From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by sourceware.org (Postfix) with ESMTPS id 504563858CDA for ; Mon, 5 Sep 2022 13:47:16 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 504563858CDA Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1662385636; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=qRqrbCxpwtx5hLvWpJLYi+KQNOXSP7M35YblJw8hCxg=; b=QAl1YPc2OULzYd8E62iHwXXQiAAslCA8ZdwDKty/S76Prt+NfGREqObtVLBP1++1LO+8En aQbBphQDBuxIXlapPz4nB1lVLeV4bvPckxmMFfwi7yzACUeqRAyFeN1qzUaVWOGugobSSf 1iiPKgmBKZFOWtP+N2Kcs5k/mv1Wrbw= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-127-fi7sSmyQMgiyT4RUFPcghg-1; Mon, 05 Sep 2022 09:47:10 -0400 X-MC-Unique: fi7sSmyQMgiyT4RUFPcghg-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 6121629AB406 for ; Mon, 5 Sep 2022 13:47:10 +0000 (UTC) Received: from abulafia.quesejoda.com (unknown [10.39.195.195]) by smtp.corp.redhat.com (Postfix) with ESMTPS id EEF1A2166B26; Mon, 5 Sep 2022 13:47:09 +0000 (UTC) Received: from abulafia.quesejoda.com (localhost [127.0.0.1]) by abulafia.quesejoda.com (8.17.1/8.17.1) with ESMTPS id 285Dl71A3330872 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Mon, 5 Sep 2022 15:47:07 +0200 Received: (from aldyh@localhost) by abulafia.quesejoda.com (8.17.1/8.17.1/Submit) id 285Dl7KG3330871; Mon, 5 Sep 2022 15:47:07 +0200 From: Aldy Hernandez To: GCC patches Cc: Jakub Jelinek , Andrew MacLeod , Aldy Hernandez Subject: [PATCH] Decimal floats can never be an frange::singleton_p. Date: Mon, 5 Sep 2022 15:47:01 +0200 Message-Id: <20220905134701.3330685-1-aldyh@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="US-ASCII"; x-default=true X-Spam-Status: No, score=-12.3 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,GIT_PATCH_0,RCVD_IN_DNSWL_LOW,SPF_HELO_NONE,SPF_NONE,TXREP,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: As Jakub mentioned in the PR, because many numbers have multiple possible representations, we can't reliably return true here. I'll commit this if tests pass. I wonder if its worth even handling decimal floats in frange, since there's a lot of things we can't represent. I suppose even though we could never propagate an actual value with VRP, we could fold conditionals (symbolic and stuff outside ranges, etc) ??. Thoughts? PR middle-end/106831 gcc/ChangeLog: * value-range.cc (frange::singleton_p): Return false for DECIMAL_FLOAT_TYPE_P. --- gcc/value-range.cc | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/gcc/value-range.cc b/gcc/value-range.cc index c3f668a811a..12a3750d078 100644 --- a/gcc/value-range.cc +++ b/gcc/value-range.cc @@ -647,6 +647,14 @@ frange::singleton_p (tree *result) const if (HONOR_NANS (m_type) && !get_nan ().no_p ()) return false; + // Because the significand is not normalized (there is no + // implicit leading "1"). Most values with less than 7 + // significant digits have multiple possible representations. + // Zero has 192 possible representations (or twice that for + // signed zeros). + if (DECIMAL_FLOAT_TYPE_P (m_type)) + return false; + // Return the appropriate zero if known. if (HONOR_SIGNED_ZEROS (m_type) && zero_p ()) { -- 2.37.1