[clang] [llvm] [clang][DependencyScanner] Remove unused -ivfsoverlay files (PR #73734)

[Ben Langmuir via cfe-commits]

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@@ -4997,6 +4997,19 @@ ASTReader::ASTReadResult ASTReader::readUnhashedControlBlockImpl(
             F->SearchPathUsage[I] = true;
       break;
     }
+    case VFS_USAGE: {
+      if (!F)
+        break;
+      unsigned Count = Record[0];
+      const char *Byte = Blob.data();
+      F->VFSUsage = llvm::BitVector(Count, false);
+      for (unsigned I = 0; I < Count; ++Byte)
+        for (unsigned Bit = 0; Bit < 8 && I < Count; ++Bit, ++I)
+          if (*Byte & (1 << Bit))
+            F->VFSUsage[I] = true;
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benlangmuir wrote:

Probably worth hoisting this read into its own function since we seem to be accumulating bit vectors.

https://github.com/llvm/llvm-project/pull/73734