Compiler interpreter and_bootstrapping
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Bootstrapping refers to techniques that rely on a partial or inefficient compiler version to create a full or better version. There are two types of bootstrapping: full and half. Full bootstrapping is needed when building a new compiler from scratch without access to a compiler for that language. It involves implementing a basic compiler in another language, using it to compile itself, then improving the compiler in iterative steps. Half bootstrapping uses an existing compiler on a different machine to cross compile a compiler for the target machine. Bootstrapping can also be used to improve a compiler's efficiency over time by starting simple and developing more sophisticated versions.
Compiler interpreter and_bootstrapping
- 1. 01/04/15 1 Submitted to:- Sandeep Manzhi TECHNOCRATS INSTITUTE OF TECHNOLOGY & SCIENCE Bootstrapping
- 2. 2 Bootstrapping • a number of techniques which rely on partial/inefficient compiler version to create a full/better version • often compiling a translator expressed in its own language
- 3. 3 Full Bootstrapping • A full bootstrap is necessary when we are building a new compiler from scratch. • Example: • We want to implement an Ada compiler for machine M. We don’t currently have access to any Ada compiler (not on M, nor on any other machine). • Idea: Ada is very large, we will implement the compiler in a subset of Ada and bootstrap it from a subset of Ada compiler in another language. (e.g. C)
- 4. 4 Full Bootstrapping continued • Step 1: build a compiler for Ada-S in another language Ada-S ->M C v1 Ada-S ->M C v1 Step 1a: build a compiler (v1) for Ada-S in another language.
- 5. 5 Full bootstrapping Ada-S ->M C v1 Ada-S- >M v1 Step 1b: Compile v1 compiler on M M C->M M This compiler can be used for bootstrapping on machine M but we do not want to rely on it permanently!
- 6. 6 Full Bootstrapping continued Ada-S ->M Ada-S v2 Step 2a: Implement v2 of Ada-S compiler in Ada-S Ada-S ->M Ada-S v2 M M Ada-S->M v2 Step 2b: Compile v2 compiler with v1 compiler Ada-S ->M M v1 We are now no longer dependent on the availability o a C compiler!
- 7. 7 Full Bootstrapping continued Step 3a: Build a full Ada compiler in Ada-S Ada->M Ada- S v3 Step 3b: Compile with v2 compiler M Ada->M v3 Ada-S ->M M v2Ada->M Ada- S v3 M From this point on we can maintain the compiler in Ada. Subsequent versions v4,v5,... of the compiler in Ada and compile each with the the previous version.
- 8. 8 Half Bootstrapping We discussed full bootstrapping which is required when we have no access to a compiler for our language at all. Q: What if we have access to an compiler for our language on a different machine HM but want to develop one for TM ? Ada- >HM HM Ada- >HM Ada Ada- >TM TM We have We want Idea: we can use cross compilation from HM to TM to bootstrap the TM compiler
- 9. Cross compiler: running on HM but emits TM code 9 Half Bootstrapping continued Step 1: Implement Ada->TM compiler in Ada Ada- >TM Ada Step 2: Compile on HM Ada- >TM Ada HM Ada- >HM HM Ada->TM HM
- 10. 10 Half Bootstrapping continued Step 3: Cross compile our TM compiler. Ada- >TM Ada Ada- >TM HM HM DONE! TM From now on we can develop subsequent versions of the compiler completely on TM Ada->TM
- 11. 11 Bootstrap to improve efficiency The efficiency of programs and compilers: Efficiency of programs: - memory usage - runtime Efficiency of compilers: - Efficiency of the compiler itself - Efficiency of the emitted code Idea: We start from a simple compiler (generating inefficient code) and develop more sophisticated version of it. We can then use bootstrapping to improve performance of the compiler.
- 12. 12 Bootstrap to improve efficiency Ada- >Mslow Ada Ada-> Mslow Mslow Ada- >Mfast Ada Ada- >Mfast Ada M Ada- >Mfast Mslow Step 1 Ada-> MslowMslow We have We want
- 13. 13 Bootstrap to improve efficiency Step 2 Ada- >Mfast Ada M Ada- >Mfast MfastAda-> MfastMslow Fast compiler that emits fast code!