src/cmd/compile/doc.go - go - Git at Google

 // Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 /*
 Compile, typically invoked as ``go tool compile,'' compiles a single Go package
 comprising the files named on the command line. It then writes a single
 object file named for the basename of the first source file with a .o suffix.
 The object file can then be combined with other objects into a package archive
 or passed directly to the linker (``go tool link''). If invoked with -pack, the compiler
 writes an archive directly, bypassing the intermediate object file.

 The generated files contain type information about the symbols exported by
 the package and about types used by symbols imported by the package from
 other packages. It is therefore not necessary when compiling client C of
 package P to read the files of P's dependencies, only the compiled output of P.

 Command Line

 Usage:

 	go tool compile [flags] file...

 The specified files must be Go source files and all part of the same package.
 The same compiler is used for all target operating systems and architectures.
 The GOOS and GOARCH environment variables set the desired target.

 Flags:

 	-D path
 		Set relative path for local imports.
 	-I dir1 -I dir2
 		Search for imported packages in dir1, dir2, etc,
 		after consulting $GOROOT/pkg/$GOOS_$GOARCH.
 	-L
 		Show complete file path in error messages.
 	-N
 		Disable optimizations.
 	-S
 		Print assembly listing to standard output (code only).
 	-S -S
 		Print assembly listing to standard output (code and data).
 	-V
 		Print compiler version and exit.
 	-asmhdr file
 		Write assembly header to file.
 	-blockprofile file
 		Write block profile for the compilation to file.
 	-complete
 		Assume package has no non-Go components.
 	-cpuprofile file
 		Write a CPU profile for the compilation to file.
 	-dynlink
 		Allow references to Go symbols in shared libraries (experimental).
 	-e
 		Remove the limit on the number of errors reported (default limit is 10).
 	-h
 		Halt with a stack trace at the first error detected.
 	-importmap old=new
 		Interpret import "old" as import "new" during compilation.
 		The option may be repeated to add multiple mappings.
 	-installsuffix suffix
 		Look for packages in $GOROOT/pkg/$GOOS_$GOARCH_suffix
 		instead of $GOROOT/pkg/$GOOS_$GOARCH.
 	-l
 		Disable inlining.
 	-largemodel
 		Generate code that assumes a large memory model.
 	-linkobj file
 		Write linker-specific object to file and compiler-specific
 		object to usual output file (as specified by -o).
 		Without this flag, the -o output is a combination of both
 		linker and compiler input.
 	-memprofile file
 		Write memory profile for the compilation to file.
 	-memprofilerate rate
 		Set runtime.MemProfileRate for the compilation to rate.
 	-msan
 		Insert calls to C/C++ memory sanitizer.
 	-mutexprofile file
 		Write mutex profile for the compilation to file.
 	-nolocalimports
 		Disallow local (relative) imports.
 	-o file
 		Write object to file (default file.o or, with -pack, file.a).
 	-p path
 		Set expected package import path for the code being compiled,
 		and diagnose imports that would cause a circular dependency.
 	-pack
 		Write a package (archive) file rather than an object file
 	-race
 		Compile with race detector enabled.
 	-trimpath prefix
 		Remove prefix from recorded source file paths.
 	-u
 		Disallow importing packages not marked as safe; implies -nolocalimports.

 There are also a number of debugging flags; run the command with no arguments
 for a usage message.

 Compiler Directives

 The compiler accepts directives in the form of comments.
 To distinguish them from non-directive comments, directives
 require no space between the comment opening and the name of the directive. However, since
 they are comments, tools unaware of the directive convention or of a particular
 directive can skip over a directive like any other comment.
 */
 // Line directives come in several forms:
 //
 // 	//line :line
 // 	//line :line:col
 // 	//line filename:line
 // 	//line filename:line:col
 // 	/*line :line*/
 // 	/*line :line:col*/
 // 	/*line filename:line*/
 // 	/*line filename:line:col*/
 //
 // In order to be recognized as a line directive, the comment must start with
 // //line or /*line followed by a space, and must contain at least one colon.
 // The //line form must start at the beginning of a line.
 // A line directive specifies the source position for the character immediately following
 // the comment as having come from the specified file, line and column:
 // For a //line comment, this is the first character of the next line, and
 // for a /*line comment this is the character position immediately following the closing */.
 // If no filename is given, the recorded filename is empty if there is also no column number;
 // otherwise is is the most recently recorded filename (actual filename or filename specified
 // by previous line directive).
 // If a line directive doesn't specify a column number, the column is "unknown" until
 // the next directive and the compiler does not report column numbers for that range.
 // The line directive text is interpreted from the back: First the trailing :ddd is peeled
 // off from the directive text if ddd is a valid number > 0. Then the second :ddd
 // is peeled off the same way if it is valid. Anything before that is considered the filename
 // (possibly including blanks and colons). Invalid line or column values are reported as errors.
 //
 // Examples:
 //
 //	//line foo.go:10      the filename is foo.go, and the line number is 10 for the next line
 //	//line C:foo.go:10    colons are permitted in filenames, here the filename is C:foo.go, and the line is 10
 //	//line  a:100 :10     blanks are permitted in filenames, here the filename is " a:100 " (excluding quotes)
 //	/*line :10:20*/x      the position of x is in the current file with line number 10 and column number 20
 //	/*line foo: 10 */     this comment is recognized as invalid line directive (extra blanks around line number)
 //
 // Line directives typically appear in machine-generated code, so that compilers and debuggers
 // will report positions in the original input to the generator.
 /*
 The line directive is an historical special case; all other directives are of the form
 //go:name and must start at the begnning of a line, indicating that the directive is defined
 by the Go toolchain.

 	//go:noescape

 The //go:noescape directive specifies that the next declaration in the file, which
 must be a func without a body (meaning that it has an implementation not written
 in Go) does not allow any of the pointers passed as arguments to escape into the
 heap or into the values returned from the function. This information can be used
 during the compiler's escape analysis of Go code calling the function.

 	//go:nosplit

 The //go:nosplit directive specifies that the next function declared in the file must
 not include a stack overflow check. This is most commonly used by low-level
 runtime sources invoked at times when it is unsafe for the calling goroutine to be
 preempted.

 	//go:linkname localname importpath.name

 The //go:linkname directive instructs the compiler to use ``importpath.name'' as the
 object file symbol name for the variable or function declared as ``localname'' in the
 source code. Because this directive can subvert the type system and package
 modularity, it is only enabled in files that have imported "unsafe".
 */
 package main
	// Copyright 2009 The Go Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	/*
	Compile, typically invoked as ``go tool compile,'' compiles a single Go package
	comprising the files named on the command line. It then writes a single
	object file named for the basename of the first source file with a .o suffix.
	The object file can then be combined with other objects into a package archive
	or passed directly to the linker (``go tool link''). If invoked with -pack, the compiler
	writes an archive directly, bypassing the intermediate object file.

	The generated files contain type information about the symbols exported by
	the package and about types used by symbols imported by the package from
	other packages. It is therefore not necessary when compiling client C of
	package P to read the files of P's dependencies, only the compiled output of P.

	Command Line

	Usage:

	go tool compile [flags] file...

	The specified files must be Go source files and all part of the same package.
	The same compiler is used for all target operating systems and architectures.
	The GOOS and GOARCH environment variables set the desired target.

	Flags:

	-D path
	Set relative path for local imports.
	-I dir1 -I dir2
	Search for imported packages in dir1, dir2, etc,
	after consulting $GOROOT/pkg/$GOOS_$GOARCH.
	-L
	Show complete file path in error messages.
	-N
	Disable optimizations.
	-S
	Print assembly listing to standard output (code only).
	-S -S
	Print assembly listing to standard output (code and data).
	-V
	Print compiler version and exit.
	-asmhdr file
	Write assembly header to file.
	-blockprofile file
	Write block profile for the compilation to file.
	-complete
	Assume package has no non-Go components.
	-cpuprofile file
	Write a CPU profile for the compilation to file.
	-dynlink
	Allow references to Go symbols in shared libraries (experimental).
	-e
	Remove the limit on the number of errors reported (default limit is 10).
	-h
	Halt with a stack trace at the first error detected.
	-importmap old=new
	Interpret import "old" as import "new" during compilation.
	The option may be repeated to add multiple mappings.
	-installsuffix suffix
	Look for packages in $GOROOT/pkg/$GOOS_$GOARCH_suffix
	instead of $GOROOT/pkg/$GOOS_$GOARCH.
	-l
	Disable inlining.
	-largemodel
	Generate code that assumes a large memory model.
	-linkobj file
	Write linker-specific object to file and compiler-specific
	object to usual output file (as specified by -o).
	Without this flag, the -o output is a combination of both
	linker and compiler input.
	-memprofile file
	Write memory profile for the compilation to file.
	-memprofilerate rate
	Set runtime.MemProfileRate for the compilation to rate.
	-msan
	Insert calls to C/C++ memory sanitizer.
	-mutexprofile file
	Write mutex profile for the compilation to file.
	-nolocalimports
	Disallow local (relative) imports.
	-o file
	Write object to file (default file.o or, with -pack, file.a).
	-p path
	Set expected package import path for the code being compiled,
	and diagnose imports that would cause a circular dependency.
	-pack
	Write a package (archive) file rather than an object file
	-race
	Compile with race detector enabled.
	-trimpath prefix
	Remove prefix from recorded source file paths.
	-u
	Disallow importing packages not marked as safe; implies -nolocalimports.

	There are also a number of debugging flags; run the command with no arguments
	for a usage message.

	Compiler Directives

	The compiler accepts directives in the form of comments.
	To distinguish them from non-directive comments, directives
	require no space between the comment opening and the name of the directive. However, since
	they are comments, tools unaware of the directive convention or of a particular
	directive can skip over a directive like any other comment.
	*/
	// Line directives come in several forms:
	//
	// //line :line
	// //line :line:col
	// //line filename:line
	// //line filename:line:col
	// /line :line/
	// /line :line:col/
	// /line filename:line/
	// /line filename:line:col/
	//
	// In order to be recognized as a line directive, the comment must start with
	// //line or /*line followed by a space, and must contain at least one colon.
	// The //line form must start at the beginning of a line.
	// A line directive specifies the source position for the character immediately following
	// the comment as having come from the specified file, line and column:
	// For a //line comment, this is the first character of the next line, and
	// for a /line comment this is the character position immediately following the closing /.
	// If no filename is given, the recorded filename is empty if there is also no column number;
	// otherwise is is the most recently recorded filename (actual filename or filename specified
	// by previous line directive).
	// If a line directive doesn't specify a column number, the column is "unknown" until
	// the next directive and the compiler does not report column numbers for that range.
	// The line directive text is interpreted from the back: First the trailing :ddd is peeled
	// off from the directive text if ddd is a valid number > 0. Then the second :ddd
	// is peeled off the same way if it is valid. Anything before that is considered the filename
	// (possibly including blanks and colons). Invalid line or column values are reported as errors.
	//
	// Examples:
	//
	// //line foo.go:10 the filename is foo.go, and the line number is 10 for the next line
	// //line C:foo.go:10 colons are permitted in filenames, here the filename is C:foo.go, and the line is 10
	// //line a:100 :10 blanks are permitted in filenames, here the filename is " a:100 " (excluding quotes)
	// /line :10:20/x the position of x is in the current file with line number 10 and column number 20
	// /line foo: 10 / this comment is recognized as invalid line directive (extra blanks around line number)
	//
	// Line directives typically appear in machine-generated code, so that compilers and debuggers
	// will report positions in the original input to the generator.
	/*
	The line directive is an historical special case; all other directives are of the form
	//go:name and must start at the begnning of a line, indicating that the directive is defined
	by the Go toolchain.

	//go:noescape

	The //go:noescape directive specifies that the next declaration in the file, which
	must be a func without a body (meaning that it has an implementation not written
	in Go) does not allow any of the pointers passed as arguments to escape into the
	heap or into the values returned from the function. This information can be used
	during the compiler's escape analysis of Go code calling the function.

	//go:nosplit

	The //go:nosplit directive specifies that the next function declared in the file must
	not include a stack overflow check. This is most commonly used by low-level
	runtime sources invoked at times when it is unsafe for the calling goroutine to be
	preempted.

	//go:linkname localname importpath.name

	The //go:linkname directive instructs the compiler to use ``importpath.name'' as the
	object file symbol name for the variable or function declared as ``localname'' in the
	source code. Because this directive can subvert the type system and package
	modularity, it is only enabled in files that have imported "unsafe".
	*/
	package main