On 3/7/2016 17:32, Benjamin Bihler wrote: > Thank you, Ruben and the others, for your answers. > > I have tried myself to find a workaround, but haven’t been successful. > > First I tried to add the O1 optimization flags one by one without using –O1 > to find out whether a special optimization flag influences this behavior. I > have learned that this is not the case, the “bug” didn’t appear without –O1. > That means that –O1 is more than the sum of the optimizations activated by > it. ;-) > > Then I tried setting calling > _controlfp_s(&fpu_cw, _PC_53, _MCW_PC); > inside the getResult method (i.e. in every thread?) to define the > floating-point precision for every thread. This also has failed. (I should > stop trying to set floating-point precisions manually, since I am not > familiar with such things.) > > So I have no workaround right now. > > Please let me explain why I am of the opinion that consistent results are > absolutely essential: I am using MinGW-w64 for CAD-related software > development (OpenCASCADE). Non-deterministic results make my unit tests fail. > But what is worse: if discrete values are computed from the results of > floating-point operations, the small 1.0e-16 difference may lead to a really > big difference in the discrete values (as different as “true” is from “false” > or “0” is from “1”; if for example it is detected whether a point is on a > line by checking whether the point has a distance smaller than 1.0e-7, and > the point actually has a distance of 1.0e-7, then one thread may say that it > is on the line and the other thread may say that it is not on the line). This > has already happened here. And things become even worse: I am creating binary > document files that store the input of my computations, not the output. When > I create such a document, close the application, and open the document the next time, I cannot be sure that the content is still the same. Maybe another thread is doing the computation this time, which means that perhaps the content is different. If the data becomes inconsistent in itself (one point on a line is expected, but none is found anymore), I cannot even open the document without getting exceptions. This also has already happened here. ☹ > > As a conclusion, I would really appreciate if you continued to consider my > report. Thank you! ☺ >
Try grabbing v4.x or master from git, tls code now calls fpreset for every new thread created.
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