On 2/6/19 12:47 PM, Connor Abbott wrote: > > > On Wed, Feb 6, 2019 at 11:46 AM Samuel Iglesias Gonsálvez > <sigles...@igalia.com <mailto:sigles...@igalia.com>> wrote: > > According to Vulkan spec, the new execution modes affect only > correctly rounded SPIR-V instructions, which includes fadd, > fsub and fmul. > > Signed-off-by: Samuel Iglesias Gonsálvez <sigles...@igalia.com > <mailto:sigles...@igalia.com>> > --- > src/compiler/nir/nir_opcodes.py | 17 +++++++++++++++++ > 1 file changed, 17 insertions(+) > > diff --git a/src/compiler/nir/nir_opcodes.py > b/src/compiler/nir/nir_opcodes.py > index f8997444c28..7b45d38f460 100644 > --- a/src/compiler/nir/nir_opcodes.py > +++ b/src/compiler/nir/nir_opcodes.py > @@ -453,9 +453,15 @@ def binop_convert(name, out_type, in_type, > alg_props, const_expr): > opcode(name, 0, out_type, [0, 0], [in_type, in_type], > False, alg_props, const_expr, "") > > +def binop_convert_rounding_mode(name, out_type, in_type, alg_props, > const_expr, rounding_mode): > + opcode(name, 0, out_type, [0, 0], [in_type, in_type], False, > alg_props, const_expr, rounding_mode) > + > def binop(name, ty, alg_props, const_expr): > binop_convert(name, ty, ty, alg_props, const_expr) > > +def binop_rounding_mode(name, ty, alg_props, const_expr, > rounding_mode): > + binop_convert_rounding_mode(name, ty, ty, alg_props, const_expr, > rounding_mode) > + > def binop_compare(name, ty, alg_props, const_expr): > binop_convert(name, tbool1, ty, alg_props, const_expr) > > @@ -490,13 +496,24 @@ def binop_reduce(name, output_size, > output_type, src_type, prereduce_expr, > final(reduce_(reduce_(src0, src1), reduce_(src2, src3))), "") > > binop("fadd", tfloat, commutative + associative, "src0 + src1") > +binop_rounding_mode("fadd_rtne", tfloat, commutative + associative, > + "_mesa_roundeven(src0 + src1)", "_rtne") > > > There are two things wrong here: > - The default floating-point environment, and the one Mesa expects, does > round-to-nearest-even so it's rtz that needs special handling. > - _mesa_roundeven here is a no-op (it'll implicitly expand to a double > and then convert back to a float). The rounding actually happens as part > of the addition itself. I'm not sure if adding as double (with > round-to-nearest-even) and then rounding back to a float will work, but > that definitely won't work for doubles. I think you'll have to implement > round-to-zero addition yourself, or fiddle with the CPU's floating-point > environment. > > The same goes multiply and fma. >
OK, thanks for the feedback. I will implement the needed RTZ ops and
send a new version.
Sam
>
> +binop_rounding_mode("fadd_rtz", tfloat, commutative + associative,
> "src0 + src1", "_rtz")
> +
> binop("iadd", tint, commutative + associative, "src0 + src1")
> binop("uadd_sat", tuint, commutative,
> "(src0 + src1) < src0 ? UINT64_MAX : (src0 + src1)")
> binop("fsub", tfloat, "", "src0 - src1")
> +binop_rounding_mode("fsub_rtne", tfloat, "",
> + "_mesa_roundeven(src0 - src1)", "_rtne")
> +binop_rounding_mode("fsub_rtz", tfloat, "", "src0 - src1", "_rtz")
> binop("isub", tint, "", "src0 - src1")
>
> binop("fmul", tfloat, commutative + associative, "src0 * src1")
> +binop_rounding_mode("fmul_rtne", tfloat, commutative + associative,
> + "_mesa_roundeven(src0 * src1)", "_rtne")
> +binop_rounding_mode("fmul_rtz", tfloat, commutative + associative,
> "src0 * src1", "_rtz")
> +
> # low 32-bits of signed/unsigned integer multiply
> binop("imul", tint, commutative + associative, "src0 * src1")
>
> --
> 2.19.1
>
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