How does complier see your app

What is a compiler
What part's it consist of
Why should you even care about it and learn

Transcript

1. How does compiler see your app
2. What is a compiler A compiler is a computer program (or a set of programs) that transforms source code written in a programming language (the source language) into another computer language (the target language) ...
3. What is a compiler Compiler(source code) -> Binary Compiler(source code) -> Object file .o Compiler(source code) -> Other source code Compiler(source code) -> YAML/JSON
4. What is a compiler • Read the source code • Analyse the source code • Optimize • Transform
5. Why should I learn it - Fun !"
6. Why should I learn it - Profit
7. Why should I learn it - Profit • New CS knowledge • Build own compiler • Building own tools: formaters, linters, code coverages, code generators ... Bonus: You will be good at working with String in Swift :D
8. Where we use it ?
10. Syntax highlighting
11. Code completion
13. Error + Warning + Fix suggestions
14. It's not IDE + Great example of Business Logic & UI separation !
15. Let's look inside a compiler
16. Source code ↓ ↓ App
17. Frondend & Backend
18. Frondend • Lexical analysis • Syntax analysis • Semantic analysis • Generates errors and warnings • Generates IR
19. Backend • Code independence optimizations • Generates target-dependent assembly code • Hardware specific optimizations • Machine code
20. Example
21. let a = 10
22. 1 - Language grammar • Finite automata (state machine) • Regular expression let
23. 2 - Lexical Analysis var a = 10 <keyword var> <identifier a> <operator => <value 10> + + + <operator +> <operator +> <operator +>
24. 3 - Syntax Analysis • Combines tokens together • Produces AST
25. var a = 10 //swiftc -dump-parse hello.swift AST source_file (top_level_code_decl (brace_stmt (pattern_binding_decl (pattern_named 'a') (integer_literal_expr type='<null>' value=10)) )) (var_decl "a" type='<null type>' storage_kind=stored))
27. 4 - Semantic Analysis var a: String = 10 • Check for correctness • Type mismatches, method call and arguments, variable refernce, violating access
28. 5 - Generate IR • Assembly like • Language & independent independent
29. Use LLVM IR & Backend C, C++, ActionScript, Ada, C#, Common Lisp, Crystal, D, Delphi, Fortran, OpenGL Shading Language, Halide, Haskell, Java bytecode, Julia, Lua, Objective-C, Pony, Python, R, Ruby, Rust, CUDA, Scala, and ... Swift :)
30. 5 - Generate IR func square(a: Int) -> Int { return a*a; } //IR define i32 @square(i32 %a) { %1 = mul i32 %a, %a ret i32 %1 }
31. 5 - Generate IR var a = 10 //swiftc -emit-ir hello.swift ; ModuleID = 'a' source_filename = "a" target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128" target triple = "x86_64-apple-macosx10.9" %Si = type <{ i64 }> %Vs5Int32 = type <{ i32 }> %Sp = type <{ i8* }> @_Tv1a1aSi = hidden global %Si zeroinitializer, align 8 @_TZvOs11CommandLine5_argcVs5Int32 = external global %Vs5Int32, align 4 @globalinit_33_FD9A49A256BEB6AF7C48013347ADC3BA_token4 = external global i64, align 8 @_TZvOs11CommandLine11_unsafeArgvGSpGSqGSpVs4Int8___ = external global %Sp, align 8 @__swift_reflection_version = linkonce_odr hidden constant i16 1 @llvm.used = appending global [1 x i8*] [i8* bitcast (i16* @__swift_reflection_version to i8*)], section "llvm.metadata", align 8 define i32 @main(i32, i8**) #0 { entry: %2 = bitcast i8** %1 to i8* store i32 %0, i32* getelementptr inbounds (%Vs5Int32, %Vs5Int32* @_TZvOs11CommandLine5_argcVs5Int32, i32 0, i32 0), align 4 %3 = load i64, i64* @globalinit_33_FD9A49A256BEB6AF7C48013347ADC3BA_token4, align 8 %4 = icmp eq i64 %3, -1 br i1 %4, label %once_done, label %once_not_done once_not_done: ; preds = %entry call void @swift_once(i64* @globalinit_33_FD9A49A256BEB6AF7C48013347ADC3BA_token4, i8* bitcast (void ()* @globalinit_33_FD9A49A256BEB6AF7C48013347ADC3BA_func4 to i8*)) br label %once_done once_done: ; preds = %once_not_done, %entry %5 = load i64, i64* @globalinit_33_FD9A49A256BEB6AF7C48013347ADC3BA_token4, align 8 %6 = icmp eq i64 %5, -1 call void @llvm.assume(i1 %6) store i8* %2, i8** getelementptr inbounds (%Sp, %Sp* @_TZvOs11CommandLine11_unsafeArgvGSpGSqGSpVs4Int8___, i32 0, i32 0), align 8 store i64 10, i64* getelementptr inbounds (%Si, %Si* @_Tv1a1aSi, i32 0, i32 0), align 8 ret i32 0 } declare void @globalinit_33_FD9A49A256BEB6AF7C48013347ADC3BA_func4() #0 declare void @swift_once(i64*, i8*) ; Function Attrs: nounwind declare void @llvm.assume(i1) #1 attributes #0 = { "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "target-cpu"="core2" "target-features"="+ssse3,+cx16,+fxsr,+mmx,+sse,+sse2,+sse3" } attributes #1 = { nounwind } !llvm.module.flags = !{!0, !1, !2, !3, !4, !5, !9, !10} !0 = !{i32 1, !"Objective-C Version", i32 2} !1 = !{i32 1, !"Objective-C Image Info Version", i32 0} !2 = !{i32 1, !"Objective-C Image Info Section", !"__DATA, __objc_imageinfo, regular, no_dead_strip"} !3 = !{i32 4, !"Objective-C Garbage Collection", i32 1024} !4 = !{i32 1, !"Objective-C Class Properties", i32 64} !5 = !{i32 6, !"Linker Options", !6} !6 = !{!7, !8} !7 = !{!"-lswiftCore"} !8 = !{!"-lobjc"} !9 = !{i32 1, !"PIC Level", i32 2} !10 = !{i32 1, !"Swift Version", i32 4}
32. 6 - Dive into darkness Backend
33. Backend - Still a lot of Magic! • Analysis and Transform ! http://llvm.org/docs/Passes.html • Generic optimizations Dead code elimination, Loop optimizations, etc. • Hardware specific optimizations Use of Registers and architecture specific commands, example - armv7s • Assembly code
35. The End! • swiftc --help • http://llvm.org • Youtube - LLVM • Compiler for dummies :D
37. @KostiaKoval