[debug][firrtl] Add source-level type debug info: dbg.enumdef/subfiel…

[fkhaidari]

…d/moduleinfo + FIRRTL intrinsic lowering

Extends the dbg dialect and the firrtl-lower-intrinsics pass to carry Chisel-level source types, enum definitions, and constructor parameters through the CIRCT pipeline, making them available to downstream consumers (Tywaves, HGDB, hw-debug-info exporters).

dbg dialect changes:

• Add dbg.enumdef op: declares an enumeration type by name, FQN, and a DictionaryAttr variant map (Int → String). Produces an !dbg.enumdef SSA token consumed by dbg.variable and dbg.subfield.
• Add dbg.subfield op: like dbg.variable but for aggregate fields; carries optional typeName, params (ArrayAttr of DictionaryAttr), and enumDef operand. Returns !dbg.subfield.
• Add dbg.moduleinfo op: records the Chisel class name and constructor params for the enclosing module.
• Extend dbg.variable with optional typeName, params, and enumDef operand (AttrSizedOperandSegments).
• Add EnumDefType and SubFieldType type definitions to DebugTypes.td.
• Add EnumDefDeduplication canonicalization pattern: collapses duplicate dbg.enumdef ops with identical FQN and variant map within a block.

FIRRTL intrinsic lowering:

• Introduce DebugIntrinsicPreScan (new header FIRRTLDebugPreScan.h): a pre-pass struct populated by buildDebugPreScan() before applyPartialConversion runs. Performs three ordered walks:
  1. circt_debug_enumdef → emit dbg.enumdef, populate enumDefMap.
  2. circt_debug_typetag (leaf, non-empty parent) → collect LeafMeta (typeName, params, enumDefVal) into leafMetaMap; erase leaf ops.
  3. circt_debug_typenode (PreOrder) → emit dbg.scope, populate scopeMap keyed by FQN; erase typenode ops.
• Add CirctDebugTypeTagConverter: lowers root circt_debug_typetag ops to dbg.variable. For aggregate signals, recursively builds dbg.struct/dbg.array via buildDebugAggregateWithMeta, wrapping annotated leaf fields in dbg.subfield with enum/type metadata.
• Add CirctDebugModuleInfoConverter: lowers circt_debug_moduleinfo to dbg.moduleinfo, parsing the ctorParams JSON string to ArrayAttr.
• Add CirctDebugTypeNodeConverter: fallback converter (should be unreachable after pre-scan); emits an error and erases the op.
• Add CirctDebugTypeDefConverter: no-op eraser for circt_debug_typedef.
• Add ElideScopeTokenNode conversion pattern: removes firrtl.node ops whose result type converts to !dbg.scope (zero-width UInt → ScopeType).
• Wire populateDebugLowerings() into LowerIntrinsicsPass::runOnOperation after the pre-scan step.
• Add dependentDialects = ["debug::DebugDialect"] to LowerIntrinsics pass.
• Link CIRCTDebug into CIRCTFIRRTL CMake target.

MaterializeDebugInfo pass:

• Skip port/wire/reg materialization for names already covered by a root circt_debug_typetag intrinsic, preventing duplicate dbg.variable ops.
• Update materializeVariable call site for the new dbg.variable operand signature (typeName, params, enumRef all null).

DebugInfo analysis:

• Propagate enumDef value from dbg.variable into DIVariable.

FIR parser:

• Reject non-passive element types for cmem/smem with a clear diagnostic (behavioral memory element type must be passive).

LowerCHIRRTL pass:

• Override visitInvalidOp to visit non-FIRRTL ops (e.g. dbg.variable) so their operands are updated when they reference CHIRRTL memory port values.

Tests:

• test/Dialect/Debug/ops.mlir: parse/print round-trip for new ops.
• test/Dialect/Debug/enumdef-ssa-roundtrip.mlir: dbg.enumdef + dbg.variable SSA round-trip.
• test/Dialect/Debug/enumdef-canonicalize.mlir: deduplication of identical/diverging dbg.enumdef ops.
• test/Dialect/Debug/subfield-enumdef-ssa.mlir: dbg.subfield with enum SSA round-trip.
• test/Dialect/Debug/variable-enumdef-ssa.mlir: dbg.variable with enumDef operand.
• test/Dialect/FIRRTL/lower-intrinsics-debug.mlir: end-to-end lowering of moduleinfo, enumdef, scalar/bundle/vec typetag, typenode hierarchy, and bundle-with-enum-field cases through firrtl-lower-intrinsics.