JDK-7175279 : Don't use x87 FPU on x86-64
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: compiler
  • Affected Version: hs24,9,10
  • Priority: P3
  • Status: Resolved
  • Resolution: Fixed
  • CPU: x86_64
  • Submitted: 2012-06-07
  • Updated: 2020-02-11
  • Resolved: 2020-01-29
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JDK 15
15 b09Fixed
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Modern x86 processors have very fast SSE unit and slow old x87 FPU. Hotspot VM still use FPU to generate code for some java Math methods. Investigate possibility and performance benefits from switching to SSE only instructions for 64bit VM where at least SSE2 is present. It should include Interpreter code and C1 (in Tiered) and C2 generated code.

Here are java methods from java/lang/Math which are implemeted in 64bit VM using x87 FPU instructions:
sin(), cos(), tan(), log(), log10(), pow(), exp()

URL: https://hg.openjdk.java.net/jdk/jdk/rev/db30f31b9a8e User: vlivanov Date: 2020-01-29 21:52:52 +0000

Review thread: https://mail.openjdk.java.net/pipermail/hotspot-dev/2019-December/040352.html

[~jcm], do you think you can handle this enhancement?