Add a comment about the additional meaning of setPreservesCFG() for

MachineFunctionPass passes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@78669 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/CodeGen/MachineFunctionPass.h b/include/llvm/CodeGen/MachineFunctionPass.h
index 6f7c216382a075a6788849862efde85f637ca64f..60460afae7a8623da01be475da54de5e1a1de878 100644 (file)
--- a/include/llvm/CodeGen/MachineFunctionPass.h
+++ b/include/llvm/CodeGen/MachineFunctionPass.h
@@ -40,6 +40,10 @@ protected:
 
   /// getAnalysisUsage - Subclasses that override getAnalysisUsage
   /// must call this.
+  ///
+  /// For MachineFunctionPasses, calling AU.preservesCFG() indicates that
+  /// the pass does not modify the MachineBasicBlock CFG.
+  ///
   virtual void getAnalysisUsage(AnalysisUsage &AU) const;
 
 private: