From patchwork Thu Jun 11 19:43:56 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Bonzini X-Patchwork-Id: 11600747 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 907C013B1 for ; Thu, 11 Jun 2020 20:26:34 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 62F1C20720 for ; Thu, 11 Jun 2020 20:26:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="KW3y33LL" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 62F1C20720 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:45248 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jjTmT-0007xS-If for patchwork-qemu-devel@patchwork.kernel.org; Thu, 11 Jun 2020 16:26:33 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:55098) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jjT92-000860-64 for qemu-devel@nongnu.org; Thu, 11 Jun 2020 15:45:48 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:44893 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jjT8y-00017q-Hk for qemu-devel@nongnu.org; Thu, 11 Jun 2020 15:45:47 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1591904743; 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: in-reply-to:in-reply-to:references:references; bh=PixQXutwcGEY5jlx8dUr7LAWNxKmNvIVWkqYGwJzOgI=; b=KW3y33LL9Yodz1KZb/Ks+Cjwft9TZ95PWZmoWDHUL8EPK3n3KoSSVDzLqoj8naT8lCHWSN pNT47L1M3crl/bKnbseOYTX9XbX7mkAPJY4xTkjD0mwD4i0x4Szn7C4Q4aPjS+wgfoF5Gr T2RNoKopQxtZ27PuQJbMz3hqFaS7imU= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-295-AUEd9WlAOrWLVLnWeRo31Q-1; Thu, 11 Jun 2020 15:45:41 -0400 X-MC-Unique: AUEd9WlAOrWLVLnWeRo31Q-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 7CB191800D41; Thu, 11 Jun 2020 19:45:40 +0000 (UTC) Received: from virtlab701.virt.lab.eng.bos.redhat.com (virtlab701.virt.lab.eng.bos.redhat.com [10.19.152.228]) by smtp.corp.redhat.com (Postfix) with ESMTP id 0FCDB61169; Thu, 11 Jun 2020 19:45:39 +0000 (UTC) From: Paolo Bonzini To: qemu-devel@nongnu.org Subject: [PULL 062/115] target/i386: fix fbstp handling of negative zero Date: Thu, 11 Jun 2020 15:43:56 -0400 Message-Id: <20200611194449.31468-63-pbonzini@redhat.com> In-Reply-To: <20200611194449.31468-1-pbonzini@redhat.com> References: <20200611194449.31468-1-pbonzini@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=207.211.31.120; envelope-from=pbonzini@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/11 08:37:10 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Joseph Myers Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" From: Joseph Myers The fbstp implementation stores +0 when the rounded result should be -0 because it compares an integer value with 0 to determine the sign. Fix this by checking the sign bit of the operand instead. Signed-off-by: Joseph Myers Message-Id: Signed-off-by: Paolo Bonzini --- target/i386/fpu_helper.c | 5 ++++- tests/tcg/i386/test-i386-fbstp.c | 25 +++++++++++++++++++++++++ 2 files changed, 29 insertions(+), 1 deletion(-) create mode 100644 tests/tcg/i386/test-i386-fbstp.c diff --git a/target/i386/fpu_helper.c b/target/i386/fpu_helper.c index 185493db8e..f0a57099ca 100644 --- a/target/i386/fpu_helper.c +++ b/target/i386/fpu_helper.c @@ -726,11 +726,14 @@ void helper_fbst_ST0(CPUX86State *env, target_ulong ptr) int v; target_ulong mem_ref, mem_end; int64_t val; + CPU_LDoubleU temp; + + temp.d = ST0; val = floatx80_to_int64(ST0, &env->fp_status); mem_ref = ptr; mem_end = mem_ref + 9; - if (val < 0) { + if (SIGND(temp)) { cpu_stb_data_ra(env, mem_end, 0x80, GETPC()); val = -val; } else { diff --git a/tests/tcg/i386/test-i386-fbstp.c b/tests/tcg/i386/test-i386-fbstp.c new file mode 100644 index 0000000000..d368949188 --- /dev/null +++ b/tests/tcg/i386/test-i386-fbstp.c @@ -0,0 +1,25 @@ +/* Test fbstp instruction. */ + +#include +#include + +int main(void) +{ + int ret = 0; + unsigned char out[10]; + memset(out, 0xfe, sizeof out); + __asm__ volatile ("fbstp %0" : "=m" (out) : "t" (-0.0L) : "st"); + out[9] &= 0x80; + if (memcmp(out, "\0\0\0\0\0\0\0\0\0\x80", sizeof out) != 0) { + printf("FAIL: fbstp -0\n"); + ret = 1; + } + memset(out, 0x12, sizeof out); + __asm__ volatile ("fbstp %0" : "=m" (out) : "t" (-0.1L) : "st"); + out[9] &= 0x80; + if (memcmp(out, "\0\0\0\0\0\0\0\0\0\x80", sizeof out) != 0) { + printf("FAIL: fbstp -0.1\n"); + ret = 1; + } + return ret; +}