From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 112025 invoked by alias); 8 Jul 2015 21:54:09 -0000 Mailing-List: contact jit-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Post: List-Help: List-Subscribe: Sender: jit-owner@gcc.gnu.org Received: (qmail 112009 invoked by uid 89); 8 Jul 2015 21:54:09 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Checked: by ClamAV 0.98.7 on sourceware.org X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.5 required=5.0 tests=AWL,BAYES_00,KAM_LAZY_DOMAIN_SECURITY,RCVD_IN_DNSWL_LOW autolearn=no version=3.3.2 X-Spam-Status: No, score=-1.5 required=5.0 tests=AWL,BAYES_00,KAM_LAZY_DOMAIN_SECURITY,RCVD_IN_DNSWL_LOW autolearn=no version=3.3.2 X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on sourceware.org X-Spam-Level: X-HELO: mail-yk0-f169.google.com X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:date :message-id:subject:from:to:cc:content-type; bh=WiVSY6413+XiO+NMzKGVzefvRR2fHEugWk8pD3li+6E=; b=Wh9iD39tFEDpbDdKxKa7slHQle7jEyC3KAbTYnAyFicHZDbyZb7knRhdtAd4pJLQPr 5XuXMi558h7s4nVZuDFQbbe4F4gIiP8lY3ruAKt1cBzAY2j50fm1XvIY6dbu2PXs6DeO kSfxRogEEGY++whGhJCkrmazeT/U27buIUCNLanG0Zz/1GKSNv4u08mEzacEBnYzKqXP YtGVwn81jTmCM8znL415wPBUrf7t7+VKZQkKvm98AC3ems0POir8/9iEO3U5WKx4g1nq /L+r5IA3F5KwT+WTfAj/xmRYK/MfpQldhzdIWe/CPtZn8IZCFruociY9z5v6QWaOCVnP NhkQ== X-Gm-Message-State: ALoCoQlpw6qG1AuNfVPUscbGyX5AOVnEsAVqggFJkJgMwEHrfqnNUD7R0a49TxQqiudBrzpcmGip MIME-Version: 1.0 X-Received: by 10.13.204.142 with SMTP id o136mr14217182ywd.171.1436392446141; Wed, 08 Jul 2015 14:54:06 -0700 (PDT) In-Reply-To: References: <1436365266.24803.65.camel@surprise> <1436367926.24803.71.camel@surprise> <1436369443.24803.75.camel@surprise> <1436377619.24803.97.camel@surprise> Date: Thu, 01 Jan 2015 00:00:00 -0000 Message-ID: Subject: Re: Filed PR jit/66812 for the code generation issue From: Dibyendu Majumdar To: David Malcolm Cc: jit@gcc.gnu.org Content-Type: text/plain; charset=UTF-8 X-SW-Source: 2015-q3/txt/msg00046.txt.bz2 Apologies I think the previous description of the flow was incorrect. Here is my second attempt (this is doing my head in so I will stop now): 1 [2] LOADNIL 0 0 entry: cl = (struct ravi_LClosure *)L->ci->func->value_.gc; (void)raviV_op_loadnil (L->ci, (int)0, (int)0); Above sets register 0 (local variable IX) to NIL 2 [3] LOADK 1 -1 ; 10 (&L->ci->u.l.base[(int)1])->value_.i = (&cl->p->k[(int)0])->value_.i; (&L->ci->u.l.base[(int)1])->tt_ = (&cl->p->k[(int)0])->tt_; This sets the register at 1 (temporary) to 10. 3 [3] TEST 1 1 4 [3] JMP 0 0 ; to 5 The above two bytecodes go together. This says that if register 1 is true then do JMP else skip JMP. So we get: comparison_0_5 = (&L->ci->u.l.base[(int)1])->tt_ == (int)0; comparison_0_6 = (&L->ci->u.l.base[(int)1])->tt_ == (int)1; comparison_0_7 = (&L->ci->u.l.base[(int)1])->value_.b == (int)0; isfalse_0_4 = comparison_0_5 || comparison_0_6 && comparison_0_7; if (!(isfalse_0_4)) goto OP_TEST_do_jmp_2_8; else goto OP_TEST_do_skip_2_9; Since register 1 is true (ie. not false) we therefore jump to jmp_2_8. OP_TEST_do_jmp_2_8: goto jmp_5_1; jmp_5_1: 5 [3] LOADBOOL 1 0 0 This is setting register 1 to false so we get: (&L->ci->u.l.base[(int)1])->value_.b = (int)0; (&L->ci->u.l.base[(int)1])->tt_ = (int)1; Next instruction is: 6 [3] TEST 1 0 7 [3] JMP 0 1 ; to 9 Now this is saying that if register 1 is false then do JMP else skip JMP. comparison_0_11 = (&L->ci->u.l.base[(int)1])->tt_ == (int)0; comparison_0_12 = (&L->ci->u.l.base[(int)1])->tt_ == (int)1; comparison_0_13 = (&L->ci->u.l.base[(int)1])->value_.b == (int)0; isfalse_0_10 = comparison_0_11 || comparison_0_12 && comparison_0_13; if (!(!(isfalse_0_10))) goto OP_TEST_do_jmp_5_14; else goto OP_TEST_do_skip_5_15; Since we know that register 1 is false as above then the code should do the jump to jmp_5_14: OP_TEST_do_jmp_5_14: goto jmp_9_2; Next we jump to 9_2 which is the start of the return statement. Here we essentially have a repeat of what was in entry block: 9 [3] LOADK 1 -1 ; 10 10 [3] TEST 1 1 11 [3] JMP 0 0 ; to 12 jmp_9_2: (&L->ci->u.l.base[(int)1])->value_.i = (&cl->p->k[(int)0])->value_.i; (&L->ci->u.l.base[(int)1])->tt_ = (&cl->p->k[(int)0])->tt_; comparison_0_17 = (&L->ci->u.l.base[(int)1])->tt_ == (int)0; comparison_0_18 = (&L->ci->u.l.base[(int)1])->tt_ == (int)1; comparison_0_19 = (&L->ci->u.l.base[(int)1])->value_.b == (int)0; isfalse_0_16 = comparison_0_17 || comparison_0_18 && comparison_0_19; if (!(isfalse_0_16)) goto OP_TEST_do_jmp_9_20; else goto OP_TEST_do_skip_9_21; So the JMP is taken and we go to 9_20: OP_TEST_do_jmp_9_20: goto jmp_12_3; jmp_12_3: 12 [3] LOADBOOL 1 0 0 (&L->ci->u.l.base[(int)1])->value_.b = (int)0; (&L->ci->u.l.base[(int)1])->tt_ = (int)1; Above sets the register 1 to false and this is the return value. Next the return instruction begins: L->top = &L->ci->u.l.base[(int)2]; comparison_0_22 = cl->p->sizep > (int)0; if (comparison_0_22) goto OP_RETURN_if_sizep_gt_0_12_23; else goto OP_RETURN_else_sizep_gt_0_12_24;