If you prefer AT&T (or you have a large body of existing AT&T code you don't want to have to translate all at once), use asm!("...", options(att_syntax)) and it'll Just Work.
1. It’s the syntax in the manual. The last thing I want to do when reading or writing asm is to mentally translate from the manual to AT&T syntax.
2. Addressing like (%rax) is tolerably. But the AT&T scale * index + offset syntax is inexcusable. Give me the verbose Intel addressing syntax any day, please.
(As a kernel programmer, I’m more familiar with AT&T. I still hate it. I’m morbidly curious how Intel syntax ought to handle things like SGDT. Maybe SGDT SIXBYTE PTR [address]? The fact that four bytes is called a DWORD isn’t great.)
Right! I worked on C++ compilers for years and I don't even know where is the canonical book of AT&T mnemonics. At the rate that Intel is adding new instructions, using anything other than their official docs (and thus their official names) seems nuts.
Nowadays GCC and LLVM support both styles and archs pick whatever they prefer and nobody cares, really.
> either fork the project, or submit a patch with a fix using Intel syntax.
That sounds a bit extreme? Reading/writing in both styles is not an issue for anyone that has dealt with x86 professionally.
Is this actually true? Admittedly I've done mostly x86 and ARM for the past several years (almost entirely Cortex-M, so v6-M and v7-M profiles, using ARM's GCC builds for embedded) and the only toolchain that prefers AT&T syntax is x86 GCC and those explicitly trying to be compatible with it. All the ARM inline assembly I've written, targetting GCC backends, has been ARM syntax, and likewise for all the disassembly output.
The DSPs and DSP-likes are... always weird. So I try to stay away from them and make them someone else's problem. But I don't think they use AT&T syntax either. It doesn't work so well for truly strange processors anyway.
I'm one of those guys who tends to have the makefiles output the disassembly, and have it open on the other monitor while I'm working, so I'd notice if it were different....
Most Rust code is quite portable, targeting ARM, x86, MIPS, PPC, WASM, Sparc, s390x, riscv, ... That means, that for many snippets of inline assembly, you might encounter ~8 of them, one for each architecture, all using different syntaxes.
Intel syntax is quite similar to that of other popular architectures `op dst, args...`.
Adding another second syntax for x86 just doesn't add that much value IMO, and adds quite a bit of cost: now everybody dealing with x86 assembly needs to learn 2 syntaxes... and everybody dealing with portable code now needs to be at least able to read 2 syntaxes for x86... Without talking about the cost of implementing a second syntax in the compiler, etc.
If you prefer AT&T, you can always write a proc macro that translates it to Intel, and use that in your projects.
If I ever need to deal with such code, I'd just expand the macro to read the actual Intel syntax, modify that, and either fork the project, or submit a patch with a fix using Intel syntax.