Add support for native image cfg files and handle jump tables

lib/cfg2asm/cfg/cfg_parser.rb

@@ -4,8 +4,9 @@
 module Cfg2asm
   module CFG
     Code = Struct.new(:arch, :arch_width, :base, :code)
+    JumpTable = Struct.new(:position, :entry_format, :low, :high)
     Comment = Struct.new(:offset, :comment)
-    NMethod = Struct.new(:code, :comments)
+    NMethod = Struct.new(:code, :comments, :jump_tables)
 
     # A parser for CFG files.
     class CFGParser
@@ -19,8 +20,34 @@ def initialize(out, file)
         @state = :any
         @cfg_name = nil
       end
+
+      def print_summar_of_content
+        state = :any
+        loop do
+          line = @reader.readline("\n")
+          case line
+          when "begin_compilation\n"
+            state = :some
+            puts "Compilation:"
+          when "end_compilation\n"
+            state = :any
+          when "begin_cfg\n"
+            state = :some
+            puts "Config:"
+          when "end_cfg\n"
+            state = :any
+          when /  name "(.*)"\n/
+            if state == :some
+              puts "name: #{Regexp.last_match(1)}"
+              state = :any
+            end
+          else
+            next
+          end
+        end
+      end
 
-      def skip_over_cfg(name)
+      def skip_over_cfg(name1, name2)
         loop do
           line = @reader.readline("\n")
           case line
@@ -35,7 +62,7 @@ def skip_over_cfg(name)
             raise unless @state == :cfg
 
             @state = :any
-            break if @cfg_name == name
+            break if @cfg_name == name1 || @cfg_name == name2
           else
             next
           end
@@ -48,6 +75,7 @@ def read_nmethod
         arch = nil
         arch_width = nil
         code = nil
+        jump_tables = []
         comments = []
         raise unless @reader.readline == "begin_nmethod\n"
 
@@ -63,6 +91,13 @@ def read_nmethod
             raise if arch.nil? || arch_width.nil?
 
             code = Code.new(arch, arch_width, base, code)
+          when /  JumpTable (\d+) (\d+) (\d+) (\d+)  <\|\|@\n/
+            position = Regexp.last_match(1).to_i
+            entry_format = Regexp.last_match(2).to_i
+            low = Regexp.last_match(3).to_i
+            high = Regexp.last_match(4).to_i
+
+            jump_tables.push JumpTable.new(position, entry_format, low, high)
           when /  Comment (\d*) (.*)  <\|\|@\n/
             offset = Regexp.last_match(1).to_i
             comment = Regexp.last_match(2)
@@ -86,7 +121,7 @@ def read_nmethod
             raise 'There is currently no case for this line. Please open an issue so it can be addressed.'
           end
         end
-        NMethod.new(code, comments)
+        NMethod.new(code, comments, jump_tables)
       end
     end
   end

lib/cfg2asm/cfg/disassembler.rb

@@ -7,6 +7,30 @@ class Disassembler
       def initialize(out)
         @out = out
       end
+
+      def turn_jump_table_into_noops(nmethod)
+        code = nmethod.code.code
+        nmethod.jump_tables.each do |t|
+          # t.:position, :entry_format, :low, :high
+          (t.low..t.high).each do |i|
+            if t.entry_format == 4
+              code.setbyte(t.position + (t.entry_format * i) + 0, 0x0F)
+              code.setbyte(t.position + (t.entry_format * i) + 1, 0x1F)
+              code.setbyte(t.position + (t.entry_format * i) + 2, 0x40)
+              code.setbyte(t.position + (t.entry_format * i) + 3, 0x00)
+            elsif t.entry_format == 8
+              code.setbyte(t.position + (t.entry_format * i) + 0, 0x0F)
+              code.setbyte(t.position + (t.entry_format * i) + 1, 0x1F)
+              code.setbyte(t.position + (t.entry_format * i) + 2, 0x84)
+              code.setbyte(t.position + (t.entry_format * i) + 3, 0x00)
+              code.setbyte(t.position + (t.entry_format * i) + 4, 0x00)
+              code.setbyte(t.position + (t.entry_format * i) + 5, 0x00)
+              code.setbyte(t.position + (t.entry_format * i) + 6, 0x00)
+              code.setbyte(t.position + (t.entry_format * i) + 7, 0x00)
+            end
+          end
+        end
+      end
 
       def disassemble(nmethod, print_comments)
         require_crabstone
@@ -23,6 +47,8 @@ def disassemble(nmethod, print_comments)
           raise "Unknown architecture #{nmethod.code.arch} and bit width #{nmethod.code.arch_width}"
         end
 
+        turn_jump_table_into_noops(nmethod)
+
         cs = Crabstone::Disassembler.new(*crabstone_arch)
         begin
           cs.disasm(nmethod.code.code, nmethod.code.base).each do |i|

lib/cfg2asm/commands.rb

@@ -7,6 +7,27 @@ class Commands
     def initialize(out)
       @out = out
     end
+
+    def get_files_and_comments_flag(args)
+      comments = true
+      files = []
+
+      until args.empty?
+        arg = args.shift
+        if arg.start_with?('-')
+          case arg
+          when '--no-comments'
+            comments = false
+          else
+            raise ArgumentError, "unknown option #{arg}"
+          end
+        else
+          files.push arg
+        end
+      end
+
+      [files, comments]
+    end
 
     def cfg2asm(*args)
       case args.first
@@ -21,27 +42,20 @@ def cfg2asm(*args)
       when 'version', '-v', '-version', '--version'
         args = args.drop(1)
         version(*args)
-      else
-        comments = true
-        files = []
-
-        until args.empty?
-          arg = args.shift
-          if arg.start_with?('-')
-            case arg
-            when '--no-comments'
-              comments = false
-            else
-              raise ArgumentError, "unknown option #{arg}"
-            end
-          else
-            files.push arg
-          end
+      when 'summary'
+        args.shift
+        files, comments = get_files_and_comments_flag(args)
+
+        files.each_with_index do |file, n|
+          parser = Cfg2asm::CFG::CFGParser.new(@out, file)
+          parser.print_summar_of_content
         end
+      else
+        files, comments = get_files_and_comments_flag(args)
 
         files.each_with_index do |file, n|
           parser = Cfg2asm::CFG::CFGParser.new(@out, file)
-          parser.skip_over_cfg 'After code installation'
+          parser.skip_over_cfg('After code installation', 'After code generation')
           nmethod = parser.read_nmethod
 
           disassembler = Cfg2asm::CFG::Disassembler.new(@out)