MachineRegionInfo: Fix pass initialization

- Adapt MachineBasicBlock::getName() to have the same behavior as the IR
  BasicBlock (Value::getName()).
- Add it to lib/CodeGen/CodeGen.cpp::initializeCodeGen so that it is linked in
  the CodeGen library.
- MachineRegionInfoPass's name conflicts with RegionInfoPass's name ("region").
- MachineRegionInfo should depend on MachineDominatorTree,
  MachinePostDominatorTree and MachineDominanceFrontier instead of their
  respective IR versions.
- Since there were no tests for this, add a X86 MIR test.

Patch by Francis Visoiu Mistrih<fvisoiumistrih@apple.com>

llvm-svn: 295518

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/MachineBasicBlock.cpp b/llvm/lib/CodeGen/MachineBasicBlock.cpp
index 4e91bb0..cbb6970 100644
--- a/llvm/lib/CodeGen/MachineBasicBlock.cpp
+++ b/llvm/lib/CodeGen/MachineBasicBlock.cpp
@@ -232,7 +232,7 @@ StringRef MachineBasicBlock::getName() const {
   if (const BasicBlock *LBB = getBasicBlock())
     return LBB->getName();
   else
-    return "(null)";
+    return StringRef("", 0);
 }
 
 /// Return a hopefully unique identifier for this block.