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/CodeGen/WinEHPrepare.cpp b/llvm/lib/CodeGen/WinEHPrepare.cpp
index b2b3130e9f1..041fb7b912b 100644
--- a/llvm/lib/CodeGen/WinEHPrepare.cpp
+++ b/llvm/lib/CodeGen/WinEHPrepare.cpp
@@ -787,7 +787,7 @@ void WinEHPrepare::cloneCommonBlocks(Function &F) {
       // Loop over all instructions, fixing each one as we find it...
       for (Instruction &I : *BB)
         RemapInstruction(&I, VMap,
-                         RF_IgnoreMissingEntries | RF_NoModuleLevelChanges);
+                         RF_IgnoreMissingLocals | RF_NoModuleLevelChanges);
 
     // Catchrets targeting cloned blocks need to be updated separately from
     // the loop above because they are not in the current funclet.