[OpenPDK] Make synthesis targets for find_index for investigation of #23

The following command works for sample `bazel_rules_hdl` based synthesis
(yosys, sky130):

```
bazel build -c opt //xls/examples:find_index_5000ps_model_unit_verilog_synth
```

Introduces `rules_pkg` dependency to XLS Bazel WORKSPACE which is required for
`bazel_rules_hdl` to produce this target output.

PiperOrigin-RevId: 447582850

dependency_support/org_tuxfamily_eigen/BUILD.bazel

@@ -20,6 +20,6 @@ cc_test(
     name = "smoke_test",
     srcs = ["smoke_test.cc"],
     deps = [
-        "@org_tuxfamily_eigen//:eigen",
+        "@org_tuxfamily_eigen//:eigen3",
     ],
 )

dependency_support/org_tuxfamily_eigen/bundled.BUILD.bazel

@@ -49,7 +49,7 @@ EIGEN_MPL2_HEADER_FILES = glob(
 )
 
 cc_library(
-    name = "eigen",
+    name = "eigen3",
     hdrs = EIGEN_MPL2_HEADER_FILES,
     defines = [
         # This define (mostly) guarantees we don't link any problematic

dependency_support/rules_hdl/workspace.bzl

@@ -19,6 +19,16 @@ load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
 load("@bazel_tools//tools/build_defs/repo:utils.bzl", "maybe")
 
 def repo():
+    # Required to support rules_hdl, 0.7.0 release is current as of 2022-05-09.
+    http_archive(
+        name = "rules_pkg",
+        sha256 = "8a298e832762eda1830597d64fe7db58178aa84cd5926d76d5b744d6558941c2",
+        urls = [
+            "https://github.com/bazelbuild/rules_pkg/releases/download/0.7.0/rules_pkg-0.7.0.tar.gz",
+            "https://mirror.bazel.build/github.com/bazelbuild/rules_pkg/releases/download/0.7.0/rules_pkg-0.7.0.tar.gz",
+        ],
+    )
+
     # Commit on 2022-03-28, current as of 2022-05-04
     git_hash = "99bd5371ed3b8551dc74bfce6a0b5b3c47adae15"
     git_sha256 = "8ebe9e237072754f4b0c9b0413bf2b7e6a7a87fa711a011c1224496ddaa28a77"

xls/examples/BUILD

@@ -24,7 +24,12 @@ load(
     "xls_dslx_opt_ir_test",
     "xls_dslx_test",
     "xls_eval_ir_test",
+    "xls_ir_verilog",
 )
+load("@rules_hdl//verilog:providers.bzl", "verilog_library")
+load("@rules_hdl//synthesis:build_defs.bzl", "synthesize_rtl")
+# TODO(cdleary): 2022-05-09 Re-enable use of this rule.
+# load("@rules_hdl//place_and_route:build_defs.bzl", "place_and_route")
 
 package(
     default_visibility = ["//xls:xls_internal"],
@@ -338,3 +343,63 @@ xls_dslx_opt_ir(
     opt_ir_file = "proc_iota.opt.ir",
     tags = ["optonly"],
 )
+
+# -- find_index sample, with OpenROAD synthesis
+
+xls_dslx_library(
+    name = "find_index_dslx",
+    srcs = ["find_index.x"],
+)
+
+xls_dslx_test(
+    name = "find_index_test",
+    library = ":find_index_dslx",
+)
+
+xls_dslx_opt_ir(
+    name = "find_index_opt_ir",
+    srcs = ["find_index.x"],
+    dslx_top = "find_index",
+    ir_file = "find_index.ir",
+    opt_ir_file = "find_index.opt.ir",
+    deps = [":find_index_dslx"],
+)
+
+xls_ir_verilog(
+    name = "find_index_5000ps_model_unit",
+    src = ":find_index.opt.ir",
+    codegen_args = {
+        "delay_model": "unit",
+        "clock_period_ps": "5000",
+        "module_name": "find_index",
+        "use_system_verilog": "false",
+    },
+    verilog_file = "find_index_5000ps_model_unit.v",
+)
+
+verilog_library(
+    name = "find_index_5000ps_model_unit_verilog",
+    srcs = [
+        ":find_index_5000ps_model_unit.v",
+    ],
+)
+
+synthesize_rtl(
+    name = "find_index_5000ps_model_unit_verilog_synth",
+    top_module = "find_index",
+    deps = [
+        ":find_index_5000ps_model_unit_verilog",
+    ],
+)
+
+# TODO(cdleary): 2022-05-09 Get this target working as well, requires
+# addressing the dependence on openmp runtime.
+# place_and_route(
+#     name = "find_index_place_and_route",
+#     # ~64 MhZ
+#     clock_period = "15.42857143",
+#     core_padding_microns = 30,
+#     placement_density = "0.8",
+#     synthesized_rtl = ":find_index_5000ps_model_unit_verilog_synth",
+#     target_die_utilization_percentage = "30",
+# )

xls/examples/find_index.x

@@ -0,0 +1,28 @@
+// Copyright 2022 The XLS Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import std
+
+fn find_index(x: u4[4], target: u4) -> (bool, u2) {
+  let (found, index) = std::find_index(x, target);
+  (found, index as u2)
+}
+
+#![test]
+fn test_sample_values() {
+  let _ = assert_eq(find_index(u4[4]:[1, 2, 3, 4], u4:1), (true, u2:0));
+  let _ = assert_eq(find_index(u4[4]:[1, 2, 3, 4], u4:3), (true, u2:2));
+  let _ = assert_eq(find_index(u4[4]:[1, 2, 3, 4], u4:5), (false, u2:0));
+  ()
+}