[mlir][dxsa] Add dcl_hs_fork_phase_instance_count instruction

mlir/include/mlir/Dialect/DXSA/IR/DXSAOps.td

@@ -819,4 +819,23 @@ def DXSA_DclHsJoinPhaseInstanceCount :
   let assemblyFormat = "$count attr-dict";
 }
 
+def DXSA_DclHsForkPhaseInstanceCount :
+    DXSA_Op<"dcl_hs_fork_phase_instance_count"> {
+  let summary = "declares the Fork Phase instance count";
+  let description = [{
+    The `dxsa.dcl_hs_fork_phase_instance_count` operation declares
+    the Fork Phase instance count.
+
+    The `$count` must be a positive 32-bit unsigned integer in the range [1, 2^32 - 1].
+
+    Example:
+
+    ```mlir
+    dxsa.dcl_hs_fork_phase_instance_count 42
+    ```
+  }];
+  let arguments = (ins ConfinedAttr<UI32Attr, [DXSA_UIntNonZero]>:$count);
+  let assemblyFormat = "$count attr-dict";
+}
+
 #endif // DXSA_OPS

mlir/lib/Target/DXSA/BinaryParser.cpp

@@ -664,6 +664,11 @@ class DXBuilder {
         builder, loc, builder.getUI32IntegerAttr(count));
   }
 
+  Instruction buildDclHsForkPhaseInstanceCount(uint32_t count, Location loc) {
+    return dxsa::DclHsForkPhaseInstanceCount::create(
+        builder, loc, builder.getUI32IntegerAttr(count));
+  }
+
 private:
   MLIRContext *context;
   ModuleOp module;
@@ -1240,6 +1245,12 @@ class Parser {
     return builder.buildDclHsJoinPhaseInstanceCount(*count, loc);
   }
 
+  FailureOr<Instruction> parseDclHsForkPhaseInstanceCount(Location loc) {
+    auto count = parseToken();
+    FAILURE_IF_FAILED(count);
+    return builder.buildDclHsForkPhaseInstanceCount(*count, loc);
+  }
+
   OptionalParseResult parseDclInstruction(uint32_t opcodeToken, Location loc,
                                           Instruction &out) {
     FailureOr<Instruction> result;
@@ -1301,6 +1312,9 @@ class Parser {
     case D3D11_SB_OPCODE_DCL_HS_JOIN_PHASE_INSTANCE_COUNT:
       result = parseDclHsJoinPhaseInstanceCount(loc);
       break;
+    case D3D11_SB_OPCODE_DCL_HS_FORK_PHASE_INSTANCE_COUNT:
+      result = parseDclHsForkPhaseInstanceCount(loc);
+      break;
     default:
       return std::nullopt;
     }

mlir/test/Target/DXSA/dcl_hs_fork_phase_instance_count.mlir

@@ -0,0 +1,5 @@
+// RUN: mlir-translate --import-dxsa-bin %S/inputs/dcl_hs_fork_phase_instance_count.bin | FileCheck %s
+
+// CHECK:      module {
+// CHECK-NEXT:   dxsa.dcl_hs_fork_phase_instance_count 42
+// CHECK-NEXT: }

mlir/test/Target/DXSA/dcl_hs_fork_phase_instance_count_invalid.mlir

@@ -0,0 +1,14 @@
+// RUN: mlir-opt %s -split-input-file -verify-diagnostics
+
+// expected-error@+1 {{attribute 'count' failed to satisfy constraint: 32-bit unsigned integer attribute whose value is non-zero}}
+dxsa.dcl_hs_fork_phase_instance_count 0
+
+// -----
+
+// expected-error@+1 {{negative integer literal not valid for unsigned integer type}}
+dxsa.dcl_hs_fork_phase_instance_count -1
+
+// -----
+
+// expected-error@+1 {{integer constant out of range for attribute}}
+dxsa.dcl_hs_fork_phase_instance_count 4294967296