On Tuesday, January 19, 2016 10:14:18 PM PST Kenneth Graunke wrote: > This is a port of Matt's GLSL IR lowering pass to NIR. It's required > because we translate SPIR-V directly to NIR, bypassing GLSL IR. > > I haven't introduced a lower_ldexp flag, as I believe all current NIR > consumers would set the flag. i965 wants this, vc4 doesn't implement > this feature, and st_glsl_to_tgsi currently lowers ldexp > unconditionally anyway. > > Signed-off-by: Kenneth Graunke <kenn...@whitecape.org> > --- > src/glsl/nir/nir_opt_algebraic.py | 63 ++++++++++++++++++++++++++++++++++++ +++ > 1 file changed, 63 insertions(+) > > diff --git a/src/glsl/nir/nir_opt_algebraic.py b/src/glsl/nir/ nir_opt_algebraic.py > index 7745b76..0976ed6 100644 > --- a/src/glsl/nir/nir_opt_algebraic.py > +++ b/src/glsl/nir/nir_opt_algebraic.py > @@ -1,4 +1,5 @@ > #! /usr/bin/env python > +# -*- encoding: utf-8 -*- > # > # Copyright (C) 2014 Intel Corporation > # > @@ -265,6 +266,68 @@ for op in ['flt', 'fge', 'feq', 'fne', > ('bcsel', 'a', (op, 'd', 'b'), (op, 'd', 'c'))), > ] > > +def ldexp_to_arith(x, exp): > + """ > + Translates > + ldexp x exp > + into > + > + extracted_biased_exp = rshift(bitcast_f2i(abs(x)), exp_shift); > + resulting_biased_exp = extracted_biased_exp + exp; > + > + if (resulting_biased_exp < 1) { > + return copysign(0.0, x); > + } > + > + return bitcast_u2f((bitcast_f2u(x) & sign_mantissa_mask) | > + lshift(i2u(resulting_biased_exp), exp_shift)); > + > + which we can't actually implement as such, since NIR doesn't have > + vectorized if-statements. We actually implement it without branches > + using conditional-select: > + > + extracted_biased_exp = rshift(bitcast_f2i(abs(x)), exp_shift); > + resulting_biased_exp = extracted_biased_exp + exp; > + > + is_not_zero_or_underflow = gequal(resulting_biased_exp, 1); > + x = csel(is_not_zero_or_underflow, x, copysign(0.0f, x)); > + resulting_biased_exp = csel(is_not_zero_or_underflow, > + resulting_biased_exp, 0); > + > + return bitcast_u2f((bitcast_f2u(x) & sign_mantissa_mask) | > + lshift(i2u(resulting_biased_exp), exp_shift)); > + """ > + > + sign_mask = 0x80000000 > + exp_shift = 23 > + exp_width = 8 > + > + # Extract the biased exponent from <x>. > + extracted_biased_exp = ('ushr', ('iabs', x), exp_shift)
This should be fabs, not iabs: + extracted_biased_exp = ('ushr', ('fabs', x), exp_shift) Then it works fine. With that change, un-NAK!
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