> The $64,000 question: What do other GLSL compilers (including, > perhaps,glslang) do?
:) Shouldn't this be the "$1e6f question"? Jose ________________________________________ From: mesa-dev <mesa-dev-boun...@lists.freedesktop.org> on behalf of Iago Toral <ito...@igalia.com> Sent: 20 November 2014 07:08 To: Ian Romanick Cc: mesa-dev@lists.freedesktop.org Subject: Re: [Mesa-dev] Using the 'f' suffix to create a float from an integer literal On Wed, 2014-11-19 at 10:27 -0800, Ian Romanick wrote: > On 11/19/2014 03:47 AM, Iago Toral Quiroga wrote: > > Hi, > > > > I came across a GLSL test that checks that doing something like this in > > a shader should fail: > > Is this one of the dEQP tests? Yes. > > float value = 1f; > > It seems like we have a test related to this in piglit somewhere... it > looks like tests/shaders/glsl-floating-constant-120.shader_test uses > that syntax, but it's not explicitly testing that feature. > > > However, this works fine in Mesa. Checking the spec I see: > > > > Floating-point constants are defined as follows. > > floating-constant: > > fractional-constant exponent-part(opt) floating-suffix(opt) > > digit-sequence exponent-part floating-suffix(opt) > > fractional-constant: > > digit-sequence . digit-sequence > > digit-sequence . > > . digit-sequence > > exponent-part: > > e sign(opt) digit-sequence > > E sign(opt) digit-sequence > > sign: one of > > + - > > digit-sequence: > > digit > > digit-sequence digit > > floating-suffix: one of > > f F > > > > which suggests that the test is correct and Mesa has a bug. According to > > the above rules, however, something like this is fine: > > > > float f = 1e2f; > > > > which I find kind of weird if the other case is not valid, so I wonder > > if there is a bug in the spec or this is on purpose for some reason that > > I am missing. > > > > Then, to make matters worse, I read this in opengl.org wiki [1]: > > > > "A numeric literal that uses a decimal is by default of type float. To > > create a float literal from an integer value, use the suffix f or F as > > in C/C++." > > > > which contradicts the spec and the test and is aligned with the current > > way Mesa works. > > > > So: does anyone know what version is right? Could this be a bug in the > > spec? and if it is not, do we want to change the behavior to follow the > > spec as it is now? > > The $64,000 question: What do other GLSL compilers (including, perhaps, > glslang) do? This seems like one of the cases where nobody is likely to > follow the spec, and some application will depend on that. If that's > the case, I'll submit a spec bug. Good point. I'll try to check a few cases and reply here. Thanks! Iago > > Thanks, > > Iago > > > > [1] > > https://urldefense.proofpoint.com/v2/url?u=https-3A__www.opengl.org_wiki_Data-5FType-5F-28GLSL-29&d=AAIGaQ&c=Sqcl0Ez6M0X8aeM67LKIiDJAXVeAw-YihVMNtXt-uEs&r=zfmBZnnVGHeYde45pMKNnVyzeaZbdIqVLprmZCM2zzE&m=-vNxCjRApDMGfEN7OH0gdQY45tX4GCnJezazsrd2DNg&s=v-iOTBhqyw5b2dul6DNiwG3s4jGuIujxKjaxWWGRqc8&e= > > > > _______________________________________________ > > mesa-dev mailing list > > mesa-dev@lists.freedesktop.org > > https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.freedesktop.org_mailman_listinfo_mesa-2Ddev&d=AAIGaQ&c=Sqcl0Ez6M0X8aeM67LKIiDJAXVeAw-YihVMNtXt-uEs&r=zfmBZnnVGHeYde45pMKNnVyzeaZbdIqVLprmZCM2zzE&m=-vNxCjRApDMGfEN7OH0gdQY45tX4GCnJezazsrd2DNg&s=YtsceeKLkQZUT8ymwqfviOL4cuiZKwMSPLqvO44zptE&e= > > _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.freedesktop.org_mailman_listinfo_mesa-2Ddev&d=AAIGaQ&c=Sqcl0Ez6M0X8aeM67LKIiDJAXVeAw-YihVMNtXt-uEs&r=zfmBZnnVGHeYde45pMKNnVyzeaZbdIqVLprmZCM2zzE&m=-vNxCjRApDMGfEN7OH0gdQY45tX4GCnJezazsrd2DNg&s=YtsceeKLkQZUT8ymwqfviOL4cuiZKwMSPLqvO44zptE&e= _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
