这不是汇编指令吧?这是ld script的语法。
info ld
ile: ld.info, Node: Location Counter, Next: Operators, Prev: Orphan Sections, Up: Expressions
3.10.5 The Location Counter
---------------------------
The special linker variable "dot" `.' always contains the current
output location counter. Since the `.' always refers to a location in
an output section, it may only appear in an expression within a
`SECTIONS' command. The `.' symbol may appear anywhere that an
ordinary symbol is allowed in an expression.
不好意思,猜错了,那就info as.
File: as.info, Node: Dot, Next: Symbol Attributes, Prev: Symbol Names, Up: Symbols
5.4 The Special Dot Symbol
==========================
The special symbol `.' refers to the current address that `as' is
assembling into. Thus, the expression `melvin: .long .' defines
`melvin' to contain its own address. Assigning a value to `.' is
treated the same as a `.org' directive. Thus, the expression `.=.+4'
is the same as saying `.space 4'.