FP context switching on i386

Till Straumann strauman at slac.stanford.edu
Fri Oct 2 21:36:16 UTC 2009


I thought the i386 sysv ABI said that FP registers
are not preserved across function calls -- doesn't
this mean that there is no need for saving/restoring
the FP context ? Am I missing something ?

I was thinking about what it takes to support SSE
and I believe it may essentially come for free
since XMM registers seem not to be callee saved
either. Hard to find that information though since
e.g.,

http://www.sco.com/developers/devspecs/abi386-4.pdf

doesn't mention SSE yet.

-- Till



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