Cross-compilation

Cross-compilation

A cross-compiler produces target code for a machine different from the one on which it is run

For example, running gcc on a Pentium Linux platform and generating code for a 68000 PalmOS platform

1. Suppose we have cross-compiler for a new language L in implementation language S generating code for machine N.

LSN

2. Suppose we also have an existing S compiler running on machine M implementing code for machine M:

SMM

3. Run LSN through SMM to produce LMN

                                                              LSN + SMM = LM

                                  

Composition Example

1. Suppose we have cross-compiler for a new language, Decaf, implemented in C++: DecafC++MIPS

2. Suppose we also have an existing C++ compiler for a PowerPC machine (e.g., Mac)

C++PowerPCPowerPC

3. Run DecafC++MIPS through C++PowerPCPowerPC to produce DecafPowerPCMIPS

Bootstrapping

Let’s create a compiler for a new language L that runs on machine M

1. Write a compiler for S, a subset of L: SMM Here, M is assembly  language

2. Write the compiler for L using language S: LSM 

3. Compile LSM under SMM to make LMM LMM is a compiler for language L that produces code 

for machine M

Retargeting and Rehosting the Compiler

Let’s make an L compiler for a different machine, N

1. Write LLN 

2. Compile LLN with LMM to produce LMB This make a cross-compiler for N that runs on machine M

 3. Compile LLN with the cross-compiler to produce LNN This makes a compiler for language L that runs on machine N