From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 97EAF2C2374 for ; Mon, 23 Mar 2026 21:15:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774300547; cv=none; b=aPFbx/TmbxfFrK8zkF52RnmJBCyk/71jSPQlP9i0Bpuuonovvxzu8My9K9pg6QCqI+Tmx06z2A3v8Dcql02SRb1HZHyD9OP77tJbiMqUUIG/UymZ9NZXTzk+nB02J3rNwLOPEAEaMKjyk8jSUZ0LfGtHwtubbzCYbf9/lubmjAI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774300547; c=relaxed/simple; bh=BWMjXNQVbhC1oNLwDOKC7aLXCrVRBF+/2eStuT+K+c8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=S/x/0vnZEu2lk0qNv1IuS6AwXEdP4zw+giM53FYhwidDoPcA3CCqSyooamBcqKvSThRrCFFlFBDAUJQJ9Pg5YA2j7NZmgrWkQ9JXswHPswdt+32Z79pKXuFy61QSNMimtzS3umzRCXJjpMgqrvLr+hhNxpPh1widrYfl4oy/OsU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fhvp/WKy; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="fhvp/WKy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3EFACC4CEF7; Mon, 23 Mar 2026 21:15:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774300547; bh=BWMjXNQVbhC1oNLwDOKC7aLXCrVRBF+/2eStuT+K+c8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fhvp/WKynvx8PjtmYiz7Vq2qfrMacC4LfTKQK6dNkiQs1FT1jMDQBxKaAmaH2IWPo dWGH6EitJx3cGq82FCuq/WRPI2QWh//9noZNujZWa6fLlJe4hx9ZXoQFWpSjjvyu+L 34WamdR5tCG+u3t+cFk+kB/FyLzqcFluGUEPmZDsMsmgdRimqhjMjmPBagjx1UcE6L KgspLwNAWnEcrQ/p0+ddmau4am+KY0RYOd72WaQDEud76ygnqeZaZXk2wxh0QRnRJW nld5zSX4trUgc/S504fDFTPOMl+mrrh/v3ErD5GJVHcfUdLrI/BSki3oXvtQy5295Y g0ywHJQ8Km0PA== From: Arnaldo Carvalho de Melo To: Alan Maguire Cc: Jiri Olsa , Clark Williams , Kate Carcia , dwarves@vger.kernel.org, Arnaldo Carvalho de Melo Subject: [PATCH 1/3] dwarf_loader: Initial support for DW_TAG_variant_part Date: Mon, 23 Mar 2026 18:15:31 -0300 Message-ID: <20260323211533.1909029-2-acme@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260323211533.1909029-1-acme@kernel.org> References: <20260323211533.1909029-1-acme@kernel.org> Precedence: bulk X-Mailing-List: dwarves@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Arnaldo Carvalho de Melo Still doesn't handle its sub hierarchy, i.e. the DW_TAG_variant entries and its underlying DW_TAG_member entries. This was noticed when running the regression test that uses a debug build of perf to process a perf.data file and test pahole's pretty printing features, as now perf has a synthetic workload that is written in rust: <0><20c95a>: Abbrev Number: 1 (DW_TAG_compile_unit) <20c95b> DW_AT_producer : (indirect string, offset: 0x4ee5a): clang LLVM (rustc version 1.93.1 (01f6ddf75 2026-02-11) (Fedora 1.93.1-1.fc43)) <20c95f> DW_AT_language : 28 (Rust) <20c961> DW_AT_name : (indirect string, offset: 0x4eeaa): tests/workloads/code_with_type.rs/@/code_with_type.d6e680867bfb8b27-cgu.0 <20c965> DW_AT_stmt_list : 0x5e1ed <20c969> DW_AT_comp_dir : (indirect string, offset: 0x487f1): /home/acme/git/perf-tools/tools/perf <20c96d> DW_AT_low_pc : 0 <20c975> DW_AT_ranges : 0x2d0 ⬢ [acme@toolbx pahole]$ So lets add some scaffolding for the Rust DWARF constructs involved for us to be able to continue using perf with DWARF to test the pretty printing features. Signed-off-by: Arnaldo Carvalho de Melo --- dwarf_loader.c | 26 +++++++++++++++++++++++++- dwarves.c | 6 ++++++ dwarves.h | 7 +++++++ 3 files changed, 38 insertions(+), 1 deletion(-) diff --git a/dwarf_loader.c b/dwarf_loader.c index 16fb7becffee56f6..f0833e8c44a944a8 100644 --- a/dwarf_loader.c +++ b/dwarf_loader.c @@ -508,6 +508,8 @@ static void tag__init(struct tag *tag, struct cu *cu, Dwarf_Die *die) if (tag->tag == DW_TAG_imported_module || tag->tag == DW_TAG_imported_declaration) dwarf_tag__set_attr_type(dtag, type, die, DW_AT_import); + else if (tag->tag == DW_TAG_variant_part) + dwarf_tag__set_attr_type(dtag, type, die, DW_AT_discr); else dwarf_tag__set_attr_type(dtag, type, die, DW_AT_type); @@ -1170,6 +1172,18 @@ static struct template_parameter_pack *template_parameter_pack__new(Dwarf_Die *d return pack; } +static struct variant_part *variant_part__new(Dwarf_Die *die, struct cu *cu, struct conf_load *conf) +{ + struct variant_part *vpart = tag__alloc(cu, sizeof(*vpart)); + + if (vpart != NULL) { + tag__init(&vpart->tag, cu, die); + INIT_LIST_HEAD(&vpart->variants); + } + + return vpart; +} + /* Returns number of locations found or negative value for errors. */ static ptrdiff_t __dwarf_getlocations(Dwarf_Attribute *attr, ptrdiff_t offset, Dwarf_Addr *basep, @@ -1990,9 +2004,19 @@ static int die__process_class(Dwarf_Die *die, struct type *class, case DW_TAG_GNU_template_template_param: #endif case DW_TAG_subrange_type: // XXX: ADA stuff, its a type tho, will have other entries referencing it... - case DW_TAG_variant_part: // XXX: Rust stuff tag__print_not_supported(die); continue; + case DW_TAG_variant_part: { + struct variant_part *vpart = variant_part__new(die, cu, conf); + + if (vpart == NULL) + return -ENOMEM; + + // For rust it seems we have just one, but DWARF, according to Gemini, support having + // more than one DW_TAG_variant_part for a given DW_TAG_structure_type, so future proof it + type__add_variant_part(class, vpart); + continue; + } case DW_TAG_template_type_parameter: { struct template_type_param *ttparm = template_type_param__new(die, cu, conf); diff --git a/dwarves.c b/dwarves.c index ef93239d26827711..efc7ae214376e1c1 100644 --- a/dwarves.c +++ b/dwarves.c @@ -428,6 +428,7 @@ void __type__init(struct type *type) INIT_LIST_HEAD(&type->type_enum); INIT_LIST_HEAD(&type->template_type_params); INIT_LIST_HEAD(&type->template_value_params); + INIT_LIST_HEAD(&type->variant_parts); type->template_parameter_pack = NULL; type->sizeof_member = NULL; type->member_prefix = NULL; @@ -1366,6 +1367,11 @@ void type__add_template_value_param(struct type *type, struct template_value_par list_add_tail(&tvparam->tag.node, &type->template_value_params); } +void type__add_variant_part(struct type *type, struct variant_part *vpart) +{ + list_add_tail(&vpart->tag.node, &type->variant_parts); +} + struct class_member *type__last_member(struct type *type) { struct class_member *pos; diff --git a/dwarves.h b/dwarves.h index d7c64742c29a9e9f..95d84b8ce3a6e95d 100644 --- a/dwarves.h +++ b/dwarves.h @@ -1011,6 +1011,11 @@ static inline struct formal_parameter_pack *tag__formal_parameter_pack(const str void formal_parameter_pack__add(struct formal_parameter_pack *pack, struct parameter *param); +struct variant_part { + struct tag tag; + struct list_head variants; +}; + /* * tag.tag can be DW_TAG_subprogram_type or DW_TAG_subroutine_type. */ @@ -1281,6 +1286,7 @@ struct type { uint8_t is_signed_enum:1; struct list_head template_type_params; struct list_head template_value_params; + struct list_head variant_parts; struct template_parameter_pack *template_parameter_pack; }; @@ -1401,6 +1407,7 @@ static inline struct class_member *class_member__next(struct class_member *membe void type__add_member(struct type *type, struct class_member *member); void type__add_template_type_param(struct type *type, struct template_type_param *ttparm); void type__add_template_value_param(struct type *type, struct template_value_param *tvparam); +void type__add_variant_part(struct type *type, struct variant_part *vpart); struct class_member * type__find_first_biggest_size_base_type_member(struct type *type, -- 2.53.0