[CodeGen] Track debug instruction identities

Add monotonic MIR debug instruction numbers and structured value substitutions. Verify live number uniqueness, meta-instruction exclusion, substitution graph integrity, and target subregister references while preserving debug identities during cloning.

1 files changed, 14 insertions, 0 deletions

diff --git a/backend/lib/CodeGen/MachineFunction.cpp b/backend/lib/CodeGen/MachineFunction.cpp
index 294158b..df1ceb5 100644
--- a/backend/lib/CodeGen/MachineFunction.cpp
+++ b/backend/lib/CodeGen/MachineFunction.cpp
@@ -10,6 +10,7 @@
 #include <algorithm>
 #include <cstddef>
 #include <cstdint>
+#include <limits>
 #include <memory>
 #include <memory_resource>
 #include <new>
@@ -86,6 +87,19 @@ Expected<void> MachineFunction::setTargetState(TargetFunctionState State) {
   return {};
 }
 
+Expected<std::uint32_t> MachineFunction::allocateDebugInstrNumber() {
+  if (DebugInstrNumberingCount == std::numeric_limits<std::uint32_t>::max()) {
+    return makeUnexpected(ErrorCode::InternalError,
+                          "machine debug instruction number space is exhausted");
+  }
+  ++DebugInstrNumberingCount;
+  return DebugInstrNumberingCount;
+}
+
+void MachineFunction::observeDebugInstrNumber(std::uint32_t Number) noexcept {
+  DebugInstrNumberingCount = std::max(DebugInstrNumberingCount, Number);
+}
+
 Expected<MachineBasicBlock *> MachineFunction::createBasicBlock() {
   auto ID = BlockIDGenerator.allocate();
   if (!ID)