## Self-compiling Litescript [LiteScript](https://github.com/luciotato/LiteScript) compiler is written in LiteScript. Since we can generate js-code or c-code from the LiteScript sources, here's a comparision of LiteScript compiler, self-compiling when using the generated-js-code vs using generated-c-code. This is also a step-by-step explanation of how each version of the compiler can compile itself. ## Source we start with LiteScript compiler v0.8 sources. Let's call this *input0* ## Phase 1 We use *the previous, executable version of the compiler* to compile this source. We feed *input0* (v0.8 sources) to v0.7 compiler Since v0.7 compiler is js-code, this compilation phase runs under node.js ---------------------- using v0.7-to-js to generate (js code) v0.8 lite-to-js compiler ---------------------- node /home/ltato/LiteScript/devel/util/liteVersion -use v0.7/lite-to-js js_lite -v 3 -D PROD_JS -o ../../generated-js/v0.8/lite-to-js compiler options: {"outDir":"/home/ltato/LiteScript/devel/generated-js/v0.8/lite-to-js","verboseLevel":3,"warningLevel":1,"debugEnabled":false,"skip":false,"generateSourceMap":true,"single":false,"browser":false,"comments":1,"perf":0,"defines":["PROD_JS"],"includeDirs":[],"mainModuleName":"js_lite"} compile: js_lite out: /home/ltato/LiteScript/devel/generated-js/v0.8/lite-to-js compiler path: ../generated-js/v0.7/lite-to-js LiteScript compiler version 0.7.9 - Build Date: 20140722 Out Dir: /home/ltato/LiteScript/devel/generated-js/v0.8/lite-to-js preprocessor #defined [ 'PROD_JS', 'ENV_NODE', 'TARGET_JS' ] 0 errors, 0 warnings. [Finished in 9.4s] The v0.7 (js) took 9.4 seconds in compilig v.08 sources to-js The output of this phase is ***(js)output1***, a js-executable version of v0.8 compiler ## Phase 2 Now that we have a executable version of the v0.8 compiler, we check if the v0.8 compiler is able to compile itself We feed **input0** (v0.8 sources) to **(js)output1** (v0.8 js-code compiler) ---------------------- using v0.8-to-js to generate (js code) v0.8 lite-to-js compiler ---------------------- node /home/ltato/LiteScript/devel/util/liteVersion -use v0.8/lite-to-js js_lite -perf 1 -v 1 -D PROD_JS -o ../../generated-js/v0.8/lite-to-js compiler options: {"outDir":"/home/ltato/LiteScript/devel/generated-js/v0.8/lite-to-js","verboseLevel":1,"warningLevel":1,"debugEnabled":false,"skip":false,"generateSourceMap":true,"single":false,"browser":false,"comments":1,"perf":1,"defines":["PROD_JS"],"includeDirs":[],"mainModuleName":"js_lite"} cwd: /home/ltato/LiteScript/devel/source/v0.8 compile: js_lite out: /home/ltato/LiteScript/devel/generated-js/v0.8/lite-to-js compiler path: ../generated-js/v0.8/lite-to-js LiteScript compiler version 0.8.5 - Build Date: Sat Aug 16 2014 05:59:39 GMT-0300 (ART) Project Dir: /home/ltato/LiteScript/devel/source/v0.8 Main Module: js_lite Out Dir: /home/ltato/LiteScript/devel/generated-js/v0.8/lite-to-js preprocessor #defined [ 'PROD_JS', 'ENV_JS', 'ENV_NODE', 'TARGET_JS' ] Compiling js_lite Producing js Generated .js files (22) at /home/ltato/LiteScript/devel/generated-js/v0.8/lite-to-js 0 errors, 0 warnings. Total Compile Project: 11383ms [Finished in 11.5s] The v0.8(js-code-compiler) took 11.5 seconds to compile itself The output of this phase, ***(js)output1-B*** is a js-executable version of v0.8 compiler by itself *and should be equal to* ***(js)output1***, i.e.: the code making the compilation. if ***(js)output1-B*** == ***(js)output1***, then the v0.8(js-code) compiler can compile itself ## Phase 3 - generating compile-to-C To be able to generate C-code we need first to obtain the 'compile-to-c' variant of the 0.8 compiler. We feed **input0** (v0.8 sources) to **(js)output1** (v0.8 js-code compiler) with the instruction to import the "produce_c" module (#define PROD_C) ---------------------- using litec v0.8-to-c to generate (js code) v0.8 lite-to-c compiler ---------------------- node /home/ltato/LiteScript/devel/util/liteVersion -use v0.8/lite-to-js js_lite -perf 1 -v 1 -D PROD_C -o ../../generated-js/v0.8/lite-to-c compiler options: {"outDir":"/home/ltato/LiteScript/devel/generated-js/v0.8/lite-to-c","verboseLevel":1,"warningLevel":1,"debugEnabled":false,"skip":false,"generateSourceMap":true,"single":false,"browser":false,"comments":1,"perf":1,"defines":["PROD_C"],"includeDirs":[],"mainModuleName":"js_lite"} cwd: /home/ltato/LiteScript/devel/source/v0.8 compile: js_lite out: /home/ltato/LiteScript/devel/generated-js/v0.8/lite-to-c compiler path: ../generated-js/v0.8/lite-to-js LiteScript compiler version 0.8.5 - Build Date: Sat Aug 16 2014 05:59:53 GMT-0300 (ART) Project Dir: /home/ltato/LiteScript/devel/source/v0.8 Main Module: js_lite Out Dir: /home/ltato/LiteScript/devel/generated-js/v0.8/lite-to-c preprocessor #defined [ 'PROD_C', 'ENV_JS', 'ENV_NODE', 'TARGET_JS' ] Compiling js_lite Producing js Generated .js files (21) at /home/ltato/LiteScript/devel/generated-js/v0.8/lite-to-c 0 errors, 0 warnings. Total Compile Project: 12928ms generated OK (js code) lite-to-c v0.8 at ../../generated-js/v0.8/lite-to-c COPY ALSO: interfaces [Finished in 13s] The v0.8(js-code-compiler) took 13 seconds in compilig it's own "compile-to-c" version (js code) We'll call the output of this phase ***(js)output2(-to-c)***: a js-executable version of v0.8 *compile-to-c* compiler ## Phase 4 - Going C now we can generate C-code for the v0.8 LiteScript Compiler We feed **input0** (v0.8 sources) to **(js)output2(-to-c)** ---------------------- using v0.8-to-c to generate (c code) v0.8 lite-to-js compiler ---------------------- node /home/ltato/LiteScript/devel/util/liteVersion -use v0.8/lite-to-c c_lite -v 1 -D PROD_JS -o ../../litec/litec-to-js/generated-c compiler options: {"outDir":"/home/ltato/LiteScript/devel/litec/litec-to-js/generated-c","verboseLevel":1,"warningLevel":1,"debugEnabled":false,"skip":false,"generateSourceMap":true,"single":false,"browser":false,"comments":1,"perf":0,"defines":["PROD_JS"],"includeDirs":[],"mainModuleName":"c_lite"} cwd: /home/ltato/LiteScript/devel/source/v0.8 compile: c_lite out: /home/ltato/LiteScript/devel/litec/litec-to-js/generated-c compiler path: ../generated-js/v0.8/lite-to-c LiteScript compiler version 0.8.5 - Build Date: Sat Aug 16 2014 06:11:10 GMT-0300 (ART) Project Dir: /home/ltato/LiteScript/devel/source/v0.8 Main Module: c_lite Out Dir: /home/ltato/LiteScript/devel/litec/litec-to-js/generated-c preprocessor #defined [ 'PROD_JS', 'ENV_JS', 'ENV_NODE', 'TARGET_C' ] Compiling c_lite Producing c Generated .c files (21) at /home/ltato/LiteScript/devel/litec/litec-to-js/generated-c 0 errors, 0 warnings. generated OK (c code) lite-to-js v0.8 at ../../litec/litec-to-js/generated-c [Finished in 14s] The (js)v0.8(-to-c) compiler took 14 seconds to compile a C-code version of itself We'll call the output of this phase ***(c)output3(-to-js)***: a c-code version of v0.8 *compile-to-js* compiler ## Phase 4.1 - Compiling the C-code Now that we have the C-code, we use gcc (Netbeans IDE) to compile to a native-exe "/usr/bin/make" -f nbproject/Makefile-Release.mk QMAKE= SUBPROJECTS= .build-conf make[1]: Entering directory `/home/ltato/LiteScript/devel/litec/litec-to-js' "/usr/bin/make" -f nbproject/Makefile-Release.mk dist/Release/GNU-Linux-x86/litec-to-js make[2]: Entering directory `/home/ltato/LiteScript/devel/litec/litec-to-js' mkdir -p build/Release/GNU-Linux-x86/_ext/761097586 ... make[1]: Leaving directory `/home/ltato/LiteScript/devel/litec/litec-to-js' BUILD SUCCESSFUL (total time: 15s) GCC took 15s to compile ***(c)output3(-to-js)*** into a *native executable* we call this native-exe *litec*, [Lite]Script [C]ompiler ## Phase 5 - Using the native exe to compile Now that we have a native executable version of the v0.8 compiler, we check if this version is able to compile itself We feed **input0** (v0.8 sources) to *litec* (v0.8 native-exe compiler) LiteScript compile-to-js v0.8.5 Sat Aug 16 2014 06:21:50 GMT-0300 (ART) (standalone executable) Project Dir: /home/ltato/LiteScript/devel/source/v0.8 Main Module: js_lite Out Dir: /home/ltato/LiteScript/devel/out/by-c-v08/js/lite-to-js-compiler preprocessor #defined PROD_JS, FROM_C, ENV_C, TARGET_JS Compiling js_lite Producing js Generated .js files (22) at /home/ltato/LiteScript/devel/out/by-c-v08/js/lite-to-js-compiler 0 errors, 0 warnings. Total Compile Project 1600 ms RUN FINISHED; exit value 0; real time: 1s; user: 240ms; system: 1s The v0.8(native-exe) took ***1.6*** seconds to compile itself The output of this phase is ***(js)output1-B***: a js-executable version of v0.8 compiler by itself *and should be equal to* ***(js)output1*** if ***(js)output1-B*** == ***(js)output1***, then the v0.8(native-exe) compiler can compile itself to js. Now here's the important performance comparision, the js-version of the v0.8 compiler, took 11.5 seconds to generate ***(js)output1-B***, and the native-exe took 1.6 seconds to do the same. Here we have a 7x performance difference. ***The native-exe runs 7 times faster than the js-version*** of the same source LiteScript code.