[clang] [llvm] [DLCov 3/5] Implement DebugLoc origin-tracking (PR #107369)

[J. Ryan Stinnett via cfe-commits]

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@@ -50,11 +50,15 @@ class TargetRegisterInfo;
     class MergePotentialsElt {
       unsigned Hash;
       MachineBasicBlock *Block;
-      DebugLoc BranchDebugLoc;
+      // We use MDNode rather than DebugLoc here because under certain CMake
+      // options*, DebugLoc may contain a SmallVector used for introspection
+      // purposes, which causes errors when stored here.
+      // *LLVM_ENABLE_DEBUGLOC_COVERAGE_TRACKING=COVERAGE_AND_ORIGIN
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jryans wrote:

What's the purpose of this line...?

https://github.com/llvm/llvm-project/pull/107369