错误：使用 gcc 编译时 armv8 中的未知助记符

Question

I am trying to compile a project with multiple c files and an assembly file written in ARMv8, which I have not done before, so I am having some trouble understanding a few error messages I am getting.

I consistently receive the "unknown mnemonic" error throughout, for almost every single line. For example, for the following snippet of code,

100    ## Save oSum to the stack.
101    pushq %rdx
102
103    ## unsigned long ulCarry
104    subq $8, %rsp
105 
106    ## unsigned long ulSum
107    subq $8, %rsp
108
109    ## long lIndex
110    subq $8, %rsp
111
112    ## long lSumLength
113    subq $8, %rsp

I receive the following messages,

file.s:101: Error: unknown mnemonic `pushq' -- `pushq %rdx'
file.s:104: Error: unknown mnemonic `subq' -- `subq $8,%rsp'
file.s:107: Error: unknown mnemonic `subq' -- `subq $8,%rsp'
file.s:110: Error: unknown mnemonic `subq' -- `subq $8,%rsp'
file.s:113: Error: unknown mnemonic `subq' -- `subq $8,%rsp'

What I am I doing wrong here? How can I fix this?

Your help is much appreciated.

Answer 1

Problem is actually really simple, what you were typing was 64-bit x86 Assembly, not ARM. The code you've written does have an equivalent in ARM Assembly, but the register names and instruction names will be different. I believe armv8 is a 32-bit architecture (there's a 64-bit version, commonly called AArch64 or arm64.) I'm not familiar with that unfortunately. Try this:

push {r4,r5,r6,lr}  //ARM calling convention requires an even number of regs to be pushed
sub sp,sp,32