compiler interpreter and_bootstrapping
TRANSCRIPT
01/04/15 1
Submitted to:-Sandeep Manzhi
TECHNOCRATS INSTITUTEOF TECHNOLOGY & SCIENCE
Bootstrapping
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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
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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)
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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.
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Full bootstrapping
Ada-S ->M
C
v1
Ada-S->M
v1
Step 1b: Compile v1 compiler on M
M
C->M
MThis compiler can be used for bootstrapping on machine M but we do not want to rely on it permanently!
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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 of
a C compiler!
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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 ->MM
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.
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Half BootstrappingWe 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->HMHM
Ada->HMAda
Ada->TMTM
We have We want
Idea: we can use cross compilation from HM to TM to
bootstrap the TM compiler
Cross compiler:
running on HM but emits
TM code
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Half Bootstrapping continued
Step 1: Implement Ada->TM compiler in Ada
Ada->TMAda
Step 2: Compile on HM
Ada->TMAda
HM
Ada->HMHM
Ada->TM
HM
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Half Bootstrapping continued
Step 3: Cross compile our TM compiler.
Ada->TMAda Ada-
>TMHM
HM
DONE!
TM
From now on we can develop subsequent versions of the compiler completely on TM
Ada->TM
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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.
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Bootstrap to improve efficiency
Ada->MslowAda
Ada-> MslowMslow
Ada->MfastAda
Ada->Mfast
Ada
M
Ada->MfastMslow
Step 1
Ada-> MslowMslow
We have We want
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Bootstrap to improve efficiency
Step 2Ada->MfastAda
M
Ada->MfastMfastAda->
MfastMslow
Fast compiler that emits fast
code!