From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx07-00178001.pphosted.com (mx07-00178001.pphosted.com [185.132.182.106]) by sourceware.org (Postfix) with ESMTPS id 1FC15385841C for ; Fri, 18 Nov 2022 16:02:01 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 1FC15385841C Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=foss.st.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=foss.st.com Received: from pps.filterd (m0288072.ppops.net [127.0.0.1]) by mx07-00178001.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 2AICAhii015712; Fri, 18 Nov 2022 17:01:59 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=foss.st.com; h=message-id : date : mime-version : subject : to : cc : references : from : in-reply-to : content-type : content-transfer-encoding; s=selector1; bh=eIf2F9E9GG7B5sFIE+yXd2dtNWvKzR9fzpW6gboccdI=; b=XxNMETC3SQTeVScSW0jGAzT+jlWLX8p0qQONbEd/K0ScSlAe8A9g9ULHNEq5HrtRz9V/ 7tX2dlqtAt42ev7Y6H3NyElY0Pl8XsnXPVj2NdyjwNNq4HL6CDaQ85xGkjfIkm2SwQLq 13G4komD7taBw12fdRQkmmX95cwYVwqQY7s8mvQyKItERdwdC1XXcmMdx2oLPZWbTjPg hTierJFKJNOZ+kF1yzEpmUPmieW8gmCYig+FWG9ff7nGO6NZDn0RRL/d5o8xtxftdZdZ 4TQlNuX6AQdJYHf65L/0iv3Ma91Yo8NH9zS3dDHuU1VEnSRwREYBFzE99MGAa2Lzj4/1 hg== Received: from beta.dmz-eu.st.com (beta.dmz-eu.st.com [164.129.1.35]) by mx07-00178001.pphosted.com (PPS) with ESMTPS id 3kx0ph4uw5-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 18 Nov 2022 17:01:59 +0100 Received: from euls16034.sgp.st.com (euls16034.sgp.st.com [10.75.44.20]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id 1B89310003B; Fri, 18 Nov 2022 17:01:55 +0100 (CET) Received: from Webmail-eu.st.com (shfdag1node3.st.com [10.75.129.71]) by euls16034.sgp.st.com (STMicroelectronics) with ESMTP id 1024323C6AA; Fri, 18 Nov 2022 17:01:55 +0100 (CET) Received: from [10.252.28.208] (10.252.28.208) by SHFDAG1NODE3.st.com (10.75.129.71) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.6; Fri, 18 Nov 2022 17:01:51 +0100 Message-ID: <549c9c1f-769e-df9a-6c39-969c1eb7eb06@foss.st.com> Date: Fri, 18 Nov 2022 17:01:50 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.4.2 Subject: Re: [PATCH v2 3/4] gdb: dwarf2 generic implementation for caching function data Content-Language: en-US To: CC: , , Yvan Roux References: <20221118155252.113476-1-torbjorn.svensson@foss.st.com> <20221118155252.113476-4-torbjorn.svensson@foss.st.com> From: Torbjorn SVENSSON In-Reply-To: <20221118155252.113476-4-torbjorn.svensson@foss.st.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.252.28.208] X-ClientProxiedBy: SHFCAS1NODE1.st.com (10.75.129.72) To SHFDAG1NODE3.st.com (10.75.129.71) X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.219,Aquarius:18.0.895,Hydra:6.0.545,FMLib:17.11.122.1 definitions=2022-11-18_04,2022-11-18_01,2022-06-22_01 X-Spam-Status: No, score=-11.8 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,GIT_PATCH_0,NICE_REPLY_A,RCVD_IN_DNSWL_LOW,SPF_HELO_NONE,SPF_PASS,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: Hi, On 2022-11-18 16:52, Torbjörn SVENSSON wrote: > When there is no dwarf2 data for a register, a function can be called > to provide the value of this register. In some situations, it might > not be trivial to determine the value to return and it would cause a > performance bottleneck to do the computation each time. > > This patch allows the called function to have a "cache" object that it > can use to store some metadata between calls to reduce the performance > impact of the complex logic. > > The cache object is unique for each function and frame, so if there are > more than one function pointer stored in the dwarf2_frame_cache->reg > array, then the appropriate pointer will be supplied (the type is not > known by the dwarf2 implementation). > > dwarf2_frame_get_fn_data can be used to retrieve the function unique > cache object. > dwarf2_frame_allocate_fn_data can be used to allocate and retrieve the > function unqiue cache object. > > Signed-off-by: Torbjörn SVENSSON > Signed-off-by: Yvan Roux > --- > gdb/dwarf2/frame.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++ > gdb/dwarf2/frame.h | 20 +++++++++++++++++-- > 2 files changed, 66 insertions(+), 2 deletions(-) > > diff --git a/gdb/dwarf2/frame.c b/gdb/dwarf2/frame.c > index 3f884abe1d5..bff3b706e7e 100644 > --- a/gdb/dwarf2/frame.c > +++ b/gdb/dwarf2/frame.c > @@ -831,6 +831,14 @@ dwarf2_fetch_cfa_info (struct gdbarch *gdbarch, CORE_ADDR pc, > } > > > +struct dwarf2_frame_fn_data > +{ > + struct value *(*fn) (frame_info_ptr this_frame, void **this_cache, > + int regnum); > + void *data; > + struct dwarf2_frame_fn_data* next; > +}; > + > struct dwarf2_frame_cache > { > /* DWARF Call Frame Address. */ > @@ -862,6 +870,8 @@ struct dwarf2_frame_cache > dwarf2_tailcall_frame_unwind unwinder so this field does not apply for > them. */ > void *tailcall_cache; > + > + struct dwarf2_frame_fn_data *fn_data; > }; > > static struct dwarf2_frame_cache * > @@ -1221,6 +1231,44 @@ dwarf2_frame_prev_register (frame_info_ptr this_frame, void **this_cache, > } > } > > +void *dwarf2_frame_get_fn_data (frame_info_ptr this_frame, void **this_cache, > + fn_prev_register fn) > +{ > + struct dwarf2_frame_fn_data *fn_data = nullptr; > + struct dwarf2_frame_cache *cache > + = dwarf2_frame_cache (this_frame, this_cache); > + > + /* Find the object for the function. */ > + for (fn_data = cache->fn_data; fn_data; fn_data = fn_data->next) > + if (fn_data->fn == fn) > + return fn_data->data; > + > + return nullptr; > +} > + > +void *dwarf2_frame_allocate_fn_data (frame_info_ptr this_frame, > + void **this_cache, > + fn_prev_register fn, unsigned long size) > +{ > + struct dwarf2_frame_fn_data *fn_data = nullptr; > + struct dwarf2_frame_cache *cache > + = dwarf2_frame_cache (this_frame, this_cache); > + > + /* First try to find an existing object. */ > + void *data = dwarf2_frame_get_fn_data (this_frame, this_cache, fn); > + if (data) > + return data; > + > + /* No object found, lets create a new instance. */ > + fn_data = FRAME_OBSTACK_ZALLOC (struct dwarf2_frame_fn_data); > + fn_data->fn = fn; > + fn_data->data = frame_obstack_zalloc (size); Since these 2 blocks (fn_data and fn_data->fn) are allocated on the obstack, do we need to release them in dwarf2_frame_dealloc_cache() or just leave them to the generic garbage collection? Kind regards, Torbjörn > + fn_data->next = cache->fn_data; > + cache->fn_data = fn_data; > + > + return fn_data->data; > +} > + > /* Proxy for tailcall_frame_dealloc_cache for bottom frame of a virtual tail > call frames chain. */ > > diff --git a/gdb/dwarf2/frame.h b/gdb/dwarf2/frame.h > index 06c8a10c178..444afd9f8eb 100644 > --- a/gdb/dwarf2/frame.h > +++ b/gdb/dwarf2/frame.h > @@ -66,6 +66,9 @@ enum dwarf2_frame_reg_rule > > /* Register state. */ > > +typedef struct value *(*fn_prev_register) (frame_info_ptr this_frame, > + void **this_cache, int regnum); > + > struct dwarf2_frame_state_reg > { > /* Each register save state can be described in terms of a CFA slot, > @@ -78,8 +81,7 @@ struct dwarf2_frame_state_reg > const gdb_byte *start; > ULONGEST len; > } exp; > - struct value *(*fn) (frame_info_ptr this_frame, void **this_cache, > - int regnum); > + fn_prev_register fn; > } loc; > enum dwarf2_frame_reg_rule how; > }; > @@ -262,4 +264,18 @@ extern int dwarf2_fetch_cfa_info (struct gdbarch *gdbarch, CORE_ADDR pc, > const gdb_byte **cfa_start_out, > const gdb_byte **cfa_end_out); > > + > +/* Allocate a new instance of the function unique data. */ > + > +extern void *dwarf2_frame_allocate_fn_data (frame_info_ptr this_frame, > + void **this_cache, > + fn_prev_register fn, > + unsigned long size); > + > +/* Retrieve the function unique data for this frame. */ > + > +extern void *dwarf2_frame_get_fn_data (frame_info_ptr this_frame, > + void **this_cache, > + fn_prev_register fn); > + > #endif /* dwarf2-frame.h */