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/Transforms/Scalar/LoopRotation.cpp b/llvm/lib/Transforms/Scalar/LoopRotation.cpp
index 1a9d1db1a53..b8148916295 100644
--- a/llvm/lib/Transforms/Scalar/LoopRotation.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopRotation.cpp
@@ -244,7 +244,7 @@ static bool rotateLoop(Loop *L, unsigned MaxHeaderSize, LoopInfo *LI,
 
     // Eagerly remap the operands of the instruction.
     RemapInstruction(C, ValueMap,
-                     RF_NoModuleLevelChanges|RF_IgnoreMissingEntries);
+                     RF_NoModuleLevelChanges | RF_IgnoreMissingLocals);
 
     // With the operands remapped, see if the instruction constant folds or is
     // otherwise simplifyable.  This commonly occurs because the entry from PHI