Add a new MachineBasicBlock utility function, isLayoutSuccessor, that
can be used when deciding if a block can transfer control to another
via a fall-through instead of a branch.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@56968 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/llvm/CodeGen/MachineBasicBlock.h b/include/llvm/CodeGen/MachineBasicBlock.h
index b47108a..09cca93 100644
--- a/include/llvm/CodeGen/MachineBasicBlock.h
+++ b/include/llvm/CodeGen/MachineBasicBlock.h
@@ -234,6 +234,13 @@
/// block.
bool isSuccessor(MachineBasicBlock *MBB) const;
+ /// isLayoutSuccessor - Return true if the specified MBB will be emitted
+ /// immediately after this block, such that if this block exits by
+ /// falling through, control will transfer to the specified MBB. Note
+ /// that MBB need not be a successor at all, for example if this block
+ /// ends with an unconditional branch to some other block.
+ bool isLayoutSuccessor(MachineBasicBlock *MBB) const;
+
/// getFirstTerminator - returns an iterator to the first terminator
/// instruction of this basic block. If a terminator does not exist,
/// it returns end()
diff --git a/lib/CodeGen/MachineBasicBlock.cpp b/lib/CodeGen/MachineBasicBlock.cpp
index 0320aff..bac0a6c 100644
--- a/lib/CodeGen/MachineBasicBlock.cpp
+++ b/lib/CodeGen/MachineBasicBlock.cpp
@@ -254,6 +254,11 @@
return I != Successors.end();
}
+bool MachineBasicBlock::isLayoutSuccessor(MachineBasicBlock *MBB) const {
+ MachineFunction::const_iterator I(this);
+ return next(I) == MachineFunction::const_iterator(MBB);
+}
+
/// removeFromParent - This method unlinks 'this' from the containing function,
/// and returns it, but does not delete it.
MachineBasicBlock *MachineBasicBlock::removeFromParent() {