gold-plugin: "Upgrade" debug info and handle its warnings.

The gold plugin never calls MaterializeModule, so any old debug info
was not deleted and could cause crashes.

Now that it is being "upgraded", the plugin also has to handle warnings
and create Modules with a nice id (it shows in the warning).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230655 91177308-0d34-0410-b5e6-96231b3b80d8

Author: espindola

test/tools/gold/Inputs/drop-debug.bc

@@ -0,0 +1,8 @@
+; RUN: %gold -plugin %llvmshlibdir/LLVMgold.so \
+; RUN:    --plugin-opt=emit-llvm -shared %p/Inputs/drop-debug.bc \
+; RUN:    -o t2.bc 2>&1 | FileCheck %s
+
+; drop-debug.bc was created from "void f(void) {}" with clang 3.5 and
+; -gline-tables-only, so it contains old debug info.
+
+; CHECK: warning: LLVM gold plugin: ignoring debug info with an invalid version (1) in {{.*}}/Inputs/drop-debug.bc

test/tools/gold/drop-debug.ll

@@ -20,6 +20,7 @@
 #include "llvm/Bitcode/ReaderWriter.h"
 #include "llvm/CodeGen/Analysis.h"
 #include "llvm/CodeGen/CommandFlags.h"
+#include "llvm/IR/AutoUpgrade.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DiagnosticInfo.h"
 #include "llvm/IR/DiagnosticPrinter.h"
@@ -273,20 +274,33 @@ static bool shouldSkip(uint32_t Symflags) {
 }
 
 static void diagnosticHandler(const DiagnosticInfo &DI, void *Context) {
-  assert(DI.getSeverity() == DS_Error && "Only expecting errors");
-  const auto &BDI = cast<BitcodeDiagnosticInfo>(DI);
-  std::error_code EC = BDI.getError();
-  if (EC == BitcodeError::InvalidBitcodeSignature)
-    return;
+  if (const auto *BDI = dyn_cast<BitcodeDiagnosticInfo>(&DI)) {
+    std::error_code EC = BDI->getError();
+    if (EC == BitcodeError::InvalidBitcodeSignature)
+      return;
+  }
 
   std::string ErrStorage;
   {
     raw_string_ostream OS(ErrStorage);
     DiagnosticPrinterRawOStream DP(OS);
     DI.print(DP);
   }
-  message(LDPL_FATAL, "LLVM gold plugin has failed to create LTO module: %s",
-          ErrStorage.c_str());
+  ld_plugin_level Level;
+  switch (DI.getSeverity()) {
+  case DS_Error:
+    message(LDPL_FATAL, "LLVM gold plugin has failed to create LTO module: %s",
+            ErrStorage.c_str());
+    llvm_unreachable("Fatal doesn't return.");
+  case DS_Warning:
+    Level = LDPL_WARNING;
+    break;
+  case DS_Remark:
+  case DS_Note:
+    Level = LDPL_INFO;
+    break;
+  }
+  message(Level, "LLVM gold plugin: %s",  ErrStorage.c_str());
 }
 
 /// Called by gold to see whether this file is one that our plugin can handle.
@@ -561,7 +575,7 @@ static void freeSymName(ld_plugin_symbol &Sym) {
 
 static std::unique_ptr<Module>
 getModuleForFile(LLVMContext &Context, claimed_file &F,
-                 off_t Filesize, raw_fd_ostream *ApiFile,
+                 ld_plugin_input_file &Info, raw_fd_ostream *ApiFile,
                  StringSet<> &Internalize, StringSet<> &Maybe) {
 
   if (get_symbols(F.handle, F.syms.size(), &F.syms[0]) != LDPS_OK)
@@ -571,7 +585,8 @@ getModuleForFile(LLVMContext &Context, claimed_file &F,
   if (get_view(F.handle, &View) != LDPS_OK)
     message(LDPL_FATAL, "Failed to get a view of file");
 
-  MemoryBufferRef BufferRef(StringRef((const char *)View, Filesize), "");
+  MemoryBufferRef BufferRef(StringRef((const char *)View, Info.filesize),
+                            Info.name);
   ErrorOr<std::unique_ptr<object::IRObjectFile>> ObjOrErr =
       object::IRObjectFile::create(BufferRef, Context);
 
@@ -583,6 +598,8 @@ getModuleForFile(LLVMContext &Context, claimed_file &F,
 
   Module &M = Obj.getModule();
 
+  UpgradeDebugInfo(M);
+
   SmallPtrSet<GlobalValue *, 8> Used;
   collectUsedGlobalVariables(M, Used, /*CompilerUsed*/ false);
 
@@ -792,6 +809,8 @@ static ld_plugin_status allSymbolsReadHook(raw_fd_ostream *ApiFile) {
     return LDPS_OK;
 
   LLVMContext Context;
+  Context.setDiagnosticHandler(diagnosticHandler);
+
   std::unique_ptr<Module> Combined(new Module("ld-temp.o", Context));
   Linker L(Combined.get());
 
@@ -804,8 +823,7 @@ static ld_plugin_status allSymbolsReadHook(raw_fd_ostream *ApiFile) {
     if (get_input_file(F.handle, &File) != LDPS_OK)
       message(LDPL_FATAL, "Failed to get file information");
     std::unique_ptr<Module> M =
-        getModuleForFile(Context, F, File.filesize, ApiFile,
-                         Internalize, Maybe);
+        getModuleForFile(Context, F, File, ApiFile, Internalize, Maybe);
     if (!options::triple.empty())
       M->setTargetTriple(options::triple.c_str());
     else if (M->getTargetTriple().empty()) {