Intel ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS MANUAL VOLUME 1 REV 2.3 Manual page 1768

Figure 4-3.
Figure 4-4.
4.6.1 Instruction Group Review
4.6.1.1 Arithmetic Instructions
Packed/Scalar Addition and Subtraction
The ADDPS (Add packed single-precision floating-point) and SUBPS (Subtract packed
single-precision floating-point) instructions add or subtract four pairs of packed
single-precision floating-point operands.
The ADDSS (Add scalar single-precision floating-point) and SUBSS (Subtract scalar
single-precision floating-point) instructions add or subtract the least significant pair of
packed single-precision floating-point operands; the upper three fields are passed
through from the source operand.
Packed/Scalar Multiplication and Division
The MULPS (Multiply packed single-precision floating-point) instruction multiplies four
pairs of packed single-precision floating-point operands.
The MULSS (Multiply scalar single-precision floating-point) instruction multiplies the
least significant pair of packed single-precision floating-point operands; the upper three
fields are passed through from the source operand.
4:466
Packed Operation
X1 (SP)
X2 (SP)
Y1 (SP)
Y2 (SP)
OP OP
X1 op Y1 (SP) X2 op Y2 (SP) X3 op Y3 (SP) X4 op Y4 (SP)
Scalar Operation
X1 (SP) X2 (SP)
Y1 (SP) Y2 (SP)
X1 (SP)
X2 (SP)
X3 (SP) X4 (SP)
Y3 (SP) Y4 (SP)
OP OP
X3 (SP) X4 (SP)
Y3 (SP) Y4 (SP)
OP
X3 (SP) X4 op Y4 (SP)
Volume 4: IA-32 SSE Instruction Reference