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What's new in GCC 4.5?What's new in GCC 4.5?Posted May 18, 2010 16:47 UTC (Tue) by pharm (guest, #22305)In reply to: What's new in GCC 4.5? by creemj Parent article: What's new in GCC 4.5?
No, Intel processors can switch between 64-bit & 80-bit floating point register mode. You can use the -mpc option to gcc to force 64-bit floats.
Why people bang on about -ffloat-store instead of pointing people to -mpc64 if they want to truncate floats to 64 bits on Intel platforms I'm not sure.
Check out the FLDCW (Floating Point Load Control Word) instruction for the gory details.
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What's new in GCC 4.5? Posted May 18, 2010 16:50 UTC (Tue) by pharm (guest, #22305) [Link]
Oh wait, I see what you're saying.
I suppose you can set the control word to 53-bit mantissa & copy a value from one FP register to another. That would be a bit slow though.
What's new in GCC 4.5? Posted May 31, 2010 15:52 UTC (Mon) by Spudd86 (guest, #51683) [Link]
Err doesn't setting the control word before doing ANYTHING mean that you'll keep a 53 bit mantissa throughout?
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