[DebugInfo] Correctly track metadata slots for DPValues

[SLTozer]

Currently, the AsmWriter can print DPValues, but does not consider them when creating slots for metadata, which can result in erroneous output where metadata is numbered incorrectly. This patch modifies the ModuleSlotTracker to correctly track slots for metadata that appears in DPValues.

[llvmbot]

@llvm/pr-subscribers-llvm-ir

@llvm/pr-subscribers-debuginfo

Author: Stephen Tozer (SLTozer)

Changes

Currently, the AsmWriter can print DPValues, but does not consider them when creating slots for metadata, which can result in erroneous output where metadata is numbered incorrectly. This patch modifies the ModuleSlotTracker to correctly track slots for metadata that appears in DPValues.

---

Full diff: https://github.com/llvm/llvm-project/pull/76941.diff

1 Files Affected:

• (modified) llvm/lib/IR/AsmWriter.cpp (+12-1)

diff --git a/llvm/lib/IR/AsmWriter.cpp b/llvm/lib/IR/AsmWriter.cpp
index 95cdec722062e3..278cdfce411050 100644
--- a/llvm/lib/IR/AsmWriter.cpp
+++ b/llvm/lib/IR/AsmWriter.cpp
@@ -859,6 +859,9 @@ class SlotTracker : public AbstractSlotTrackerStorage {
 
   /// Add all of the metadata from an instruction.
   void processInstructionMetadata(const Instruction &I);
+
+  /// Add all of the metadata from an instruction.
+  void processDPValueMetadata(const DPValue &DPV);
 };
 
 } // end namespace llvm
@@ -1126,11 +1129,19 @@ void SlotTracker::processGlobalObjectMetadata(const GlobalObject &GO) {
 void SlotTracker::processFunctionMetadata(const Function &F) {
   processGlobalObjectMetadata(F);
   for (auto &BB : F) {
-    for (auto &I : BB)
+    for (auto &I : BB) {
+      for (const DPValue &DPV : I.getDbgValueRange())
+        processDPValueMetadata(DPV);
       processInstructionMetadata(I);
+    }
   }
 }
 
+void SlotTracker::processDPValueMetadata(const DPValue &DPV) {
+  CreateMetadataSlot(DPV.getVariable());
+  CreateMetadataSlot(DPV.getDebugLoc());
+}
+
 void SlotTracker::processInstructionMetadata(const Instruction &I) {
   // Process metadata used directly by intrinsics.
   if (const CallInst *CI = dyn_cast<CallInst>(&I))

[jmorse]

IIRC there's a reproducer somewhere that stimulates this, would we be able to add that as a regression test? Otherwise LGTM.

[jmorse]

Oh, right, #76952 stimulates the change, I see. LGTM.