[llvm] [RemoveDIs] Read/write DbgRecords directly from/to bitcode (PR #83251)

[Orlando Cazalet-Hyams via llvm-commits]

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@@ -6357,6 +6354,81 @@ Error BitcodeReader::parseFunctionBody(Function *F) {
       InstructionList.push_back(I);
       break;
     }
+    case bitc::FUNC_CODE_DEBUG_RECORD_LABEL: {
+      // DPLabels are placed after the Instructions that they are attached to.
+      Instruction *Inst = getLastInstruction();
+      if (!Inst)
+        return error("Invalid record");
+      DILocation *DIL = cast<DILocation>(getFnMetadataByID(Record[0]));
+      DILabel *Label = cast<DILabel>(getFnMetadataByID(Record[1]));
+      Inst->getParent()->insertDPValueBefore(new DPLabel(Label, DIL),
+                                             Inst->getIterator());
+      continue; // This isn't an instruction.
+    }
+    case bitc::FUNC_CODE_DEBUG_RECORD_VALUE_SIMPLE:
+    case bitc::FUNC_CODE_DEBUG_RECORD_VALUE:
+    case bitc::FUNC_CODE_DEBUG_RECORD_DECLARE:
+    case bitc::FUNC_CODE_DEBUG_RECORD_ASSIGN: {
+      // DPValues are placed after the Instructions that they are attached to.
+      Instruction *Inst = getLastInstruction();
+      if (!Inst)
+        return error("Invalid record");
+
+      // First 3 fields are common to all kinds:
+      //   DILocation, DILocalVariable, DIExpression
+      // dbg_value (FUNC_CODE_DEBUG_RECORD_VALUE)
+      //   ..., LocationMetadata
+      // dbg_value (FUNC_CODE_DEBUG_RECORD_VALUE_SIMPLE - abbrev'd)
+      //   ..., Value
+      // dbg_declare (FUNC_CODE_DEBUG_RECORD_DECLARE)
+      //   ..., LocationMetadata
+      // dbg_assign (FUNC_CODE_DEBUG_RECORD_ASSIGN)
+      //   ..., LocationMetadata, DIAssignID, DIExpression, LocationMetadata
+      unsigned Slot = 0;
+      // Common fields (0-2).
+      DILocation *DIL = cast<DILocation>(getFnMetadataByID(Record[Slot++]));
+      DILocalVariable *Var =
+          cast<DILocalVariable>(getFnMetadataByID(Record[Slot++]));
+      DIExpression *Expr =
+          cast<DIExpression>(getFnMetadataByID(Record[Slot++]));
+
+      // Union field (3: LocationMetadata | Value).
+      Metadata *RawLocation = nullptr;
+      if (BitCode == bitc::FUNC_CODE_DEBUG_RECORD_VALUE_SIMPLE) {
+        Value *V = nullptr;
+        unsigned TyID = 0;
+        if (getValueTypePair(Record, Slot, NextValueNo, V, TyID, CurBB))
+          return error("Invalid record");
+        RawLocation = ValueAsMetadata::get(V);
----------------
OCHyams wrote:

Done

https://github.com/llvm/llvm-project/pull/83251