Except in asm-verbose mode, avoid printing labels for blocks that are

only reachable via fall-through edges. This dramatically reduces the
number of labels printed, and thus also the number of labels the
assembler must parse and remember.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@68073 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 9 insertions, 0 deletions

diff --git a/include/llvm/CodeGen/MachineBasicBlock.h b/include/llvm/CodeGen/MachineBasicBlock.h
index 1ba7e798f8..f962273d2b 100644
--- a/include/llvm/CodeGen/MachineBasicBlock.h
+++ b/include/llvm/CodeGen/MachineBasicBlock.h
@@ -253,6 +253,15 @@ public:
   /// it returns end()
   iterator getFirstTerminator();
 
+  /// isOnlyReachableViaFallthough - Return true if this basic block has
+  /// exactly one predecessor and the control transfer mechanism between
+  /// the predecessor and this block is a fall-through.
+  bool isOnlyReachableByFallthrough() const {
+    return !pred_empty() &&
+           next(pred_begin()) == pred_end() &&
+           (*pred_begin())->getFirstTerminator() == (*pred_begin())->end();
+  }
+
   void pop_front() { Insts.pop_front(); }
   void pop_back() { Insts.pop_back(); }
   void push_back(MachineInstr *MI) { Insts.push_back(MI); }