[ELF] - Change -t implementation to print which archive members are used.

[grimar]

Summary

This fixes PR27243.

Previously each archive file was reported no matter was it's member used or not:
lib/libLLVMSupport.a

Now lld prints line for each used internal file, like:
lib/libLLVMSupport.a(lib/Support/CMakeFiles/LLVMSupport.dir/StringSaver.cpp.o)
lib/libLLVMSupport.a(lib/Support/CMakeFiles/LLVMSupport.dir/Host.cpp.o)
lib/libLLVMSupport.a(lib/Support/CMakeFiles/LLVMSupport.dir/ConvertUTF.c.o)

That should be consistent with what gold do.

[ruiu]

ELF/Driver.cpp

101–102

Is there any reason to keep this code here?

ELF/SymbolTable.cpp

73

I mean you could make this Config->Trace||Config->Verbose

[grimar]

ELF/Driver.cpp

101–102

I leaved it intentionally, but the answer on your question should be based on what Verbose should do.
I assumed that it should not behave as -t. For example when we using archives, -t will output only
those members that are used during link. If members are not used - you`ll never see archive name using -t.
Verbose in opposite - always prints any file processed. Including script files by the way, which are not
handled by -t (and that is equal to gold behavior, it does not print script files names).

So my opinion - Verbose is separate option and usefull itself, I would not combine it with -t.

ELF/SymbolTable.cpp

73

Please see answer above.

[ruiu]

ELF/Driver.cpp

101–102

Makes sense.

ELF/SymbolTable.cpp

108–109

You want to move this code before if (Config->Trace).

test/ELF/Inputs/trace-ar1.s

2

Remove ;

test/ELF/Inputs/trace-ar2.s

2

Remove ;

[grimar]

• Addressed review comments.

ELF/SymbolTable.cpp

108–109

Right. Added testcase for that.

Not relative to this patch - I didn't find any testcase that checks --end-lib

test/ELF/Inputs/trace-ar1.s

2

Done.

test/ELF/Inputs/trace-ar2.s

2

Done.

[ruiu]

LGTM

[grimar]

In D19011#400095, @ruiu wrote:

LGTM

Thanks for review !

ELF/Driver.cpp

LinkerDriver::getArchiveMembers(MemoryBufferRef MB) {
 
   return V;
 }
 
 // Opens and parses a file. Path has to be resolved already.
 // Newly created memory buffers are owned by this driver.
 void LinkerDriver::addFile(StringRef Path) {
   using namespace llvm::sys::fs;
-  if (Config->Verbose || Config->Trace)
+  if (Config->Verbose)
     llvm::outs() << Path << "\n";
   auto MBOrErr = MemoryBuffer::getFile(Path);
   if (!MBOrErr) {
     error(MBOrErr, "cannot open " + Path);
     return;
   }
   std::unique_ptr<MemoryBuffer> &MB = *MBOrErr;
   MemoryBufferRef MBRef = MB->getMemBufferRef();
   OwningMBs.push_back(std::move(MB)); // take MB ownership

ELF/SymbolTable.cpp

template <class ELFT> static bool isCompatible(InputFile *FileP) {
   StringRef A = F->getName();
   StringRef B = Config->Emulation;
   if (B.empty())
     B = Config->FirstElf->getName();
   error(A + " is incompatible with " + B);
   return false;
 }
 
+// Returns "(internal)", "foo.a(bar.o)" or "baz.o".
+static std::string getFilename(InputFile *F) {
+  if (!F)
+    return "(internal)";
+  if (!F->ArchiveName.empty())
+    return (F->ArchiveName + "(" + F->getName() + ")").str();
+  return F->getName();
+}
+
 // Add symbols in File to the symbol table.
 template <class ELFT>
 void SymbolTable<ELFT>::addFile(std::unique_ptr<InputFile> File) {
   InputFile *FileP = File.get();
   if (!isCompatible<ELFT>(FileP))
     return;
 
   // .a file
   if (auto *F = dyn_cast<ArchiveFile>(FileP)) {
     ArchiveFiles.emplace_back(cast<ArchiveFile>(File.release()));
     F->parse();
     for (Lazy &Sym : F->getLazySymbols())
       addLazy(&Sym);
     return;
   }
 
+  // Lazy object file
+  if (auto *F = dyn_cast<LazyObjectFile>(FileP)) {
+    LazyObjectFiles.emplace_back(cast<LazyObjectFile>(File.release()));
+    F->parse();
+    for (Lazy &Sym : F->getLazySymbols())
+      addLazy(&Sym);
+    return;
+  }
+
+  if (Config->Trace)
+    llvm::outs() << getFilename(FileP) << "\n";
+
   // .so file
   if (auto *F = dyn_cast<SharedFile<ELFT>>(FileP)) {
     // DSOs are uniquified not by filename but by soname.
     F->parseSoName();
     if (!SoNames.insert(F->getSoName()).second)
       return;
 
     SharedFiles.emplace_back(cast<SharedFile<ELFT>>(File.release()));
     F->parseRest();
     for (SharedSymbol<ELFT> &B : F->getSharedSymbols())
       resolve(&B);
     return;
   }
 
   // LLVM bitcode file
   if (auto *F = dyn_cast<BitcodeFile>(FileP)) {
     BitcodeFiles.emplace_back(cast<BitcodeFile>(File.release()));
     F->parse(ComdatGroups);
     for (SymbolBody *B : F->getSymbols())
       if (B)
         resolve(B);
     return;
   }
 
-  // Lazy object file
-  if (auto *F = dyn_cast<LazyObjectFile>(FileP)) {
-    LazyObjectFiles.emplace_back(cast<LazyObjectFile>(File.release()));
-    F->parse();
-    for (Lazy &Sym : F->getLazySymbols())
-      addLazy(&Sym);
-    return;
-  }
-
   // Regular object file
   auto *F = cast<ObjectFile<ELFT>>(FileP);
   ObjectFiles.emplace_back(cast<ObjectFile<ELFT>>(File.release()));
   F->parse(ComdatGroups);
   for (SymbolBody *B : F->getNonLocalSymbols())
     resolve(B);
 }
 
 template <class ELFT> void SymbolTable<ELFT>::addCombinedLtoObject() {
template <class ELFT> InputFile *SymbolTable<ELFT>::findFile(SymbolBody *B) {
   for (const std::unique_ptr<BitcodeFile> &F : BitcodeFiles) {
     ArrayRef<SymbolBody *> Syms = F->getSymbols();
     if (std::find(Syms.begin(), Syms.end(), B) != Syms.end())
       return F.get();
   }
   return nullptr;
 }
 
-// Returns "(internal)", "foo.a(bar.o)" or "baz.o".
-static std::string getFilename(InputFile *F) {
-  if (!F)
-    return "(internal)";
-  if (!F->ArchiveName.empty())
-    return (F->ArchiveName + "(" + F->getName() + ")").str();
-  return F->getName();
-}
-
 // Construct a string in the form of "Sym in File1 and File2".
 // Used to construct an error message.
 template <class ELFT>
 std::string SymbolTable<ELFT>::conflictMsg(SymbolBody *Old, SymbolBody *New) {
   InputFile *F1 = findFile(Old);
   InputFile *F2 = findFile(New);
   StringRef Sym = Old->getName();
   return demangle(Sym) + " in " + getFilename(F1) + " and " + getFilename(F2);

test/ELF/Inputs/trace-ar1.s

+.globl _used
+_used:

test/ELF/Inputs/trace-ar2.s

+.globl _notused
+_notused:

test/ELF/trace-ar.s

+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.foo.o
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %p/Inputs/trace-ar1.s -o %t.obj1.o
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %p/Inputs/trace-ar2.s -o %t.obj2.o
+# RUN: llvm-ar rcs %t.boo.a %t.obj1.o %t.obj2.o
+
+## Check how -t works with achieves
+# RUN: ld.lld %t.foo.o %t.boo.a -o %t.out -t 2>&1 | FileCheck %s
+# CHECK:      {{.*}}.foo.o
+# CHECK-NEXT: {{.*}}.boo.a({{.*}}.obj1.o)
+# CHECK-NOT:  {{.*}}.boo.a({{.*}}.obj2.o)
+
+## Test output with --start-lib
+# RUN: ld.lld %t.foo.o --start-lib %t.obj1.o %t.obj2.o -o %t.out -t 2>&1 | FileCheck --check-prefix=STARTLIB %s
+# STARTLIB:      {{.*}}.foo.o
+# STARTLIB-NEXT: {{.*}}.obj1.o
+# STARTLIB-NOT:  {{.*}}.obj2.o
+
+.globl _start, _used
+_start:
+ call _used