public inbox for gcc-prs@sourceware.org help / color / mirror / Atom feed
From: jkain@nvidia.com To: gcc-gnats@gcc.gnu.org Subject: optimization/10667: Optimizer confused when operating on floats as ints. Date: Wed, 07 May 2003 16:36:00 -0000 [thread overview] Message-ID: <20030507163232.30957.qmail@sources.redhat.com> (raw) >Number: 10667 >Category: optimization >Synopsis: Optimizer confused when operating on floats as ints. >Confidential: no >Severity: critical >Priority: medium >Responsible: unassigned >State: open >Class: sw-bug >Submitter-Id: net >Arrival-Date: Wed May 07 16:36:00 UTC 2003 >Closed-Date: >Last-Modified: >Originator: Joseph Kain >Release: gcc version 3.2.3 >Organization: >Environment: Linux 2.4, i686. >Description: The program below was built as: gcc -v -save-temps -O3 -c -o bug.o bug.c $ gcc -v Reading specs from /home/joseph/t/gcc/lib/gcc-lib/i686-pc-linux-gnu/3.2.3/specs Configured with: ../gcc-3.2.3/configure --prefix=/home/joseph/t/gcc Thread model: posix gcc version 3.2.3 If I examine the assembly output I find that the compiler has completely removed the multiply. Code for the compare is generated but the compare result may be wrong since f.x was never computed. >How-To-Repeat: # 1 "bug.c" # 1 "<built-in>" # 1 "<command line>" # 1 "bug.c" struct vector { float x, y, z, w; }; int func (float f1, float f2) { struct vector f; f.x = f1 * f2; if ((*(int *) &(f.x)) > 0) { return 1; } return 0; } >Fix: >Release-Note: >Audit-Trail: >Unformatted:
next reply other threads:[~2003-05-07 16:36 UTC|newest] Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top 2003-05-07 16:36 jkain [this message] 2003-05-07 17:01 ebotcazou
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=20030507163232.30957.qmail@sources.redhat.com \ --to=jkain@nvidia.com \ --cc=gcc-gnats@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).