[Mesa-dev] [PATCH v2] r600g: Fix special negative immediate constants when using ABS modifier.

[Nick Sarnie]

On Sun, Oct 25, 2015 at 7:27 AM, Ivan Kalvachev <ikalvachev at gmail.com>
wrote:

> On 10/25/15, Ivan Kalvachev <ikalvachev at gmail.com> wrote:
> > Some constants (like 1.0 and 0.5) could be inlined as immediate inputs
> > without using their literal value. The r600_bytecode_special_constants()
> > function emulates the negative of these constants by using NEG modifier.
> >
> > However some shaders define -1.0 constant and want to use it as 1.0.
> > They do so by using ABS modifier. But r600_bytecode_special_constants()
> > set NEG in addition to ABS. Since NEG modifier have priority over ABS
> one,
> > we get -|1.0| as result, instead of |1.0|.
> >
> > The patch simply prevents the additional switching of NEG when ABS is
> set.
> >
> > Signed-off-by: Ivan Kalvachev <ikalvachev at gmail.com>
> > ---
> >  src/gallium/drivers/r600/r600_asm.c    | 9 +++++----
> >  src/gallium/drivers/r600/r600_shader.c | 2 +-
> >  2 files changed, 6 insertions(+), 5 deletions(-)
> >
> > diff --git a/src/gallium/drivers/r600/r600_asm.c
> > b/src/gallium/drivers/r600/r600_asm.c
> > index bc69806..8fc622c 100644
> > --- a/src/gallium/drivers/r600/r600_asm.c
> > +++ b/src/gallium/drivers/r600/r600_asm.c
> > @@ -635,8 +635,9 @@ static int replace_gpr_with_pv_ps(struct
> r600_bytecode
> > *bc,
> >         return 0;
> >  }
> >
> > -void r600_bytecode_special_constants(uint32_t value, unsigned *sel,
> > unsigned *neg)
> > +void r600_bytecode_special_constants(uint32_t value, unsigned *sel,
> > unsigned *neg, unsigned abs)
> >  {
> > +
> >         switch(value) {
> >         case 0:
> >                 *sel = V_SQ_ALU_SRC_0;
> > @@ -655,11 +656,11 @@ void r600_bytecode_special_constants(uint32_t
> > value, unsigned *sel, unsigned *ne
> >                 break;
> >         case 0xBF800000: /* -1.0f */
> >                 *sel = V_SQ_ALU_SRC_1;
> > -               *neg ^= 1;
> > +               *neg ^= !abs;
> >                 break;
> >         case 0xBF000000: /* -0.5f */
> >                 *sel = V_SQ_ALU_SRC_0_5;
> > -               *neg ^= 1;
> > +               *neg ^= !abs;
> >                 break;
> >         default:
> >                 *sel = V_SQ_ALU_SRC_LITERAL;
> > @@ -1208,7 +1209,7 @@ int r600_bytecode_add_alu_type(struct r600_bytecode
> > *bc,
> >                 }
> >                 if (nalu->src[i].sel == V_SQ_ALU_SRC_LITERAL)
> >
>  r600_bytecode_special_constants(nalu->src[i].value,
> > -                               &nalu->src[i].sel, &nalu->src[i].neg);
> > +                               &nalu->src[i].sel, &nalu->src[i].neg,
> > nalu->src[i].abs);
> >         }
> >         if (nalu->dst.sel >= bc->ngpr) {
> >                 bc->ngpr = nalu->dst.sel + 1;
> > diff --git a/src/gallium/drivers/r600/r600_shader.c
> > b/src/gallium/drivers/r600/r600_shader.c
> > index 8efe902..50c0329 100644
> > --- a/src/gallium/drivers/r600/r600_shader.c
> > +++ b/src/gallium/drivers/r600/r600_shader.c
> > @@ -1008,7 +1008,7 @@ static void tgsi_src(struct r600_shader_ctx *ctx,
> >                         (tgsi_src->Register.SwizzleX ==
> > tgsi_src->Register.SwizzleW)) {
> >
> >                         index = tgsi_src->Register.Index * 4 +
> > tgsi_src->Register.SwizzleX;
> > -
> > r600_bytecode_special_constants(ctx->literals[index], &r600_src->sel,
> > &r600_src->neg);
> > +
> > r600_bytecode_special_constants(ctx->literals[index], &r600_src->sel,
> > &r600_src->neg, r600_src->abs);
> >                         if (r600_src->sel != V_SQ_ALU_SRC_LITERAL)
> >                                 return;
> >                 }
> > --
> > 2.5.1
> >
>
> It's the same patch, I've just forgotten to add the header file change:
>
> diff --git a/src/gallium/drivers/r600/r600_asm.h
> b/src/gallium/drivers/r600/r600_asm.h
> index 7cf3a09..d48ad1e 100644
> --- a/src/gallium/drivers/r600/r600_asm.h
> +++ b/src/gallium/drivers/r600/r600_asm.h
> @@ -255,7 +255,7 @@ int r600_bytecode_add_cfinst(struct r600_bytecode *bc,
>  int r600_bytecode_add_alu_type(struct r600_bytecode *bc,
>                 const struct r600_bytecode_alu *alu, unsigned type);
>  void r600_bytecode_special_constants(uint32_t value,
> -               unsigned *sel, unsigned *neg);
> +               unsigned *sel, unsigned *neg, unsigned abs);
>  void r600_bytecode_disasm(struct r600_bytecode *bc);
>  void r600_bytecode_alu_read(struct r600_bytecode *bc,
>                 struct r600_bytecode_alu *alu, uint32_t word0, uint32_t
> word1);
>
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>
>
Tested-By: Nick Sarnie <commendsarnex at gmail.com>
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