Mesa (main): nir/lower_task_shader: insert barrier before/after shared memory read/write

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Module: Mesa
Branch: main
Commit: 49b8fffeed9dc9b6002d69cf16edffe059112daf
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=49b8fffeed9dc9b6002d69cf16edffe059112daf

Author: Marcin Ślusarz <marcin.slusarz at intel.com>
Date:   Mon Jun 20 15:41:38 2022 +0200

nir/lower_task_shader: insert barrier before/after shared memory read/write

Fixes: 8aff8d3dd42 ("nir: Add common task shader lowering to make the backend's job easier.")
Reviewed-by: Timur Kristóf <timur.kristof at gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17143>

---

 src/compiler/nir/nir_lower_task_shader.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/src/compiler/nir/nir_lower_task_shader.c b/src/compiler/nir/nir_lower_task_shader.c
index e242c0d1171..6d7040828fe 100644
--- a/src/compiler/nir/nir_lower_task_shader.c
+++ b/src/compiler/nir/nir_lower_task_shader.c
@@ -88,10 +88,23 @@ append_launch_mesh_workgroups_to_nv_task(nir_builder *b,
    nir_ssa_def *zero = nir_imm_int(b, 0);
    nir_store_shared(b, zero, zero, .base = s->task_count_shared_addr);
 
+   nir_scoped_barrier(b,
+         .execution_scope = NIR_SCOPE_WORKGROUP,
+         .memory_scope = NIR_SCOPE_WORKGROUP,
+         .memory_semantics = NIR_MEMORY_RELEASE,
+         .memory_modes = nir_var_mem_shared);
+
    /* At the end of the shader, read the task count from shared memory
     * and emit launch_mesh_workgroups.
     */
    b->cursor = nir_after_cf_list(&b->impl->body);
+
+   nir_scoped_barrier(b,
+         .execution_scope = NIR_SCOPE_WORKGROUP,
+         .memory_scope = NIR_SCOPE_WORKGROUP,
+         .memory_semantics = NIR_MEMORY_ACQUIRE,
+         .memory_modes = nir_var_mem_shared);
+
    nir_ssa_def *task_count =
       nir_load_shared(b, 1, 32, zero, .base = s->task_count_shared_addr);