[lld] Write the PDB absolute path to the debug directory header

[zturner]

Summary

This matches the behavior of MSVC

[rnk]

lgtm

lld/COFF/Writer.cpp

81 ↗

(On Diff #109793)

Can we group this at the end with the other fields? That's more consistent with the rest of LLD, access labels be damned.

83 ↗

(On Diff #109793)

How about moving the public: label up here, since these are method overrides, so they are actually public.

lld/trunk/COFF/Writer.cpp

void writeTo(uint8_t *B) const override {
     }
   }
 
 private:
   const std::vector<Chunk *> &Records;
 };
 
 class CVDebugRecordChunk : public Chunk {
+public:
+  CVDebugRecordChunk() {
+    PDBAbsPath = Config->PDBPath;
+    if (!PDBAbsPath.empty())
+      llvm::sys::fs::make_absolute(PDBAbsPath);
+  }
+
   size_t getSize() const override {
-    return sizeof(codeview::DebugInfo) + Config->PDBPath.size() + 1;
+    return sizeof(codeview::DebugInfo) + PDBAbsPath.size() + 1;
   }
 
   void writeTo(uint8_t *B) const override {
     // Save off the DebugInfo entry to backfill the file signature (build id)
     // in Writer::writeBuildId
     DI = reinterpret_cast<codeview::DebugInfo *>(B + OutputSectionOff);
 
     DI->Signature.CVSignature = OMF::Signature::PDB70;
 
     // variable sized field (PDB Path)
     auto *P = reinterpret_cast<char *>(B + OutputSectionOff + sizeof(*DI));
-    if (!Config->PDBPath.empty())
-      memcpy(P, Config->PDBPath.data(), Config->PDBPath.size());
-    P[Config->PDBPath.size()] = '\0';
+    if (!PDBAbsPath.empty())
+      memcpy(P, PDBAbsPath.data(), PDBAbsPath.size());
+    P[PDBAbsPath.size()] = '\0';
   }
 
-public:
+private:
+  SmallString<128> PDBAbsPath;
   mutable codeview::DebugInfo *DI = nullptr;
 };
 
 // The writer writes a SymbolTable result to a file.
 class Writer {
 public:
   Writer(SymbolTable *T) : Symtab(T) {}
   void run();