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APPLICATION PROGRAMMING MODEL

 

 

 

 

 

 

 

 

x

y

z

r=(x*y)

r=(x*y)

r =

r=

Comment

(multiplicand)

(multiplier)

+z

-z

-(x*y)+z

-(x*y)-z

 

 

 

 

 

 

 

 

 

 

F

0

F

z

-z

z

-z

 

 

 

 

 

 

 

 

 

F

F

0

x*y

x*y

-x*y

-x*y

Rounded to the

 

 

 

 

 

 

 

destination pre-

 

 

 

 

 

 

 

cision, with

 

 

 

 

 

 

 

bounded expo-

 

 

 

 

 

 

 

nent

 

 

 

 

 

 

 

 

F

F

F

(x*y)+z

(x*y)-z

-(x*y)+z

-(x*y)-z

Rounded to the

 

 

 

 

 

 

 

destination pre-

 

 

 

 

 

 

 

cision, with

 

 

 

 

 

 

 

bounded expo-

 

 

 

 

 

 

 

nent; however,

 

 

 

 

 

 

 

if the exact val-

 

 

 

 

 

 

 

ues of x*y and z

 

 

 

 

 

 

 

are equal in

 

 

 

 

 

 

 

magnitude with

 

 

 

 

 

 

 

signs resulting

 

 

 

 

 

 

 

in the FMA

 

 

 

 

 

 

 

operation pro-

 

 

 

 

 

 

 

ducing 0, the

 

 

 

 

 

 

 

rounding behav-

 

 

 

 

 

 

 

ior described in

 

 

 

 

 

 

 

Table 2-1.

 

 

 

 

 

 

 

 

If unmasked floating-point exceptions are signaled (invalid operation, denormal operand, overflow, underflow, or inexact result) the result register is left unchanged and a floating-point exception handler is invoked.

2.3.1FMA Instruction Operand Order and Arithmetic Behavior

FMA instruction mnemonics are defined explicitly with an ordered three digits, e.g. VFMADD132PD. The value of each digit refers to the ordering of the three source operand as defined by instruction encoding specification:

‘1’: The first source operand (also the destination operand) in the syntactical order listed in this specification.

‘2’: The second source operand in the syntactical order. This is a YMM/XMM register, encoded using VEX prefix.

‘3’: The third source operand in the syntactical order. The first and third operand are encoded following ModR/M encoding rules.

The ordering of each digit within the mnemonic refers to the floating-point data listed on the right-hand side of the arithmetic equation of each FMA operation (see

Table 2-2):

Ref. # 319433-011

2-11

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