.globl 全局对象
.data 数据区
.align 4 对齐 16字节对齐
.type
For ELF targets, the .type directive is used like this:
.type name , type description
This sets the type of symbol name to be either a function symbol or an object symbol. There are five different syntaxes supported for the type description field, in order to provide compatibility with various other assemblers.
STT_FUNCfunction
Mark the symbol as being a function name.
STT_GNU_IFUNCgnu_indirect_function
Mark the symbol as an indirect function when evaluated during reloc processing. (This is only supported on assemblers targeting GNU systems).
STT_OBJECTobject
Mark the symbol as being a data object.
https://sourceware.org/binutils/docs/as/Type.html#index-ELF-symbol-type
Here, the dot . means "current location".
Then .-main would be the distance to the start of main. If placed at the end of main, it would also be the size of main.
"-" means minus and this expression means "size of main" = "." (current address) minus "address of main
movl c(%rip), %eax rip 相对寻指 x86 64
https://www.ruanyifeng.com/blog/2010/06/ieee_floating-point_representation.html
https://tooltt.com/floatconverter/
leaq 获取地址 获取-12(%rbp) 指向的地址