Added a late machine instruction copy propagation pass. This catches

opportunities that only present themselves after late optimizations
such as tail duplication .e.g.
## BB#1:
        movl    %eax, %ecx
        movl    %ecx, %eax
        ret

The register allocator also leaves some of them around (due to false
dep between copies from phi-elimination, etc.)

This required some changes in codegen passes. Post-ra scheduler and the
pseudo-instruction expansion passes have been moved after branch folding
and tail merging. They were before branch folding before because it did
not always update block livein's. That's fixed now. The pass change makes
independently since we want to properly schedule instructions after
branch folding / tail duplication.

rdar://10428165
rdar://10640363

llvm-svn: 147716

1 files changed, 1 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/CMakeLists.txt b/llvm/lib/CodeGen/CMakeLists.txt
index ce9d0d4d0d6..7fa5e47f9eb 100644
--- a/llvm/lib/CodeGen/CMakeLists.txt
+++ b/llvm/lib/CodeGen/CMakeLists.txt
@@ -40,6 +40,7 @@ add_llvm_library(LLVMCodeGen
   MachineBlockPlacement.cpp
   MachineBranchProbabilityInfo.cpp
   MachineCodeEmitter.cpp
+  MachineCopyPropagation.cpp
   MachineCSE.cpp
   MachineDominators.cpp
   MachineFunction.cpp