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Re: [PATCH, rs6000, libitm] Enable Hardware Transactional Memory (HTM) support on Power


On Mon, Jul 15, 2013 at 02:46:56PM -0500, Peter Bergner wrote:
> > I'd say something like (but, untested and can't test it right now (and no
> > access to power8 anyway)):
> 
> Do we also need to update DWARF_REG_TO_UNWIND_COLUMN similarly, which
> also uses FIRST_PSEUDO_REGISTER when the dwarf reg is an SPE synthetic
> register?

Looks like it.  Guess that "- 1" in there:
#define DWARF_REG_TO_UNWIND_COLUMN(r) \
  ((r) > 1200 ? ((r) - 1200 + FIRST_PSEUDO_REGISTER - 1) : (r))
stands for the sfp register and thus it would be "- 4".

>  Or should we just break the dependence on FIRST_PSEUDO_REGISTER
> altogether so this type of thing doesn't happen again?  Otherwise, we
> should place a comment at the definition of FIRST_PSEUDO_REGISTER
> warning of it's use in DWARF_FRAME_REGISTER.

That is surely an option too.  Or use (DWARF_FRAME_REGISTERS - 32)
in the DWARF_REG_TO_UNWIND_COLUMN definition instead of the current
FIRST_PSEUDO_REGISTER - 1, and perhaps make DWARF_FRAME_REGISTERS
just a number (independent on FIRST_PSEUDO_REGISTER).
Guess this depends on what David prefers.

	Jakub


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