2018 Jul 25th LINE Developer Meetup #41 in Fukuoka Session Slide in English / セッションスライドです。 Graal in GraalVM - A New JIT Compiler オラクル社からGraalVMというものが発表され、話題を呼んでいます。GraalVMはHotSpot VM上に新しいJITコンパイラGraalと言語実装用フレームワーク/ASTインタプリタであるTruffle、さらにネイティブイメージ作成機能とその実行に使われるSubstrateVMを併せ持ったものです。すでにTruffleを使用したJavaScriptやRuby、R、Pythonの実装も提供されており、これらの言語とJavaはコードから相互に呼び出しができます。このセッションではGraalVMを概観したあと、JITコンパイラGraalにとくに注力して解説します。GraalとTruffleはOracle Labsとヨハネス・ケプラー大学で共同研究されており、多くの論文が発表されています。HotSpotのJITコンパイラとパフォーマンスや構造などを比較しつつ、GraalのJITコンパイルのテクニックについてもいくつか触れます。とにかく、私がGraalをとても好きなのです。デモも実施しつつ、Graalのすごさを伝えられればと考えています。

1. Graal in GraalVM
- A New JIT Compiler -
KanJava JUG
PONOS Corporation
Koichi Sakata(@jyukutyo)
#LINE_DM

2. About Me
• Koichi Sakata / 阪田 浩一
– @jyukutyo
• JUG Leader (KanJava JUG)
• JVM Devotee
– Want to Be A JVM / JVMになりたい
• PONOS Corporation
– Kyoto

3. About KanJava
• Kansai Java Engineer Group
– Kansai Region (Osaka/Kyoto/Kobe)
– JCP (Java Community Process)
Member
• Founded in 2009
• Over 800 Members
• Event Every Two Month

4. Today’s Theme
New Java JIT Compiler:
Graal

5. Before That

6. http://www.graalvm.org/

7. http://www.graalvm.org/

9. GraalVM
• Graal
– JIT Compiler
• Truffle
– Language Implementation Framework
• Substrate VM
– Runtime Library and a Set of Tools for
Building Java AOT Compiled Code

10. Top 10 Things To Do With GraalVM
1. High-performance modern
Java
2. Low-footprint, fast-
startup Java
3. Combine JavaScript, Java,
Ruby, and R
4. Run native languages on
the JVM
5. Tools that work across
all languages
6. Extend a JVM-based
application
7. Extend a native
application
8. Java code as a native
library
9. Polyglot in the database
10.Create your own language

11. http://www.graalvm.org/

12. Top 10 Things To Do With GraalVM
1. High-performance modern
Java
2. Low-footprint, fast-
startup Java
3. Combine JavaScript, Java,
Ruby, and R
4. Run native languages on
the JVM
5. Tools that work across
all languages
6. Extend a JVM-based
application
7. Extend a native
application
8. Java code as a native
library
9. Polyglot in the database
10.Create your own language

13. Polyglot
HotSpot VM
JVMCI
Graal
JVM lang Truffle
LLVMJS R Ruby
C C++
Fortran
Interpreter

14. Interoperability

15. Demo: Polyglot Shell
Polyglot.eval('ruby', '"100".to_i')

16. Polyglot on the JVM with Graal

17. Create Your Own Language
• https://github.com/jyukutyo/JVM-Math-Language

18. GraalVM ≠ Graal

19. Today’s Theme
New Java JIT Compiler:
Graal

20. What is
a JIT Compiler?

21. Run Java Code on JVM

22. JVM interprets
Java Bytecode

23. Interpreting is
very slow...

24. JIT Compiler
Java Bytecode
↓
Machine Code

25. Speculation Without Regret: Reducing Deoptimization Meta-data in the Graal compiler

26. JIT Compilation
Fast Compilation Speed
vs
Better Optimization

27. JIT Compilation
• Case: Fast Compilation Speed
– Fast Compilation
– Not Efficient
• Case: Better Optimization
– Slow Compilation
– Efficient

28. HotSpot VM
Compiler Interface
C2C1
HotSpot VM
C++

29. GraalVM
Compiler
Interface
GraalC1
HotSpot VM
JVMCI
Java

30. JVMCI
http://openjdk.java.net/jeps/243

31. JVMCI
• JVM Compiler Interface
–Write our own
JIT compiler in Java
–Use another JIT compiler
at runtime

32. Graal Uses JVMCI!

33. We can use Graal
only in GraalVM?

34. Not Only in GraalVM
http://openjdk.java.net/jeps/295

35. In Java 9
Graal is used
for AOT compilation
(jaotc)
* only supports Linux/x64

36. JIT Compiler
Java Bytecode
↓
Machine Code

37. Not Only in GraalVM
http://openjdk.java.net/jeps/317

38. In Java 10
Java-Based JIT Compiler
=
Graal

39. Java 10 Demo
• java
-XX:+UnlockExperimentalVMOptions
-XX:+UseJVMCICompiler
-XX:+PrintCompilation
Demo

40. Graal is
written in Java!

41. It’s
Human-readable

42. HotSpot VM
Compiler Interface
C2C1
HotSpot VM
C++

43. Real-World
Example

44. Twitter uses Graal
in PRODUCTION!

45. Twitter & Graal
• Twitter’s JDK
– Based on OpenJDK 8u
– JEP 243 (JVMCI) Backport, Graal etc.
• Twitter's Quest for a Wholly Graal Runtime – YouTube
• Improve Performance & Save $$$

46. TWITTER'S QUEST FOR A WHOLLY GRAAL RUNTIME

47. TWITTER'S QUEST FOR A WHOLLY GRAAL RUNTIME

48. TWITTER'S QUEST FOR A WHOLLY GRAAL RUNTIME

49. Performance
Compiling Scala Faster with GraalVM
Scala Compiler Benchmark with Scala 2.12.6

50. Graal
• Actively Developed/Researched by
– Oracle Labs
– Johannes Kepler University of Linz
• Institute for System Software
• Compiler and JVM Research at JKU

51. JIT Compilation
Process

52. Linear Scan Register Allocation for the Java HotSpot™ Client Compiler

53. IR (中間表現)
• HIR
– High-level Intermediate Representation
– Platform Independent
• LIR
– Low-level Intermediate Representation
– Platform Dependent

54. Graal IR
Partial Escape Analysis and Scalar Replacement for Java

55. Graal Graph
int average(int a, int b) {
return (a + b) / 2;
}

56. Graal Graph
int average(int[] values) {
int sum = 0;
for (int n = 0; n < values.length; n++) {
sum += values[n];
}
return sum / values.length;
}

57. Graal Graph

58. Partial Escape Analysis and Scalar Replacement for Java

59. Snippets: Taking the High Road to a Low Level

60. Many Optimizations
• Assumptions
• Type-Checked
Inlining
• Polymorphic Inlining
• Intrinsification
• Read Optimization
• Loop Refactoring
• Loop Unrolling
• Tail Duplication
• Partial Escape
Analysis
• Graph Caching
• Use Exception
Probability
• Conditional
Elimination
• Simulation Based
Path Duplication

61. Optimazaions
More Inlining
As the Result

62. Partial Escape Analysis

63. Escape Analysis
• Analyze where references
to new objects flow
– Look for “escapes”
• Method call parameter
• Static field
• Return value
• Throw
• etc.

64. Escape Analysis
static Object field;
static Object foo() {
Object a = new Object();
field = a;
Object b = new Object();
method(b);
Object c = new Object();
return c;
}
static void method(Object o) {...}
Object a,b,c
escapes
Optimizing Allocations with Partial Escape Analysis

65. If the object doesn’t escape,
there might be
optimization opportunities

66. Escape Analysis
public Person get(String name, int age) {
Person p = new Person(name, age);
Person cachedPerson = null;
for (int i = 0; i < cache.length(); i++) {
Person c = cache[i];
if (p.name.equals(c.name) && p.age == c.age) {
cachedPerson = c;
break;
}
}
if (cachedPerson != null) {
return cachedPerson;
}
return null;
}
Object p doesn’t
escape
Optimizing Allocations with Partial Escape Analysis

67. Scalar Replacement
public Person get(String name, int age) {
Person cachedPerson = null;
for (int i = 0; i < cache.length(); i++) {
Person c = cache[i];
if (name.equals(c.name) && age == c.age) {
cachedPerson = c;
break;
}
}
if (cachedPerson != null) {
return cachedPerson;
}
return null;
}
• Field loads replaced
with local variables
• Allocation was
removed
Optimizing Allocations with Partial Escape Analysis

68. Partial Escape Analysis
public Person get(String name, int age) {
Person p = new Person(name, age);
Person cachedPerson = null;
for (int i = 0; i < cache.length(); i++) {
Person c = cache[i];
if (p.name.equals(c.name) && p.age == c.age) {
cachedPerson = c;
break;
}
}
if (cachedPerson != null) {
return cachedPerson;
}
addToCache(p);
return p;
}
Object p
escapes...
Optimizing Allocations with Partial Escape Analysis

69. Partial Escape Analysis
public Person get(String name, int age) {
Person p = new Person(name, age);
Person cachedPerson = null;
for (int i = 0; i < cache.length(); i++) {
Person c = cache[i];
if (p.name.equals(c.name) && p.age == c.age) {
cachedPerson = c;
break;
}
}
if (cachedPerson != null) {
return cachedPerson;
}
addToCache(p);
return p;
}
If the if statement is true,
object p doesn’t escape
Optimizing Allocations with Partial Escape Analysis

70. Partial Escape Analysis
public Person get(String name, int age) {
Person p = new Person(name, age);
Person cachedPerson = null;
for (int i = 0; i < cache.length(); i++) {
Person c = cache[i];
if (name.equals(c.name) && age == c.age) {
cachedPerson = c;
break;
}
}
if (cachedPerson != null) {
return cachedPerson;
}
Person p = new Person(name, age);
addToCache(p);
return p;
}
Optimizing Allocations with Partial Escape Analysis
No allocation in this path
(It might be a frequent path)

71. Partial Escape Analysis
Analyzing
the Escapability of Objects
for Individual Branches