[Mesa-dev] [Mesa-stable] [PATCH 2/3] i965/vec4: fix register width for DF VGRF and UNIFORM

[Samuel Iglesias Gonsálvez]

El Viernes, 28 de abril de 2017 16:27:56 Francisco Jerez escribió:
> Samuel Iglesias Gonsálvez <siglesias at igalia.com> writes:
> > On gen7, the swizzles used in DF align16 instructions works for element
> > size of 32 bits, so we can address only 2 consecutive DFs. As we assumed
> > that in the rest of the code and prepare the instructions for this
> > (scalarize_df()), we need to set it to two again.
> > 
> > However, for DF align1 instructions, a width of 2 is wrong as we are not
> > reading the data we want. For example, an uniform would have a region of
> > <0, 2, 1> so it would repeat the first 2 DFs, when we wanted to access
> > to the first 4.
> > 
> > This patch sets the default one to 4 and then modifies the width of
> > align16 instruction's DF sources when we translate the logical swizzle
> > to the physical one.
> > 
> > Signed-off-by: Samuel Iglesias Gonsálvez <siglesias at igalia.com>
> > Cc: "17.1" <mesa-stable at lists.freedesktop.org>
> > ---
> > 
> >  src/intel/compiler/brw_vec4.cpp | 13 ++++++++-----
> >  1 file changed, 8 insertions(+), 5 deletions(-)
> > 
> > diff --git a/src/intel/compiler/brw_vec4.cpp
> > b/src/intel/compiler/brw_vec4.cpp index 95f96ea69c0..8b755e1b75e 100644
> > --- a/src/intel/compiler/brw_vec4.cpp
> > +++ b/src/intel/compiler/brw_vec4.cpp
> > @@ -2003,9 +2003,7 @@ vec4_visitor::convert_to_hw_regs()
> > 
> >           struct brw_reg reg;
> >           switch (src.file) {
> >           case VGRF: {
> > 
> > -            const unsigned type_size = type_sz(src.type);
> > -            const unsigned width = REG_SIZE / 2 / MAX2(4, type_size);
> > -            reg = byte_offset(brw_vecn_grf(width, src.nr, 0),
> > src.offset);
> > +            reg = byte_offset(brw_vecn_grf(4, src.nr, 0), src.offset);
> > 
> >              reg.type = src.type;
> >              reg.abs = src.abs;
> >              reg.negate = src.negate;
> > 
> > @@ -2013,12 +2011,11 @@ vec4_visitor::convert_to_hw_regs()
> > 
> >           }
> >           
> >           case UNIFORM: {
> > 
> > -            const unsigned width = REG_SIZE / 2 / MAX2(4,
> > type_sz(src.type));> 
> >              reg = stride(byte_offset(brw_vec4_grf(
> >              
> >                                          prog_data->base.dispatch_grf_star
> >                                          t_reg +
> >                                          src.nr / 2, src.nr % 2 * 4),
> >                                       
> >                                       src.offset),
> > 
> > -                         0, width, 1);
> > +                         0, 4, 1);
> > 
> >              reg.type = src.type;
> >              reg.abs = src.abs;
> >              reg.negate = src.negate;
> > 
> > @@ -2576,6 +2573,12 @@ vec4_visitor::apply_logical_swizzle(struct brw_reg
> > *hw_reg,> 
> >     assert(brw_is_single_value_swizzle(reg.swizzle) ||
> >     
> >            is_supported_64bit_region(inst, arg));
> > 
> > +   /* Apply the region <2, 2, 1> for GRF or <0, 2, 1> for uniforms, as
> > align16 +    * HW can only do 32-bit swizzle channels.
> > +    */
> > +   if (reg.file == UNIFORM || reg.file == VGRF)
> > +      hw_reg->width = BRW_WIDTH_2;
> 
> Any reason this is conditional on the register file?  Originally we were
> only setting the width to 2 for the UNIFORM and VGRF files, but that was
> probably an oversight...
> 

No reason, this was an oversight. I have removed locally the conditional.

Do you get your R-b to it then?

Sam

> > +
> > 
> >     if (is_supported_64bit_region(inst, arg) &&
> >     
> >         !is_gen7_supported_64bit_swizzle(inst, arg)) {
> >        
> >        /* Supported 64-bit swizzles are those such that their first two
> > 
> > _______________________________________________
> > mesa-stable mailing list
> > mesa-stable at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/mesa-stable
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