IR: RF_IgnoreMissingValues => RF_IgnoreMissingLocals, NFC

Clarify what this RemapFlag actually means.

  - Change the flag name to match its intended behaviour.
  - Clearly document that it's not supposed to affect globals.
  - Add a host of FIXMEs to indicate how to fix the behaviour to match
    the intent of the flag.

RF_IgnoreMissingLocals should only affect the behaviour of
RemapInstruction for function-local operands; namely, for operands of
type Argument, Instruction, and BasicBlock.  Currently, it is *only*
passed into RemapInstruction calls (and the transitive MapValue calls
that it makes).

When I split Metadata from Value I didn't understand the flag, and I
used it in a bunch of places for "global" metadata.

This commit doesn't have any functionality change, but prepares to
cleanup MapMetadata and MapValue.

llvm-svn: 265628

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/Linker/IRMover.cpp b/llvm/lib/Linker/IRMover.cpp
index 5351bd5948a..2958d96cbc7 100644
--- a/llvm/lib/Linker/IRMover.cpp
+++ b/llvm/lib/Linker/IRMover.cpp
@@ -997,7 +997,7 @@ bool IRLinker::linkFunctionBody(Function &Dst, Function &Src) {
     A.mutateType(TypeMap.get(A.getType()));
   for (BasicBlock &BB : Dst)
     for (Instruction &I : BB)
-      RemapInstruction(&I, ValueMap, RF_IgnoreMissingEntries | ValueMapperFlags,
+      RemapInstruction(&I, ValueMap, RF_IgnoreMissingLocals | ValueMapperFlags,
                        &TypeMap, &GValMaterializer);
 
   return false;