[lld][COFF] Add /linkreprofullpathrsp flag

This patch adds the /linkreprofullpathrsp flag with the same behaviour
as link.exe. This flag emits a file containing the full paths to each
object passed to the link line.

This is used in particular when linking Arm64X binaries, as you need the
full path to all the Arm64 objects that were used in a standard Arm64
build.

See:
https://learn.microsoft.com/en-us/cpp/build/reference/link-repro-full-path-rsp
for the Microsoft documentation of the flag.

Author: DavidTruby

lld/COFF/Driver.cpp

@@ -318,7 +318,8 @@ void LinkerDriver::addBuffer(std::unique_ptr<MemoryBuffer> mb,
   }
 }
 
-void LinkerDriver::enqueuePath(StringRef path, bool wholeArchive, bool lazy) {
+void LinkerDriver::enqueuePath(StringRef path, bool wholeArchive, bool lazy,
+                               llvm::raw_ostream *reproFile, bool defaultlib) {
   auto future = std::make_shared<std::future<MBErrPair>>(
       createFutureForFile(std::string(path)));
   std::string pathStr = std::string(path);
@@ -356,8 +357,17 @@ void LinkerDriver::enqueuePath(StringRef path, bool wholeArchive, bool lazy) {
         Err(ctx) << msg;
       else
         Err(ctx) << msg << "; did you mean '" << nearest << "'";
-    } else
+    } else {
+      // Write full path to library to repro file if /linkreprofullpathrsp
+      // is specified.
+      if (reproFile) {
+        *reproFile << '"';
+        if (defaultlib)
+          *reproFile << "/defaultlib:";
+        *reproFile << pathStr << "\"\n";
+      }
       ctx.driver.addBuffer(std::move(mb), wholeArchive, lazy);
+    }
   });
 }
 
@@ -514,7 +524,7 @@ void LinkerDriver::parseDirectives(InputFile *file) {
       break;
     case OPT_defaultlib:
       if (std::optional<StringRef> path = findLibIfNew(arg->getValue()))
-        enqueuePath(*path, false, false);
+        enqueuePath(*path, false, false, nullptr);
       break;
     case OPT_entry:
       if (!arg->getValue()[0])
@@ -2204,6 +2214,17 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
     config->incremental = false;
   }
 
+  // Handle /linkreprofullpathrsp.
+  std::unique_ptr<llvm::raw_ostream> reproFile;
+  if (auto *arg = args.getLastArg(OPT_linkreprofullpathrsp)) {
+    std::error_code ec;
+    reproFile = std::make_unique<llvm::raw_fd_ostream>(arg->getValue(), ec);
+    if (ec) {
+      Err(ctx) << "cannot open " << arg->getValue() << ": " << ec.message();
+      reproFile.reset();
+    }
+  }
+
   if (errCount(ctx))
     return;
 
@@ -2245,11 +2266,11 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
         break;
       case OPT_wholearchive_file:
         if (std::optional<StringRef> path = findFileIfNew(arg->getValue()))
-          enqueuePath(*path, true, inLib);
+          enqueuePath(*path, true, inLib, reproFile.get());
         break;
       case OPT_INPUT:
         if (std::optional<StringRef> path = findFileIfNew(arg->getValue()))
-          enqueuePath(*path, isWholeArchive(*path), inLib);
+          enqueuePath(*path, isWholeArchive(*path), inLib, reproFile.get());
         break;
       default:
         // Ignore other options.
@@ -2289,7 +2310,7 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
   // addWinSysRootLibSearchPaths(), which is why they are in a separate loop.
   for (auto *arg : args.filtered(OPT_defaultlib))
     if (std::optional<StringRef> path = findLibIfNew(arg->getValue()))
-      enqueuePath(*path, false, false);
+      enqueuePath(*path, false, false, reproFile.get(), true);
   run();
   if (errorCount())
     return;

lld/COFF/Driver.h

@@ -88,11 +88,12 @@ class LinkerDriver {
   void enqueueArchiveMember(const Archive::Child &c, const Archive::Symbol &sym,
                             StringRef parentName);
 
-  void enqueuePDB(StringRef Path) { enqueuePath(Path, false, false); }
+  void enqueuePDB(StringRef Path) { enqueuePath(Path, false, false, nullptr); }
 
   MemoryBufferRef takeBuffer(std::unique_ptr<MemoryBuffer> mb);
 
-  void enqueuePath(StringRef path, bool wholeArchive, bool lazy);
+  void enqueuePath(StringRef path, bool wholeArchive, bool lazy,
+                   raw_ostream *reproFile, bool defaultlib = false);
 
   // Returns a list of chunks of selected symbols.
   std::vector<Chunk *> getChunks() const;

lld/COFF/Options.td

@@ -74,6 +74,9 @@ def libpath : P<"libpath", "Additional library search path">;
 def linkrepro : Joined<["/", "-", "/?", "-?"], "linkrepro:">,
     MetaVarName<"directory">,
     HelpText<"Write repro.tar containing inputs and command to reproduce link">;
+def linkreprofullpathrsp : Joined<["/", "-", "/?", "-?"], "linkreprofullpathrsp:">,
+    MetaVarName<"directory">,
+    HelpText<"Write .rsp file containing inputs used to link with full paths">;
 def lldignoreenv : F<"lldignoreenv">,
     HelpText<"Ignore environment variables like %LIB%">;
 def lldltocache : P<"lldltocache",

lld/test/COFF/linkreprofullpathrsp.test

@@ -0,0 +1,38 @@
+# REQUIRES: x86
+# Unsupported on Windows due to maximum path length limitations.
+
+# RUN: rm -rf %t.dir
+# RUN: split-file %s %t.dir
+# RUN: yaml2obj %p/Inputs/hello32.yaml -o %t.obj
+# RUN: llvm-mc -filetype=obj -triple=i386-windows %t.dir/drectve.s -o %t.dir/drectve.obj
+# RUN: echo '_main@0' > %t.order
+# RUN: touch %t.def
+# RUN: touch %t.cg
+
+
+
+Test link.exe-style /linkreprofullpathrsp: flag.
+# RUN: mkdir -p %t.dir/build1
+# RUN: cd %t.dir/build1
+# RUN: lld-link %t.obj %p/Inputs/std32.lib /subsystem:console /defaultlib:%p/Inputs/library.lib \
+# RUN:   /entry:main@0 /linkreprofullpathrsp:%t.rsp /out:%t.exe
+# RUN: FileCheck %s --check-prefix=RSP -DT=%t -DP=%p < %t.rsp
+
+# RSP: [[T]].obj
+# RSP-NEXT: "[[P]]/Inputs/std32.lib"
+# RSP-NEXT: "/defaultlib:[[P]]/Inputs/library.lib"
+
+#--- drectve.s
+        .section .drectve, "yn"
+        .ascii "/defaultlib:std32"
+
+#--- archive.s
+	.text
+	.intel_syntax noprefix
+	.globl	exportfn3
+	.p2align	4
+exportfn3:
+	ret
+
+	.section	.drectve,"yni"
+	.ascii	" /EXPORT:exportfn3"