From e0c77d80585428818c32886eb8c26755ea8ed159 Mon Sep 17 00:00:00 2001
From: Richard-Qin-X <richard.qin.001@gmail.com>
Date: Sat, 1 Aug 2026 18:17:33 +0800
Subject: [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.
---
 backend/lib/CodeGen/MachineInstr.cpp | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

(limited to 'backend/lib/CodeGen/MachineInstr.cpp')

diff --git a/backend/lib/CodeGen/MachineInstr.cpp b/backend/lib/CodeGen/MachineInstr.cpp
index b201533..aaeeacd 100644
--- a/backend/lib/CodeGen/MachineInstr.cpp
+++ b/backend/lib/CodeGen/MachineInstr.cpp
@@ -8,7 +8,9 @@
 #include "rcc/CodeGen/MachineRegisterInfo.h"
 
 #include <cstddef>
+#include <cstdint>
 #include <functional>
+#include <limits>
 #include <optional>
 #include <utility>
 
@@ -30,6 +32,30 @@ Expected<void> MachineInstr::setOpcode(Opcode NewOpcode) {
   return {};
 }
 
+Expected<void> MachineInstr::setDebugInstrNumber(std::uint64_t Number) {
+  if (Number == 0 || Number > std::numeric_limits<std::uint32_t>::max()) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "machine debug instruction number must fit in nonzero uint32");
+  }
+  if (DebugInstrNumber != 0 && DebugInstrNumber != Number) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "machine instruction already has a different debug number");
+  }
+  DebugInstrNumber = static_cast<std::uint32_t>(Number);
+  OwnerFunction->observeDebugInstrNumber(DebugInstrNumber);
+  return {};
+}
+
+Expected<std::uint32_t> MachineInstr::assignDebugInstrNumber() {
+  if (DebugInstrNumber != 0)
+    return DebugInstrNumber;
+  auto Number = OwnerFunction->allocateDebugInstrNumber();
+  if (!Number)
+    return std::unexpected(Number.error());
+  DebugInstrNumber = *Number;
+  return DebugInstrNumber;
+}
+
 MachineOperand *MachineInstr::operandAt(std::size_t Index) noexcept {
   if (Index >= Operands.size())
     return nullptr;
-- 
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