HexDevs 2021

Slides from my session on HexDevs with TenderJIT

Transcript

1. https://github.com/tenderlove/tenderjit TenderJIT Intro Short Intro to TenderJIT
2. Pure Ruby JIT Compiler For Ruby
3. Agenda Why? Machine Types What is JIT? TenderJIT & Code
4. Why?
5. 1. I’m not good at JITs
6. 2. To See If I Could
7. I ❤ Ruby
8. Is this “real”?
9. Yes. It is Le JIT
10. But is it really “real”?
11. Is this a “real” JIT or a learning project?
13. Code Execution How do machines work?
14. Two Machine Types Stack Machines Register Machines
15. Stack Machines
16. Stack Machine 5 + 3 push 5 push 3 plus Source Code Machine Code 5 3 8 Machine Stack
17. YARV is a Stack Machine
18. YARV Instructions $ cat thing.rb 5 + 3 $ ruby --dump=insns thing.rb == disasm: #<ISeq:<main>@thing.rb:1 (1,0)-(1,5)> (catch: FALSE) 0000 putobject 5 ( 1)[Li] 0002 putobject 3 0004 opt_plus <calldata!mid:+, argc:1, ARGS_SIMPLE>[CcCr] 0006 leave
19. Terminology
20. Stack Machine 5 + 3 push 5 push 3 plus Source Code Machine Code 5 3 Machine Stack PC (Program Counter) SP (Stack Pointer)
21. Stack Machine 5 + 3 push 5 push 3 plus Source Code Machine Code 5 3 Machine Stack 0 1 2 … -1 1 0
22. CFP = “Control Frame Pointer”
23. Control Frame Pointer Contains Information About the Current Frame def baz end def bar baz end def foo bar end foo Main Control Frame Pointers foo bar baz
24. Control Frame Pointer Contains Information About the Current Frame def add 5 + 3 end Field Description iseq Instruction Sequence (the method) PC Program Counter (what are we running right now?) SP Stack Pointer (what is on the stack?) opt_plus 3 5
25. EC = “Execution Context”
26. Register Machine (x86, ARM, etc)
27. Register Machine 5 + 3 mov r1, 5 mov r2, 3 add r1, r2 Source Code Machine Code Machine Registers Register Name Value r1 r2 r3 … 5 3 8
28. x86 Instructions int main(int argc, char *argv[]) { int x = 5; int y = 3; return x + y; } 100003fa2: mov dword ptr [rbp - 20], 5 100003fa9: mov dword ptr [rbp - 24], 3 100003fb0: mov eax, dword ptr [rbp - 20] 100003fb3: add eax, dword ptr [rbp - 24] Source Code Machine Code
29. x86 Instructions int main(int argc, char *argv[]) { int x = 5; int y = 3; return x + y; } 100003fa2: mov dword ptr [rbp - 20], 5 100003fa9: mov dword ptr [rbp - 24], 3 100003fb0: mov eax, dword ptr [rbp - 20] 100003fb3: add eax, dword ptr [rbp - 24] Source Code Machine Code
30. x86 Instructions int main(int argc, char *argv[]) { int x = 5; int y = 3; return x + y; } 100003fa2: mov dword ptr [rbp - 20], 5 100003fa9: mov dword ptr [rbp - 24], 3 100003fb0: mov eax, dword ptr [rbp - 20] 100003fb3: add eax, dword ptr [rbp - 24] Source Code Machine Code
31. x86 Instructions int main(int argc, char *argv[]) { int x = 5; int y = 3; return x + y; } 100003fa2: mov dword ptr [rbp - 20], 5 100003fa9: mov dword ptr [rbp - 24], 3 100003fb0: mov eax, dword ptr [rbp - 20] 100003fb3: add eax, dword ptr [rbp - 24] Source Code Machine Code Register “EAX”
32. x86 Instructions int main(int argc, char *argv[]) { int x = 5; int y = 3; return x + y; } 100003fa2: mov dword ptr [rbp - 20], 5 100003fa9: mov dword ptr [rbp - 24], 3 100003fb0: mov eax, dword ptr [rbp - 20] 100003fb3: add eax, dword ptr [rbp - 24] Source Code Machine Code
33. What is a JIT?
34. JIT: Machine Code at Runtime
35. Machine Code in Ruby require "fisk" require "fisk/helpers" # Allocate executable memory jitbuf = Fisk::Helpers.jitbuffer 4096 fisk = Fisk.new # Add 5 and 3 in machine language, and write to the JIT buffer fisk.asm(jitbuf) do mov rax, imm(5) # Store 5 in RAX mov r9, imm(3) # Store 3 in R9 add rax, r9 # Add R9 to RAX ret # Return from this function end # Define an add method define_method :add, &jitbuf.to_function([], Fiddle::TYPE_INT) p add # Call add and print it
36. TenderJIT: Translate YARV to Machine Code
37. Stack Machine to Register Machine