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From: Sebastian Pop <sebpop@gmail.com> To: gcc-bugzilla@gcc.gnu.org Cc: gcc-bugs@gcc.gnu.org Subject: Re: [Bug middle-end/42512] [4.5 Regression] integer wrong code bug with loop Date: Fri, 08 Jan 2010 17:55:00 -0000 [thread overview] Message-ID: <cb9d34b21001080954y6f28c8del6f673b02774987@mail.gmail.com> (raw) In-Reply-To: <20100108172139.25590.qmail@sourceware.org> > Ok, I have that fixed locally at the place of the patch but I wonder if > initial_condition () shouldn't return for example > > 1ul for (unsigned long) { 1, +, 1 }_1 > This is correct. > and > > (int) i_2 for (int) { i_2, +, 1 }_1 > > and further (for short i_2) > > i_2 for (short) { (int) { i_2, +, 1 }_2, +, 1 }_1 > > ? Can the latter two happen all? Yes, these could happen, and you are right, we should see the initial value of a chrec through the type conversion lenses. > Is it even correct to talk about a > general initial condition in this case? Consider > > { { 1, +, 1 }_2, +, 1 }_1 > > initial_condition will return 1 for the chrec even though that is not > correct because the initial condition is not constant in loop 1. If you want, there is an initial condition for the loop_1 and that would be {1, +, 1}_2, and there is an initial condition 1 for loop nest loop_2: loop_2 i = loop_2_phi (0, i+1) = {1, +, 1}_2 loop_1 j = loop_1_phi (i, j+1) = {{1, +, 1}_2, +, 1}_1 > I suppose I'd only see that if instantiating the chrec at the point > where I placed the fix? So I really only see at most a single outer > conversion around the chrec? Yes, I think that at most you can have only one conversion around a chrec.
next prev parent reply other threads:[~2010-01-08 17:55 UTC|newest] Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top 2009-12-26 19:27 [Bug c/42512] New: possible integer wrong code bug regehr at cs dot utah dot edu 2009-12-26 20:00 ` [Bug middle-end/42512] [4.5 Regression] integer wrong code bug with loop jakub at gcc dot gnu dot org 2009-12-26 22:13 ` hjl dot tools at gmail dot com 2009-12-26 22:16 ` hjl dot tools at gmail dot com 2009-12-27 14:43 ` ebotcazou at gcc dot gnu dot org 2010-01-08 14:07 ` rguenth at gcc dot gnu dot org 2010-01-08 15:00 ` rguenth at gcc dot gnu dot org 2010-01-08 16:20 ` spop at gcc dot gnu dot org 2010-01-08 16:53 ` rguenth at gcc dot gnu dot org 2010-01-08 17:07 ` rguenth at gcc dot gnu dot org 2010-01-08 17:21 ` rguenth at gcc dot gnu dot org 2010-01-08 17:55 ` Sebastian Pop [this message] 2010-01-08 17:55 ` sebpop at gmail dot com 2010-01-09 12:04 ` rguenth at gcc dot gnu dot org 2010-01-09 12:04 ` rguenth at gcc dot gnu dot org 2010-02-07 4:49 ` hjl at gcc dot gnu dot org [not found] <bug-42512-4@http.gcc.gnu.org/bugzilla/> 2022-10-25 11:40 ` cvs-commit at gcc dot gnu.org
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