Now with patch On Fri, May 11, 2012 at 8:42 PM, Steven Bosscher <stevenb....@gmail.com> wrote: >>>> 2012-05-10 Vladimir Makarov<vmaka...@redhat.com> >>>> >>>> PR rtl-optimization/53125 >>>> * ira.c (ira): Call find_moveable_pseudos and >>>> move_unallocated_pseudos if only ira_conflicts_p is true. > > And the attached patch fixes the reginfo slowness. > > The reginfo pass was doing: > > for each bb: > for each insn in bb, from BB_END(bb) to BB_HEAD(bb): > for each reg that died between BB_END(bb) and insn: // i.e. > register is live at insn > REG_LIVE_LENGTH(reg)++ > > With very large basic blocks, and the kind of code for the test case > of the PR results in many live registers for SPARC (for x86_64 there > are far fewer live registers). For SPARC, there are O(1e5) insns and > O(1e4) registers live for most of the basic block. That is effectively > almost quadratic behavior in the number of insns per basic block. > > But the above loop is a bit silly. It is much easier and > computationally cheaper to just remember at what insn reg died (last > used), and add to REG_LIVE_LENGTH the distance from the insn that sets > reg to the insn that used reg. > > It turns out that (before or after the patch) partial or conditional > sets never kill a register, so that REG_LIVE_LENGTH for registers set > by partial or conditional stores is not very accurate. I have a few > ideas for how to improve that situation a bit, but I'm not sure if > it's worth the trouble. > > I also think that the computation of REG_FREQ and > REG_FREQ_CALLS_CROSSED has been wrong for some time. The maximum > REG_FREQ is REG_FREQ_MAX (see regs.h) but regstat.c just accumulates > REG_FREQ_FROM_BB. I've added a few lines to limit the REG_FREQ to > REG_FREQ_MAX, e.g.: > > REG_FREQ (dregno) += REG_FREQ_FROM_BB (bb); > + REG_FREQ (dregno) = > + MIN (REG_FREQ (dregno), REG_FREQ_MAX); > > With this patch, the reginfo pass disappears from the time report for > the test case attached to PR53125, compiled at -O0. > > Bootstrapped and tested on x86_64-unknown-linux-gnu, and I verified > for a few simple test cases that the computed REG_LIVE_LENGHTs are > unchanged. OK for trunk? > > Ciao! > Steven
regstat_smarter_local_live_v2.diff
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