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List:       gcc
Subject:    Re: rtl semantics
From:       Russell Shaw <rjshaw () netspace ! net ! au>
Date:       2004-12-31 17:25:29
Message-ID: 41D58B89.9050707 () netspace ! net ! au
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Ian Lance Taylor wrote:
> Russell Shaw <rjshaw@netspace.net.au> writes:
> 
> 
>>Are the templates in <machine>.md real RTL, or only templates used to generate RTL?
>>Is "RTL" a textual language, or just some C struct?
> 
> 
> I don't think anybody has bothered to define the terms formally.  RTL
> is both a text language and a C struct.  The text language appears in
> the .md files and in debugging dumps.  The C struct is defined in
> rtl.h.  Which one is meant by "RTL" has to be determined by context.
> 
> Note that not all information about the compiled code is represented
> in RTL.
> 
> gcc is not an academic exercise which can be described usefully in
> formal terms.  It is a large untidy body of working code.  RTL is an
> important concept used in various ways to represent the compiled
> program in terms of the instruction set supported by a specific
> processor.
> 
> Besides the internals manual, you may find some helpful hints at the
> gcc wiki:
>     http://www.dberlin.org/gccwiki/

I understand now the format in rtl.def and how the fields are
stripped out with cpp. It makes more sense now after reading some .md files too.
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