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()