Roman wrote: I don't think so. That ship has sailed long ago, those opcodes are taken for a long, long time already. Forget about using them. ![]() |
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