x86 Instruction Set Reference

HADDPS

Packed Single-FP Horizontal Add

Opcode Mnemonic Description
F2 0F 7C /r HADDPS xmm1, xmm2/m128 Add horizontally packed SP FP numbers from xmm2/m128 to xmm1.
Description

Adds the single-precision floating-point values in the first and second dwords of the destination operand and stores the result in the first dword of the destination operand.

Adds single-precision floating-point values in the third and fourth dword of the destination operand and stores the result in the second dword of the destination operand.

Adds single-precision floating-point values in the first and second dword of the source operand and stores the result in the third dword of the destination operand.

Adds single-precision floating-point values in the third and fourth dword of the source operand and stores the result in the fourth dword of the destination operand.
Operation 
xmm1[0..31] = xmm1[0..31] + xmm1[32..63];
xmm1[32..63] = xmm1[64..95] + xmm1[96..127];
xmm1[64..95] = xmm2/m128[0..31] + xmm2/m128[32..63];
xmm1[96..127] = xmm2/m128[64..95] + xmm2/m128[96..127];
Exceptions
When the source operand is a memory operand, the operand must be aligned on a 16-byte boundary or a general-protection exception (#GP) will be generated.
Numeric Exceptions
Overflow, Underflow, Invalid, Precision, Denormal.
Protected Mode Exceptions
#GP(0)For an illegal memory operand effective address in the CS, DS, ES, FS or GS segments. If a memory operand is not aligned on a 16-byte boundary, regardless of segment.
#GP(0)For an illegal memory operand effective address in the CS, DS, ES, FS or GS segments. If a memory operand is not aligned on a 16-byte boundary, regardless of segment.
#SS(0)For an illegal address in the SS segment.
#PF(fault-code)For a page fault.
#NMIf TS bit in CR0 is set.
#XMFor an unmasked Streaming SIMD Extensions numeric exception (CR4.OSXMMEXCPT = 1).
Real-Address Mode Exceptions
#GP(0)If any part of the operand would lie outside of the effective address space from 0 to 0FFFFH. If a memory operand is not aligned on a 16-byte boundary, regardless of segment.
#GP(0)If any part of the operand would lie outside of the effective address space from 0 to 0FFFFH. If a memory operand is not aligned on a 16-byte boundary, regardless of segment.
#NMIf TS bit in CR0 is set.
#XMFor an unmasked Streaming SIMD Extensions numeric exception (CR4.OSXMMEXCPT = 1).
Virtual-8086 Mode Exceptions
#GP(0)If any part of the operand would lie outside of the effective address space from 0 to 0FFFFH. If a memory operand is not aligned on a 16-byte boundary, regardless of segment.
#GP(0)If any part of the operand would lie outside of the effective address space from 0 to 0FFFFH. If a memory operand is not aligned on a 16-byte boundary, regardless of segment.
#NMIf TS bit in CR0 is set.
#XMFor an unmasked Streaming SIMD Extensions numeric exception (CR4.OSXMMEXCPT = 1).
#UDIf CR0.EM = 1. For an unmasked Streaming SIMD Extensions numeric exception (CR4.OSXMMEXCPT = 0). If CR4.OSFXSR(bit 9) = 0. If CPUID.SSE3(ECX bit 0) = 0.
Instruction Latency Throughput Execution Unit
CPUID0F3n0F3n0F3n
HADDPS134FP_ADD FP_MISC