inlining parameters documentation

[Kurt Garloff <garloff at suse dot de>]

Hi,

I finally took the time to split the pieces of my patches that were not
integrated back in April into gcc-3.

Dale, sorry for taking so long after you pointed me to this problem a 
month ago. It somehow fell off my TODO list.


The first patch does three things:
1. Separate parameter for RTL inlining, max-inline-insns-rtl
    (same default of 600 as max-inline-insns)
2. Initialize max-inline-insns, max-inline-insns-single and
   max-inline-insns-rtl from -finline-limit= parameter
   Also limit min-inline-insns to MIN(130,val/4);
3. Document this.

No.1 is not strictly necessary, but helps to make things more clear, also
for documentation purposes. The missing of No.2 and No.3 from the April
merge should be considered bugs, as Dale correctly insists on.


Second patch does the following:
1. Record whether functions have been inlined because of declaration or
   because of compiler flag.
2. Apply a different limit (max-inline-insns-auto) to the compiler-flag
   inlined ones. Default for limit is same as for normal functions
   (max-inline-limit-single).
3. Document it.

In my opinion the auto-inlining limit should be lower than the inlining
limit for inline-declared functions. For well written code, where authors
thought about using the inline keyword where necessary, -O3 often is a
regression compared to -O2 and using a more restrictive auto-inlining limit
helps this. However, I was reluctant to change the default to not risk any
regressions. A change can easily be done later or introduced at the command
line.


I would propose patch 1 for both gcc-3_2-branch and HEAD and patch 2 only
for HEAD. Both diffs are against HEAD from CVS (a few days old).
The docu patch, that I'd like to go into 3.2 as well, needs some adjustments
to apply to 3.2. I this is deemed useful, I can create and submit a patch
against 3.2 as well.


Code has been tested on two platforms (GNU/Linux-ix86 and -alpha) and has
produced identical binaries, if -finline-limits was not used.
Michael Matz and Gerald Pfeifer have looked at the code and given some
useful feedback. Thanks!


PS: Please Cc: any comments to me.
-- 
Kurt Garloff  <garloff@suse.de>                          Eindhoven, NL
GPG key: See mail header, key servers                        SuSE Labs
SuSE Linux AG, Nuernberg, DE                            SCSI, Security

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