public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
From: "wilbert at jdg dot info" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c/35885] New: unsinged long long and while loop evaluation regression? Date: Wed, 09 Apr 2008 10:33:00 -0000 [thread overview] Message-ID: <bug-35885-16037@http.gcc.gnu.org/bugzilla/> (raw) The following program: #include <stdio.h> int main(int argc, char **argv) { unsigned int testu32a = 0x506f85f; unsigned long long testu64a = 0x9afa246709018f48ULL; printf("before: testu64a = %08x%08x, testu32a = %08x\n", (unsigned int)( testu64a >> 32 ), (unsigned int)( testu64a & 0xffffffff ), testu32a ); while ((unsigned long long)testu32a * (unsigned long long)0xffffffff < testu64a) testu64a /= 2; printf("after: testu64a = %08x%08x, testu32a = %08x\n", (unsigned int)( testu64a >> 32 ), (unsigned int)( testu64a & 0xffffffff ), testu32a ); return 0; } When compiled under freebsd 6 using "gcc -o test test.c" gives different results when using gcc 3.4.4 or gcc 4.2.4: Using 3.4.4: before: testu64a = 9afa246709018f48, testu32a = 0506f85f after: testu64a = 04d7d12338480c7a, testu32a = 0506f85f Using 4.2.4: before: testu64a = 9afa246709018f48, testu32a = 0506f85f after: testu64a = 9afa246709018f48, testu32a = 0506f85f The behavior of 4.2.4 has also been seen on a linux gentoo machine running gcc 4.1.2, a 64bit xp machine running gcc 4.2.1, and a regular xp machine running gcc 4.2.1. -- Summary: unsinged long long and while loop evaluation regression? Product: gcc Version: 4.2.4 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: wilbert at jdg dot info GCC build triplet: several GCC host triplet: several GCC target triplet: several http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35885
next reply other threads:[~2008-04-09 10:33 UTC|newest] Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top 2008-04-09 10:33 wilbert at jdg dot info [this message] 2008-04-09 13:06 ` [Bug c/35885] unsigned " rguenth at gcc dot gnu dot org 2008-04-09 15:37 ` wilbert at jdg dot info 2008-04-12 0:46 ` wilson at tuliptree dot org 2008-04-12 3:11 ` [Bug middle-end/35885] " pinskia at gcc dot gnu dot org 2008-04-15 0:26 ` wilson at gcc dot gnu dot org 2009-03-31 16:07 ` [Bug middle-end/35885] [4.3/4.4/4.5 Regression] " jsm28 at gcc dot gnu dot org 2009-04-01 8:19 ` jakub at gcc dot gnu dot org
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=bug-35885-16037@http.gcc.gnu.org/bugzilla/ \ --to=gcc-bugzilla@gcc.gnu.org \ --cc=gcc-bugs@gcc.gnu.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).