From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from simark.ca by simark.ca with LMTP id Qf7QJ0m5jmks3jgAWB0awg (envelope-from ) for ; Fri, 13 Feb 2026 00:40:25 -0500 Authentication-Results: simark.ca; dkim=pass (2048-bit key; unprotected) header.d=polymtl.ca header.i=@polymtl.ca header.a=rsa-sha256 header.s=oct2025 header.b=sLqgxNkW; dkim-atps=neutral Received: by simark.ca (Postfix, from userid 112) id 9ECB51E0BA; Fri, 13 Feb 2026 00:40:25 -0500 (EST) X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-25) on simark.ca X-Spam-Level: X-Spam-Status: No, score=-2.4 required=5.0 tests=ARC_SIGNED,ARC_VALID,BAYES_00, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED,RCVD_IN_VALIDITY_CERTIFIED_BLOCKED, RCVD_IN_VALIDITY_RPBL_BLOCKED,RCVD_IN_VALIDITY_SAFE_BLOCKED autolearn=ham autolearn_force=no version=4.0.1 Received: from vm01.sourceware.org (vm01.sourceware.org [38.145.34.32]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by simark.ca (Postfix) with ESMTPS id 7FA021E089 for ; Fri, 13 Feb 2026 00:40:24 -0500 (EST) Received: from vm01.sourceware.org (localhost [127.0.0.1]) by sourceware.org (Postfix) with ESMTP id E92774B9DB77 for ; Fri, 13 Feb 2026 05:40:23 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org E92774B9DB77 Authentication-Results: sourceware.org; dkim=pass (2048-bit key, unprotected) header.d=polymtl.ca header.i=@polymtl.ca header.a=rsa-sha256 header.s=oct2025 header.b=sLqgxNkW Received: from smtp.polymtl.ca (smtp.polymtl.ca [132.207.4.11]) by sourceware.org (Postfix) with ESMTPS id 55DF64BA23FE for ; Fri, 13 Feb 2026 05:39:22 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 55DF64BA23FE Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=polymtl.ca Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=polymtl.ca ARC-Filter: OpenARC Filter v1.0.0 sourceware.org 55DF64BA23FE Authentication-Results: server2.sourceware.org; arc=none smtp.remote-ip=132.207.4.11 ARC-Seal: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1770961162; cv=none; b=NUXQdZrHjPe/NSHiy2qQqLERGlrpBFfZ2oLK8tH16bqfsXSI2wCInj/wRUuBwjz/CkbjF4H541qn5OAJQoUGZtMdqcqW3sPcSUdAmIPkPYVrVHhtL89PzOvzqtqZ03/bxAu65RNhw/awWieLAnUDYu7awnTFJAVWW6fH62emNI4= ARC-Message-Signature: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1770961162; c=relaxed/simple; bh=DKHSB9YATa+IzHy0qfU0nu7RvRaXhGmuEIa51Rhicfg=; h=DKIM-Signature:From:To:Subject:Date:Message-ID:MIME-Version; b=Zf34aFYXwqH+l3DkYwg70t8eUBFtpVc7vz/GPeOrp49bIt/HXuWEYGoHqjHnjapryMEXXZ84IO06iGSj6UO4EokEsd0U6dN4UBDx9POYVaQnTHyiH0VUt4gML3yeQ35Wi9/fR7ibJneIK9VB9c90rLfJK8EmqibOSwJYSVUucf0= ARC-Authentication-Results: i=1; server2.sourceware.org DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 55DF64BA23FE Received: from simark.ca (simark.ca [158.69.221.121]) (authenticated bits=0) by smtp.polymtl.ca (8.14.7/8.14.7) with ESMTP id 61D5dFrd014807 (version=TLSv1/SSLv3 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 13 Feb 2026 00:39:20 -0500 DKIM-Filter: OpenDKIM Filter v2.11.0 smtp.polymtl.ca 61D5dFrd014807 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=polymtl.ca; s=oct2025; t=1770961160; bh=n/HHBpJnoG/Hb4z5GKEdMtOi3REKW+9KKBzLW6mOmJ4=; h=From:To:Cc:Subject:Date:In-Reply-To:From; b=sLqgxNkWqGm53uKz9UTwJaFcYDOmkXr9RYvYRbWQjOoDJbkTCEJZ1k+fMcZ8aM/r0 kHzHF+n289Q7bYtySgqL9ZnnLY9fr2waaDUSDUH4rigbWPG3pusCio3whjLqNt6YVh TRopPfbBxRH3EsWA5xb00hGaphoij5KTZVNIMRppe71VUjV+CoF0WmRZuBBUZCNXsC T6mY6DdVxipBUk6li5aRRPd/rcvkyFA1sAf+Pg5VW+IySUbT0b25kiLDWtZfv0nc5Z sfep3tJuANEi2sjk+sS6ZcwG8MJgMfU3hytqddlbnF45YUtI5sp4ymZVwCMXsYngqx zg/+ZR+TDv2yA== Received: by simark.ca (Postfix) id 994511E0BA; Fri, 13 Feb 2026 00:39:15 -0500 (EST) From: simon.marchi@polymtl.ca To: gdb-patches@sourceware.org Cc: Simon Marchi Subject: [PATCH 3/4] gdbsupport: add gdb::unordered_string_map Date: Fri, 13 Feb 2026 00:38:50 -0500 Message-ID: <20260213053912.3520505-3-simon.marchi@polymtl.ca> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260213053912.3520505-1-simon.marchi@polymtl.ca> References: <20260213053912.3520505-1-simon.marchi@polymtl.ca> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Poly-FromMTA: (simark.ca [158.69.221.121]) at Fri, 13 Feb 2026 05:39:15 +0000 X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: gdb-patches-bounces~public-inbox=simark.ca@sourceware.org From: Simon Marchi It occurred to me that when we use a gdb::unordered_map we construct a temporary std::string for each lookup from a `const char *`, possibly doing dynamic allocation. This is really unnecessary, because it's easy to compare an existing `const char *` (or std::string_view) with an std::string. This can therefore be avoided by having transparent hash and eq types. Because this is a common enough case, add it to gdbsupport/unordered_map.h, so it can easily be reused. Define the gdb::unordered_string_map type, which uses hash and eq types that work on std::string_view. Both `const char *` and `std::string` can implicitly be converted to std::string_view, so this should be sufficient. Change-Id: Id93448d831696d25472f13c15212f13712ad8492 --- gdbsupport/unordered_map.h | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) diff --git a/gdbsupport/unordered_map.h b/gdbsupport/unordered_map.h index b615f2422f62..e0b97764d0b3 100644 --- a/gdbsupport/unordered_map.h +++ b/gdbsupport/unordered_map.h @@ -32,6 +32,40 @@ using unordered_map >, ankerl::unordered_dense::bucket_type::standard>; +/* An unordered_map with std::string keys that supports transparent + lookup from std::string_view, avoiding the construction of temporary + std::string objects during lookups. std::string_view is implicitly + constructible from `const char *` and `std::string`, so it covers those + too. */ + +namespace detail +{ + +struct unordered_string_map_hash +{ + using is_transparent = void; + using is_avalanching = void; + + std::uint64_t operator() (std::string_view sv) const noexcept + { return ankerl::unordered_dense::hash () (sv); } +}; + +struct unordered_string_map_eq +{ + using is_transparent = void; + + bool operator() (std::string_view lhs, std::string_view rhs) const noexcept + { return lhs == rhs; } +}; + +} /* namespace detail */ + +template +using unordered_string_map + = gdb::unordered_map; + } /* namespace gdb */ #endif /* GDBSUPPORT_UNORDERED_MAP_H */ -- 2.53.0