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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/84407] incorrect constant propagation with -frounding-math
Date: Wed, 27 Oct 2021 13:28:16 +0000	[thread overview]
Message-ID: <bug-84407-4-rVHCn58tMY@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-84407-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84407

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
Created attachment 51676
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=51676&action=edit
patch

Testing for exact real-to-int / int-to-real conversions is a bit awkward but
maybe I am missing interesting details in real.c that could be exercised here.

Also a question is the behavior on overflow when converting a real to an
integer (IIRC the behavior here is undefined, but we constant fold to the
largest/smallest integer here).

For integer to float conversions is the overflow considered before or after
applying the rounding?  That is, are there integer values that invoke
undefined behavior when converted to a real dependent on the rounding mode?

  parent reply	other threads:[~2021-10-27 13:28 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <bug-84407-4@http.gcc.gnu.org/bugzilla/>
2021-10-27 13:09 ` rguenth at gcc dot gnu.org
2021-10-27 13:28 ` rguenth at gcc dot gnu.org [this message]
2021-10-27 17:16 ` joseph at codesourcery dot com
2021-10-28  9:29 ` rguenth at gcc dot gnu.org
2021-10-28 13:45 ` cvs-commit at gcc dot gnu.org
2021-10-28 13:46 ` rguenth at gcc dot gnu.org

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