RE: Survey of intermediate program representations?

koodailar@gmail.com wrote:
> I Am Also Interested In This. It Seems That Different IR are for
> different hardware. the only exception i know is RTL, register
> transfer language for GCC> IR.


RTL representation is machine independent, but actual RTL that GCC
generates for a target is different for each target processor. RTL is
a low level IR as far its classification is concerned.


For the original question, IIRC different approaches to intermediate
representations would be covered in most compiler texts.


Briefly, I think choice depends on the objectives to be achieved.
Typically several forms of IR would be used in a production compiler
because effectiveness of several optimizations depend on kind of IR
chosen. A quick classification is based on the abstraction level -
High-Level, Mid-Level, Low-Level and various shades in between. Again,
some HLRs, might be very close to a language e.g. for a language like
f95 where semantic analysis will almost always need additional passes
after the initial parse.


GCC-4.X, for example, uses GIMPLE (which is a high level IR for SSA
based framework) and later RTL (not the ideal choice, but difficult to
replace.)


Best Regards,
Naveen Sharma

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