Frama-C The documentation of the correctly-rounded CRlibm floating-point library states for the difficult pow() function (p. 159): Directed rounding requires additional work in particular in subnormal handling and in exact case management. There are more exact cases in directed rounding modes therefore the performance should also be inferior. The phrase “exact...
Read MoreQuiz time What does the program below do? #include <stdio.h> int main(){ struct { int t[4]; int u; } v; v.u = 3; v.t[4] = 4; printf(\v.u=%d" v.u); return 0; } Two answers are “it prints v.u=4” and “it prints v.u=3”: $ gcc t.c && ./a.out v.u=4 $ gcc -O2...
Read More… but that's only because I created it. If you are more familiar than me with Wikipedia etiquette feel free to adjust edit or delete this page. Also although a Wikipedia account is necessary to create a page I think it is not required for editing so you can add...
Read MoreIntroduction It started innocently enough. My colleagues were talking of supporting target compilers with excess floating-point precision. We saw that if analyzing programs destined to be compiled with strict IEEE 754 compilers was a lovely Spring day at the beach analyzing for compilers that allow excess precision was Normandy in...
Read MoreThere is a C quiz in the middle of this post, lost in the middle of all the reminiscing. A history of arithmetic overflows in Frama-C From the very beginnings in 2005, until after the first Open Source release in 2008, Frama-C's value analysis was assuming that all arithmetic overflows...
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