Source/JavaScriptCore/offlineasm/asm.rb - WebKit - Git at Google

 #!/usr/bin/env ruby

 # Copyright (C) 2011-2021 Apple Inc. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions
 # are met:
 # 1. Redistributions of source code must retain the above copyright
 #    notice, this list of conditions and the following disclaimer.
 # 2. Redistributions in binary form must reproduce the above copyright
 #    notice, this list of conditions and the following disclaimer in the
 #    documentation and/or other materials provided with the distribution.
 #
 # THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
 # AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 # THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 # PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
 # BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 # CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 # SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 # INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 # CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 # ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 # THE POSSIBILITY OF SUCH DAMAGE.

 $: << File.dirname(__FILE__)

 require "config"
 require "backends"
 require "digest/sha1"
 require "offsets"
 require 'optparse'
 require "parser"
 require "self_hash"
 require "settings"
 require "shellwords"
 require "transform"

 class Assembler
     def initialize(outp)
         @outp = outp
         @state = :cpp
         resetAsm
     end

     def resetAsm
         @comment = nil
         @internalComment = nil
         @annotation = nil
         @codeOrigin = nil
         @numLocalLabels = 0
         @numGlobalLabels = 0
         @deferredActions = []
         @deferredNextLabelActions = []
         @count = 0
         @debugAnnotationStr = nil
         @lastDebugAnnotationStr = nil

         @newlineSpacerState = :none
         @lastlabel = ""
     end

     def enterAsm
         @outp.puts ""
         putStr "OFFLINE_ASM_BEGIN" if !$emitWinAsm

         if !$emitWinAsm
             putStr "OFFLINE_ASM_GLOBAL_LABEL(llintPCRangeStart)"
         else
             putsProc("llintPCRangeStart", "")
             putsProcEndIfNeeded
         end
         @state = :asm
         SourceFile.outputDotFileList(@outp) if $enableDebugAnnotations
     end

     def leaveAsm
         putsProcEndIfNeeded if $emitWinAsm
         if !$emitWinAsm
             putStr "OFFLINE_ASM_GLOBAL_LABEL(llintPCRangeEnd)"
         else
             putsProc("llintPCRangeEnd", "")
             putsProcEndIfNeeded
         end
         putsLastComment
         (@deferredNextLabelActions + @deferredActions).each {
             | action |
             action.call()
         }
         putStr "OFFLINE_ASM_END" if !$emitWinAsm
         @state = :cpp
     end

     def deferAction(&proc)
         @deferredActions << proc
     end

     def deferNextLabelAction(&proc)
         @deferredNextLabelActions << proc
     end

     def newUID
         @count += 1
         @count
     end

     def inAsm
         resetAsm
         enterAsm
         yield
         leaveAsm
     end

     # Concatenates all the various components of the comment to dump.
     def lastComment
         separator = " "
         result = ""
         result = "#{@comment}" if @comment
         if @annotation and $enableInstrAnnotations
             result += separator if result != ""
             result += "#{@annotation}"
         end
         if @internalComment
             result += separator if result != ""
             result += "#{@internalComment}"
         end
         if $enableCodeOriginComments and @codeOrigin and @codeOrigin != @lastCodeOrigin
             @lastCodeOrigin = @codeOrigin
             result += separator if result != ""
             result += "#{@codeOrigin}"
         end
         if result != ""
             result = $commentPrefix + " " + result
         end

         # Reset all the components that we've just sent to be dumped.
         @comment = nil
         @annotation = nil
         @codeOrigin = nil
         @internalComment = nil
         result
     end

     # Puts a C Statement in the output stream.
     def putc(*line)
         raise unless @state == :asm
         @outp.puts(formatDump("    " + line.join(''), lastComment))
     end

     def formatDump(dumpStr, comment, commentColumns=$preferredCommentStartColumn)
         result = ""
         if comment.length > 0
             result = "%-#{commentColumns}s %s" % [dumpStr, comment]
         else
             result = dumpStr
         end
         if $enableDebugAnnotations
             if @debugAnnotationStr and @debugAnnotationStr != @lastDebugAnnotationStr
                 result = "%-#{$preferredDebugAnnotationColumns}s%s" % [@debugAnnotationStr, result]
             else
                 result = "%-#{$preferredDebugAnnotationColumns}s%s" % ["", result]
             end
             @lastDebugAnnotationStr = @debugAnnotationStr
             @debugAnnotationStr = nil
         end
         result
     end

     # private method for internal use only.
     def putAnnotation(text)
         raise unless @state == :asm
         if $enableInstrAnnotations
             @outp.puts text
             @annotation = nil
         end
     end

     def putLocalAnnotation()
         putAnnotation "    // #{@annotation}" if @annotation
     end

     def putGlobalAnnotation()
         putsNewlineSpacerIfAppropriate(:annotation)
         putAnnotation "// #{@annotation}" if @annotation
     end

     def putsLastComment
         comment = lastComment
         unless comment.empty?
             @outp.puts comment
         end
     end

     def putStr(str)
         if $enableDebugAnnotations
             @outp.puts "%-#{$preferredDebugAnnotationColumns}s%s" % ["", str]
         else
             @outp.puts str
         end
     end

     def puts(*line)
         raise unless @state == :asm
         if !$emitWinAsm
             @outp.puts(formatDump("    \"" + line.join('') + " \\n\"", lastComment))
         else
             @outp.puts(formatDump("    " + line.join(''), lastComment))
         end
     end

     def print(line)
         raise unless @state == :asm
         @outp.print("\"" + line + "\"")
     end

     def putsNewlineSpacerIfAppropriate(state)
         if @newlineSpacerState != state
             @outp.puts("\n")
             @newlineSpacerState = state
         end
     end

     def putsProc(label, comment)
         raise unless $emitWinAsm
         @outp.puts(formatDump("#{label} PROC PUBLIC", comment))
         @lastlabel = label
     end

     def putsProcEndIfNeeded
         raise unless $emitWinAsm
         if @lastlabel != ""
             @outp.puts("#{@lastlabel} ENDP")
         end
         @lastlabel = ""
     end

     def putsLabel(labelName, isGlobal)
         raise unless @state == :asm
         @deferredNextLabelActions.each {
             | action |
             action.call()
         }
         @deferredNextLabelActions = []
         @numGlobalLabels += 1
         putsProcEndIfNeeded if $emitWinAsm and isGlobal
         putsNewlineSpacerIfAppropriate(:global)
         @internalComment = $enableLabelCountComments ? "Global Label #{@numGlobalLabels}" : nil
         if isGlobal
             if !$emitWinAsm
                 @outp.puts(formatDump("OFFLINE_ASM_GLOBAL_LABEL(#{labelName})", lastComment))
             else
                 putsProc(labelName, lastComment)
             end
         elsif /\Allint_op_/.match(labelName)
             if !$emitWinAsm
                 @outp.puts(formatDump("OFFLINE_ASM_OPCODE_LABEL(op_#{$~.post_match})", lastComment))
             else
                 label = "llint_" + "op_#{$~.post_match}"
                 @outp.puts(formatDump("  _#{label}:", lastComment))
             end
         else
             if !$emitWinAsm
                 @outp.puts(formatDump("OFFLINE_ASM_GLUE_LABEL(#{labelName})", lastComment))
             else
                 @outp.puts(formatDump("  _#{labelName}:", lastComment))
             end
         end
         if $emitELFDebugDirectives
             deferNextLabelAction {
                 putStr("    \".size #{labelName} , . - #{labelName} \\n\"")
                 putStr("    \".type #{labelName} , function \\n\"")
             }
         end
         @newlineSpacerState = :none # After a global label, we can use another spacer.
     end

     def putsLocalLabel(labelName)
         raise unless @state == :asm
         @numLocalLabels += 1
         @outp.puts("\n")
         @internalComment = $enableLabelCountComments ? "Local Label #{@numLocalLabels}" : nil
         if !$emitWinAsm
             @outp.puts(formatDump("  OFFLINE_ASM_LOCAL_LABEL(#{labelName})", lastComment))
         else
             @outp.puts(formatDump("  #{labelName}:", lastComment))
         end
     end

     def self.externLabelReference(labelName)
         if !$emitWinAsm
             "\" LOCAL_REFERENCE(#{labelName}) \""
         else
             "#{labelName}"
         end
     end

     def self.labelReference(labelName)
         if !$emitWinAsm
             "\" LOCAL_LABEL_STRING(#{labelName}) \""
         else
             "_#{labelName}"
         end
     end

     def self.localLabelReference(labelName)
         if !$emitWinAsm
             "\" LOCAL_LABEL_STRING(#{labelName}) \""
         else
             "#{labelName}"
         end
     end

     def self.cLabelReference(labelName)
         if /\Allint_op_/.match(labelName)
             "op_#{$~.post_match}"  # strip opcodes of their llint_ prefix.
         else
             "#{labelName}"
         end
     end

     def self.cLocalLabelReference(labelName)
         "#{labelName}"
     end

     def codeOrigin(text)
         @codeOrigin = text
     end

     def comment(text)
         @comment = text
     end

     def annotation(text)
         @annotation = text
     end

     def debugAnnotation(text)
         @debugAnnotationStr = text
     end
 end

 IncludeFile.processIncludeOptions()

 asmFile = ARGV.shift
 offsetsFile = ARGV.shift
 outputFlnm = ARGV.shift
 variants = ARGV.shift.split(/[,\s]+/)

 $options = {}
 OptionParser.new do |opts|
     opts.banner = "Usage: asm.rb asmFile offsetsFile outputFileName [--assembler=<ASM>] [--webkit-additions-path=<path>] [--binary-format=<format>] [--depfile=<depfile>]"
     # This option is currently only used to specify the masm assembler
     opts.on("--assembler=[ASM]", "Specify an assembler to use.") do |assembler|
         $options[:assembler] = assembler
     end
     opts.on("--webkit-additions-path=PATH", "WebKitAdditions path.") do |path|
         $options[:webkit_additions_path] = path
     end
     opts.on("--binary-format=FORMAT", "Specify the binary format used by the target system.") do |format|
         $options[:binary_format] = format
     end
     opts.on("--depfile=DEPFILE", "Path to write Makefile-style discovered dependencies to.") do |path|
         $options[:depfile] = path
     end
 end.parse!

 begin
     configurationList = offsetsAndConfigurationIndexForVariants(offsetsFile, variants)
 rescue MissingMagicValuesException
     $stderr.puts "offlineasm: No magic values found. Skipping assembly file generation."
     exit 1
 end

 # The MS compiler doesn't accept DWARF2 debug annotations.
 if isMSVC
     $enableDebugAnnotations = false
 end

 $emitWinAsm = isMSVC ? outputFlnm.index(".asm") != nil : false
 $commentPrefix = $emitWinAsm ? ";" : "//"

 # We want this in all ELF systems we support, except for C_LOOP (we'll disable it later on if we are building cloop)
 $emitELFDebugDirectives = $options.has_key?(:binary_format) && $options[:binary_format] == "ELF"

 inputHash =
     $commentPrefix + " offlineasm input hash: " + parseHash(asmFile, $options) +
     " " + Digest::SHA1.hexdigest(configurationList.map{|v| (v[0] + [v[1]]).join(' ')}.join(' ')) +
     " " + selfHash +
     " " + Digest::SHA1.hexdigest($options.has_key?(:assembler) ? $options[:assembler] : "")

 if FileTest.exist?(outputFlnm) and (not $options[:depfile] or FileTest.exist?($options[:depfile]))
     lastLine = nil
     File.open(outputFlnm, "r") {
         | file |
         file.each_line {
             | line |
             line = line.chomp
             unless line.empty?
                 lastLine = line
             end
         }
     }
     if lastLine and lastLine == inputHash
         # Nothing changed.
         exit 0
     end
 end

 File.open(outputFlnm, "w") {
     | outp |
     $output = outp

     $asm = Assembler.new($output)

     sources = Set.new
     ast = parse(asmFile, $options, sources)
     settingsCombinations = computeSettingsCombinations(ast)

     if $options[:depfile]
         depfile = File.open($options[:depfile], "w")
         depfile.print(Shellwords.escape(outputFlnm), ": ")
         depfile.puts(Shellwords.join(sources.sort))
     end

     configurationList.each {
         | configuration |
         offsetsList = configuration[0]
         configIndex = configuration[1]
         forSettings(settingsCombinations[configIndex], ast) {
             | concreteSettings, lowLevelAST, backend |

             # There could be multiple backends we are generating for, but the C_LOOP is
             # always by itself so this check to turn off $enableDebugAnnotations won't
             # affect the generation for any other backend.
             if backend == "C_LOOP" || backend == "C_LOOP_WIN"
                 $enableDebugAnnotations = false
                 $preferredCommentStartColumn = 60
                 $emitELFDebugDirectives = false
             end

             lowLevelAST = lowLevelAST.demacroify({})
             lowLevelAST = lowLevelAST.resolve(buildOffsetsMap(lowLevelAST, offsetsList))
             lowLevelAST.validate
             emitCodeInConfiguration(concreteSettings, lowLevelAST, backend) {
                 $currentSettings = concreteSettings
                 $asm.inAsm {
                     lowLevelAST.lower(backend)
                 }
             }
         }
     }

     $output.fsync
     $output.puts inputHash
 }
	#!/usr/bin/env ruby

	# Copyright (C) 2011-2021 Apple Inc. All rights reserved.
	#
	# Redistribution and use in source and binary forms, with or without
	# modification, are permitted provided that the following conditions
	# are met:
	# 1. Redistributions of source code must retain the above copyright
	# notice, this list of conditions and the following disclaimer.
	# 2. Redistributions in binary form must reproduce the above copyright
	# notice, this list of conditions and the following disclaimer in the
	# documentation and/or other materials provided with the distribution.
	#
	# THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
	# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
	# THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
	# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
	# BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
	# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
	# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
	# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
	# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
	# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
	# THE POSSIBILITY OF SUCH DAMAGE.

	$: << File.dirname(__FILE__)

	require "config"
	require "backends"
	require "digest/sha1"
	require "offsets"
	require 'optparse'
	require "parser"
	require "self_hash"
	require "settings"
	require "shellwords"
	require "transform"

	class Assembler
	def initialize(outp)
	@outp = outp
	@state = :cpp
	resetAsm
	end

	def resetAsm
	@comment = nil
	@internalComment = nil
	@annotation = nil
	@codeOrigin = nil
	@numLocalLabels = 0
	@numGlobalLabels = 0
	@deferredActions = []
	@deferredNextLabelActions = []
	@count = 0
	@debugAnnotationStr = nil
	@lastDebugAnnotationStr = nil

	@newlineSpacerState = :none
	@lastlabel = ""
	end

	def enterAsm
	@outp.puts ""
	putStr "OFFLINE_ASM_BEGIN" if !$emitWinAsm

	if !$emitWinAsm
	putStr "OFFLINE_ASM_GLOBAL_LABEL(llintPCRangeStart)"
	else
	putsProc("llintPCRangeStart", "")
	putsProcEndIfNeeded
	end
	@state = :asm
	SourceFile.outputDotFileList(@outp) if $enableDebugAnnotations
	end

	def leaveAsm
	putsProcEndIfNeeded if $emitWinAsm
	if !$emitWinAsm
	putStr "OFFLINE_ASM_GLOBAL_LABEL(llintPCRangeEnd)"
	else
	putsProc("llintPCRangeEnd", "")
	putsProcEndIfNeeded
	end
	putsLastComment
	(@deferredNextLabelActions + @deferredActions).each {
	\| action \|
	action.call()
	}
	putStr "OFFLINE_ASM_END" if !$emitWinAsm
	@state = :cpp
	end

	def deferAction(&proc)
	@deferredActions << proc
	end

	def deferNextLabelAction(&proc)
	@deferredNextLabelActions << proc
	end

	def newUID
	@count += 1
	@count
	end

	def inAsm
	resetAsm
	enterAsm
	yield
	leaveAsm
	end

	# Concatenates all the various components of the comment to dump.
	def lastComment
	separator = " "
	result = ""
	result = "#{@comment}" if @comment
	if @annotation and $enableInstrAnnotations
	result += separator if result != ""
	result += "#{@annotation}"
	end
	if @internalComment
	result += separator if result != ""
	result += "#{@internalComment}"
	end
	if $enableCodeOriginComments and @codeOrigin and @codeOrigin != @lastCodeOrigin
	@lastCodeOrigin = @codeOrigin
	result += separator if result != ""
	result += "#{@codeOrigin}"
	end
	if result != ""
	result = $commentPrefix + " " + result
	end

	# Reset all the components that we've just sent to be dumped.
	@comment = nil
	@annotation = nil
	@codeOrigin = nil
	@internalComment = nil
	result
	end

	# Puts a C Statement in the output stream.
	def putc(*line)
	raise unless @state == :asm
	@outp.puts(formatDump(" " + line.join(''), lastComment))
	end

	def formatDump(dumpStr, comment, commentColumns=$preferredCommentStartColumn)
	result = ""
	if comment.length > 0
	result = "%-#{commentColumns}s %s" % [dumpStr, comment]
	else
	result = dumpStr
	end
	if $enableDebugAnnotations
	if @debugAnnotationStr and @debugAnnotationStr != @lastDebugAnnotationStr
	result = "%-#{$preferredDebugAnnotationColumns}s%s" % [@debugAnnotationStr, result]
	else
	result = "%-#{$preferredDebugAnnotationColumns}s%s" % ["", result]
	end
	@lastDebugAnnotationStr = @debugAnnotationStr
	@debugAnnotationStr = nil
	end
	result
	end

	# private method for internal use only.
	def putAnnotation(text)
	raise unless @state == :asm
	if $enableInstrAnnotations
	@outp.puts text
	@annotation = nil
	end
	end

	def putLocalAnnotation()
	putAnnotation " // #{@annotation}" if @annotation
	end

	def putGlobalAnnotation()
	putsNewlineSpacerIfAppropriate(:annotation)
	putAnnotation "// #{@annotation}" if @annotation
	end

	def putsLastComment
	comment = lastComment
	unless comment.empty?
	@outp.puts comment
	end
	end

	def putStr(str)
	if $enableDebugAnnotations
	@outp.puts "%-#{$preferredDebugAnnotationColumns}s%s" % ["", str]
	else
	@outp.puts str
	end
	end

	def puts(*line)
	raise unless @state == :asm
	if !$emitWinAsm
	@outp.puts(formatDump(" \"" + line.join('') + " \\n\"", lastComment))
	else
	@outp.puts(formatDump(" " + line.join(''), lastComment))
	end
	end

	def print(line)
	raise unless @state == :asm
	@outp.print("\"" + line + "\"")
	end

	def putsNewlineSpacerIfAppropriate(state)
	if @newlineSpacerState != state
	@outp.puts("\n")
	@newlineSpacerState = state
	end
	end

	def putsProc(label, comment)
	raise unless $emitWinAsm
	@outp.puts(formatDump("#{label} PROC PUBLIC", comment))
	@lastlabel = label
	end

	def putsProcEndIfNeeded
	raise unless $emitWinAsm
	if @lastlabel != ""
	@outp.puts("#{@lastlabel} ENDP")
	end
	@lastlabel = ""
	end

	def putsLabel(labelName, isGlobal)
	raise unless @state == :asm
	@deferredNextLabelActions.each {
	\| action \|
	action.call()
	}
	@deferredNextLabelActions = []
	@numGlobalLabels += 1
	putsProcEndIfNeeded if $emitWinAsm and isGlobal
	putsNewlineSpacerIfAppropriate(:global)
	@internalComment = $enableLabelCountComments ? "Global Label #{@numGlobalLabels}" : nil
	if isGlobal
	if !$emitWinAsm
	@outp.puts(formatDump("OFFLINE_ASM_GLOBAL_LABEL(#{labelName})", lastComment))
	else
	putsProc(labelName, lastComment)
	end
	elsif /\Allint_op_/.match(labelName)
	if !$emitWinAsm
	@outp.puts(formatDump("OFFLINE_ASM_OPCODE_LABEL(op_#{$~.post_match})", lastComment))
	else
	label = "llint_" + "op_#{$~.post_match}"
	@outp.puts(formatDump(" _#{label}:", lastComment))
	end
	else
	if !$emitWinAsm
	@outp.puts(formatDump("OFFLINE_ASM_GLUE_LABEL(#{labelName})", lastComment))
	else
	@outp.puts(formatDump(" _#{labelName}:", lastComment))
	end
	end
	if $emitELFDebugDirectives
	deferNextLabelAction {
	putStr(" \".size #{labelName} , . - #{labelName} \\n\"")
	putStr(" \".type #{labelName} , function \\n\"")
	}
	end
	@newlineSpacerState = :none # After a global label, we can use another spacer.
	end

	def putsLocalLabel(labelName)
	raise unless @state == :asm
	@numLocalLabels += 1
	@outp.puts("\n")
	@internalComment = $enableLabelCountComments ? "Local Label #{@numLocalLabels}" : nil
	if !$emitWinAsm
	@outp.puts(formatDump(" OFFLINE_ASM_LOCAL_LABEL(#{labelName})", lastComment))
	else
	@outp.puts(formatDump(" #{labelName}:", lastComment))
	end
	end

	def self.externLabelReference(labelName)
	if !$emitWinAsm
	"\" LOCAL_REFERENCE(#{labelName}) \""
	else
	"#{labelName}"
	end
	end

	def self.labelReference(labelName)
	if !$emitWinAsm
	"\" LOCAL_LABEL_STRING(#{labelName}) \""
	else
	"_#{labelName}"
	end
	end

	def self.localLabelReference(labelName)
	if !$emitWinAsm
	"\" LOCAL_LABEL_STRING(#{labelName}) \""
	else
	"#{labelName}"
	end
	end

	def self.cLabelReference(labelName)
	if /\Allint_op_/.match(labelName)
	"op_#{$~.post_match}" # strip opcodes of their llint_ prefix.
	else
	"#{labelName}"
	end
	end

	def self.cLocalLabelReference(labelName)
	"#{labelName}"
	end

	def codeOrigin(text)
	@codeOrigin = text
	end

	def comment(text)
	@comment = text
	end

	def annotation(text)
	@annotation = text
	end

	def debugAnnotation(text)
	@debugAnnotationStr = text
	end
	end

	IncludeFile.processIncludeOptions()

	asmFile = ARGV.shift
	offsetsFile = ARGV.shift
	outputFlnm = ARGV.shift
	variants = ARGV.shift.split(/[,\s]+/)

	$options = {}
	OptionParser.new do \|opts\|
	opts.banner = "Usage: asm.rb asmFile offsetsFile outputFileName [--assembler=<ASM>] [--webkit-additions-path=<path>] [--binary-format=<format>] [--depfile=<depfile>]"
	# This option is currently only used to specify the masm assembler
	opts.on("--assembler=[ASM]", "Specify an assembler to use.") do \|assembler\|
	$options[:assembler] = assembler
	end
	opts.on("--webkit-additions-path=PATH", "WebKitAdditions path.") do \|path\|
	$options[:webkit_additions_path] = path
	end
	opts.on("--binary-format=FORMAT", "Specify the binary format used by the target system.") do \|format\|
	$options[:binary_format] = format
	end
	opts.on("--depfile=DEPFILE", "Path to write Makefile-style discovered dependencies to.") do \|path\|
	$options[:depfile] = path
	end
	end.parse!

	begin
	configurationList = offsetsAndConfigurationIndexForVariants(offsetsFile, variants)
	rescue MissingMagicValuesException
	$stderr.puts "offlineasm: No magic values found. Skipping assembly file generation."
	exit 1
	end

	# The MS compiler doesn't accept DWARF2 debug annotations.
	if isMSVC
	$enableDebugAnnotations = false
	end

	$emitWinAsm = isMSVC ? outputFlnm.index(".asm") != nil : false
	$commentPrefix = $emitWinAsm ? ";" : "//"

	# We want this in all ELF systems we support, except for C_LOOP (we'll disable it later on if we are building cloop)
	$emitELFDebugDirectives = $options.has_key?(:binary_format) && $options[:binary_format] == "ELF"

	inputHash =
	$commentPrefix + " offlineasm input hash: " + parseHash(asmFile, $options) +
	" " + Digest::SHA1.hexdigest(configurationList.map{\|v\| (v[0] + [v[1]]).join(' ')}.join(' ')) +
	" " + selfHash +
	" " + Digest::SHA1.hexdigest($options.has_key?(:assembler) ? $options[:assembler] : "")

	if FileTest.exist?(outputFlnm) and (not $options[:depfile] or FileTest.exist?($options[:depfile]))
	lastLine = nil
	File.open(outputFlnm, "r") {
	\| file \|
	file.each_line {
	\| line \|
	line = line.chomp
	unless line.empty?
	lastLine = line
	end
	}
	}
	if lastLine and lastLine == inputHash
	# Nothing changed.
	exit 0
	end
	end

	File.open(outputFlnm, "w") {
	\| outp \|
	$output = outp

	$asm = Assembler.new($output)

	sources = Set.new
	ast = parse(asmFile, $options, sources)
	settingsCombinations = computeSettingsCombinations(ast)

	if $options[:depfile]
	depfile = File.open($options[:depfile], "w")
	depfile.print(Shellwords.escape(outputFlnm), ": ")
	depfile.puts(Shellwords.join(sources.sort))
	end

	configurationList.each {
	\| configuration \|
	offsetsList = configuration[0]
	configIndex = configuration[1]
	forSettings(settingsCombinations[configIndex], ast) {
	\| concreteSettings, lowLevelAST, backend \|

	# There could be multiple backends we are generating for, but the C_LOOP is
	# always by itself so this check to turn off $enableDebugAnnotations won't
	# affect the generation for any other backend.
	if backend == "C_LOOP" \|\| backend == "C_LOOP_WIN"
	$enableDebugAnnotations = false
	$preferredCommentStartColumn = 60
	$emitELFDebugDirectives = false
	end

	lowLevelAST = lowLevelAST.demacroify({})
	lowLevelAST = lowLevelAST.resolve(buildOffsetsMap(lowLevelAST, offsetsList))
	lowLevelAST.validate
	emitCodeInConfiguration(concreteSettings, lowLevelAST, backend) {
	$currentSettings = concreteSettings
	$asm.inAsm {
	lowLevelAST.lower(backend)
	}
	}
	}
	}

	$output.fsync
	$output.puts inputHash
	}