Date: Thu, 02 Apr 2026 20:09:56 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 294214] clang builtin functions break libm Message-ID: <bug-294214-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=294214 Bug ID: 294214 Summary: clang builtin functions break libm Product: Base System Version: CURRENT Hardware: Any OS: Any Status: New Severity: Affects Only Me Priority: --- Component: bin Assignee: bugs@FreeBSD.org Reporter: kargl@FreeBSD.org It has been brought to my attention that the use of some clang builtin functions break libm. Consider, #include <math.h> #include <stdio.h> int main(void) { double f, x, y; x = 0.; y = copysign(x, -1.); printf("fmax(% lf % lf) = % lf\n", x, x, fmax(x,x)); printf("fmax(% lf % lf) = % lf\n", x, y, fmax(x,y)); printf("fmax(% lf % lf) = % lf\n", y, x, fmax(y,x)); return (0); } % cc -o z fmax.c -lm && ./z fmax( 0.000000 0.000000) = 0.000000 fmax( 0.000000 -0.000000) = 0.000000 fmax(-0.000000 0.000000) = -0.000000 <--- this is wrong % cc -o z fmax.c -lm -fno-builtin && ./z fmax( 0.000000 0.000000) = 0.000000 fmax( 0.000000 -0.000000) = 0.000000 fmax(-0.000000 0.000000) = 0.000000 % gcc15 -o z fmax.c -lm && ./z fmax( 0.000000 0.000000) = 0.000000 fmax( 0.000000 -0.000000) = 0.000000 fmax(-0.000000 0.000000) = 0.000000 <--- this is correct % -o z fmax.c -lm -fno-builtin && ./z fmax( 0.000000 0.000000) = 0.000000 fmax( 0.000000 -0.000000) = 0.000000 fmax(-0.000000 0.000000) = 0.000000 The FreeBSD documentation has % man fmax ... DESCRIPTION The fmax(), fmaxf(), and fmaxl() functions return the larger of x and y, and likewise, the fmin(), fminf(), and fminl() functions return the smaller of x and y. They treat +0.0 as being larger than -0.0. -- You are receiving this mail because: You are the assignee for the bug.home | help
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