asahi: defer fixed->float to tess

this should parallelize better.

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/31908>

src/asahi/lib/shaders/tessellation.cl

@@ -96,7 +96,10 @@ libagx_load_tess_coord(constant struct libagx_tess_args *p, uint raw_id)
       &p->patch_coord_buffer[p->coord_allocs[patch] + vtx];
 
    /* Written weirdly because NIR struggles with loads of structs */
-   return *((global float2 *)t);
+   uint2 fixed = *((global uint2 *)t);
+
+   /* Convert fixed point to float */
+   return convert_float2(fixed) / (1u << 16);
 }
 
 uintptr_t

src/asahi/lib/shaders/tessellator.cl

@@ -353,13 +353,6 @@ floatToFixed(const float input)
    return mad(input, FXP_ONE, 0.5f);
 }
 
-static float
-fixedToFloat(const FXP input)
-{
-   // Don't need to worry about special cases because the bounds are reasonable.
-   return ((float)input) / FXP_ONE;
-}
-
 static bool
 isOdd(const float input)
 {
@@ -414,8 +407,8 @@ PatchIndexValue(private struct CHWTessellator *ctx, int index)
 static void
 DefinePoint(global struct libagx_tess_point *out, FXP fxpU, FXP fxpV)
 {
-   out->u = fixedToFloat(fxpU);
-   out->v = fixedToFloat(fxpV);
+   out->u = fxpU;
+   out->v = fxpV;
 }
 
 static void

src/asahi/lib/shaders/tessellator.h

@@ -31,8 +31,8 @@ enum libagx_tess_mode {
 };
 
 struct libagx_tess_point {
-   float u;
-   float v;
+   uint32_t u;
+   uint32_t v;
 };
 AGX_STATIC_ASSERT(sizeof(struct libagx_tess_point) == 8);