Mesa (master): spirv: Add output memory semantics to OpControlBarrier in TCS

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Module: Mesa
Branch: master
Commit: a4125b4d261df39189f67dffaa5c90c0f6f66fe6
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=a4125b4d261df39189f67dffaa5c90c0f6f66fe6

Author: Jason Ekstrand <jason at jlekstrand.net>
Date:   Tue Jan  7 12:01:13 2020 -0600

spirv: Add output memory semantics to OpControlBarrier in TCS

Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira at intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3307>

---

 src/compiler/spirv/spirv_to_nir.c | 24 +++++++++++++++++++++---
 1 file changed, 21 insertions(+), 3 deletions(-)

diff --git a/src/compiler/spirv/spirv_to_nir.c b/src/compiler/spirv/spirv_to_nir.c
index 42895b542ff..2ed2bf34875 100644
--- a/src/compiler/spirv/spirv_to_nir.c
+++ b/src/compiler/spirv/spirv_to_nir.c
@@ -2106,9 +2106,6 @@ vtn_emit_scoped_memory_barrier(struct vtn_builder *b, SpvScope scope,
    if (semantics & SpvMemorySemanticsWorkgroupMemoryMask)
       modes |= nir_var_mem_shared;
    if (semantics & SpvMemorySemanticsOutputMemoryMask) {
-      vtn_fail_if(!b->options->caps.vk_memory_model,
-                  "To use Output memory semantics, the VulkanMemoryModel "
-                  "capability must be declared.");
       modes |= nir_var_shader_out;
    }
 
@@ -3619,6 +3616,10 @@ vtn_emit_memory_barrier(struct vtn_builder *b, SpvScope scope,
       case SpvMemorySemanticsImageMemoryMask:
          vtn_emit_barrier(b, nir_intrinsic_memory_barrier_image);
          break;
+      case SpvMemorySemanticsOutputMemoryMask:
+         if (b->nb.shader->info.stage == MESA_SHADER_TESS_CTRL)
+            vtn_emit_barrier(b, nir_intrinsic_memory_barrier_tcs_patch);
+         break;
       default:
          break;;
       }
@@ -3691,6 +3692,23 @@ vtn_handle_barrier(struct vtn_builder *b, SpvOp opcode,
                             SpvMemorySemanticsWorkgroupMemoryMask;
       }
 
+      /* From the SPIR-V spec:
+       *
+       *    "When used with the TessellationControl execution model, it also
+       *    implicitly synchronizes the Output Storage Class: Writes to Output
+       *    variables performed by any invocation executed prior to a
+       *    OpControlBarrier will be visible to any other invocation after
+       *    return from that OpControlBarrier."
+       */
+      if (b->nb.shader->info.stage == MESA_SHADER_TESS_CTRL) {
+         memory_semantics &= ~(SpvMemorySemanticsAcquireMask |
+                               SpvMemorySemanticsReleaseMask |
+                               SpvMemorySemanticsAcquireReleaseMask |
+                               SpvMemorySemanticsSequentiallyConsistentMask);
+         memory_semantics |= SpvMemorySemanticsAcquireReleaseMask |
+                             SpvMemorySemanticsOutputMemoryMask;
+      }
+
       vtn_emit_memory_barrier(b, memory_scope, memory_semantics);
 
       if (execution_scope == SpvScopeWorkgroup)