> -----Original Message----- > From: Jan Hubicka <hubi...@kam.mff.cuni.cz> > This is interesting idea. Basically we want to guess if inlining will > make SRA and or strore->load propagation possible. I think the > solution using INLINE_HINT may be bit too trigger happy, since it is very > common that this happens and with -O3 the hints are taken quite sriously. > > We already have mechanism to predict this situaiton by simply expeciting > that stores to addresses pointed to by function parameter will be > eliminated by 50%. See eliminated_by_inlining_prob. > > I was thinking that we may combine it with a knowledge that the parameter > points to caller local memory (which is done by llvm's > heuristics) which can be added to IPA predicates. > > The idea of checking that the actual sotre in question is paired with load at > caller side is bit harder: one needs to invent representation for such > conditions. So I wonder how much extra help we need for critical inlning to > happen at imagemagics?
Hi Honza, Really appreciate for the feedback. I found that eliminated_by_inlining_prob does eliminated the stmt 50% of the time, but the gap is still big. SRA cannot split callee's parameter for "Do not decompose non-BLKmode parameters in a way that would create a BLKmode parameter. Especially for pass-by-reference (hence, pointer type parameters), it's not worth it." Critical inline function information Caller: GetVirtualPixelsFromNexus size: 541 time: 484.08 e->freq: 0.83 Callee: SetPixelCacheNexusPixels nonspec time: 46.60 time : 36.18 size: 87 Since the insns number 87 of callee function is bigger than inline_insns_auto (30) and there is no hint, so inline depends on "big_speedup_p (e)". 484.08 (caller_time) * 0.15 (param_inline_min_speedup == 15) = 72.61, which means callee's time should be at least 72.61, but callee's time is 46.60, so we need to lower param_inline_min_speedup to 3 or 4. I checked the history(https://gcc.gnu.org/bugzilla/show_bug.cgi?format=multiple&id=83665), that you tried changing it to 8, but that increases the gzip code size by 2.5KB. so I want to add a heuristic hit for it. Thanks, Lili. > > Honza
