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

[Francisco Jerez]

Samuel Iglesias Gonsálvez <siglesias at igalia.com> writes:

> On Mon, 2017-05-01 at 14:55 +0200, Samuel Iglesias Gonsálvez wrote:
>> 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?
>> 
>
> s/get/give
>

Yeah, with that change patch looks reasonable to me:

Reviewed-by: Francisco Jerez <currojerez at riseup.net>

>> 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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