Enable sharing of state elements between continuation values and static variables with superficially different layouts. For example, bits[64] and (bits[64]). This sharing is done by LeafTypeTree index. This allows sharing of state elements between base and derived classes, for example. It also allows unused parts of a struct to be pruned.

- Replaced NamedDecl* with DeclLeaf for continuations, where DeclLeaf also indicates the LeafTypeTree element index of the continuation values.

- Also fixes small bugs with pass through finding and direct in marking.
- Changes to the data flow visitor are needed to support these fixes. For example, a select between two direct ins with a non-direct-in selector should not be marked as direct-in.

PiperOrigin-RevId: 861456858

Author: Sean Purser-Haskell

xls/contrib/xlscc/BUILD

@@ -160,6 +160,7 @@ cc_library(
         "@com_google_absl//absl/container:btree",
         "@com_google_absl//absl/container:flat_hash_map",
         "@com_google_absl//absl/container:flat_hash_set",
+        "@com_google_absl//absl/container:inlined_vector",
         "@com_google_absl//absl/log",
         "@com_google_absl//absl/log:check",
         "@com_google_absl//absl/status",
@@ -253,6 +254,7 @@ cc_library(
         "//xls/passes:inlining_pass",
         "//xls/passes:node_source_analysis",
         "//xls/passes:optimization_pass",
+        "//xls/passes:optimization_pass_pipeline",
         "//xls/passes:partial_info_query_engine",
         "//xls/passes:pass_base",
         "//xls/solvers:z3_ir_translator",