nir: add shader_clock intrinsic

v2: Add flags and inline comment/description.
v3: None of the input/outputs are variables
v4: Drop clockARB reference, relate code motion barrier comment wrt
intrinsic flag.
v5: Drop the "thus we can eliminate..." comment (Connor)

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Connor Abbott <cwabbott0@gmail.com>
Reviewed-by: Matt Turner <mattst88@gmail.com>

diff --git a/src/glsl/nir/glsl_to_nir.cpp b/src/glsl/nir/glsl_to_nir.cpp
index 7275b48eff07b17b04c5d7ce5be22e8b04a867bb..57aba5be0f5482208e627a1b11f2034cb854dba8 100644 (file)
--- a/src/glsl/nir/glsl_to_nir.cpp
+++ b/src/glsl/nir/glsl_to_nir.cpp
@@ -717,6 +717,8 @@ nir_visitor::visit(ir_call *ir)
          op = nir_intrinsic_ssbo_atomic_exchange;
       } else if (strcmp(ir->callee_name(), "__intrinsic_ssbo_atomic_comp_swap_internal") == 0) {
          op = nir_intrinsic_ssbo_atomic_comp_swap;
+      } else if (strcmp(ir->callee_name(), "__intrinsic_shader_clock") == 0) {
+         op = nir_intrinsic_shader_clock;
       } else {
          unreachable("not reached");
       }
@@ -821,6 +823,10 @@ nir_visitor::visit(ir_call *ir)
       case nir_intrinsic_memory_barrier:
          nir_instr_insert_after_cf_list(this->cf_node_list, &instr->instr);
          break;
+      case nir_intrinsic_shader_clock:
+         nir_ssa_dest_init(&instr->instr, &instr->dest, 1, NULL);
+         nir_instr_insert_after_cf_list(this->cf_node_list, &instr->instr);
+         break;
       case nir_intrinsic_store_ssbo: {
          exec_node *param = ir->actual_parameters.get_head();
          ir_rvalue *block = ((ir_instruction *)param)->as_rvalue();

diff --git a/src/glsl/nir/nir_intrinsics.h b/src/glsl/nir/nir_intrinsics.h
index c1fb1bad4bc3086691a01753d5f518abcae02769..c2b6fe7166d4813544b04f6df06da6828539f8f8 100644 (file)
--- a/src/glsl/nir/nir_intrinsics.h
+++ b/src/glsl/nir/nir_intrinsics.h
@@ -83,6 +83,14 @@ BARRIER(discard)
  */
 BARRIER(memory_barrier)
 
+/*
+ * Shader clock intrinsic with semantics analogous to the clock2x32ARB()
+ * GLSL intrinsic.
+ * The latter can be used as code motion barrier, which is currently not
+ * feasible with NIR.
+ */
+INTRINSIC(shader_clock, 0, ARR(), true, 1, 0, 0, NIR_INTRINSIC_CAN_ELIMINATE)
+
 /** A conditional discard, with a single boolean source. */
 INTRINSIC(discard_if, 1, ARR(1), false, 0, 0, 0, 0)