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Command asm

Asm, typically invoked as “go tool asm”, assembles the source file into an object file named for the basename of the argument source file with a .o suffix. The object file can then be combined with other objects into a package archive.

Command Line


go tool asm [flags] file

The specified file must be a Go assembly file. The same assembler is used for all target operating systems and architectures. The GOOS and GOARCH environment variables set the desired target.


-D name[=value]
	Predefine symbol name with an optional simple value.
	Can be repeated to define multiple symbols.
-I dir1 -I dir2
	Search for #include files in dir1, dir2, etc,
	after consulting $GOROOT/pkg/$GOOS_$GOARCH.
	Print assembly and machine code.
	Print assembler version and exit.
	Dump instructions as they are parsed.
	Support references to Go symbols defined in other shared libraries.
	Write symbol ABI information to output file. Don't assemble.
-o file
	Write output to file. The default is foo.o for /a/b/c/foo.s.
	Generate code that can be linked into a shared library.
-spectre list
	Enable spectre mitigations in list (all, ret).
-trimpath prefix
	Remove prefix from recorded source file paths.

Input language:

The assembler uses mostly the same syntax for all architectures, the main variation having to do with addressing modes. Input is run through a simplified C preprocessor that implements #include, #define, #ifdef/endif, but not #if or ##.

For more information, see