From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 123860 invoked by alias); 7 Mar 2015 00:22:41 -0000 Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org Received: (qmail 123794 invoked by uid 48); 7 Mar 2015 00:22:38 -0000 From: "hubicka at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/44563] GCC uses a lot of RAM when compiling a large numbers of functions Date: Sat, 07 Mar 2015 00:22:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: tree-optimization X-Bugzilla-Version: 4.3.4 X-Bugzilla-Keywords: compile-time-hog, memory-hog X-Bugzilla-Severity: normal X-Bugzilla-Who: hubicka at gcc dot gnu.org X-Bugzilla-Status: NEW X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-SW-Source: 2015-03/txt/msg00771.txt.bz2 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=44563 --- Comment #14 from Jan Hubicka --- Yeah, this is the old problem that after each inline we recompute the size of the whole function inlined into. This means walking the whole inline tree and sum size of all non-inlined call sites. If you get very many functions inlined into single caller, the nonlinearity kicks in. Here the main() function calls 65536 empty functions that takes time to process. My plan is to turn the sizes/times to sreal and then update them incrementally (subtract size of the call statement and account changes). With old fixed point+capping this did not work well and I always ended up with too many of misaccounting issues. This is however more intrussive then what I would like to do in stage3. I did not completed the sreal conversion because sreal class came bit too late in this development cycle. Have unfinished patch for that but it is >100K and hits interestin problems like gengtype not understanding sreal.h header. I will perf it and check for micro-optimization possibilities.