AMD 250 manual Avoid

Software Optimization Guide for AMD64 Processors 25112 Rev. 3.06 September 2005

Example 3

Avoid:

mov al, bl

Preferred:

movzx eax, bl

Example 4

Avoid:

mov al, [ebx]

Preferred:

movzx eax, byte ptr [ebx]

Example 5

Avoid:

mov al, 01h

Preferred:

mov eax, 00000001h

Example 6

Avoid:

movss xmm1, xmm2

Preferred:

movaps xmm1, xmm2

82 Instruction-Decoding Optimizations Chapter 4