github.com/huandu/go@v0.0.0-20151114150818-04e615e41150/src/cmd/compile/doc.go (about)

     1  // Copyright 2009 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  /*
     6  Compile, typically invoked as ``go tool compile,'' compiles a single Go package
     7  comprising the files named on the command line. It then writes a single
     8  object file named for the basename of the first source file with a .o suffix.
     9  The object file can then be combined with other objects into a package archive
    10  or passed directly to the linker (``go tool link''). If invoked with -pack, the compiler
    11  writes an archive directly, bypassing the intermediate object file.
    12  
    13  The generated files contain type information about the symbols exported by
    14  the package and about types used by symbols imported by the package from
    15  other packages. It is therefore not necessary when compiling client C of
    16  package P to read the files of P's dependencies, only the compiled output of P.
    17  
    18  Command Line
    19  
    20  Usage:
    21  
    22  	go tool compile [flags] file...
    23  
    24  The specified files must be Go source files and all part of the same package.
    25  The same compiler is used for all target operating systems and architectures.
    26  The GOOS and GOARCH environment variables set the desired target.
    27  
    28  Flags:
    29  
    30  	-D path
    31  		Set relative path for local imports.
    32  	-I dir1 -I dir2
    33  		Search for imported packages in dir1, dir2, etc,
    34  		after consulting $GOROOT/pkg/$GOOS_$GOARCH.
    35  	-L
    36  		Show complete file path in error messages.
    37  	-N
    38  		Disable optimizations.
    39  	-S
    40  		Print assembly listing to standard output (code only).
    41  	-S -S
    42  		Print assembly listing to standard output (code and data).
    43  	-V
    44  		Print compiler version and exit.
    45  	-asmhdr file
    46  		Write assembly header to file.
    47  	-complete
    48  		Assume package has no non-Go components.
    49  	-cpuprofile file
    50  		Write a CPU profile for the compilation to file.
    51  	-dynlink
    52  		Allow references to Go symbols in shared libraries (experimental).
    53  	-e
    54  		Remove the limit on the number of errors reported (default limit is 10).
    55  	-h
    56  		Halt with a stack trace at the first error detected.
    57  	-importmap old=new
    58  		Interpret import "old" as import "new" during compilation.
    59  		The option may be repeated to add multiple mappings.
    60  	-installsuffix suffix
    61  		Look for packages in $GOROOT/pkg/$GOOS_$GOARCH_suffix
    62  		instead of $GOROOT/pkg/$GOOS_$GOARCH.
    63  	-largemodel
    64  		Generated code that assumes a large memory model.
    65  	-memprofile file
    66  		Write memory profile for the compilation to file.
    67  	-memprofilerate rate
    68  		Set runtime.MemProfileRate for the compilation to rate.
    69  	-nolocalimports
    70  		Disallow local (relative) imports.
    71  	-o file
    72  		Write object to file (default file.o or, with -pack, file.a).
    73  	-p path
    74  		Set expected package import path for the code being compiled,
    75  		and diagnose imports that would cause a circular dependency.
    76  	-pack
    77  		Write a package (archive) file rather than an object file
    78  	-race
    79  		Compile with race detector enabled.
    80  	-u
    81  		Disallow importing packages not marked as safe; implies -nolocalimports.
    82  
    83  There are also a number of debugging flags; run the command with no arguments
    84  for a usage message.
    85  
    86  Compiler Directives
    87  
    88  The compiler accepts compiler directives in the form of // comments at the
    89  beginning of a line. To distinguish them from non-directive comments, the directives
    90  require no space between the slashes and the name of the directive. However, since
    91  they are comments, tools unaware of the directive convention or of a particular
    92  directive can skip over a directive like any other comment.
    93  
    94  	//line path/to/file:linenumber
    95  
    96  The //line directive specifies that the source line that follows should be recorded
    97  as having come from the given file path and line number. Successive lines are
    98  recorded using increasing line numbers, until the next directive. This directive
    99  typically appears in machine-generated code, so that compilers and debuggers
   100  will show lines in the original input to the generator.
   101  
   102  The //line directive is an historical special case; all other directives are of the form
   103  //go:name, indicating that the directive is defined by the Go toolchain.
   104  
   105  	//go:noescape
   106  
   107  The //go:noescape directive specifies that the next declaration in the file, which
   108  must be a func without a body (meaning that it has an implementation not written
   109  in Go) does not allow any of the pointers passed as arguments to escape into the
   110  heap or into the values returned from the function. This information can be used as
   111  during the compiler's escape analysis of Go code calling the function.
   112  
   113  	//go:nosplit
   114  
   115  The //go:nosplit directive specifies that the next function declared in the file must
   116  not include a stack overflow check. This is most commonly used by low-level
   117  runtime sources invoked at times when it is unsafe for the calling goroutine to be
   118  preempted.
   119  
   120  	//go:linkname localname importpath.name
   121  
   122  The //go:linkname directive instructs the compiler to use ``importpath.name'' as the
   123  object file symbol name for the variable or function declared as ``localname'' in the
   124  source code. Because this directive can subvert the type system and package
   125  modularity, it is only enabled in files that have imported "unsafe".
   126  */
   127  package main