我们如何在实际程序中使用 strictfp 方法？

Question

此问题与 this question. I know that the strictfp keyword in java is used for this 目的不重复。但是我们如何在现实生活中使用它。它有什么优势？

Answer 1

自 Java 17 和 JEP 306 起，您不会使用它：

Make floating-point operations consistently strict, rather than have both strict floating-point semantics (strictfp) and subtly different default floating-point semantics.

[T]he SSE2 (Streaming SIMD Extensions 2) extensions, shipped in Pentium 4 and later processors starting circa 2001, could support strict JVM floating-point operations in a straightforward manner without undue overhead.

Since Intel and AMD have both long supported SSE2 and later extensions which allow natural support for strict floating-point semantics, the technical motivation for having a default floating-point semantics different than strict is no longer present.

另见 JLS §8.4.3.5:

The strictfp modifier on a method declaration is obsolete and should not be used in new code. Its presence or absence has has no effect at run time.

从 Java 的最新 LTE 版本开始，语义上不再有任何差异，并且对使用 strictfp 修饰符有一个新的编译器警告。

public class Strictly {
    public strictfp double calc(double d1, double d2) {
        return d1 * d2;
    }
}

$ javac Strictly.java
Strictly.java:2: warning: [strictfp] as of release 17, all floating-point expressions are evaluated strictly and 'strictfp' is not required
    public strictfp double calc(double d1, double d2) {
                           ^
1 warning

Answer 2

strictfp in java 用于在处理浮点数时产生相同的结果，与平台无关。

由于硬件的处理能力，不同平台上的精度可能会有所不同。所以它确保了当代码在不同平台上执行时，输出不应该由于不同的精度而被操纵。

一些优点是，

在各种机器上提供准确性
结果不偏向于硬件架构

我们如何在实际程序中使用 strictfp 方法？

How can we use the strictfp method in a real life pogram?

java

strictfp

java-17