thanks everyone for replies. I am referring intel sw dev manual and it is sufficient for my work. It is true intel provides instructions but when instruction support is added in gnu assembler i was sort of hoping it will be documented somewhere. However, that is not necessary because gnu syntax is quite intuitive and if instruction is supported, it is easy to figure out how it will work by gnu syntax. Regards Anand ________________________________ From: LIU Hao Sent: Wednesday, May 15, 2024 17:27 To: Segher Boessenkool Cc: anand akhare; gcc-help@xxxxxxxxxxx Subject: Re: official gnu as reference for x86 instructions - specifically cmpxchg 在 2024-05-15 19:39, Segher Boessenkool 写道: > The source code of GAS (well, libopcodes) is the ultimate reference to > what instruction syntax is accepted by GAS. See > https://sourceware.org/git/?p=binutils-gdb.git;a=blob&f=opcodes/i386-opc.tbl > and files around that. Having read that page, I don't see any syntax construction about CMPXCHG. Given the fact that CMPXCHG looks much similar to MOV, it's reasonable to assume the same convention as MOV; and it is the case. I don't recommend reading the source code. Both dialects have not been well defined, and both contain a lot of ad-hoc solutions to non-issues, e.g. why is there the `OFFSET` keyword in Intel syntax, and why is `jmp *%rax` not `jmp (%rax)` in AT&T syntax. Compiler output is really the only thing worth reading. -- Best regards, LIU Hao
