Re: Fixed point cairo.. or no cairo?

[Michael Meeks <michael meeks novell com>]

On Fri, 2006-08-11 at 10:24 +0300, Jorn Baayen wrote:
> > Done: http://www.o-hand.com/~jorn/pango-benchmarks/210-softfloat/

	Wow - nice :-)

> Now if we look at the cairo profile here (cairo.txt), we see that 7.7%
> and 3.8% are you used by __muldf3() and __adddf3(), respectively. These
> are softfloat functions, confirming suspicions that FP is a problem.

	Sure - but we can (I hope) also see that a chunk of these come from a
small number of code paths, and (possibly) we can optimise that.

	The burn in:

  12        5.0420  libcairo.so.2.9.0        _cairo_pattern_transform
  28       11.7647  libcairo.so.2.9.0        _cairo_color_init_rgba
  152      63.8655  libcairo.so.2.9.0        cairo_matrix_transform_point
  372       7.6559  libcairo.so.2.9.0        __muldf3

	Seems to have some lying stack pieces ;-) but presumably the muls are
from either the (inlined) cairo_matrix_transform_distance, or from
cairo_matrix_multiply ?

	Is the common case of that a multiplication by a unit matrix, [ ie. a
no-op ;-] that could be elided if that's detectable /  propagate-able ?
[ though it seems there is no space in 'matrix' to ram an 'unsigned int
is-unit : 1' into ;-) Or is it perhaps a simple scaling [ reduce by 2x
the muls ? ].

	Anyhow - it's wonderful to see a clearer profile; though the numbers
are slightly confusing - is it the case that the pango_cairo_fc_ stuff
is burning way more emulated fpu ?

	Regards,

		Michael.

-- 
 michael meeks novell com  <><, Pseudo Engineer, itinerant idiot