[PATCH] D38833: BitstreamWriter: Better assertion when a block's abbrev code size is too small

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri added inline comments.


================
Comment at: unittests/Bitcode/BitstreamWriterTest.cpp:75-182
+TEST(BitstreamWriterTest, trapOnSmallAbbrev_CodeLength2) {
+  SmallString<64> Buffer;
+  BitstreamWriter W(Buffer);
+  W.EnterSubblock(bitc::FIRST_APPLICATION_BLOCKID, /*CodeLen*/2);
+  auto Abbrev = std::make_shared<BitCodeAbbrev>();
+  Abbrev->Add(BitCodeAbbrevOp(42U));
+  unsigned AbbrevCode = W.EmitAbbrev(std::move(Abbrev));
----------------
This looks rather monstrous, with a lot of duplication.
I was suggesting to just do:
```
TEST(BitstreamWriterTest, trapOnSmallAbbrevUsingBlockInfo_CodeLength3_Ok) {
  SmallString<64> Buffer;
  BitstreamWriter W(Buffer);
  W.EnterBlockInfoBlock();
  auto Abbrev = std::make_shared<BitCodeAbbrev>();
  Abbrev->Add(BitCodeAbbrevOp(2U);
  (void)W.EmitBlockInfoAbbrev(bitc::FIRST_APPLICATION_BLOCKID,
                              std::move(Abbrev));
  W.ExitBlock();
  W.EnterSubblock(bitc::FIRST_APPLICATION_BLOCKID, /*CodeLen*/3);
  W.EmitRecordWithAbbrev(Abbrev, makeArrayRef(2U));
  W.ExitBlock();
}

TEST(BitstreamWriterTest, trapOnSmallAbbrevUsingBlockInfo_CodeLength3_LastOk) {
  SmallString<64> Buffer;
  BitstreamWriter W(Buffer);
  W.EnterBlockInfoBlock();
  auto Abbrev = std::make_shared<BitCodeAbbrev>();
  Abbrev->Add(BitCodeAbbrevOp(3U);
  (void)W.EmitBlockInfoAbbrev(bitc::FIRST_APPLICATION_BLOCKID,
                              std::move(Abbrev));
  W.ExitBlock();
  W.EnterSubblock(bitc::FIRST_APPLICATION_BLOCKID, /*CodeLen*/3);
  W.EmitRecordWithAbbrev(Abbrev, makeArrayRef(3U));
  W.ExitBlock();
}

TEST(BitstreamWriterTest, trapOnSmallAbbrevUsingBlockInfo_CodeLength3_NotOk) {
  SmallString<64> Buffer;
  BitstreamWriter W(Buffer);
  W.EnterBlockInfoBlock();
  auto Abbrev = std::make_shared<BitCodeAbbrev>();
  Abbrev->Add(BitCodeAbbrevOp(4U);
  (void)W.EmitBlockInfoAbbrev(bitc::FIRST_APPLICATION_BLOCKID,
                              std::move(Abbrev));
  W.ExitBlock();
  W.EnterSubblock(bitc::FIRST_APPLICATION_BLOCKID, /*CodeLen*/3);
  W.EmitRecordWithAbbrev(Abbrev, makeArrayRef(4U));
  W.ExitBlock();

TEST(BitstreamWriterTest, trapOnSmallAbbrevUsingBlockInfo_CodeLength3_NoOverFlow) {
  SmallString<64> Buffer;
  BitstreamWriter W(Buffer);
  W.EnterBlockInfoBlock();
  auto Abbrev = std::make_shared<BitCodeAbbrev>();
  Abbrev->Add(BitCodeAbbrevOp(4294967295U); // i32 -1 
  (void)W.EmitBlockInfoAbbrev(bitc::FIRST_APPLICATION_BLOCKID,
                              std::move(Abbrev));
  W.ExitBlock();
  W.EnterSubblock(bitc::FIRST_APPLICATION_BLOCKID, /*CodeLen*/32);
  W.EmitRecordWithAbbrev(Abbrev, makeArrayRef(4294967295U));
  W.ExitBlock();
}
```


Repository:
  rL LLVM

https://reviews.llvm.org/D38833