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From: Andrew Pinski <pinskia@physics.uc.edu> To: nobody@gcc.gnu.org Cc: gcc-prs@gcc.gnu.org, Subject: Re: optimization/9566: Inline function produces much worse code than manual inlining. Date: Tue, 15 Apr 2003 00:16:00 -0000 [thread overview] Message-ID: <20030415001601.17348.qmail@sources.redhat.com> (raw) The following reply was made to PR optimization/9566; it has been noted by GNATS. From: Andrew Pinski <pinskia@physics.uc.edu> To: Andrew Pinski <pinskia@physics.uc.edu> Cc: gcc-gnats@gcc.gnu.org, osv@javad.ru, gcc-bugs@gcc.gnu.org, nobody@gcc.gnu.org, gcc-prs@gcc.gnu.org Subject: Re: optimization/9566: Inline function produces much worse code than manual inlining. Date: Mon, 14 Apr 2003 20:12:39 -0400 Actually it is because C++'s this is pointer, so it spills the struct the stack because of it. This g3 is the same as g1. Sorry about the pervious message, I did not look at it too much. struct A { char const* src; char* dest; void copy() { *++dest = *++src; } }; void g1() { A a; for(int i = 0; i < 10; ++i) a.copy(); } void g3() { A a; for(int i = 0; i < 10; ++i) { A *b = &a; *++b->dest = *++b->src; } } A way to fix if the pointer to a local variable is only used for load/store and not used for passing into a function or the pointer does not change, is to remove the pointer and change it to what the pointer points to (this might only be able to do on the ssa-branch). (As a side, it is still bad also on the ssa-branch from `3.5-tree-ssa 20030117`.) Thanks, Andrew Pinski
next reply other threads:[~2003-04-15 0:16 UTC|newest] Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top 2003-04-15 0:16 Andrew Pinski [this message] -- strict thread matches above, loose matches on Subject: below -- 2003-04-14 23:46 Andrew Pinski 2003-02-04 10:26 osv
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