入門：JVM 〜5 分で完全に理解する JVM の仕組み〜

2024/5/11 (Sat.) UNTIL.LT #0x04 の登壇資料

Transcript

1. ೖ໳ɿ+7. 
   ෼Ͱ׬શʹཧղ͢Δ +7.
   ͷ࢓૊Έ ஜ೾େֶ ৘ใϝσΟΞ૑੒ֶྨ 
   ೥ ͪΎΔΓʢ!DIVSVSJ@ʣ UNTIL.LT #0x04
2. ͪΎΔΓ @chururi_ @itsu-dev • ໺຀ थʢͷ·͖ ͍ͭΔʣ • ৘ใϝσΟΞ૑੒ֶྨ 
   ೥ • ϓϩάϥϛϯάݴޠݚڀࣨʢதҪݚʣ • ֶज़৘ใϝσΟΞηϯλʔʹੜଉ • શ୅ձ ৘ใॲཧਪਐಛผҕһձʢ*1$ʣ • ֶԂࡇ࣮ߦҕһձ ৘ใϝσΟΞਪਐہʢKTZTʣ 👀 8FC
   ݴޠॲཧܥ
   FUD 📍
3. +BWB
   ͕ಈ͘·Ͱ +BWB
   ϓϩάϥϜ ʢ KBWBʣ +BWB
   ΫϥεϑΝΠϧ ʢ DMBTTʣ +BWB
   Ծ૝Ϛγϯ ʢ+7.ʣ Hello, World! ਓ͕ಡΊΔ ܇࿅͞ΕͨਓͰ ͳ͍ݶΓಡΊͳ͍ ✅ ❌ javac java public class Main... 0xCA0xFE0xBA0xBE...
4. +7.
   ͷߏ଄ Ϋϥεϩʔμ ϩʔυɺಈతϦϯΫɺॳظԽ ࣮ߦΤϯδϯ ໋ྩ࣮ߦثɺ+*5ɺ($ ࣮ߦ࣌σʔλྖҬ ϝιουɺώʔϓɺεϨου ਤ͸ 6OEFSTUBOEJOH
   +BWB
   7JSUVBM
   .BDIJOF
   +7.
   "SDIJUFDUVSF
   ΑΓҾ༻
5. +BWB
   ΫϥεϑΝΠϧͷߏ଄ɿ֓؍ • ӈ͸ΫϥεϑΝΠϧͷத਎ • ܕ σʔλ໊ ͷϑΥʔϚοτ • V
   ͸  
   CZUF
   ੔਺஋ • V
   ΋ಉ༷ɺ΄͔͸ߏ଄ମ • ಛʹॏཁͳ΋ͷ • DPOTUBOU@QPPM • ఆ਺ϓʔϧ • NFUIPET • ໋ྩؚΉϝιου৘ใ u4 magic; u2 minor_version; u2 major_version; u2 constant_pool_count; cp_info constant_pool[constant_pool_count-1]; u2 access_flags; u2 this_class; u2 super_class; u2 interfaces_count; u2 interfaces[interfaces_count]; u2 fields_count; field_info fields[fields_count]; u2 methods_count; method_info methods[methods_count]; u2 attributes_count; attribute_info attributes[attributes_count]; 5IF
   +BWBš
   7JSUVBM
   .BDIJOF
   4QFDJGJDBUJPO
   +BWB
   4&
   
   &EJUJPO $IBQUFS
    ΑΓҾ༻
6. +BWB
   ΫϥεϑΝΠϧͷߏ଄ɿఆ਺ϓʔϧ • ܕ΍ϝιου໊ɺ ϓϩάϥϜதͷจࣈྻ΍ ఆ਺Λ֨ೲ • ਺छྨͷܕͷσʔλͷ഑ྻ • FY
   6UG
   ܕ • V
   UBHʢܕΛද͢ఆ਺ɺʣ • V
   MFOHUIʢจࣈྻ௕ʣ • V
   CZUFT<MFOHUI> ʢ࣮ࡍͷ
   6UG
   จࣈྻʣ javap –v -p Main.java ͷ࣮ߦ݁ՌͷҰ෦
7. +BWB
   ΫϥεϑΝΠϧͷߏ଄ɿϝιου • Ҿ਺΍ฦ஋ɺ+7.
   ໋ྩͳͲ ΛؚΉ • +7.
   ໋ྩ͸ $PEF"UUSJCVUF ͱͯ͠ ؚ·ΕΔ javap –v -p Main.java ͷ࣮ߦ݁ՌͷҰ෦ u2 access_flags; u2 name_index; u2 descriptor_index; u2 attributes_count; attribute_info attributes[attributes_count]; Method ߏ଄ମ – 4.6 Methods ΑΓ
8. ໋ྩ࣮ߦΤϯδϯɿ࢓૊Έ • +7.
   ໋ྩΛ 
   ࣮ͭͣͭߦ͍ͯ͘͠ • 
   CZUF
   ͷ໋ྩʢΦϖίʔυʣͱ 
   ݸҎ্ͷҾ਺ʢΦϖϥϯυʣͰߏ੒ • ΦϖϥϯυελοΫʹ஋Λ௥ՃɾऔΓग़͠Λߦ͏͜ͱͰ໋ྩΛ࣮ߦ System.out.println(“Hello, World!”); getstatic #7 ldc #13 invokevirtual #15 return #7 = Fieldref #8.#9 // java/lang/System.out:Ljava/io/PrintStream; #13 = String #14 // Hello, World! #15 = Methodref #16.#17 // java/io/PrintStream.println:(Ljava/lang/String;)V ίϯύΠϧ͞Εͨ +7.
   ໋ྩ ఆ਺ϓʔϧʢൈਮʣ
9. ໋ྩ࣮ߦΤϯδϯɿ࣮ߦྫ #7 = Fieldref #8.#9 // java/lang/System.out:Ljava/io/PrintStream; #13 = String #14 // Hello, World! #15 = Methodref #16.#17 // java/io/PrintStream.println:(Ljava/lang/String;)V • getstatic #7 • ελοΫʹࢦఆͷ static ม਺ͷࢀরΛੵΉ • ldc #13 • ελοΫʹࢦఆͷఆ਺ΛੵΉ • invokevirtual #15 • ࢦఆͷϝιουΛ࣮ߦ͢Δ • ϝιουͷҾ਺ͷ਺ pop • ϝιουͷॴ༗ऀΛ pop • return System.out System.out “Hello, World!” ্ σΟεΫϦϓλ ʢ͜ͷ৔߹ɺ4USJOH
   ܕͷҾ਺Λ Ұ͚ͭͩऔΔͱΘ͔Δʣ ্ /&8 /&8
10. ͍͞͝ʹ • ͜͜·Ͱ෼͔Ε͹೚ҙͷݴޠͰ +7.
    ΋Ͳ͖Λ࣮૷Ͱ͖Δʂ • Ϋϥεϩʔμ • ໋ྩ࣮ߦΤϯδϯ • ࣮༻తʹ͢Δͷ͸मཏͷಓ • ܧঝɺॳظԽɺಈతϦϯΫɺྫ֎ • +/*ʢ+BWB
    /BUJWF
    *OUFSGBDFʣ • ඪ४ϥΠϒϥϦ • 54
    ʹΑΔ੿ +7.
    ࣮૷ɿ $IVSV7. 1MBZHSPVOE • ্هͷ΄΅શͯΛ࣮૷ ˞
    +BWB
    
    ͰίϯύΠϧ͞ΕͨΫϥεϑΝΠϧΛ ࣮ߦՄೳ