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Thu, 18 Jan 2024 01:02:33 -0800 (PST) References: In-Reply-To: From: Fangrui Song Date: Thu, 18 Jan 2024 01:02:22 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: RFC: Formalization of the Intel assembly syntax (PR53929) To: LIU Hao Cc: binutils@sourceware.org, GCC Development Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-TMN: [o9SA9ILBu6VRXfO1XRqicIO09/WkEVlG] X-ClientProxiedBy: SG2P153CA0027.APCP153.PROD.OUTLOOK.COM (2603:1096:4:c7::14) To MN0PR12MB5761.namprd12.prod.outlook.com (2603:10b6:208:374::6) X-Microsoft-Original-Message-ID: MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: MN0PR12MB5761:EE_|SJ0PR12MB7036:EE_ X-MS-Office365-Filtering-Correlation-Id: 5957ba13-090c-4b1d-dee5-08dc1804437e X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?V0xrNjRBK0NENG1JMGp1OWxQOEJwaWJ5amIvWS9WbFh2bXRLN2s2TDdjWS9W?= =?utf-8?B?cEJQeFd5Z0VGTEZoWjZBOGhsWkZBMzZIRko2WnNvb3dxVDRHZE03bHdIbWtM?= =?utf-8?B?WjE0R0VTMS9CenR5cTBMSTYyNVdNVExkRGFTSlFtMVY4MWFwRCs4SXNEdE04?= =?utf-8?B?OEcrdFB1VlA3OFh1aEtZT3FKR1NKdUp6YzdmSHFBY0d6bDVQRkpiT1E1ZGd5?= =?utf-8?B?ZFVqZzlKbHBqSkRmM1JHMlFMc0orbDYyQkpTVWhuU3JLa1JrMGxxMTVXeHFh?= =?utf-8?B?YWVGUFNMTW9PU1lQQXY4LzZOV2RkUnhzL3dsQmRzNnJoWGl4MXdkMmxQZVlG?= =?utf-8?B?Y2RXeVp5YjFwS1lISDR3Y2l1ZUFRdGdrYXhQSVRITVRHN1lwKytockpib0Rx?= =?utf-8?B?emNWS3IxWmgvclJmMGg2MnhrRWZ6Mm92WG9HczJ5b0FLTExkNWxNTUl0b2ps?= =?utf-8?B?bHlPUHI3SmlqVDdDK3NFOU1VZUpoWllJVVN1RGtEWlAzVGovLzlZRlJrc3dW?= =?utf-8?B?UzdVeERuTnBWUkRDdWU5WU1QSnY2aExFeUVPeTNscXdCOXUxc0JyeUgrcTdo?= =?utf-8?B?RTBHNEpKcHIyNzJFQmprM1VsaG45OWhWU3FGUGFHNzlaWE1TTWF0V3liZ2Ux?= =?utf-8?B?bnN6TjljUFNTUDlCblVJK2h1TnVlYU9tZnlReEhIMW5FT2FzWVFkM0d1T2JL?= =?utf-8?B?MUdWY0dPbDZMTTJPa3dKUTh4WFNTK1pJZGJPVVE0SkpaNTVFajdVSjh2ekF2?= =?utf-8?B?cmgveGJNM3IwUkJJT1hCSk5NUENvR2VEemsrN1NyZnYxSmtkS3czdWtvOGRz?= =?utf-8?B?bnFxK1lVK09kUEwyODJqTGM5Q3c0YVBvODNaenFrU0xiTGtnbkgzams2U2ND?= =?utf-8?B?OU5QTUtTeldDbGNSN1BCNkNHanhyVzg1ZTdvYi83Vi8wWU9LcVBOWUZCUFp6?= =?utf-8?B?dkloSW5JeEVvQXh4NWxmKzEraU4vSFB3QWN2MDNWVkQrTy9kS1Z4c0dmZ0ph?= =?utf-8?B?K082Z2xxZUJ6Wkt2NWVGNjhnYXhvU0J6ZEhBYVhkRlBXWlJqTWtHQi9ZYVp6?= =?utf-8?B?OXlFdXNsWC9JdnIzSG1PbVhLeHpCS2tNWE8wVHF3RmhUdElWbHRwRGUxeW0v?= =?utf-8?B?Z3BPMkdGRkkvdUFVK2xsRks4RnlTNHVSOEVrWlJpRjRDQ2JocXRSUXVMUjJK?= =?utf-8?B?b2h6clJxZndvdWVGL1FlSnp3bGZldSs1TStnTUpiSC9kYzBkSzA3R0kwNUc4?= =?utf-8?B?Y1JoK1prMlFaSTdFaEVjaFZZWjBBcEJwMkhpWlBRY3ZFYTBLdzBGWEtEb0Np?= =?utf-8?B?YkptNC8rNGgzTlhhRTBBV0JLeEN2YjNDWGRBdXlrREZQZ3Z4R0MvMDlUdUNL?= =?utf-8?B?R2d0S2R1QmN6NnRWWGVIR2lGSUNlQU05UkRubm1uMmMwK1J4TTNVVzNKbUtH?= =?utf-8?B?OVA1OGkrZ2RvS1Y0eTRVY25lQXVnSDhOSnRZbllWcFhvcmVjbXA4QmlNWExI?= =?utf-8?B?UEt4dkZDVEp5L28rZ0NuallqS1lIY2tyaE1pa1cvcTkwa3dCZ0lsNktFSE1p?= =?utf-8?Q?QurK5K0YMTeT2hFSwLaI4jrexLbBqKT2Qvk7cA6ZJJdf7+?= X-OriginatorOrg: sct-15-20-4755-11-msonline-outlook-5183d.templateTenant X-MS-Exchange-CrossTenant-Network-Message-Id: 5957ba13-090c-4b1d-dee5-08dc1804437e X-MS-Exchange-CrossTenant-AuthSource: MN0PR12MB5761.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 18 Jan 2024 09:02:57.4240 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 84df9e7f-e9f6-40af-b435-aaaaaaaaaaaa X-MS-Exchange-CrossTenant-RMS-PersistedConsumerOrg: 00000000-0000-0000-0000-000000000000 X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ0PR12MB7036 X-Spam-Status: No, score=-2.5 required=5.0 tests=BAYES_00,KAM_DMARC_STATUS,KAM_INFOUSMEBIZ,KAM_SHORT,RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H2,SPF_HELO_PASS,SPF_PASS,TXREP,T_SCC_BODY_TEXT_LINE autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On Wed, Jan 17, 2024 at 9:34=E2=80=AFPM LIU Hao wrote: > > Hello, > > There hasn't been an solution to https://gcc.gnu.org/PR53929 since almost= a dozen years ago, mostly > due to compatibility with MASM. I was told that the ambiguity of Intel sy= ntax should be classified > as its own limitation and disrecommendation. > > Notwithstanding, I am proposing a permanent solution to this issue, by ba= nning constructions that > cause ambiguity. This is likely to effect incompatibility with other asse= mblers, but it should make > GAS parse the output of GCC flawlessly. > > > PR53929 contains a known ambiguous construction > > lea rax, bx[rip] > > where `bx` could denote the BX register and causes confusion. The Intel S= oftware Developer Manual > also contains an ambiguous construction > > MOV EBX, RAM_START > > which would look like loading the offset of `RAM_START`. My proposal is t= hat these two constructions > are ambiguous and should be rejected. The compiler should generate assemb= ly in the unambiguous > subset, and we can start to implement the assembler to reject the ambiguo= us ones. > > Their are formalized as > > lea rax, BYTE PTR bx[rip] > mov EBX, DWORD PTR RAM_START > > Roughly speaking, anything after `PTR`/`BCST` (and before `[` if any) is = considered a symbol even if > it matches a keyword; any identifier between `[` and `]` is a register an= d not a symbol. > > > My complete proposal can be found at > . Some ideas actually > reflect the AT&T syntax. I hope it helps. Thanks for the proposal. I hope that -masm=3Dintel becomes more useful:) Do you have a list of assembly in the unambiguous cases that fail to be parsed today as a gas PR? For example, % as -msyntax=3Dintel -mnaked-reg <<< 'lea rax, BYTE PTR bxx[rip]' -o a.o && objdump -d -M intel a.o | grep -A1 '>:' 0000000000000000 <.text>: 0: 48 8d 05 00 00 00 00 lea rax,[rip+0x0] # 0x7 % as -msyntax=3Dintel -mnaked-reg <<< 'lea rax, BYTE PTR bx[rip]' -o a.o && objdump -d -M intel a.o | grep -A1 '>:' {standard input}: Assembler messages: {standard input}:1: Error: invalid use of register % as -msyntax=3Dintel -mnaked-reg <<< 'mov EBX, DWORD PTR ebx' -o a.o {standard input}: Assembler messages: {standard input}:1: Error: invalid use of register