Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752401AbcDSAZy (ORCPT ); Mon, 18 Apr 2016 20:25:54 -0400 Received: from mailapp01.imgtec.com ([195.59.15.196]:58524 "EHLO mailapp01.imgtec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751451AbcDSAZx (ORCPT ); Mon, 18 Apr 2016 20:25:53 -0400 Date: Tue, 19 Apr 2016 01:25:38 +0100 From: "Maciej W. Rozycki" To: Ralf Baechle , Matthew Fortune CC: "Maciej W. Rozycki" , kbuild test robot , Paul Burton , , Subject: Re: {standard input}:136: Error: number (0x9000000080000000) larger than 32 bits In-Reply-To: Message-ID: References: <201604170836.kTyP1sCY%fengguang.wu@intel.com> <20160417011926.GA4014@linux-mips.org> <20160418133449.GB24051@linux-mips.org> <20160418155440.GC24051@linux-mips.org> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" X-Originating-IP: [10.20.78.14] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1464 Lines: 37 On Mon, 18 Apr 2016, Maciej W. Rozycki wrote: > The thing is that to match some software's (such as ours) requirements an > ISA override -- as a side effect -- relaxes ABI restrictions on certain > operations. E.g. the DLI macro and its 64-bit immediate argument are not > valid in the o32 ABI. When no actual override happens, such as with > `-march=r4600' which already implies `mips3' for the ISA, the side effect > is lost: > > /* The use of .set [arch|cpu]= historically 'fixes' the width of gp and fp > registers based on what is supported by the arch/cpu. */ > if (mips_opts.isa != prev_isa) It's worse yet actually, as operations such as `.set pop' and `.set mips0' may not restore the ABI restrictions, possibly leading to wrong code generation elsewhere, generally in handcoded assembly only. This can be illustrated with a program like: .set push .set mips3 dli $2, 0x9000000080000000 .set mips0 dli $2, 0x9000000080000000 .set mips3 .set pop dli $2, 0x9000000080000000 -- try building it with `-mips3' and `-mips4' to see how it fails or succeeds to assemble all the three DLI macros respectively, where it is supposed to succeed with the first macro only and fail with the other two in both cases. I have a fix in the works and to have it integrated upstream I just need to accompany it with suitable cases -- like the fragment above -- for the GAS testsuite. I'll send an update when it's ready. Maciej