FPU Exception

This pattern sometimes happens where we least expect it. Here's an extract from one crash dump raw stack analysis showing exception context, record and the usage of r WinDbg command variant to display FPU registers:

0:002> dps 056c1000 057c0000
[...]
057bdee0 00000008
057bdee4 00000000
057bdee8 057bed6c
057bdeec 0d6e3130
057bdef0 057c0000
057bdef4 057b9000
057bdef8 006e3138
057bdefc 057be200
057bdf00 7c90e48a ntdll!KiUserExceptionDispatcher+0xe
057bdf04 057bed6c
057bdf08 057bdf2c
057bdf0c 057bdf14
057bdf10 057bdf2c
057bdf14 c0000090
057bdf18 00000010
057bdf1c 00000000
057bdf20 79098cc0 mscorjit!Compiler::FlatFPIsSameAsFloat+0xd
057bdf24 00000001
057bdf28 00000000
057bdf2c 0001003f
057bdf30 00000000
057bdf34 00000000
057bdf38 00000000
057bdf3c 00000000
057bdf40 00000000
057bdf44 00000000
057bdf48 ffff1372
057bdf4c fffffda1
057bdf50 ffffbfff
[...]

0:002> .cxr 057bdf2c
eax=c0000090 ebx=00000000 ecx=c0000090 edx=00000000 esi=057be244
edi=001d4388
eip=79f5236b esp=057be1f8 ebp=057be200 iopl=0 nv up ei ng nz ac pe cy
cs=001b ss=0023 ds=0023 es=0023 fs=003b gs=0000 efl=00010297
mscorwks!SOTolerantBoundaryFilter+0x22:
79f5236b d9059823f579 fld dword ptr [mscorwks!_real (79f52398)]
ds:0023:79f52398=40800000

0:002> .exr 057bdf14
ExceptionAddress: 79098cc0
(mscorjit!Compiler::FlatFPIsSameAsFloat+0x0000000d)
ExceptionCode: c0000090
ExceptionFlags: 00000010
NumberParameters: 1
Parameter[0]: 00000000

0:002> !error c0000090
Error code: (NTSTATUS) 0xc0000090 (3221225616) - {EXCEPTION} Floating-
point invalid operation.

0:002> rMF
Last set context:
eax=c0000090 ebx=00000000 ecx=c0000090 edx=00000000 esi=057be244
edi=001d4388
eip=79f5236b esp=057be1f8 ebp=057be200 iopl=0 nv up ei ng nz ac pe cy
cs=001b ss=0023 ds=0023 es=0023 fs=003b gs=0000 efl=00010297
fpcw=1372: rn 64 pu- d- fpsw=FDA1: top=7 cc=1101 b-p- -i fptw=BFFF
fopcode=045D fpip=001b:79098cc0 fpdp=0023:057bea7c
st0=-1.#IND00000000000000000e+0000 st1= 0.006980626232475338220e-4916
st2= 6.543831490564206840810e-4932 st3=-0.003025663186207448300e+2614
st4= 2.000000000000000000000e+0000 st5= 6.291456000000000000000e+0006
st6= 1.000000000000000000000e+0000 st7= 2.500000000000000000000e-0001
mscorwks!SOTolerantBoundaryFilter+0×22:
79f5236b d9059823f579 fld dword ptr [mscorwks!_real (79f52398)]
ds:0023:79f52398=40800000