Merging identical functions in GCC

[Ross Ridge]

Ross Ridge writes:
>I don't think this is a good idea.  With different compiler options the
>same RTL can generate different assembly instructions.  Consider the case
>of compiling the same function multiple times with different names and
>different CPU architectures selected.  You'd actually want the linker
>to merge the functions that ended up having the same assembly, but not
>the ones with the same RTL but different assembly.

Daniel Berlin writes:
>So basically you are saying if you don't know what you are doing, or
>know you don't want to use it, you shouldn't be using it.

No, and I can't see how how you've came up with such an abusurd
misintepretation of what I said.  As I said clearly and explicity,
the example I gave was where you'd want to use function merging.

>The current hash actually takes into account compiler options as a
>starting value for the hash, btw!)

Well, then that brings up the other problem I have with this, figuring
out exactly which options and which parts of the RTL should be hashed
seems to be too error prone.  I think this is best done by linker which
can much more reliably compare the contents of functions to see if they
are the same.

                                                Ross Ridge