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([2a0a:ef40:7d8:fa01:60c8:18fb:2acc:d4f]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-488f0ed4c67sm20646455e9.33.2026.04.15.06.54.43 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 15 Apr 2026 06:54:44 -0700 (PDT) Message-ID: <50ea6e41-6b29-46ad-aa97-0eaa289db7cf@gmail.com> Date: Wed, 15 Apr 2026 14:54:40 +0100 Precedence: bulk X-Mailing-List: git@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Reply-To: phillip.wood@dunelm.org.uk Subject: Re: [PATCH v4 4/6] xdiff/xdl_cleanup_records: make limits more clear To: Junio C Hamano , Ezekiel Newren Cc: phillip.wood@dunelm.org.uk, Ezekiel Newren via GitGitGadget , git@vger.kernel.org, Yee Cheng Chin , =?UTF-8?Q?Ren=C3=A9_Scharfe?= , Jeff King , "D. Ben Knoble" References: <75fe3ea1250ab7dfa4e029f49f2ad353185afded.1774890003.git.gitgitgadget@gmail.com> <32c34d0d-9358-43e3-9d58-5999b3ffd6c2@gmail.com> Content-Language: en-US From: Phillip Wood In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 14/04/2026 23:15, Junio C Hamano wrote: > Ezekiel Newren writes: > >>>> + mlim1 = XDL_MIN(xdl_bogosqrt(xdf1->nrec), XDL_MAX_EQLIMIT); >>>> + mlim2 = XDL_MIN(xdl_bogosqrt(xdf2->nrec), XDL_MAX_EQLIMIT); >>> >>> As Junio has pointed out we now evaluate xdl_bogosqrt() twice which is >>> unfortunate. It would have been nice to mention that in the commit >>> message and explain why it does not matter. >> >> It doesn't matter because xdl_bogosqrt() was being called twice before >> and is being called twice now. There is no change in that regard. >> That's why I split mlim into 2 variables to make it more clear. >> >> It looks like you and Junio have both missed that xdl_bogo_sqrt() is >> being called on different values. > > I think Phillip's point is that XDL_MIN(a, b) would evaluate (a) > twice. Exactly, thanks for clarifying Phillip > > #define XDL_MIN(a, b) ((a) < (b) ? (a): (b)) > > So the code you have above > > mlim1 = XDL_MIN(xdl_bogosqrt(xdf1->nrec), XDL_MAX_EQLIMIT); > > actually is > > mlim1 = ((xdl_bogosqrt(xdf1->nrec) < XDL_MAX_EQLIMIT) > ? xdl_bogosqrt(xdf1->nrec) > : XDL_MAX_EQLIMIT); > > If you are lucky and xdf1->nrec is so large, there is only one call > to xdl_bogosqrt() before mlim1 gets assigned XDL_MAX_EQLIMIT, but > usually you'll call it on the same xdf1->nrec twice before you > assign the result to mlim1, no? > > The original lost by the patch looked like this: > > /* > * Initialize temporary arrays with DISCARD, KEEP, or INVESTIGATE. > */ > - if ((mlim = (long)xdl_bogosqrt((uint64_t)xdf1->nrec)) > XDL_MAX_EQLIMIT) > - mlim = XDL_MAX_EQLIMIT; > > which computed it once, assigned it to mlim, and then clamped. >