Verifier: Check accessors of MDLocation

Check accessors of `MDLocation`, and change them to `cast<>` down to the
right types.  Also add type-safe factory functions.

All the callers that handle broken code need to use the new versions of
the accessors (`getRawScope()` instead of `getScope()`) that still
return `Metadata*`.  This is also necessary for things like
`MDNodeKeyImpl<MDLocation>` (in LLVMContextImpl.h) that need to unique
the nodes when their operands might still be forward references of the
wrong type.

In the `Value` hierarchy, consumers that handle broken code use
`getOperand()` directly.  However, debug info nodes have a ton of
operands, and their order (even their existence) isn't stable yet.  It's
safer and more maintainable to add an explicit "raw" accessor on the
class itself.

llvm-svn: 233322

1 files changed, 4 insertions, 3 deletions

diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index 66831cced41..84753ffd181 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -1691,14 +1691,15 @@ std::error_code BitcodeReader::ParseMetadata() {
       if (Record.size() != 5)
         return Error("Invalid record");
 
-      auto get = Record[0] ? MDLocation::getDistinct : MDLocation::get;
       unsigned Line = Record[1];
       unsigned Column = Record[2];
       MDNode *Scope = cast<MDNode>(MDValueList.getValueFwdRef(Record[3]));
       Metadata *InlinedAt =
           Record[4] ? MDValueList.getValueFwdRef(Record[4] - 1) : nullptr;
-      MDValueList.AssignValue(get(Context, Line, Column, Scope, InlinedAt),
-                              NextMDValueNo++);
+      MDValueList.AssignValue(
+          GET_OR_DISTINCT(MDLocation, Record[0],
+                          (Context, Line, Column, Scope, InlinedAt)),
+          NextMDValueNo++);
       break;
     }
     case bitc::METADATA_GENERIC_DEBUG: {