Building a DSL with GraalVM (Oracle Groundbreaker APAC Virtual Tour)

B    DSL 
G VM
 
 
 
 
 
M  M
@mthmuldersOGB APAC Virtual Tour

D  S  L
https://pxhere.com/en/photo/1057524

SELECT   country, 
         COUNT(1) AS count 
FROM     Customer 
GROUP BY country; 

Given my account has a balance of € 430 
When I receive a money transfer of € 500 
Then my account should have a balance of € 930 

Setup( 
    Boat on StartingShore, 
    Wolf on StartingShore, 
    Sheep on StartingShore, 
    Cabbage on StartingShore 
) execute ( 
    Boat move Cabbage to StartingShore, 
    Boat move Sheep to DestinationShore, 
    Boat move None to StartingShore, 
    Boat move Cabbage to DestinationShore, 
    Boat move Sheep to StartingShore, 
    Boat move Wolf to DestinationShore, 
    Boat move None to StartingShore, 
    Boat move Sheep to DestinationShore 
) 
https://github.com/NRBPerdijk/dsl-for-the-dense/

+ + > + + + + + [ < + > - ] + + + + + + + + [ < + + + + + + > - ] < . 

B
This program adds the numbers 2 and 5 
 
+ +                Store the number 2 in the f rst slot 
> + + + + +        Store the number 5 in the second slot 
 
[                  Move back and forth between f rst and second slot 
 
    < + > -        While "moving" ones from the second to the f rst slot 
] 
 
The f rst slot now has '7' in it but we need to output the ASCII value for that 
The ASCII value is 48 higher than the number we have 
 
The second slot is now empty 
It will act as a counter so we can add 6 * 8 to the f rst slot 
+ + + + + + + +    Store 8 in it 
 
[                  Again move back and forth between f rst and second slot 
    < + + + + + +  while adding 6 to the f rst slot 
    > -            before reducing the counter in the second slot 
] 
 
< .                Go back to the f rst slot and print it 

0 1 2 3 4 ... 29 997 29 998 29 999
2 5 3 0 0 0 0 0
↑

command meaning
+ increase value
decrease value
. print value to std out
, read one byte from std in
[ if value eq 0, jump after matching ]
] if value neq 0, jump after matching [
< move pointer left
> move pointer right

https://www.thepinkhumanist.com/articles/330-life-of-alan-turing-examined-in-a-new-graphic-novel

https://commons.wikimedia.org/wiki/File:USA_tar_bubble_la_brea_CA.jpg

G VM
“One VM to rule them all
cc-by-sa/2.0 - © Lairich Rig - https://www.geograph.org.uk/photo/3203827

B
yapi.bf calculating 15 digits of π
Runtime Average time (ms/op) Error
Java HotSpot(TM) 64-Bit Server VM 53 ± 1
OpenJDK GraalVM CE 19.0.0 45 ± 1
All tests are ran on an 2018 MacBook Pro with 2.6 GHz Intel Core i7 and 16 GB 2400 MHz DDR4. The machine runs macOS Mojave 10.14.4 and JDK
1.8.0_212. Tests measured with  . Each test ran 5 times with 5 warmup iterations.jmh

B
yapi.bf calculating 45 digits of π
Runtime Average time (ms/op) Error
Java HotSpot(TM) 64-Bit Server VM 207 ± 2
OpenJDK GraalVM CE 19.0.0 185 ± 3
All tests are ran on an 2018 MacBook Pro with 2.6 GHz Intel Core i7 and 16 GB 2400 MHz DDR4. The machine runs macOS Mojave 10.14.4 and JDK
1.8.0_212. Tests measured with  . Each test ran 5 times with 5 warmup iterations.jmh

T
cc-by-sa/2.5 - © Darvin DeShazer - https://mushroomobserver.org/2538
“open source library for building
programming language
implementations as interpreters for
self-modifying Abstract Syntax Trees.

A  S  T
ROOT
INCR_VAL INCR_VAL INCR_VAL INCR_VAL INCR_VAL JUMP INCR_VAL INCR_VAL
DECR_PTR INCR_VAL INCR_PTR DECR_VAL
(part of the program that adds 5 and 2)

https://chrisseaton.com/rubytruffle/pldi17-truffle/pldi17-truffle.pdf

P  E
Calculate   for positive integers
If we know (or assume) that  , the program becomes simpler:
x
n
f (x, n) =
⎧
⎩
⎨
⎪
⎪
1
,(f (x, 0.5 ∗ n))
2
x ∗ f (x, n − 1),
if n = 0
if n is even
otherwise
n = 5
f (x) = x ∗ ( )x
2
2

N    POJO
public class BFIncrementByteNode extends Node { 
    /** The slot that holds the data pointer.   
    private f nal FrameSlot dataPointerSlot; 
 
    public BFIncrementByteNode(f nal FrameSlot dataPointerSlot) { 
        this.dataPointerSlot = dataPointerSlot; 
    } 
 
    @Override public void execute(f nal VirtualFrame frame) { 
          Find the memory location 
        f nal int dataPointer = FrameUtil.getIntSafe(frame, dataPointerSlot); 
        f nal FrameSlot currentByteSlot = frame.getFrameDescriptor().f ndFrameSlot(dataPointer); 
 
          Find the current value in that location 
        f nal byte currentValue = FrameUtil.getByteSafe(frame, currentByteSlot); 
 
          Increase the current value 
        f nal byte newValue = (byte) (1 + currentValue); 
 
          Store the current value 
        frame.setByte(getSlot(frame), newValue); 
    } 
} 

B

B
@Override 
public void execute(f nal VirtualFrame frame) { 
    f nal int currentValue = someCalculation(); 
    doPrint(getContext().getOutput(), (char) currentValue); 
} 
 
@TruffleBoundary 
private void doPrint(f nal PrintWriter out, f nal char value) { 
    out.print(value); 
    out.flush(); 
} 

S
https://www.mammoet.com/cases/Tennet/

S
@Specialization(guards = "b   0") 
public double divide(int a, int b) { 
    return a / b; 
} 

S
@Specialization(rewriteOn = ArithmeticException.class) 
int doAddNoOverflow(int a, int b) { 
    return Math.addExact(a, b); 
} 
 
@Specialization 
long doAddWithOverflow(int a, int b) { 
    return a + b; 
} 
execute(Integer.MAX_VALUE - 1, 1)   doAddNoOverflow(Integer.MAX_VALUE - 1, 1) 
 
execute(Integer.MAX_VALUE    , 1)   doAddNoOverflow(Integer.MAX_VALUE, 1) 
                                     throws ArithmeticException 
                                    doAddWithOverflow(Integer.MAX_VALUE, 1) 
 
execute(Integer.MAX_VALUE - 1, 1)   doAddWithOverflow(Integer.MAX_VALUE - 1, 1) 

W    G VM         JVM
function abs (int i)  
    if (   we saw only positive integers in the input   ) { 
        return i; 
    } else {  
        transferToInterpreterAndInvalidate; 
        return i < 0 ?  i : i; 
    } 
} 

B        T

L
Converts a sequence of characters into a sequence of tokens.
 
 
 
 

P
Converts a sequence of tokens into (hierarchical) data structure.
 
 
 
 

P    L  
1. Write some regular expressions
2. Use a parser generator (like  )ANTLR
cc-by-nc/2.5 - © Randall Munroe - https://www.xkcd.com/1171/

I    

G VM U
GraalVM comes with the GraalVM Updater (gu)
Use gu to install components, such as language packs or tools.
e.g. gu install nativeimage
gu -L install brainfuck-0.1-SNAPSHOT-component.jar 

C
Distribute your language implementation as a component:
$ tree 
. 
├── META-INF 
│   ├── MANIFEST.MF 
│   ├── permissions 
│   └── symlinks 
└── jre 
    └── languages 
        └── bf 
            ├── bin 
            │   └── bf 
            ├── brainfuck.jar 
            └── launcher 
                └── bf launcher.jar 
 
6 directories, 6 f les 

U      
1. Prepare source code
2. Prepare GraalVM polyglot context
3. Evaluate the source code
input = "+ + > + + + + + [ < + > - ] + + + + + + + + [ < + + + + + + > - ] < ."; 
source = Source.newBuilder("bf", input, "user input").build(); 
output = new ByteArrayOutputStream(); 
context = Context.newBuilder("bf").out(output).build(); 
context.eval(source); 
System.out.println(output.toString()); 

T
“Implementing your own language
using GraalVM will not only give you
high performance. More importantly, it
allows your language to connect with
the rich tooling provided by the
GraalVM ecosystem.
https://www.graalvm.org/docs/graalvm-as-a-platform/

G  L  D
Start the launcher with inspect
Debugger listening on port 9229. 
To start debugging, open the following URL in Chrome: 
    chromedevtools://devtools/bundled/js_app.html?ws=127.0.0.1:9229/77b52d1253f20cb0ab35 

G  L  C  
Start the launcher with coverage, and optionally  
coverage.Output=detailed 
coverage.OutputFile=coverage.txt
 
Code coverage histogram. 
  Shows what percent of each element was covered during execution 
 
 Path                                                       |  Statements |    Lines |    Roots  
 
 ~/Code/brainfuck jvm/launcher/src/test/resources/sample.bf |     100.00% |  100.00% |    0.00%  
 

W      
The Trufﬂe framework has an Instrument API to write other tools:
1. Source code-related events
2. Allocation events
3. Language runtime and thread creation events
4. Application execution events

W  
Yes, you can run any language with GraalVM. 
... but it may take some time.
It's certainly fun 
... and it might even be proﬁtable.

T  
You don't need to write a parser yourself 
(and maybe you don't want to, either)
Take time to think about the AST
using a wrong structure leads to hard-to-track bugs
refactoring it later is very hard and time-consuming

Q   A
 
 
 
 
Sample code: 
Follow-up project: 
http://bit.ly/brainfuck-jvm
https://bit.ly/scheme4graalvm

Building a DSL with GraalVM (Oracle Groundbreaker APAC Virtual Tour)

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