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偵錯 Kotlin/Native

目前，Kotlin/Native 編譯器產生的除錯資訊與 DWARF 2 規範相容，因此現代除錯工具可以執行以下操作：

  • 斷點 (breakpoints)
  • 單步執行 (stepping)
  • 類型資訊檢查 (inspection of type information)
  • 變數檢查 (variable inspection)
備註

支援 DWARF 2 規範意味著除錯工具將 Kotlin 識別為 C89，因為在 DWARF 5 規範之前，規範中沒有 Kotlin 語言類型的識別符。

使用 Kotlin/Native 編譯器產生帶有除錯資訊的二進位檔​

若要使用 Kotlin/Native 編譯器產生帶有除錯資訊的二進位檔，請在命令列中使用 -g 選項。

0:b-debugger-fixes:minamoto@unit-703(0)# cat - > hello.kt
fun main(args: Array<String>) {
  println("Hello world")
  println("I need your clothes, your boots and your motocycle")
}
0:b-debugger-fixes:minamoto@unit-703(0)# dist/bin/konanc -g hello.kt -o terminator
KtFile: hello.kt
0:b-debugger-fixes:minamoto@unit-703(0)# lldb terminator.kexe
(lldb) target create "terminator.kexe"
Current executable set to 'terminator.kexe' (x86_64).
(lldb) b kfun:main(kotlin.Array<kotlin.String>)
Breakpoint 1: where = terminator.kexe`kfun:main(kotlin.Array<kotlin.String>) + 4 at hello.kt:2, address = 0x00000001000012e4
(lldb) r
Process 28473 launched: '/Users/minamoto/ws/.git-trees/debugger-fixes/terminator.kexe' (x86_64)
Process 28473 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1
    frame #0: 0x00000001000012e4 terminator.kexe`kfun:main(kotlin.Array<kotlin.String>) at hello.kt:2
   1    fun main(args: Array<String>) {
`->` 2      println("Hello world")
   3      println("I need your clothes, your boots and your motocycle")
   4    }
(lldb) n
Hello world
Process 28473 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = step over
    frame #0: 0x00000001000012f0 terminator.kexe`kfun:main(kotlin.Array<kotlin.String>) at hello.kt:3
   1    fun main(args: Array<String>) {
   2      println("Hello world")
`->` 3      println("I need your clothes, your boots and your motocycle")
   4    }
(lldb)

斷點 (Breakpoints)​

現代除錯器提供幾種設定斷點的方法，以下是按工具細分的資訊：

lldb​

  • 依名稱 (by name)

    (lldb) b -n kfun:main(kotlin.Array<kotlin.String>)
    Breakpoint 4: where = terminator.kexe`kfun:main(kotlin.Array<kotlin.String>) + 4 at hello.kt:2, address = 0x00000001000012e4

-n 是可選的，預設會套用此標誌

  • 依位置 (檔案名稱、行號) (by location (filename, line number))

    (lldb) b -f hello.kt -l 1
    Breakpoint 1: where = terminator.kexe`kfun:main(kotlin.Array<kotlin.String>) + 4 at hello.kt:2, address = 0x00000001000012e4

  • 依地址 (by address)

    (lldb) b -a 0x00000001000012e4
    Breakpoint 2: address = 0x00000001000012e4

  • 依正規表示式 (by regex)，您可能會發現它對於除錯產生的工件 (artifacts) 很有用，例如 lambda 等（在名稱中使用 # 符號）。

    3: regex = 'main\(', locations = 1
      3.1: where = terminator.kexe`kfun:main(kotlin.Array<kotlin.String>) + 4 at hello.kt:2, address = terminator.kexe[0x00000001000012e4], unresolved, hit count = 0

gdb​

  • 依正規表示式 (by regex)

    (gdb) rbreak main(
    Breakpoint 1 at 0x1000109b4
    struct ktype:kotlin.Unit &kfun:main(kotlin.Array<kotlin.String>);

  • 依名稱 (by name) 無法使用 (unusable)，因為 : 是依位置設定斷點的分隔符

    (gdb) b kfun:main(kotlin.Array<kotlin.String>)
    No source file named kfun.
    Make breakpoint pending on future shared library load? (y or [n]) y
    Breakpoint 1 (kfun:main(kotlin.Array<kotlin.String>)) pending

  • 依位置 (by location)

    (gdb) b hello.kt:1
    Breakpoint 2 at 0x100001704: file /Users/minamoto/ws/.git-trees/hello.kt, line 1.

  • 依地址 (by address)

    (gdb) b *0x100001704
    Note: breakpoint 2 also set at pc 0x100001704.
    Breakpoint 3 at 0x100001704: file /Users/minamoto/ws/.git-trees/hello.kt, line 2.

單步執行 (Stepping)​

單步執行函數的工作方式與 C/C++ 程式大致相同。

變數檢查 (Variable inspection)​

對於基本類型，var 變數的變數檢查可以直接使用。 對於非基本類型，konan_lldb.py 中有 lldb 的自訂美化列印器 (pretty printers)：

λ cat main.kt | nl
     1  fun main(args: Array<String>) {
     2      var x = 1
     3      var y = 2
     4      var p = Point(x, y)
     5      println("p = $p")
     6  }
       
     7  data class Point(val x: Int, val y: Int)

λ lldb ./program.kexe -o 'b main.kt:5' -o
(lldb) target create "./program.kexe"
Current executable set to './program.kexe' (x86_64).
(lldb) b main.kt:5
Breakpoint 1: where = program.kexe`kfun:main(kotlin.Array<kotlin.String>) + 289 at main.kt:5, address = 0x000000000040af11
(lldb) r
Process 4985 stopped
* thread #1, name = 'program.kexe', stop reason = breakpoint 1.1
    frame #0: program.kexe`kfun:main(kotlin.Array<kotlin.String>) at main.kt:5
   2        var x = 1
   3        var y = 2
   4        var p = Point(x, y)
`->` 5        println("p = $p")
   6    }
   7   
   8    data class Point(val x: Int, val y: Int)

Process 4985 launched: './program.kexe' (x86_64)
(lldb) fr var
(int) x = 1
(int) y = 2
(ObjHeader *) p = 0x00000000007643d8
(lldb) command script import dist/tools/konan_lldb.py
(lldb) fr var
(int) x = 1
(int) y = 2
(ObjHeader *) p = [x: ..., y: ...]
(lldb) p p
(ObjHeader *) $2 = [x: ..., y: ...]
(lldb) script lldb.frame.FindVariable("p").GetChildMemberWithName("x").Dereference().GetValue()
'1'
(lldb)

也可以使用內建模組執行階段函數 Konan_DebugPrint 取得物件變數 (var) 的表示形式（此方法也適用於 gdb，使用命令語法模組）：

0:b-debugger-fixes:minamoto@unit-703(0)# cat ../debugger-plugin/1.kt | nl -p
     1  fun foo(a:String, b:Int) = a + b
     2  fun one() = 1
     3  fun main(arg:Array<String>) {
     4    var a_variable = foo("(a_variable) one is ", 1)
     5    var b_variable = foo("(b_variable) two is ", 2)
     6    var c_variable = foo("(c_variable) two is ", 3)
     7    var d_variable = foo("(d_variable) two is ", 4)
     8    println(a_variable)
     9    println(b_variable)
    10    println(c_variable)
    11    println(d_variable)
    12  }
0:b-debugger-fixes:minamoto@unit-703(0)# lldb ./program.kexe -o 'b -f 1.kt -l 9' -o r
(lldb) target create "./program.kexe"
Current executable set to './program.kexe' (x86_64).
(lldb) b -f 1.kt -l 9
Breakpoint 1: where = program.kexe`kfun:main(kotlin.Array<kotlin.String>) + 463 at 1.kt:9, address = 0x0000000100000dbf
(lldb) r
(a_variable) one is 1
Process 80496 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1
    frame #0: 0x0000000100000dbf program.kexe`kfun:main(kotlin.Array<kotlin.String>) at 1.kt:9
   6      var c_variable = foo("(c_variable) two is ", 3)
   7      var d_variable = foo("(d_variable) two is ", 4)
   8      println(a_variable)
`->` 9      println(b_variable)
   10     println(c_variable)
   11     println(d_variable)
   12   }

Process 80496 launched: './program.kexe' (x86_64)
(lldb) expression -- (int32_t)Konan_DebugPrint(a_variable)
(a_variable) one is 1(int32_t) $0 = 0
(lldb)

已知問題 (Known issues)​

  • Python 綁定的效能 (performance of Python bindings)。