[MemorySSA & LoopPassManager] Enable MemorySSA as loop dependency. Update tests.

Summary:
I'm not planning to check this in at the moment, but feedback is very welcome, in particular how this affects performance.
The feedback obtains here will guide the next steps towards enabling this.

This patch enables the use of MemorySSA in the loop pass manager.

Passes that currently use MemorySSA:
 - EarlyCSE
Passes that use MemorySSA after this patch:
 - EarlyCSE
 - LICM
 - SimpleLoopUnswitch
Loop passes that update MemorySSA (and do not use it yet, but could use it after this patch):
 - LoopInstSimplify
 - LoopSimplifyCFG
 - LoopUnswitch
 - LoopRotate
 - LoopSimplify
 - LCSSA
Loop passes that do *not* update MemorySSA:
 - IndVarSimplify
 - LoopDelete
 - LoopIdiom
 - LoopSink
 - LoopUnroll
 - LoopInterchange
 - LoopUnrollAndJam
 - LoopVectorize
 - LoopReroll
 - IRCE

Reviewers: chandlerc, george.burgess.iv, davide, sanjoy, gberry

Subscribers: jlebar, Prazek, dmgreen, jdoerfert, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D58311

llvm-svn: 370384

1 files changed, 4 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Utils/LoopUtils.cpp b/llvm/lib/Transforms/Utils/LoopUtils.cpp
index 4c6c2edc385..b4d7f35d2d9 100644
--- a/llvm/lib/Transforms/Utils/LoopUtils.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUtils.cpp
@@ -19,6 +19,7 @@
 #include "llvm/Analysis/InstructionSimplify.h"
 #include "llvm/Analysis/LoopInfo.h"
 #include "llvm/Analysis/LoopPass.h"
+#include "llvm/Analysis/MemorySSA.h"
 #include "llvm/Analysis/MemorySSAUpdater.h"
 #include "llvm/Analysis/MustExecute.h"
 #include "llvm/Analysis/ScalarEvolution.h"
@@ -170,6 +171,8 @@ void llvm::getLoopAnalysisUsage(AnalysisUsage &AU) {
   AU.addPreserved<SCEVAAWrapperPass>();
   AU.addRequired<ScalarEvolutionWrapperPass>();
   AU.addPreserved<ScalarEvolutionWrapperPass>();
+  // FIXME: When all loop passes preserve MemorySSA, it can be required and
+  // preserved here instead of the individual handling in each pass.
 }
 
 /// Manually defined generic "LoopPass" dependency initialization. This is used
@@ -190,6 +193,7 @@ void llvm::initializeLoopPassPass(PassRegistry &Registry) {
   INITIALIZE_PASS_DEPENDENCY(GlobalsAAWrapperPass)
   INITIALIZE_PASS_DEPENDENCY(SCEVAAWrapperPass)
   INITIALIZE_PASS_DEPENDENCY(ScalarEvolutionWrapperPass)
+  INITIALIZE_PASS_DEPENDENCY(MemorySSAWrapperPass)
 }
 
 /// Create MDNode for input string.