public inbox for gcc-patches@gcc.gnu.org
 help / color / mirror / Atom feed
From: Aldy Hernandez <aldyh@redhat.com>
To: GCC patches <gcc-patches@gcc.gnu.org>
Cc: Richard Biener <richard.guenther@gmail.com>,
	Andrew MacLeod <amacleod@redhat.com>,
	Aldy Hernandez <aldyh@redhat.com>
Subject: [COMMITTED] [PR106967] Set known NANs to undefined for flag_finite_math_only.
Date: Wed, 21 Sep 2022 13:30:40 +0200	[thread overview]
Message-ID: <20220921113039.2173181-1-aldyh@redhat.com> (raw)

Richard, this is what you suggested.  Thanks.

Explicit NANs in the IL can be treated as undefined for
flag_finite_math_only.  This causes all the right things to happen wrt
threading, folding, etc.  It also saves us special casing throughout.

It occurs to me that we should do something similar for infinities for
-ffinite-math-only.  That is, drop them to the min/max representable
numbers, and adjust everything (including VARYING endpoints)
accordingly.  Furthermore, we should saturate to min/max representable
in the setter, so (upcoming) binary operators don't have to worry about
going over min/max.

Sigh...floating point... the gift that keeps on giving.

gcc/ChangeLog:

	* value-range.cc (frange::set): Set known NANs to undefined for
	flag_finite_math_only.
---
 gcc/value-range.cc | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/gcc/value-range.cc b/gcc/value-range.cc
index 505eb9211a7..7e8028eced2 100644
--- a/gcc/value-range.cc
+++ b/gcc/value-range.cc
@@ -313,8 +313,13 @@ frange::set (tree min, tree max, value_range_kind kind)
       gcc_checking_assert (real_identical (TREE_REAL_CST_PTR (min),
 					   TREE_REAL_CST_PTR (max)));
       tree type = TREE_TYPE (min);
-      bool sign = real_isneg (TREE_REAL_CST_PTR (min));
-      set_nan (type, sign);
+      if (HONOR_NANS (type))
+	{
+	  bool sign = real_isneg (TREE_REAL_CST_PTR (min));
+	  set_nan (type, sign);
+	}
+      else
+	set_undefined ();
       return;
     }
 
-- 
2.37.1


                 reply	other threads:[~2022-09-21 11:33 UTC|newest]

Thread overview: [no followups] expand[flat|nested]  mbox.gz  Atom feed

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=20220921113039.2173181-1-aldyh@redhat.com \
    --to=aldyh@redhat.com \
    --cc=amacleod@redhat.com \
    --cc=gcc-patches@gcc.gnu.org \
    --cc=richard.guenther@gmail.com \
    /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: link
Be 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).