ld.lld: Demangle symbols from archives in diagnostics

This ports r366573 from COFF to ELF.

There are now to toString(Archive::Symbol), one doing MSVC demangling
in COFF and one doing Itanium demangling in ELF, so rename these two
to toCOFFString() and to toELFString() to not get a duplicate symbol.

Nothing ever passes a raw Archive::Symbol to CHECK(), so these not
being part of the normal toString() machinery seems ok.

There are two code paths in the ELF linker that emits this type of
diagnostic:

1. The "normal" one in InputFiles.cpp. This is covered by the tweaked test.

2. An additional one that's only used for libcalls if there's at least
   one bitcode in the link, and if the libcall symbol is lazy, and
   lazily loaded from an archive (i.e. not from a lazy .o file).
   (This code path was added in r339301.) Since all libcall names so far
   are C symbols and never mangled, the change there is not observable
   and hence not covered by tests.

Differential Revision: https://reviews.llvm.org/D65095

llvm-svn: 366836

Author: nico

lld/COFF/Driver.cpp

@@ -273,7 +273,7 @@ void LinkerDriver::enqueueArchiveMember(const Archive::Child &c,
 
   auto reportBufferError = [=](Error &&e, StringRef childName) {
     fatal("could not get the buffer for the member defining symbol " +
-          toString(sym) + ": " + parentName + "(" + childName + "): " +
+          toCOFFString(sym) + ": " + parentName + "(" + childName + "): " +
           toString(std::move(e)));
   };
 
@@ -284,23 +284,25 @@ void LinkerDriver::enqueueArchiveMember(const Archive::Child &c,
       reportBufferError(mbOrErr.takeError(), check(c.getFullName()));
     MemoryBufferRef mb = mbOrErr.get();
     enqueueTask([=]() {
-      driver->addArchiveBuffer(mb, toString(sym), parentName, offsetInArchive);
+      driver->addArchiveBuffer(mb, toCOFFString(sym), parentName,
+                               offsetInArchive);
     });
     return;
   }
 
   std::string childName = CHECK(
       c.getFullName(),
       "could not get the filename for the member defining symbol " +
-      toString(sym));
+      toCOFFString(sym));
   auto future = std::make_shared<std::future<MBErrPair>>(
       createFutureForFile(childName));
   enqueueTask([=]() {
     auto mbOrErr = future->get();
     if (mbOrErr.second)
       reportBufferError(errorCodeToError(mbOrErr.second), childName);
     driver->addArchiveBuffer(takeBuffer(std::move(mbOrErr.first)),
-                             toString(sym), parentName, /*OffsetInArchive=*/0);
+                             toCOFFString(sym), parentName,
+                             /*OffsetInArchive=*/0);
   });
 }
 

lld/COFF/InputFiles.cpp

@@ -86,8 +86,9 @@ void ArchiveFile::parse() {
 
 // Returns a buffer pointing to a member file containing a given symbol.
 void ArchiveFile::addMember(const Archive::Symbol &sym) {
-  const Archive::Child &c = CHECK(
-      sym.getMember(), "could not get the member for symbol " + toString(sym));
+  const Archive::Child &c =
+      CHECK(sym.getMember(),
+            "could not get the member for symbol " + toCOFFString(sym));
 
   // Return an empty buffer if we have already returned the same buffer.
   if (!seen.insert(c.getChildOffset()).second)

lld/COFF/Symbols.cpp

@@ -33,7 +33,9 @@ static std::string demangle(StringRef symName) {
   return symName;
 }
 std::string toString(coff::Symbol &b) { return demangle(b.getName()); }
-std::string toString(const Archive::Symbol &b) { return demangle(b.getName()); }
+std::string toCOFFString(const Archive::Symbol &b) {
+  return demangle(b.getName());
+}
 
 namespace coff {
 

lld/COFF/Symbols.h

@@ -21,6 +21,14 @@
 #include <vector>
 
 namespace lld {
+
+std::string toString(coff::Symbol &b);
+
+// There are two different ways to convert an Archive::Symbol to a string:
+// One for Microsoft name mangling and one for Itanium name mangling.
+// Call the functions toCOFFString and toELFString, not just toString.
+std::string toCOFFString(const coff::Archive::Symbol &b);
+
 namespace coff {
 
 using llvm::object::Archive;
@@ -429,8 +437,6 @@ void replaceSymbol(Symbol *s, ArgT &&... arg) {
 }
 } // namespace coff
 
-std::string toString(coff::Symbol &b);
-std::string toString(const coff::Archive::Symbol &b);
 } // namespace lld
 
 #endif

lld/ELF/InputFiles.cpp

@@ -1148,7 +1148,7 @@ void ArchiveFile::fetch(const Archive::Symbol &sym) {
   Archive::Child c =
       CHECK(sym.getMember(), toString(this) +
                                  ": could not get the member for symbol " +
-                                 sym.getName());
+                                 toELFString(sym));
 
   if (!seen.insert(c.getChildOffset()).second)
     return;
@@ -1157,7 +1157,7 @@ void ArchiveFile::fetch(const Archive::Symbol &sym) {
       CHECK(c.getMemoryBufferRef(),
             toString(this) +
                 ": could not get the buffer for the member defining symbol " +
-                sym.getName());
+                toELFString(sym));
 
   if (tar && c.getParent()->isThin())
     tar->append(relativeToRoot(CHECK(c.getFullName(), this)), mb.getBuffer());

lld/ELF/Symbols.cpp

@@ -42,6 +42,20 @@ Defined *ElfSym::relaIpltEnd;
 Defined *ElfSym::riscvGlobalPointer;
 Defined *ElfSym::tlsModuleBase;
 
+// Returns a symbol for an error message.
+static std::string demangle(StringRef symName) {
+  if (config->demangle)
+    if (Optional<std::string> s = demangleItanium(symName))
+      return *s;
+  return symName;
+}
+namespace lld {
+std::string toString(const Symbol &b) { return demangle(b.getName()); }
+std::string toELFString(const Archive::Symbol &b) {
+  return demangle(b.getName());
+}
+} // namespace lld
+
 static uint64_t getSymVA(const Symbol &sym, int64_t &addend) {
   switch (sym.kind()) {
   case Symbol::DefinedKind: {
@@ -250,12 +264,13 @@ void Symbol::fetch() const {
 }
 
 MemoryBufferRef LazyArchive::getMemberBuffer() {
-  Archive::Child c = CHECK(
-      sym.getMember(), "could not get the member for symbol " + sym.getName());
+  Archive::Child c =
+      CHECK(sym.getMember(),
+            "could not get the member for symbol " + toELFString(sym));
 
   return CHECK(c.getMemoryBufferRef(),
                "could not get the buffer for the member defining symbol " +
-                   sym.getName());
+                   toELFString(sym));
 }
 
 uint8_t Symbol::computeBinding() const {
@@ -331,14 +346,6 @@ void elf::maybeWarnUnorderableSymbol(const Symbol *sym) {
     report(": unable to order discarded symbol: ");
 }
 
-// Returns a symbol for an error message.
-std::string lld::toString(const Symbol &b) {
-  if (config->demangle)
-    if (Optional<std::string> s = demangleItanium(b.getName()))
-      return *s;
-  return b.getName();
-}
-
 static uint8_t getMinVisibility(uint8_t va, uint8_t vb) {
   if (va == STV_DEFAULT)
     return vb;

lld/ELF/Symbols.h

@@ -33,7 +33,11 @@ class Undefined;
 } // namespace elf
 
 std::string toString(const elf::Symbol &);
-std::string toString(const elf::InputFile *);
+
+// There are two different ways to convert an Archive::Symbol to a string:
+// One for Microsoft name mangling and one for Itanium name mangling.
+// Call the functions toCOFFString and toELFString, not just toString.
+std::string toELFString(const elf::Archive::Symbol &);
 
 namespace elf {
 

lld/test/ELF/archive-thin-missing-member.s

@@ -8,17 +8,19 @@
 # RUN: rm %t.o
 
 # Test error when loading symbols from missing thin archive member.
-# RUN: not ld.lld %t-no-syms.a -o /dev/null 2>&1 | FileCheck %s --check-prefix=ERR1
+# RUN: not ld.lld --entry=_Z1fi %t-no-syms.a -o /dev/null 2>&1 | FileCheck %s --check-prefix=ERR1
 # ERR1: {{.*}}-no-syms.a: could not get the buffer for a child of the archive: '{{.*}}.o': {{[Nn]}}o such file or directory
 
 # Test error when thin archive has symbol table but member is missing.
-# RUN: not ld.lld -m elf_amd64_fbsd %t-syms.a -o /dev/null 2>&1 | FileCheck %s --check-prefix=ERR2
-# ERR2: {{.*}}-syms.a: could not get the buffer for the member defining symbol _start: '{{.*}}.o': {{[Nn]}}o such file or directory
+# RUN: not ld.lld --entry=_Z1fi -m elf_amd64_fbsd %t-syms.a -o /dev/null 2>&1 | FileCheck %s --check-prefix=ERR2
+# ERR2: {{.*}}-syms.a: could not get the buffer for the member defining symbol f(int): '{{.*}}.o': {{[Nn]}}o such file or directory
+# RUN: not ld.lld --entry=_Z1fi --no-demangle -m elf_amd64_fbsd %t-syms.a -o /dev/null 2>&1 | FileCheck %s --check-prefix=ERR2MANGLE
+# ERR2MANGLE: {{.*}}-syms.a: could not get the buffer for the member defining symbol _Z1fi: '{{.*}}.o': {{[Nn]}}o such file or directory
 
 # Test error when thin archive is linked using --whole-archive but member is missing.
-# RUN: not ld.lld --whole-archive %t-syms.a -o /dev/null 2>&1 | FileCheck %s --check-prefix=ERR3
+# RUN: not ld.lld --entry=_Z1fi --whole-archive %t-syms.a -o /dev/null 2>&1 | FileCheck %s --check-prefix=ERR3
 # ERR3: {{.*}}-syms.a: could not get the buffer for a child of the archive: '{{.*}}.o': {{[Nn]}}o such file or directory
 
-.global _start
-_start:
+.global _Z1fi
+_Z1fi:
     nop