Date: Wed, 14 Sep 2016 14:44:25 -0500 From: Pedro Giffuni <pfg@FreeBSD.org> To: Cedric Blancher <cedric.blancher@gmail.com> Cc: FreeBSD Hackers <freebsd-hackers@freebsd.org> Subject: Re: Is replacing alloca(3) where possible a good thing to do? Message-ID: <5cb743dd-60fd-8018-eaf7-fe10b8db211c@FreeBSD.org> In-Reply-To: <CALXu0UdbDdpu3LZp3_VtwEkgmbj28hOQ5EET%2Bmwj-ZNSSS3GzQ@mail.gmail.com> References: <d192dbeb-5647-e552-9db1-b478aa7ac057@FreeBSD.org> <CALXu0UcbMtevEx8DP-557MQHVDsJuyBHz9FOWE8OV3UXErPOYA@mail.gmail.com> <90f37d14-a187-06b2-6187-7a9c1890a73f@FreeBSD.org> <CALXu0UdbDdpu3LZp3_VtwEkgmbj28hOQ5EET%2Bmwj-ZNSSS3GzQ@mail.gmail.com>
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Hello; On 14/09/2016 14:14, Cedric Blancher wrote: > dtrace can do VLA > > Are there other arguments? It was a while ago and I don't remember other than the fact that alloca() exists on all platforms and just works fine so why bother. This was only a discussion in the context of printf(1) and as I wrote we parted different ways there. If there are other notable cases then please upstream those changes first. Pedro. > Ced > > On 14 September 2016 at 21:11, Pedro Giffuni <pfg@freebsd.org> wrote: >> >> On 14/09/2016 13:54, Cedric Blancher wrote: >>> Who was the "principal Illumos developer"? I remember some heated >>> discussions, mostly rooted in 'we stick with ANSI C' and because the >>> CTF/dwarf tools in Illumos were unable to handle VLA and no one was >>> interested in fixing the BUGS in their toolchain, so the cheapest >>> solution was done: VLA was declared persona non grata. Saves company >>> money. >> >> Yes, the non-accessibility of VLAs for Dtrace was the main argument. This >> was a private conversation with Garrett D'Amore who did some nice >> enhancements to our printf(1). >> >>> Typical Sun policy which was one of the reasons which sealed the >>> downfall of Sun Microsystems. >>> >>> But this is NO ARGUMENT for FreeBSD... >> >> Our printf(1) implementation has all their enhancements but uses a VLA >> instead of alloca. >> >> This said, whatever illumos wants to keep in their code is relevant as we >> want to make it easy to merge ZFS and Dtrace changes back and forth. >> >> Pedro. > >
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