From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Paul Eggert Newsgroups: gmane.emacs.bugs Subject: bug#42147: 28.0.50; pure vs side-effect-free, missing optimizations? 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Sun, 5 Jul 2020 16:57:41 -0700 (PDT) Original-Received: from [192.168.1.9] (cpe-75-82-69-226.socal.res.rr.com [75.82.69.226]) by zimbra.cs.ucla.edu (Postfix) with ESMTPSA id 73106160084; Sun, 5 Jul 2020 16:57:41 -0700 (PDT) Autocrypt: addr=eggert@cs.ucla.edu; prefer-encrypt=mutual; keydata= LS0tLS1CRUdJTiBQR1AgUFVCTElDIEtFWSBCTE9DSy0tLS0tCgptUUlOQkV5QWNtUUJFQURB QXlIMnhvVHU3cHBHNUQzYThGTVpFb243NGRDdmM0K3ExWEEySjJ0QnkycHdhVHFmCmhweHhk R0E5Smo1MFVKM1BENGJTVUVnTjh0TFowc2FuNDdsNVhUQUZMaTI0NTZjaVNsNW04c0thSGxH ZHQ5WG0KQUF0bVhxZVpWSVlYL1VGUzk2ZkR6ZjR4aEVtbS95N0xiWUVQUWRVZHh1NDd4QTVL aFRZcDVibHRGM1dZRHoxWQpnZDdneDA3QXV3cDdpdzdlTnZub0RUQWxLQWw4S1lEWnpiRE5D UUdFYnBZM2VmWkl2UGRlSStGV1FONFcra2doCnkrUDZhdTZQcklJaFlyYWV1YTdYRGRiMkxT MWVuM1NzbUUzUWpxZlJxSS9BMnVlOEpNd3N2WGUvV0szOEV6czYKeDc0aVRhcUkzQUZINmls QWhEcXBNbmQvbXNTRVNORnQ3NkRpTzFaS1FNcjlhbVZQa25qZlBtSklTcWRoZ0IxRApsRWR3 MzRzUk9mNlY4bVp3MHhmcVQ2UEtFNDZMY0ZlZnpzMGtiZzRHT1JmOHZqRzJTZjF0azVlVThN Qml5Ti9iClowM2JLTmpOWU1wT0REUVF3dVA4NGtZTGtYMndCeHhNQWhCeHdiRFZadWR6eERa SjFDMlZYdWpDT0pWeHEya2wKakJNOUVUWXVVR3FkNzVBVzJMWHJMdzYrTXVJc0hGQVlBZ1Jy NytLY3dEZ0JBZndoU In-Reply-To: Content-Language: en-US X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Original-Sender: "bug-gnu-emacs" Xref: news.gmane.io gmane.emacs.bugs:182757 Archived-At: On 7/5/20 3:03 AM, Andrea Corallo wrote: > Wow I'm really surprised by this result! Are we doing so much floating > point while compiling Emacs? No, and you are right to be skeptical. I checked again, and unfortunately I originally measured the performance incorrectly, as I used a script that I had forgotten adds '-march=native' which makes the benchmark results not reflect what distros normally do (unless one is assuming something like Gentoo which is far less common). When I removed -march=native and stuck with just CC='gcc -m32' versus CC='gcc -m32 -msse2 -mfpmath=sse', the performance difference went the other way on my AMD Phenom II X4 910e (2010): the version generated with -msse2 -mfpmath=sse was 3.7% slower on the 'make compile-always' benchmark. I suppose it's possible both of these numbers are artifacts, though I don't know what would cause the artifacts. At any rate obviously I was wrong to suggest that -msse2 improves performance on this benchmark. Sorry about the noise. On 7/5/20 8:07 AM, Stefan Monnier wrote: > Could it be that your measurements also included the time spent > compiling C files and that GCC is significantly faster at generating > code for SSE2? I do a plain 'make' before running 'cd lisp; make compile-always' so GCC is not involved; it's mostly an Emacs byte-compiler benchmark.