r600: fix vertex state update clover regression

This change handles the case when "vertex_fetch_shader.cso" is null,
it implements the previous behavior in this specific case. This
situation is happening with clover.

For instance, this issue is triggered with "piglit/bin/cl-custom-buffer-flags":
==6467==ERROR: AddressSanitizer: SEGV on unknown address 0x00000000000c (pc 0x7ff92908fe6e bp 0x7ffe86ae5ad0 sp 0x7ffe86ae5a30 T0)
==6467==The signal is caused by a READ memory access.
==6467==Hint: address points to the zero page.
    #0 0x7ff92908fe6e in evergreen_emit_vertex_buffers ../src/gallium/drivers/r600/evergreen_state.c:2123
    #1 0x7ff92908444b in r600_emit_atom ../src/gallium/drivers/r600/r600_pipe.h:627
    #2 0x7ff92908444b in compute_emit_cs ../src/gallium/drivers/r600/evergreen_compute.c:798
    #3 0x7ff92908444b in evergreen_launch_grid ../src/gallium/drivers/r600/evergreen_compute.c:927
    #4 0x7ff9349f9350 in clover::kernel::launch(clover::command_queue&, std::vector<unsigned long, std::allocator<unsigned long> > const&, std::vector<unsigned long, std::allocator<unsigned long> > const&, std::vector<unsigned long, std::allocator<unsigned long> > const&) ../src/gallium/frontends/clover/core/kernel.cpp:105
    #5 0x7ff9349c331d in std::function<void (clover::event&)>::operator()(clover::event&) const /usr/include/c++/11.4.0/bits/std_function.h:590
    #6 0x7ff9349c331d in clover::event::trigger() ../src/gallium/frontends/clover/core/event.cpp:54
    #7 0x7ff9349c82f1 in clover::hard_event::hard_event(clover::command_queue&, unsigned int, clover::ref_vector<clover::event> const&, std::function<void (clover::event&)>) ../src/gallium/frontends/clover/core/event.cpp:138
    #8 0x7ff9348daa47 in create<clover::hard_event, clover::command_queue&, int, clover::ref_vector<clover::event>&, clEnqueueNDRangeKernel(cl_command_queue, cl_kernel, cl_uint, const size_t*, const size_t*, const size_t*, cl_uint, _cl_event* const*, _cl_event**)::<lambda(clover::event&)> > ../src/gallium/frontends/clover/util/pointer.hpp:241
    #9 0x7ff9348daa47 in clEnqueueNDRangeKernel ../src/gallium/frontends/clover/api/kernel.cpp:334

Fixes: 659b7eb ("r600: better tracking for vertex buffer emission")
Related: https://gitlab.freedesktop.org/mesa/mesa/-/issues/10079
Signed-off-by: Patrick Lerda <patrick9876@free.fr>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/29163>
(cherry picked from commit f8a1d9f)

Author: Patrick Lerda

.pick_status.json

@@ -594,7 +594,7 @@
         "description": "r600: fix vertex state update clover regression",
         "nominated": true,
         "nomination_type": 1,
-        "resolution": 0,
+        "resolution": 1,
         "main_sha": null,
         "because_sha": "659b7eb2799bccfff817961518d0ff2ab9e65bca",
         "notes": null

src/gallium/drivers/r600/evergreen_state.c

@@ -2137,7 +2137,8 @@ static void evergreen_emit_vertex_buffers(struct r600_context *rctx,
 {
 	struct radeon_cmdbuf *cs = &rctx->b.gfx.cs;
 	struct r600_fetch_shader *shader = (struct r600_fetch_shader*)rctx->vertex_fetch_shader.cso;
-	uint32_t dirty_mask = state->dirty_mask & shader->buffer_mask;
+	uint32_t buffer_mask = shader ? shader->buffer_mask : ~0;
+	uint32_t dirty_mask = state->dirty_mask & buffer_mask;
 
 	while (dirty_mask) {
 		struct pipe_vertex_buffer *vb;
@@ -2176,7 +2177,7 @@ static void evergreen_emit_vertex_buffers(struct r600_context *rctx,
 		radeon_emit(cs, radeon_add_to_buffer_list(&rctx->b, &rctx->b.gfx, rbuffer,
 						      RADEON_USAGE_READ | RADEON_PRIO_VERTEX_BUFFER));
 	}
-	state->dirty_mask &= ~shader->buffer_mask;
+	state->dirty_mask &= ~buffer_mask;
 }
 
 static void evergreen_fs_emit_vertex_buffers(struct r600_context *rctx, struct r600_atom * atom)