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From: "glisse at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/57742] memset(malloc(n),0,n) -> calloc(n,1) Date: Sun, 23 Feb 2014 18:46:00 -0000 [thread overview] Message-ID: <bug-57742-4-F9hlkiHfIm@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-57742-4@http.gcc.gnu.org/bugzilla/> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57742 Marc Glisse <glisse at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Attachment #30981|0 |1 is obsolete| | Attachment #31003|0 |1 is obsolete| | --- Comment #14 from Marc Glisse <glisse at gcc dot gnu.org> --- Created attachment 32204 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=32204&action=edit New patch This seems to work. It also handles the fortran example from comment #3. With a comment before the new function and a testcase, it will be good to go to gcc-patches. Side note: at -O3, if I provide an inline version of operator new (see PR 59894), it handles std::vector<int>(n). However, I had to provide a simple one (call malloc, if null throw). The one in libsupc++ is way too complicated (2 calls to malloc), and if I refactor it slightly so "malloc" only appears once, I end up with the following. The edge probabilities are strange (malloc fails in 95% of cases?), but mostly we have a PHI node with a single argument which hides the fact that the variables are the same. It is far from the first time I notice this, is there a real reason to keep those unary PHIs, or should we optimize them more aggressively? p_24 = mallocD.1405 (sz_20); if (p_24 == 0B) goto <bb 7>; else goto <bb 11>; ;; succ: 7 [95.5%] (TRUE_VALUE,EXECUTABLE) ;; 11 [4.5%] (FALSE_VALUE,EXECUTABLE) ;; basic block 11, loop depth 0, count 0, freq 349, maybe hot ;; prev block 10, next block 12, flags: (NEW, REACHABLE) ;; pred: 10 [4.5%] (FALSE_VALUE,EXECUTABLE) # PT = { D.16587 } (escaped heap) # ALIGN = 8, MISALIGN = 0 # p_41 = PHI <p_24(10)> # .MEM_42 = VDEF <.MEM_34> MEM[(struct _Vector_baseD.14156 *)p_2(D)]._M_implD.15030._M_startD.15032 = p_41; # PT = { D.16587 } (escaped heap) # ALIGN = 4, MISALIGN = 0 _19 = p_41 + sz_20; # .MEM_44 = VDEF <.MEM_42> MEM[(struct _Vector_baseD.14156 *)p_2(D)]._M_implD.15030._M_end_of_storageD.15034 = _19; # .MEM_8 = VDEF <.MEM_44> # USE = anything # CLB = anything memsetD.1000 (p_41, 0, sz_20);
next prev parent reply other threads:[~2014-02-23 18:46 UTC|newest] Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top 2013-06-27 22:28 [Bug tree-optimization/57742] New: " glisse at gcc dot gnu.org 2013-10-11 16:44 ` [Bug tree-optimization/57742] " glisse at gcc dot gnu.org 2013-10-14 8:55 ` rguenth at gcc dot gnu.org 2013-10-14 9:51 ` Joost.VandeVondele at mat dot ethz.ch 2013-10-14 10:07 ` glisse at gcc dot gnu.org 2013-10-14 10:46 ` rguenth at gcc dot gnu.org 2013-10-14 11:48 ` glisse at gcc dot gnu.org 2013-10-14 20:51 ` glisse at gcc dot gnu.org 2013-10-14 20:53 ` glisse at gcc dot gnu.org 2013-10-15 7:57 ` rguenth at gcc dot gnu.org 2013-10-15 14:11 ` glisse at gcc dot gnu.org 2013-10-15 16:38 ` glisse at gcc dot gnu.org 2013-10-16 14:11 ` rguenth at gcc dot gnu.org 2014-02-22 15:44 ` glisse at gcc dot gnu.org 2014-02-23 18:46 ` glisse at gcc dot gnu.org [this message] 2014-06-24 19:04 ` glisse at gcc dot gnu.org 2014-06-25 6:46 ` Joost.VandeVondele at mat dot ethz.ch 2014-06-25 7:41 ` Joost.VandeVondele at mat dot ethz.ch 2014-06-25 7:53 ` glisse at gcc dot gnu.org 2014-06-25 8:09 ` glisse at gcc dot gnu.org 2014-06-25 12:27 ` glisse at gcc dot gnu.org 2014-06-25 12:29 ` glisse at gcc dot gnu.org 2015-09-17 19:32 ` daniel.gutson at tallertechnologies dot com
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