Intel 64 and IA-32 Architectures Software Developers Manual Volume 1, Basic Architecture

E-26 Vol. 1
GUIDELINES FOR WRITING SIMD FLOATING-POINT EXCEPTION HANDLERS
case MULPS:
case MULSS:
// perform the multiplication
__asm {
fnclex;
// load input operands
fld DWORD PTR uiopd1; // may set denormal or invalid status flags
fld DWORD PTR uiopd2; // may set denormal or invalid status flags
fmulp st(1), st(0); // may set inexact or invalid status flags
// store result
fstp QWORD PTR dbl_res24; // exact
}
break;
case DIVPS:
case DIVSS:
// perform the division
__asm {
fnclex;
// load input operands
fld DWORD PTR uiopd1; // may set denormal or invalid status flags
fld DWORD PTR uiopd2; // may set denormal or invalid status flags
fdivp st(1), st(0); // may set the inexact, divide by zero, or
// invalid status flags
// store result
fstp QWORD PTR dbl_res24; // exact
}
break;
default:
; // will never occur
}
// read status word
__asm {
fstsw WORD PTR sw;
}
if (sw & ZERODIVIDE_MASK)
sw = sw & ~DENORMAL_MASK; // clear D flag for (denormal / 0)
// if invalid flag is set, and invalid exceptions are enabled, take trap
if (!(exc_env->exc_masks & INVALID_MASK) && (sw & INVALID_MASK)) {
exc_env->status_flag_invalid_operation = 1;
exc_env->exception_cause = INVALID_OPERATION;
return (RAISE_EXCEPTION);
}
// checking for NaN operands has priority over denormal exceptions;