x86 浮点指令_x86-64浮点比较指令-优快云博客

本文介绍X86-64架构中用于浮点数比较的SSE3扩展指令，包括ucomiss和ucomisd，分别用于单精度和双精度的浮点数比较。这些指令遵循GAS约定，参数S2必须位于XMM寄存器中，而S1可以位于XMM寄存器或内存中。

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x86 浮点指令

What are the x86-64 instructions for floating-point comparisons like the cmpq for quard-word integer comparison?

什么是X86-64用于浮点指令点像比较cmpq为quard字整数比较？

The SSE3 extenstions provide two instructions for comparing ﬂoating values:

SSE3扩展提供了两条用于比较浮动值的指令：

Instruction       Based on    Description
ucomiss S2, S1    S1 - S2     Compare single precision
ucomisd S2, S1    S1 - S2     Compare double precision

As with cmpq, they follow the GAS convention of listing the operands in reverse order. Argument S2 must be in an XMM register, while S1 can either be in an XMM register or in memory.

与cmpq一样，它们遵循GAS约定以相反的顺序列出操作数。参数S2必须在XMM寄存器中，而S1可以在XMM寄存器中或在存储器中。

Reference: https://www.cs.cmu.edu/~fp/courses/15213-s07/misc/asm64-handout.pdf

参考： https : //www.cs.cmu.edu/~fp/courses/15213-s07/misc/asm64-handout.pdf

Check more: https://www.systutorials.com/3024/x86-64-isa-assembly-references/

Answered by Eric Z Ma.

埃里克·马（Eric Z Ma）回答。