LTO and the inlining of functions only called once.

[Toon Moene]

Richard Guenther wrote:

> It'll be in /tmp and named after the first object file, in your case it will
> be ccGGS24.o.047i.inline (because the first object file will be a
> tempfile).  A minor inconvenience that maybe is going to be fixed.

Now that Richard has pointed out to me where the info is, I can post it 
here.  This are the inlining decision on my mini-example (just 5 
subroutines and a "main"):

gemini.f  hlprog.f  main.f  phcall.f  phtask.f  sl2tim.f


Reclaiming functions:
Deciding on inlining.  Starting with size 45477.

Inlining always_inline functions:

Deciding on smaller functions:
Considering inline candidate phcall_.clone.3.
Inlining failed: --param max-inline-insns-auto limit reached
Considering inline candidate phtask_.clone.2.
Inlining failed: --param max-inline-insns-auto limit reached
Considering inline candidate gemini_.clone.1.
Inlining failed: --param max-inline-insns-auto limit reached
Considering inline candidate sl2tim_.clone.0.
Inlining failed: --param max-inline-insns-auto limit reached
Considering inline candidate hlprog.
Inlining failed: --param max-inline-insns-auto limit reached

Deciding on functions called once:

Considering gemini_.clone.1 size 11443.
  Called once from hlprog 462 insns.
  Inlined into hlprog which now has 10728 size for a net change of 
-12620 size.

Considering hlprog size 10728.
  Called once from main 7 insns.
  Inline limit reached, not inlined.

Inlined 1 calls, eliminated 1 functions, size 45477 turned to 32857 size.


The mistake made here is that *all* the above functions are "called 
once", but only GEMINI is considered for some reason (probably simply 
because it's the first one ?).

Jan, if you're interested, I can send you the mini-example so that you 
can see for yourself.

HLPROG calls GEMINI, which calls SL2TIM, which calls PHCALL, which calls 
PHTASK (all "only-once calls").

-- 
Toon Moene - e-mail: toon@moene.org - phone: +31 346 214290
Saturnushof 14, 3738 XG  Maartensdijk, The Netherlands
At home: http://moene.org/~toon/
Progress of GNU Fortran: http://gcc.gnu.org/gcc-4.5/changes.html