Add error recovery for abbreviations outside blocks in bitcode.

Adds error recovery to the bitcode munger writer that handles
abbreviation definitions that do not appear in any block (not
allowed by the bitcode writer).

BUG=None
[email protected]

Review URL: https://codereview.chromium.org/1150183010

Author: KarlSchimpf

lib/Bitcode/NaCl/TestUtils/NaClBitcodeMungeWriter.cpp

@@ -404,6 +404,11 @@ bool WriteState::emitRecord(NaClBitstreamWriter &Writer,
       markCurrentBlockWithOmittedAbbreviations();
       return Flags.getTryToRecover();
     }
+    if (atOutermostScope()) {
+      RecoverableError() << "Abbreviation definition not in block: "
+                         << Record << "\n";
+      return Flags.getTryToRecover();
+    }
     if (getCurWriteBlockID() == naclbitc::BLOCKINFO_BLOCK_ID) {
       Writer.EmitBlockInfoAbbrev(SetBID, Abbrev);
     } else {

unittests/Bitcode/NaClMungeWriteErrorTests.cpp

@@ -663,4 +663,21 @@ TEST(NaClMungeWriteErrorTests, SpecifiesTooManyOperands) {
       ExpectedDumpedBitcode);
 }
 
+// Show what happens if an abbreviation definition is defined outside a block.
+TEST(NaClMungeWriteErrorTests, AbbreviationNotInBlock) {
+  // Add abbreviation before all records.
+  const uint64_t Edit[] = {
+    0, NaClMungedBitcode::AddBefore,
+    naclbitc::DEFINE_ABBREV, naclbitc::BLK_CODE_DEFINE_ABBREV, 1,
+    1, 10,                          // lit(10)
+    Terminator
+  };
+  CheckDumpEdits(
+      ARRAY(Edit),
+      "Error (Block unknown): Abbreviation definition not in block: 2:"
+      " [65533, 1, 1, 10]\n",
+      NoErrorRecoveryMessages,
+      ExpectedDumpedBitcode);
+}
+
 } // end of namespace naclmungetest