[Mesa-stable] [Mesa-dev] [PATCH 2/2] glsl: Relax ir_quadop_bitfield_insert type restrictions.

[Jason Ekstrand]

On Jan 5, 2016 5:34 AM, "Kenneth Graunke" <kenneth at whitecape.org> wrote:
>
> While GLSL restricts bitfieldInsert's offset and bits parameters to
> be scalars, we shouldn't require this in the IR.
>
> In particular, opt_vectorize() tries to combine
>
> result.x = bitfieldInsert(src0.x, src1.x, src2.x, src3.x);
> result.y = bitfieldInsert(src0.y, src1.y, src2.y, src3.y);
> result.z = bitfieldInsert(src0.z, src1.z, src2.z, src3.z);
> result.w = bitfieldInsert(src0.w, src1.w, src2.w, src3.w);
>
> into a single ivec4 bitfieldInsert operation.  This currently breaks,
> because the last two types become ivec4 rather than int.  It seems
> perfectly reasonable to allow this.

You also need to fix NIR to handle this. At the moment, it splats the
offset and bits to all channels.  This will affect the opcode definition,
the constant folding expression, and possibly alu_to_scalar as well.

--Jason

> i965 lowers ir_quadop_bitfield_insert to ir_binop_bfm and ir_triop_bfi,
> which already lift these restrictions.
>
> (I debated about using is_integer() or base_type == GLSL_TYPE_INT here;
> I ended up relaxing it to allow either int/uint because ir_binop_bfm
> and ir_triop_bfi do that already.)
>
> Fixes assertion failures when compiling Shadow of Mordor vertex shaders
> on i965 in vec4 mode (where OptimizeForAOS enables opt_vectorize()).
>
> Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
> Cc: Matt Turner <mattst88 at gmail.com>
> Cc: mesa-stable at lists.freedesktop.org
> ---
>  src/glsl/ir_validate.cpp | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/src/glsl/ir_validate.cpp b/src/glsl/ir_validate.cpp
> index dcc079c..b5eaaff 100644
> --- a/src/glsl/ir_validate.cpp
> +++ b/src/glsl/ir_validate.cpp
> @@ -661,8 +661,8 @@ ir_validate::visit_leave(ir_expression *ir)
>     case ir_quadop_bitfield_insert:
>        assert(ir->operands[0]->type == ir->type);
>        assert(ir->operands[1]->type == ir->type);
> -      assert(ir->operands[2]->type == glsl_type::int_type);
> -      assert(ir->operands[3]->type == glsl_type::int_type);
> +      assert(ir->operands[2]->type->is_integer());
> +      assert(ir->operands[3]->type->is_integer());
>        break;
>
>     case ir_quadop_vector:
> --
> 2.6.4
>
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