[BranchRelaxation] Correct JumpToFT value

[gandhi21299]

Summary

Toggle true/false values of the JumpToFallThrough
parameter to simplify code and make it consistent
with the documentation for the getFallThrough(..)
method.

[gandhi21299]

• Applied clang-format

llvm/include/llvm/CodeGen/MachineBasicBlock.h

return const_cast<MachineBasicBlock *>(
         static_cast<const MachineBasicBlock *>(this)->getSingleSuccessor());
   }
 
   /// Return the fallthrough block if the block can implicitly
   /// transfer control to the block after it by falling off the end of
   /// it. If an explicit branch to the fallthrough block is not allowed,
   /// set JumpToFallThrough to be false. Non-null return is a conservative
   /// answer.
-  MachineBasicBlock *getFallThrough(bool JumpToFallThrough = false);
+  MachineBasicBlock *getFallThrough(bool JumpToFallThrough = true);
 
   /// Return the fallthrough block if the block can implicitly
   /// transfer control to it's successor, whether by a branch or
   /// a fallthrough. Non-null return is a conservative answer.
-  MachineBasicBlock *getLogicalFallThrough() { return getFallThrough(true); }
+  MachineBasicBlock *getLogicalFallThrough() { return getFallThrough(false); }
 
   /// Return true if the block can implicitly transfer control to the
   /// block after it by falling off the end of it.  This should return
   /// false if it can reach the block after it, but it uses an
   /// explicit branch to do so (e.g., a table jump).  True is a
   /// conservative answer.
   bool canFallThrough();
 

llvm/lib/CodeGen/MachineBasicBlock.cpp

return (empty() || !back().isBarrier() || TII->isPredicated(back()))
                : nullptr;
   }
 
   // If there is no branch, control always falls through.
   if (!TBB) return &*Fallthrough;
 
   // If there is some explicit branch to the fallthrough block, it can obviously
   // reach, even though the branch should get folded to fall through implicitly.
-  if (!JumpToFallThrough && (MachineFunction::iterator(TBB) == Fallthrough ||
+  if (JumpToFallThrough && (MachineFunction::iterator(TBB) == Fallthrough ||
                             MachineFunction::iterator(FBB) == Fallthrough))
     return &*Fallthrough;
 
   // If it's an unconditional branch to some block not the fall through, it
   // doesn't fall through.
   if (Cond.empty()) return nullptr;
 
   // Otherwise, if it is conditional and has no explicit false block, it falls
   // through.