Date: Tue, 02 Sep 2025 00:27:53 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 289232] i386 (x87) signal incorrectly reports FPE_FLTRES over FPE_FLTUND when both are present Message-ID: <bug-289232-227-olzMXotm7n@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-289232-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=289232 --- Comment #13 from Konstantin Belousov <kib@FreeBSD.org> --- Sorry, the pasted code has the bug, I divided larger number by smaller. It should be reverse. Now you could expect an underflow, but CPUs, both Intel and AMD, report only inexact result. I also checked it under Linux. /* $Id$ */ #include <stdint.h> #include <stdio.h> static const double small_num = 1.0E-300; static const double large_num = 1.0E+300; int main(void) { uint16_t sw; __asm __volatile( "\tfldl large_num\n" "\tfldl small_num\n" "\tfdivp\n" "\tfstsw %%ax\n" : "=a"(sw) : "m"(small_num), "m"(large_num) : "flags" ); printf("x87 FPU Status Word (FSW): 0x%04x\n", sw); if (sw & 0x01) printf(" INVALID OP\n"); if (sw & 0x02) printf(" DENORMAL OPERAND\n"); if (sw & 0x04) printf(" ZERO DIVIDE\n"); if (sw & 0x08) printf(" OVERFLOW\n"); if (sw & 0x10) printf(" UNDERFLOW\n"); if (sw & 0x20) printf(" INEXACT\n"); } -- You are receiving this mail because: You are the assignee for the bug.home | help
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