Add a MachineFunction pass, which runs post register allocation, that turns subreg insert/extract instruction into register copies. This ensures correct code gen if the coalescer isn't able to remove all subreg instructions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40521 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 6 insertions, 0 deletions

diff --git a/include/llvm/CodeGen/Passes.h b/include/llvm/CodeGen/Passes.h
index eda6a5dc8b..290e86f37e 100644
--- a/include/llvm/CodeGen/Passes.h
+++ b/include/llvm/CodeGen/Passes.h
@@ -88,6 +88,12 @@ namespace llvm {
   /// and eliminates abstract frame references.
   ///
   FunctionPass *createPrologEpilogCodeInserter();
+  
+  /// LowerSubregs Pass - This pass lowers subregs to register-register copies
+  /// which yields suboptimial, but correct code if the register allocator
+  /// cannot coalesce all subreg operations during allocation.
+  ///
+  FunctionPass *createLowerSubregsPass();
 
   /// createPostRAScheduler - under development.
   FunctionPass *createPostRAScheduler();