panvk: Support blend shaders for alpha_to_one_enable

As in OpenGL, if alpha-to-one is required for Vulkan generate a
blend shader for it (since the hardware does not support alpha_to_one
natively).

Signed-off-by: Eric R. Smith <eric.smith@collabora.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/31194>

src/panfrost/vulkan/csf/panvk_vX_cmd_draw.c

@@ -495,6 +495,7 @@ prepare_blend(struct panvk_cmd_buffer *cmdbuf)
 {
    bool dirty =
       is_dirty(cmdbuf, CB_LOGIC_OP_ENABLE) || is_dirty(cmdbuf, CB_LOGIC_OP) ||
+      is_dirty(cmdbuf, MS_ALPHA_TO_ONE_ENABLE) ||
       is_dirty(cmdbuf, CB_ATTACHMENT_COUNT) ||
       is_dirty(cmdbuf, CB_COLOR_WRITE_ENABLES) ||
       is_dirty(cmdbuf, CB_BLEND_ENABLES) ||
@@ -522,7 +523,7 @@ prepare_blend(struct panvk_cmd_buffer *cmdbuf)
       return VK_ERROR_OUT_OF_DEVICE_MEMORY;
 
    panvk_per_arch(blend_emit_descs)(
-      dev, cb, cmdbuf->state.gfx.render.color_attachments.fmts,
+      dev, dyns, cmdbuf->state.gfx.render.color_attachments.fmts,
       cmdbuf->state.gfx.render.color_attachments.samples, fs_info, fs_code, bds,
       &cmdbuf->state.gfx.cb.info);
 

src/panfrost/vulkan/jm/panvk_vX_cmd_draw.c

@@ -375,7 +375,7 @@ panvk_draw_prepare_fs_rsd(struct panvk_cmd_buffer *cmdbuf,
 
    if (fs_info != NULL) {
       panvk_per_arch(blend_emit_descs)(
-         dev, cb, cmdbuf->state.gfx.render.color_attachments.fmts,
+         dev, dyns, cmdbuf->state.gfx.render.color_attachments.fmts,
          cmdbuf->state.gfx.render.color_attachments.samples, fs_info, fs_code,
          bds, &binfo);
    } else {

src/panfrost/vulkan/panvk_blend.h

@@ -17,6 +17,7 @@
 #include "panvk_mempool.h"
 
 struct vk_color_blend_state;
+struct vk_dynamic_graphics_state;
 struct panvk_device;
 
 struct panvk_blend_shader {
@@ -42,7 +43,7 @@ struct panvk_blend_info {
 };
 
 VkResult panvk_per_arch(blend_emit_descs)(
-   struct panvk_device *dev, const struct vk_color_blend_state *cb,
+   struct panvk_device *dev, const struct vk_dynamic_graphics_state *dy,
    const VkFormat *color_attachment_formats, uint8_t *color_attachment_samples,
    const struct pan_shader_info *fs_info, mali_ptr fs_code,
    struct mali_blend_packed *bds, struct panvk_blend_info *blend_info);

src/panfrost/vulkan/panvk_vX_blend.c

@@ -104,9 +104,10 @@ get_blend_shader_locked(struct panvk_device *dev,
       .logicop_func = state->logicop_func,
       .nr_samples = state->rts[rt].nr_samples,
       .equation = state->rts[rt].equation,
+      .alpha_to_one = state->alpha_to_one,
    };
 
-   assert(state->logicop_enable ||
+   assert(state->logicop_enable || state->alpha_to_one ||
           !pan_blend_is_opaque(state->rts[rt].equation));
    assert(state->rts[rt].equation.color_mask != 0);
    simple_mtx_assert_locked(&dev->blend_shader_cache.lock);
@@ -308,6 +309,10 @@ blend_needs_shader(const struct pan_blend_state *state, unsigned rt_idx,
    if (state->logicop_enable)
       return state->logicop_func != PIPE_LOGICOP_NOOP;
 
+   /* alpha-to-one always requires a blend shader */
+   if (state->alpha_to_one)
+      return true;
+
    /* If the output is opaque, we don't need a blend shader, no matter the
     * format.
     */
@@ -353,12 +358,14 @@ blend_needs_shader(const struct pan_blend_state *state, unsigned rt_idx,
 
 VkResult
 panvk_per_arch(blend_emit_descs)(
-   struct panvk_device *dev, const struct vk_color_blend_state *cb,
+   struct panvk_device *dev, const struct vk_dynamic_graphics_state *dyns,
    const VkFormat *color_attachment_formats, uint8_t *color_attachment_samples,
    const struct pan_shader_info *fs_info, mali_ptr fs_code,
    struct mali_blend_packed *bds, struct panvk_blend_info *blend_info)
 {
+   const struct vk_color_blend_state *cb = &dyns->cb;
    struct pan_blend_state bs = {
+      .alpha_to_one = dyns->ms.alpha_to_one_enable,
       .logicop_enable = cb->logic_op_enable,
       .logicop_func = vk_logic_op_to_pipe(cb->logic_op),
       .rt_count = cb->attachment_count,