Date: Sat, 25 Nov 2023 03:42:00 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 275322] Improper handling of mxcsr register during debug (gdb/lldb) Message-ID: <bug-275322-227@https.bugs.freebsd.org/bugzilla/>
next in thread | raw e-mail | index | archive | help
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D275322 Bug ID: 275322 Summary: Improper handling of mxcsr register during debug (gdb/lldb) Product: Base System Version: 14.0-RELEASE Hardware: Any OS: Any Status: New Severity: Affects Only Me Priority: --- Component: misc Assignee: bugs@FreeBSD.org Reporter: cheyenne.wills@gmail.com Attachment #246554 text/plain mime type: Created attachment 246554 --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=3D246554&action= =3Dedit C code to demonstrate the problem There is improper handling of the mxcsr register when debugging. It appears that the current mxcsr register is not being given to the debugger. The attached program illustrates the problem. compile the attached program:lang -mfpmath=3Dsse -mlong-double-64 -g -lm -o= {x} {x.c} Run the following debug session: gdb ./{x} break main run ** program should run to end with the following output: ra=3D7.01209994486364354e-310 reatt=3D10000000000 ra * reatt-> result =3D0 = savemxcsr 00001f80 mxcsr_set 00009fc0 showmxcsr 00009fc0 mxcsr 00001f80 disassemble main ** set a break at the mulsd instruction (should be around offset +81) run ** should now be at the mulsd instruction continue ** output should be the same as above run ** should now be at the mulsd instruction info register mxcsr ** output should be: mxcsr 0x1f80 [ IM DM ZM OM UM PM ] ** which is incorrect since it there was a ldmxcsr instruction around offset +39 and the result should be: mxcsr 0x9fc0 [ DAZ IM DM ZM OM UM PM FZ ] continue ** output shows incorrect output: ra=3D7.01209994486364354e-310 reatt=3D10000000000 ra * reatt-> result =3D7.01209994486364403e-300 savemxcsr 00001f80 mxcsr_set 00009fc0 showmxcsr 00009fc0 mxcsr 00001fa2 ** since it appears that the mxcsr register is being reset back to the 0x1f= 80 value after it was displayed --=20 You are receiving this mail because: You are the assignee for the bug.=
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?bug-275322-227>