From nobody Mon Jun 03 18:32:08 2024 X-Original-To: dev-commits-src-all@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4VtMlD6ZBMz5Jmq2; Mon, 03 Jun 2024 18:32:08 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4VtMlD68Dfz4N7d; Mon, 3 Jun 2024 18:32:08 +0000 (UTC) (envelope-from git@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1717439528; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=piqRJ0MNyYi6zLnCtGjqZv8OmceaeopFKl3w/Ir8d48=; b=ceKt/5UBGmoWBhImoZo9XKt9P7RRp75rQf9LPHIQ+gZsepBzZHdJF2r56rdJZnKj0si3u8 sKD9pkW6BcPxok6awgTZ29gutYraVpW8icJ1lJRoS0VJKWTuQNENaZJtES+nFja/tOCTq6 EDjqau/sXOM9EHaCoKTH6zAfyqkPMyC0wlOkknZJJRGGslxxPtnGd0ohct5b/Vf03mM/rz 949vxmhSxGP0qNlvB1RqcmRN2zm54N156liRMwOWczjIBEHuGAeHQ3MgZj7cg3gB2LgcbQ Wh8fhP04MYt/ORiqDvHMCvZJfB2pSoewiUbymugVMIfOPBudQICNIIL5ZGtJuQ== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1717439528; a=rsa-sha256; cv=none; b=YC0t1DrErP68GQs2nR7yvpUwAvgz/kyDLRDVkVtbvGx5hpOMwhv6jwZB+FJbARSszjpnXj kzgED3XtwTvsTjOFp9RaR6KukY2JOLxoDwEIgEJujBbvFAfXRqGteuKHMFbiFtVCyF8ySB 8VU0Nu+og3STvOSoQppypNYB3YEegQHcAqlg8xe348npXlVGsfORDpNesBbq3QM9aIQPeO pyC6OitHZ2oaEvmw9O8Vuw5+QfEiAMdJjYhT7rWm0JpXIUP8qlPDOXjWg2iz9kkds04mPf pVCZ8BROHmKfthJGiR33fklhMZehjjHeHcuFeIBcVvI+gpa5T+cfUsN1e9Xj3A== ARC-Authentication-Results: i=1; mx1.freebsd.org; none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1717439528; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=piqRJ0MNyYi6zLnCtGjqZv8OmceaeopFKl3w/Ir8d48=; b=Yp3b5JcCpgPnPA0i19FHxhcgGiJFvIohmiKu1dfKg85UjTjvOm6qUtUb3Z+4pOhvHuHHrK iMEzvc/SMD8zHC3hIMzbJt7eTjILNVaxSn4J8JsnnlOIcRdCXBcf5OR6clt6qp/8w24IGZ Kbs4evJauTGFCATwUKcVTrxaixPFdXDhb+aTQl73hREpIlXvTA93B2mp7SJ2YBTiniUSj8 EB/Ws2hrISjkM6oLU2wwhyJQjbtf63r58c0wAyPBijINCfYrQDXqIFy0f5LgTfWGWUbZPy e1662BmRIA9KDX/IXyhn2+pxnKgxbiusJod1XPWMiaZUQGzPbR+OHOB74cm8dA== Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 4VtMlD5lYbzlqs; Mon, 3 Jun 2024 18:32:08 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org ([127.0.1.44]) by gitrepo.freebsd.org (8.17.1/8.17.1) with ESMTP id 453IW8UD080804; Mon, 3 Jun 2024 18:32:08 GMT (envelope-from git@gitrepo.freebsd.org) Received: (from git@localhost) by gitrepo.freebsd.org (8.17.1/8.17.1/Submit) id 453IW87i080801; Mon, 3 Jun 2024 18:32:08 GMT (envelope-from git) Date: Mon, 3 Jun 2024 18:32:08 GMT Message-Id: <202406031832.453IW87i080801@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org From: Doug Moore Subject: git: 749c249dc3b6 - main - subr_pctrie: use ilog2(x) instead of fls(x)-1 List-Id: Commit messages for all branches of the src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-all List-Help: List-Post: List-Subscribe: List-Unsubscribe: X-BeenThere: dev-commits-src-all@freebsd.org Sender: owner-dev-commits-src-all@FreeBSD.org MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: dougm X-Git-Repository: src X-Git-Refname: refs/heads/main X-Git-Reftype: branch X-Git-Commit: 749c249dc3b656fea69149f8f7ad3e1a7f935986 Auto-Submitted: auto-generated The branch main has been updated by dougm: URL: https://cgit.FreeBSD.org/src/commit/?id=749c249dc3b656fea69149f8f7ad3e1a7f935986 commit 749c249dc3b656fea69149f8f7ad3e1a7f935986 Author: Doug Moore AuthorDate: 2024-06-03 18:31:19 +0000 Commit: Doug Moore CommitDate: 2024-06-03 18:31:19 +0000 subr_pctrie: use ilog2(x) instead of fls(x)-1 In three instances where fls(x)-1 is used, the compiler does not know that x is nonzero and so adds needless zero checks. Using ilog(x) instead saves, in each instance, about 4 instructions, including a conditional, and 16 or so bytes, on an amd64 build. Reviewed by: alc Differential Revision: https://reviews.freebsd.org/D45330 --- sys/kern/subr_pctrie.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/sys/kern/subr_pctrie.c b/sys/kern/subr_pctrie.c index 85df0a9bf9e4..76f4ee17a8ca 100644 --- a/sys/kern/subr_pctrie.c +++ b/sys/kern/subr_pctrie.c @@ -350,7 +350,7 @@ pctrie_insert_node(void *parentp, struct pctrie_node *parent, uint64_t *val) "uint64 too wide"); _Static_assert(sizeof(uint64_t) * NBBY <= (1 << (sizeof(parent->pn_clev) * NBBY)), "pn_clev too narrow"); - parent->pn_clev = rounddown(flsll(index ^ newind) - 1, PCTRIE_WIDTH); + parent->pn_clev = rounddown(ilog2(index ^ newind), PCTRIE_WIDTH); parent->pn_owner = PCTRIE_COUNT; parent->pn_owner = index & -(parent->pn_owner << parent->pn_clev); @@ -546,14 +546,14 @@ pctrie_lookup_le(struct pctrie *ptree, uint64_t index) KASSERT((pred->pn_popmap & ((1 << slot) - 1)) != 0, ("%s: no popmap siblings before slot %d in node %p", __func__, slot, pred)); - slot = fls(pred->pn_popmap & ((1 << slot) - 1)) - 1; + slot = ilog2(pred->pn_popmap & ((1 << slot) - 1)); pred = pctrie_node_load(&pred->pn_child[slot], NULL, PCTRIE_LOCKED); } while (!pctrie_isleaf(pred)) { KASSERT(pred->pn_popmap != 0, ("%s: no popmap children in node %p", __func__, pred)); - slot = fls(pred->pn_popmap) - 1; + slot = ilog2(pred->pn_popmap); pred = pctrie_node_load(&pred->pn_child[slot], NULL, PCTRIE_LOCKED); }