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Re: I give up.


On Wednesday, October 22, 2003, at 03:55 AM, Jonathan Wilson wrote:
I cant find anything on google about the various RTL functions (like gen_rtx_UNSPEC).

google isn't quite the right tool for this.


I cant find anything in the GCC docs.

Read an memorize them all, that way, you will trivially know everything in them, and you won't have to find much. Seriously though, M-x grep, then '\<unspec\>' doc/*.texi finds 6 hits in 1/2 second or less. And from that, we can read up on unspec and what it does. After you step around in code you want to work in, you start noticing things, like function that start with gen_ usually generate things, what what they generate is given by the rest of the name (and maybe in the arguments). What you see this pattern, you will just know that gen_unspec generates an unspec, and a quick glace at the texi file tells you in rough terms what an unspec is.


Think of them as self-contained black boxes, into which the compiler doesn't peer.

And I cant find anything in the source code for these specific functions (I cant even FIND their code)

Standard technique 3:


Just fire up emacs, type M-x gdb, then gdb cc1, then set a breakpoint just before the area you are interested in, then type step and you can watch it go into the routine you're interested in. Emacs will just pull up the source code for you automagically.

handy gcc specific knowledge:

In time, you realize all source code is in gcc/*.[ch] gcc/config/*.[ch] gcc/config/*/*.[ch] and in the build directory in gcc/*.[ch], and that make TAGS will build an index for you, and M-. in emacs will take you to just about any of them, though not things in the build tree like gen_rtx_UNSPEC.


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