Intel® C++ Compiler 16.0 User and Reference Guide
You should be familiar with the hardware features provided by Intel® Streaming SIMD Extensions (Intel® SSE) when writing programs with the intrinsics. The following are four important issues to keep in mind:
Certain intrinsics, such as _mm_loadr_ps and _mm_cmpgt_ss, are not directly supported by the instruction set. While these intrinsics are convenient programming aids, be mindful that they may consist of more than one machine-language instruction.
Floating-point data loaded or stored as __m128 objects must be generally 16-byte-aligned.
Some intrinsics require that their argument be immediates, that is, constant integers (literals), due to the nature of the instruction.
The result of arithmetic operations acting on two NaN (Not a Number) arguments is undefined. Therefore, FP operations using NaN arguments will not match the expected behavior of the corresponding assembly instructions.