Bitcode: Collect all MDString records into a single blob

Optimize output of MDStrings in bitcode.  This emits them in big blocks
(currently 1024) in a pair of records:
  - BULK_STRING_SIZES: the sizes of the strings in the block, and
  - BULK_STRING_DATA: a single blob, which is the concatenation of all
    the strings.

Inspired by Mehdi's similar patch, http://reviews.llvm.org/D18342, this
should (a) slightly reduce bitcode size, since there is less record
overhead, and (b) greatly improve reading speed, since blobs are super
cheap to deserialize.

I needed to add support for blobs to streaming input to get the test
suite passing.
  - StreamingMemoryObject::getPointer reads ahead and returns the
    address of the blob.
  - To avoid a possible reallocation of StreamingMemoryObject::Bytes,
    BitstreamCursor::readRecord needs to move the call to JumpToEnd
    forward so that getPointer is the last bitstream operation.

llvm-svn: 264409

1 files changed, 3 insertions, 1 deletions

diff --git a/llvm/tools/llvm-bcanalyzer/llvm-bcanalyzer.cpp b/llvm/tools/llvm-bcanalyzer/llvm-bcanalyzer.cpp
index 32179c168de..8560cf79446 100644
--- a/llvm/tools/llvm-bcanalyzer/llvm-bcanalyzer.cpp
+++ b/llvm/tools/llvm-bcanalyzer/llvm-bcanalyzer.cpp
@@ -312,7 +312,9 @@ static const char *GetCodeName(unsigned CodeID, unsigned BlockID,
   case bitc::METADATA_BLOCK_ID:
     switch(CodeID) {
     default:return nullptr;
-      STRINGIFY_CODE(METADATA, STRING)
+      STRINGIFY_CODE(METADATA, STRING_OLD)
+      STRINGIFY_CODE(METADATA, BULK_STRING_SIZES)
+      STRINGIFY_CODE(METADATA, BULK_STRING_DATA)
       STRINGIFY_CODE(METADATA, NAME)
       STRINGIFY_CODE(METADATA, KIND) // Older bitcode has it in a MODULE_BLOCK
       STRINGIFY_CODE(METADATA, NODE)