[Nouveau] [PATCH mesa v2 3/3] nouveau: codegen: LOAD: Take src swizzle into account

[Ilia Mirkin]

[+radeon folk]

Marek, Nicolai, Bas - please have a look at the doc change and let us
know if you think this will cause a problem for radeon.

Hans is solving the issue that he wants to swizzle the data loaded
from the image/buffer/whatever before sticking it into the dst
register.

  -ilia

On Thu, Apr 21, 2016 at 8:39 AM, Hans de Goede <hdegoede at redhat.com> wrote:
> The llvm TGSI backend uses pointers in registers and does things
> like:
>
> LOAD TEMP[0].y, MEMORY[0], TEMP[0]
>
> Expecting the data at address TEMP[0].x to get loaded to
> TEMP[0].y. But this will cause the data at TEMP[0].x + 4 to be
> loaded instead.
>
> This commit adds support for a swizzle suffix for the 1st source
> operand, which allows using:
>
> LOAD TEMP[0].y, MEMORY[0].xxxx, TEMP[0]
>
> And actually getting the desired behavior
>
> Signed-off-by: Hans de Goede <hdegoede at redhat.com>
> ---
> Changes in v2:
> -Tweaked commit msg a bit
> -Add documentation for this to src/gallium/docs/source/tgsi.rst
> ---
>  src/gallium/docs/source/tgsi.rst                          | 3 +++
>  src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp | 8 ++++++--
>  2 files changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/src/gallium/docs/source/tgsi.rst b/src/gallium/docs/source/tgsi.rst
> index 85c302f..4315707 100644
> --- a/src/gallium/docs/source/tgsi.rst
> +++ b/src/gallium/docs/source/tgsi.rst
> @@ -2288,6 +2288,9 @@ Resource Access Opcodes
>                 texture arrays and 2D textures.  address.w is always
>                 ignored.
>
> +               A swizzle suffix may be added to the resource argument
> +               this will cause the resource data to be swizzled accordingly.
> +
>  .. opcode:: STORE - Write data to a shader resource
>
>                 Syntax: ``STORE resource, address, src``
> diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp
> index e2db731..01df4f3 100644
> --- a/src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp
> +++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp
> @@ -2279,13 +2279,17 @@ Converter::handleLOAD(Value *dst0[4])
>
>           Value *off;
>           Symbol *sym;
> +         uint32_t src0_component_offset = tgsi.getSrc(0).getSwizzle(c) * 4;
> +
>           if (tgsi.getSrc(1).getFile() == TGSI_FILE_IMMEDIATE) {
>              off = NULL;
>              sym = makeSym(tgsi.getSrc(0).getFile(), r, -1, c,
> -                          tgsi.getSrc(1).getValueU32(0, info) + 4 * c);
> +                          tgsi.getSrc(1).getValueU32(0, info) +
> +                          src0_component_offset);
>           } else {
>              off = fetchSrc(1, 0);
> -            sym = makeSym(tgsi.getSrc(0).getFile(), r, -1, c, 4 * c);
> +            sym = makeSym(tgsi.getSrc(0).getFile(), r, -1, c,
> +                          src0_component_offset);
>           }
>
>           Instruction *ld = mkLoad(TYPE_U32, dst0[c], sym, off);
> --
> 2.7.3
>