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Re: [RFC] Port libitm to powerpc
On 1 Dec 2011, at 20:20, Richard Henderson wrote:
On 12/01/2011 10:47 AM, Joseph S. Myers wrote:
As I previously noted in the ARM discussion, C specifically says that
setjmp/longjmp should *not* save/restore floating-point exceptions
and
rounding modes. Think of the floating-point state as being a global
variable (well, thread-local).
Exactly.
If the fpscr _were_ a TLS variable, seen to be modified inside a
transaction, we would log its initial value so that we could restore
that original value on a transaction restart or transaction cancel.\
well, I saw ...
mffs f0
stfd f14, 0+OFS_FR+BASE(r1)
[snip]
stfd f0, OFS_FPSCR+BASE(r1)
in your posted code ... and wondered ..
So, as you say the ARM libc setjmp/longjmp implementation is wrong,
but we do need that save and restore here.
now I'm slightly confused - do we need to preserve if across the call
or not?
cheers
Iain