COFF: Implement /pdbaltpath flag.

[pcc]

Summary

I needed to revert r330223 because we were embedding an absolute PDB
path in the .rdata section, which ended up being laid out before the
.idata section and affecting its RVAs. This flag will let us control
the embedded path.

[ruiu]

LGTM

lld/COFF/Driver.cpp

1317

nit: remove llvm::

lld/COFF/Config.h

struct Configuration {
   bool Relocatable = true;
   bool Force = false;
   bool Debug = false;
   bool DebugDwarf = false;
   bool DebugGHashes = false;
   bool ShowTiming = false;
   unsigned DebugTypes = static_cast<unsigned>(DebugType::None);
   std::vector<std::string> NatvisFiles;
+  llvm::SmallString<128> PDBAltPath;
   llvm::SmallString<128> PDBPath;
   std::vector<llvm::StringRef> Argv;
 
   // Symbols in this set are considered as live by the garbage collector.
   std::vector<Symbol *> GCRoot;
 
   std::set<StringRef> NoDefaultLibs;
   bool NoDefaultLibAll = false;

lld/COFF/Driver.cpp

else
       Config->DebugTypes = getDefaultDebugType(Args);
   }
 
   // Handle /pdb
   bool ShouldCreatePDB = Args.hasArg(OPT_debug, OPT_debug_ghash);
   if (ShouldCreatePDB) {
     if (auto *Arg = Args.getLastArg(OPT_pdb))
       Config->PDBPath = Arg->getValue();
+    if (auto *Arg = Args.getLastArg(OPT_pdbaltpath))
+      Config->PDBAltPath = Arg->getValue();
     if (Args.hasArg(OPT_natvis))
       Config->NatvisFiles = Args.getAllArgValues(OPT_natvis);
   }
 
   // Handle /noentry
   if (Args.hasArg(OPT_noentry)) {
     if (Args.hasArg(OPT_dll))
       Config->NoEntry = true;
void LinkerDriver::link(ArrayRef<const char *> ArgsArr) {
   }
 
   // Set default image name if neither /out or /def set it.
   if (Config->OutputFile.empty()) {
     Config->OutputFile =
         getOutputPath((*Args.filtered(OPT_INPUT).begin())->getValue());
   }
 
+  if (ShouldCreatePDB) {
     // Put the PDB next to the image if no /pdb flag was passed.
-  if (ShouldCreatePDB && Config->PDBPath.empty()) {
+    if (Config->PDBPath.empty()) {
       Config->PDBPath = Config->OutputFile;
       sys::path::replace_extension(Config->PDBPath, ".pdb");
     }
 
+    // The embedded PDB path should be the absolute path to the PDB if no
+    // /pdbaltpath flag was passed.
+    if (Config->PDBAltPath.empty()) {
+      Config->PDBAltPath = Config->PDBPath;
+      llvm::sys::fs::make_absolute(Config->PDBAltPath);
+    }
+  }
+
   // Set default image base if /base is not given.
   if (Config->ImageBase == uint64_t(-1))
     Config->ImageBase = getDefaultImageBase();
 
   Symtab->addSynthetic(mangle("__ImageBase"), nullptr);
   if (Config->Machine == I386) {
     Symtab->addAbsolute("___safe_se_handler_table", 0);
     Symtab->addAbsolute("___safe_se_handler_count", 0);

lld/COFF/Writer.cpp

 
 private:
   mutable std::vector<support::ulittle32_t *> TimeDateStamps;
   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) + PDBAbsPath.size() + 1;
+    return sizeof(codeview::DebugInfo) + Config->PDBAltPath.size() + 1;
   }
 
   void writeTo(uint8_t *B) const override {
     // Save off the DebugInfo entry to backfill the file signature (build id)
     // in Writer::writeBuildId
     BuildId = reinterpret_cast<codeview::DebugInfo *>(B + OutputSectionOff);
 
     // variable sized field (PDB Path)
     char *P = reinterpret_cast<char *>(B + OutputSectionOff + sizeof(*BuildId));
-    if (!PDBAbsPath.empty())
-      memcpy(P, PDBAbsPath.data(), PDBAbsPath.size());
-    P[PDBAbsPath.size()] = '\0';
+    if (!Config->PDBAltPath.empty())
+      memcpy(P, Config->PDBAltPath.data(), Config->PDBAltPath.size());
+    P[Config->PDBAltPath.size()] = '\0';
   }
 
-  SmallString<128> PDBAbsPath;
   mutable codeview::DebugInfo *BuildId = nullptr;
 };
 
 // The writer writes a SymbolTable result to a file.
 class Writer {
 public:
   Writer() : Buffer(errorHandler().OutputBuffer) {}
   void run();

lld/test/COFF/rsds.test

 # RUN: yaml2obj %s > %t.obj
 
 # RUN: rm -f %t.dll %t.pdb
-# RUN: lld-link /debug /dll /out:%t.dll /entry:DllMain %t.obj
+# RUN: lld-link /debug /pdbaltpath:test1.pdb /dll /out:%t.dll /entry:DllMain %t.obj
 # RUN: llvm-readobj -coff-debug-directory %t.dll > %t.1.txt
-# RUN: lld-link /debug /dll /out:%t.dll /entry:DllMain %t.obj
+# RUN: lld-link /debug /pdbaltpath:test2.pdb /dll /out:%t.dll /entry:DllMain %t.obj
 # RUN: llvm-readobj -coff-debug-directory %t.dll > %t.2.txt
 # RUN: cat %t.1.txt %t.2.txt | FileCheck %s
 
 # RUN: rm -f %t.dll %t.pdb
-# RUN: lld-link /debug /pdb:%t.pdb /dll /out:%t.dll /entry:DllMain %t.obj
+# RUN: lld-link /debug /pdb:%t1.pdb /dll /out:%t.dll /entry:DllMain %t.obj
 # RUN: llvm-readobj -coff-debug-directory %t.dll > %t.3.txt
-# RUN: lld-link /debug /pdb:%t.pdb /dll /out:%t.dll /entry:DllMain %t.obj
+# RUN: lld-link /debug /pdb:%t2.pdb /dll /out:%t.dll /entry:DllMain %t.obj
 # RUN: llvm-readobj -coff-debug-directory %t.dll > %t.4.txt
 # RUN: cat %t.3.txt %t.4.txt | FileCheck %s
 
 # CHECK: File: [[FILE:.*]].dll
 # CHECK: DebugDirectory [
 # CHECK:   DebugEntry {
 # CHECK:     Characteristics: 0x0
 # CHECK:     TimeDateStamp: 
 # CHECK:     MajorVersion: 0x0
 # CHECK:     MinorVersion: 0x0
 # CHECK:     Type: CodeView (0x2)
 # CHECK:     SizeOfData: 0x{{[^0]}}
 # CHECK:     AddressOfRawData: 0x{{[^0]}}
 # CHECK:     PointerToRawData: 0x{{[^0]}}
 # CHECK:     PDBInfo {
 # CHECK:       PDBSignature: 0x53445352
 # CHECK:       PDBGUID: [[GUID:\(([A-Za-z0-9]{2} ?){16}\)]]
 # CHECK:       PDBAge: 1
-# CHECK:       PDBFileName: {{.*}}.pdb
+# CHECK:       PDBFileName: {{.*}}1.pdb
 # CHECK:     }
 # CHECK:   }
 # CHECK: ]
 # CHECK: File: [[FILE]].dll
 # CHECK: DebugDirectory [
 # CHECK:   DebugEntry {
 # CHECK:     Characteristics: 0x0
 # CHECK:     TimeDateStamp: 
 # CHECK:     MajorVersion: 0x0
 # CHECK:     MinorVersion: 0x0
 # CHECK:     Type: CodeView (0x2)
 # CHECK:     SizeOfData: 0x{{[^0]}}
 # CHECK:     AddressOfRawData: 0x{{[^0]}}
 # CHECK:     PointerToRawData: 0x{{[^0]}}
 # CHECK:     PDBInfo {
 # CHECK:       PDBSignature: 0x53445352
 # CHECK:       PDBGUID: [[GUID]]
 # CHECK:       PDBAge: 2
-# CHECK:       PDBFileName: {{.*}}.pdb
+# CHECK:       PDBFileName: {{.*}}2.pdb
 # CHECK:     }
 # CHECK:   }
 # CHECK: ]
 
 --- !COFF
 header:
   Machine:         IMAGE_FILE_MACHINE_I386
   Characteristics: [  ]