From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg1-x529.google.com (mail-pg1-x529.google.com [IPv6:2607:f8b0:4864:20::529]) by sourceware.org (Postfix) with ESMTPS id 6D2F23858408 for ; Wed, 7 Feb 2024 15:03:04 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 6D2F23858408 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=gmail.com ARC-Filter: OpenARC Filter v1.0.0 sourceware.org 6D2F23858408 Authentication-Results: server2.sourceware.org; arc=none smtp.remote-ip=2607:f8b0:4864:20::529 ARC-Seal: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1707318185; cv=none; b=kgdFFtBIdi9C4oHWs4epTvw8lGy7m45UN/R8mNYLTL5dyXmNsJRHdqdXfXOUyAzDiha1Wj9np44os7PoQkOzmxwnyQBw9HalSu3DQmDFwkr4GUmH1slC+tOc2LKU7lshWb0fomL3h1LVClvDQCQBVd7v3Pube2EOTmlupbud4W4= ARC-Message-Signature: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1707318185; c=relaxed/simple; bh=NM6jIQTZNvJb9j4UseN9G8mwvM2g3wNDEeim169KhgY=; h=DKIM-Signature:MIME-Version:From:Date:Message-ID:Subject:To; b=nR6EwJXpN4T0phdq08wby8n+Jlat9dPLR/U2/QJpuau2nwdWqNR75Fgu8j9dzYWoxNlAlLEKZ1w4q3ELjqW5f2nM2d6zTRFakgRDi3m+lvHwE6PkxlrMlrIT3jCFBRxQyqTa7DDxuoy5n9W0T5rL7HXxOH/o90ydkRSswLFsreg= ARC-Authentication-Results: i=1; server2.sourceware.org Received: by mail-pg1-x529.google.com with SMTP id 41be03b00d2f7-5dbcfa0eb5dso629157a12.3 for ; Wed, 07 Feb 2024 07:03:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1707318183; x=1707922983; darn=gcc.gnu.org; h=to:subject:message-id:date:from:mime-version:from:to:cc:subject :date:message-id:reply-to; bh=i3FnQ8So6VMh2u/W1hYe2KiFesbUFMguihWFLNCZuhc=; b=hjzZG5Zn9usoufpL/0ubTMsLMEQHj65HY8u1yTTjsO11qn8Sx/4Oct37mNjSCt5Kle s9KBbrHecsgFay5CiVCZ8CbKYc3bbiLaFtNdDhrImnEuCo+Tk4NpA9QQQixXN1E1ELbg t2DUFibVTz3PRxlkwsaJWsaXmNrCRpf8ztZz0AlUg76bSpH0KMZ0cniuV/gBXThxKqeZ t8MX+okPTxM+1ACM/pfi1ME3l3iPomZ6NoUxUoF5EmGTDA3Ooz+FX8efz5ugW+4Mz6dK iabEqRurkAS8GdlFAVe89IUmNH71snlseTpiINfqGMVdPcIC1vt/RIBKFxbTI0cSQ0P3 9KEQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1707318183; x=1707922983; h=to:subject:message-id:date:from:mime-version:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=i3FnQ8So6VMh2u/W1hYe2KiFesbUFMguihWFLNCZuhc=; b=Mud1mlOQLu+YxPpp+gQF9b8d+DzElalKmM7eAlfB72QQAokOWGMGJBYbRWwUOjR2aj r7lPUdHL+XZGLmk9FgjZ6TJHVY3lYmU2aKl2RFMHgMxKRiPpcFnmbAyl00Qa5bMbBNdW l+McJlhptZoozmAdsa9K4HZJkOsroD2A9pVT47djIxNkuhUDkkNvkJ/g3MK9Uv3Oj4ds mnZaAq3OQQlcmplu0pPi8qv1sqR5I9VkhGQaisgNgMj36G9dbGiuE4xDBdxvHXzo60GA xVnkBn/q1ETnL2vJ7JqnPwy4TqdR36AM+VIsHROHo55bWs1ei5Rj0gpgvVa/7Zmfj5E3 oU1w== X-Gm-Message-State: AOJu0YyHsOd5/hNFFCzGJp7BSlM5nLk+4FltxN9piz6EAx70upiQausI XAX9lsBUqsbmiX95ZfYMVpLeDfi7PBEzo1pl5YxhJIP/3OAdD3SwolO8nO8hZ3aWFhNwFJuCfPv ZCz7Z0AeztcmA01iFMdShC+wjtQ/303wkGQQ= X-Google-Smtp-Source: AGHT+IHgkYHjZpMiLxwqhoFREH5+I4zFg/GhbiUDqEzGOL7hgxn2H5fuXxxwcHWonNVrkheqhS8GPodjoHSvejPGhiU= X-Received: by 2002:a17:90a:5646:b0:294:a53:4418 with SMTP id d6-20020a17090a564600b002940a534418mr3178172pji.2.1707318183048; Wed, 07 Feb 2024 07:03:03 -0800 (PST) MIME-Version: 1.0 From: Paul Edwards Date: Wed, 7 Feb 2024 23:02:51 +0800 Message-ID: Subject: gcc 3.2.3 x64 negative indexes To: GCC Development Content-Type: multipart/alternative; boundary="000000000000d1bd780610cbfdcc" X-Spam-Status: No, score=0.5 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,HTML_MESSAGE,LOTS_OF_MONEY,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,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: --000000000000d1bd780610cbfdcc Content-Type: text/plain; charset="UTF-8" Hi. I am using a slightly modified gcc 3.2.3 for x86_64 and for this code: int fff(char *x) { return (x[-1]); } It is generating: .globl fff fff: .LFB2: movl $4294967295, %eax movsbl (%rax,%rcx),%eax ret My understanding is that that move of -1 into eax does NOT sign-extend, and thus results in a very high index, which causes a crash. I may have stuffed something up myself. Anyone know which code governs this behavior? Thanks. Paul. --000000000000d1bd780610cbfdcc--