Bitcode: Serialize (and recover) use-list order

Predict and serialize use-list order in bitcode.  This makes the option
`-preserve-bc-use-list-order` work *most* of the time, but this is still
experimental.

  - Builds a full value-table up front in the writer, sets up a list of
    use-list orders to write out, and discards the table.  This is a
    simpler first step than determining the order from the various
    overlapping IDs of values on-the-fly.

  - The shuffles stored in the use-list order list have an unnecessarily
    large memory footprint.

  - `blockaddress` expressions cause functions to be materialized
    out-of-order.  For now I've ignored this problem, so use-list orders
    will be wrong for constants used by functions that have block
    addresses taken.  There are a couple of ways to fix this, but I
    don't have a concrete plan yet.

  - When materializing functions lazily, the use-lists for constants
    will not be correct.  This use case is out of scope: what should the
    use-list order be, if it's incomplete?

This is part of PR5680.

llvm-svn: 214125

1 files changed, 2 insertions, 1 deletions

diff --git a/llvm/tools/llvm-bcanalyzer/llvm-bcanalyzer.cpp b/llvm/tools/llvm-bcanalyzer/llvm-bcanalyzer.cpp
index 15567cf3123..63145c087a6 100644
--- a/llvm/tools/llvm-bcanalyzer/llvm-bcanalyzer.cpp
+++ b/llvm/tools/llvm-bcanalyzer/llvm-bcanalyzer.cpp
@@ -271,7 +271,8 @@ static const char *GetCodeName(unsigned CodeID, unsigned BlockID,
   case bitc::USELIST_BLOCK_ID:
     switch(CodeID) {
     default:return nullptr;
-    case bitc::USELIST_CODE_ENTRY:   return "USELIST_CODE_ENTRY";
+    case bitc::USELIST_CODE_DEFAULT: return "USELIST_CODE_DEFAULT";
+    case bitc::USELIST_CODE_BB:      return "USELIST_CODE_BB";
     }
   }
 }