Remove LCSSA's bogus dependence on LoopSimplify and LoopSimplify's bogus

dependence on DominanceFrontier. Instead, add an explicit DominanceFrontier
pass in StandardPasses.h to ensure that it gets scheduled at the right
time.

Declare that loop unrolling preserves ScalarEvolution, and shuffle some
getAnalysisUsages.

This eliminates one LoopSimplify and one LCCSA run in the standard
compile opts sequence.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@109413 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 5 insertions, 2 deletions

diff --git a/lib/Transforms/Scalar/LoopUnrollPass.cpp b/lib/Transforms/Scalar/LoopUnrollPass.cpp
index 1b4583d0b3..3d446f0f37 100644
--- a/lib/Transforms/Scalar/LoopUnrollPass.cpp
+++ b/lib/Transforms/Scalar/LoopUnrollPass.cpp
@@ -17,6 +17,7 @@
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/Analysis/LoopPass.h"
 #include "llvm/Analysis/InlineCost.h"
+#include "llvm/Analysis/ScalarEvolution.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
@@ -55,17 +56,19 @@ namespace {
     /// loop preheaders be inserted into the CFG...
     ///
     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+      AU.addRequired<LoopInfo>();
+      AU.addPreserved<LoopInfo>();
       AU.addRequiredID(LoopSimplifyID);
+      AU.addPreservedID(LoopSimplifyID);
       AU.addRequiredID(LCSSAID);
-      AU.addRequired<LoopInfo>();
       AU.addPreservedID(LCSSAID);
-      AU.addPreserved<LoopInfo>();
       // FIXME: Loop unroll requires LCSSA. And LCSSA requires dom info.
       // If loop unroll does not preserve dom info then LCSSA pass on next
       // loop will receive invalid dom info.
       // For now, recreate dom info, if loop is unrolled.
       AU.addPreserved<DominatorTree>();
       AU.addPreserved<DominanceFrontier>();
+      AU.addPreserved<ScalarEvolution>();
     }
   };
 }