Fix error reporting in the PNaCl bitcode reader.

tools/llvm-dis/llvm-dis.cpp

 //===-- llvm-dis.cpp - The low-level LLVM disassembler --------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This utility may be invoked in the following manner:
@@ skipping 47 matching lines @@
 // @LOCALMOD-BEGIN
 static cl::opt<NaClFileFormat>
 InputFileFormat(
     "bitcode-format",
     cl::desc("Define format of input bitcode file:"),
     cl::values(
         clEnumValN(LLVMFormat, "llvm", "LLVM bitcode file (default)"),
         clEnumValN(PNaClFormat, "pnacl", "PNaCl bitcode file"),
         clEnumValEnd),
     cl::init(LLVMFormat));
+
+static cl::opt<bool>
+VerboseErrors(
+    "verbose-parse-errors",
+    cl::desc("Print out more descriptive PNaCl bitcode parse errors"),
+    cl::init(false));
 // @LOCALMOD-END
 
 namespace {
 
 static void printDebugLoc(const DebugLoc &DL, formatted_raw_ostream &OS) {
   OS << DL.getLine() << ":" << DL.getCol();
   if (MDNode *N = DL.getInlinedAt(getGlobalContext())) {
     DebugLoc IDL = DebugLoc::getFromDILocation(N);
     if (!IDL.isUnknown()) {
       OS << "@";
@@ skipping 75 matching lines @@
       DisplayFilename = InputFilename;
 
     // @LOCALMOD-BEGIN
     switch (InputFileFormat) {
       case LLVMFormat:
         // The Module's BitcodeReader's BitstreamReader takes ownership
         // of the StreamingMemoryObject.
         M.reset(getStreamedBitcodeModule(
             DisplayFilename, Buffer.release(), Context, &ErrorMessage));
         break;
-      case PNaClFormat:
+      case PNaClFormat: {
+        raw_ostream *Verbose = VerboseErrors ? &errs() : nullptr;

[jvoung (off chromium), 2014/12/03 19:43:46]

I guess I was okay with this unconditionally having VerboseErrors. Thoughts?

[Karl, 2014/12/03 20:53:44]

Since this is an LLVM tool, I guess we should be just as cryptic. Changing to
use nullptr.

         M.reset(getNaClStreamedBitcodeModule(
-            DisplayFilename, Buffer.release(), Context, &ErrorMessage));
+            DisplayFilename, Buffer.release(), Context, Verbose,
+            &ErrorMessage));
         break;
+      }
       default:
         ErrorMessage = "Don't understand specified bitcode format";
         break;
     }
     // @LOCALMOD-END
 
     if(M.get()) {
       if (std::error_code EC = M->materializeAllPermanently()) {
         ErrorMessage = EC.message();
         M.reset();
@@ skipping 42 matching lines @@
 
   // All that llvm-dis does is write the assembly to a file.
   if (!DontPrint)
     M->print(Out->os(), Annotator.get());
 
   // Declare success.
   Out->keep();
 
   return 0;
 }