[MLIR][EmitC] Bugfix in emitc.call_opaque operand emission (#153980)

The operand emission needed the operand to be in scope which lead to
failure when the emitc.call_opaque is in an emitc.expression's body.

Author: gdehame

mlir/lib/Target/Cpp/TranslateToCpp.cpp

@@ -749,11 +749,7 @@ static LogicalResult printOperation(CppEmitter &emitter,
       if (t.getType().isIndex()) {
         int64_t idx = t.getInt();
         Value operand = op.getOperand(idx);
-        if (!emitter.hasValueInScope(operand))
-          return op.emitOpError("operand ")
-                 << idx << "'s value not defined in scope";
-        os << emitter.getOrCreateName(operand);
-        return success();
+        return emitter.emitOperand(operand);
       }
     }
     if (failed(emitter.emitAttribute(op.getLoc(), attr)))

mlir/test/Target/Cpp/expressions.mlir

@@ -418,3 +418,24 @@ func.func @expression_with_load_and_call(%arg0: !emitc.ptr<i32>) -> i1 {
   }
   return %result : i1
 }
+
+
+// CPP-DEFAULT: void expression_with_call_opaque_with_args_array(int32_t [[v1:v.+]], int32_t [[v2:v.+]]) {
+// CPP-DEFAULT-NEXT:   bool [[v3:v.+]] = f(([[v1]] < [[v2]]));
+// CPP-DEFAULT-NEXT:   return;
+// CPP-DEFAULT-NEXT: }
+
+// CPP-DECLTOP: void expression_with_call_opaque_with_args_array(int32_t [[v1:v.+]], int32_t [[v2:v.+]]) {
+// CPP-DECLTOP-NEXT:   bool [[v3:v.+]];
+// CPP-DECLTOP-NEXT:   [[v3]] = f(([[v1]] < [[v2]]));
+// CPP-DECLTOP-NEXT:   return;
+// CPP-DECLTOP-NEXT: }
+
+emitc.func @expression_with_call_opaque_with_args_array(%0 : i32, %1 : i32) {
+  %2 = expression : i1 {
+    %3 = cmp lt, %0, %1 : (i32, i32) -> i1
+    %4 = emitc.call_opaque "f"(%3) {"args" = [0: index]} : (i1) -> i1
+    yield %4 : i1
+  }
+  return
+}