[PATCH v6 3/3] vkd3d-shader/tpf: For sample_l/sample_b, set lod swizzle to SCALAR.

[Ethan Lee]

From: Ethan Lee

Per Francisco Casas :

I just realized one more thing. I think we are not properly following the specification for both sample_l and sample_b.

In the Restrictions section of the documentation for sample_b it is mentioned that the last src register must use a single component selector if it is not a scalar immediate. This "select_component" is also ilustrated in the sample_l format:

sample_l[_aoffimmi(u,v,w)] dest[.mask], srcAddress[.swizzle], srcResource[.swizzle], srcSampler, srcLOD.select_component

Currently, we are not respecting that since sm4_src_from_node() sets

src->swizzle_type = VKD3D_SM4_SWIZZLE_VEC4;

by default.

It should be VKD3D_SM4_SWIZZLE_SCALAR in this case... The disassembly should show a single component in the swizzle of the last src register.

Signed-off-by: Ethan Lee 
---
 libs/vkd3d-shader/tpf.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/libs/vkd3d-shader/tpf.c b/libs/vkd3d-shader/tpf.c
index f39491e2..a82b79bb 100644
--- a/libs/vkd3d-shader/tpf.c
+++ b/libs/vkd3d-shader/tpf.c
@@ -3742,6 +3742,7 @@ static void write_sm4_sample(struct hlsl_ctx *ctx, struct vkd3d_bytecode_buffer
            || load->load_type == HLSL_RESOURCE_SAMPLE_LOD_BIAS)
     {
         sm4_src_from_node(&instr.srcs[3], load->lod.node, VKD3DSP_WRITEMASK_ALL);
+        instr.srcs[3].swizzle_type = VKD3D_SM4_SWIZZLE_SCALAR;
         ++instr.src_count;
     }