3 files changed, 22 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp b/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
index cf16aaacb0d..36ae6b2d717 100644
--- a/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
+++ b/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
@@ -326,6 +326,24 @@ void PassManagerBuilder::populateModulePassManager(
   // we must insert a no-op module pass to reset the pass manager.
   MPM.add(createBarrierNoopPass());
 
+  if (EnableNonLTOGlobalsModRef)
+    // We add a fresh GlobalsModRef run at this point. This is particularly
+    // useful as the above will have inlined, DCE'ed, and function-attr
+    // propagated everything. We should at this point have a reasonably minimal
+    // and richly annotated call graph. By computing aliasing and mod/ref
+    // information for all local globals here, the late loop passes and notably
+    // the vectorizer will be able to use them to help recognize vectorizable
+    // memory operations.
+    //
+    // Note that this relies on a bug in the pass manager which preserves
+    // a module analysis into a function pass pipeline (and throughout it) so
+    // long as the first function pass doesn't invalidate the module analysis.
+    // Thus both Float2Int and LoopRotate have to preserve AliasAnalysis for
+    // this to work. Fortunately, it is trivial to preserve AliasAnalysis
+    // (doing nothing preserves it as it is required to be conservatively
+    // correct in the face of IR changes).
+    MPM.add(createGlobalsModRefPass());
+
   if (RunFloat2Int)
     MPM.add(createFloat2IntPass());
 
diff --git a/llvm/lib/Transforms/Scalar/Float2Int.cpp b/llvm/lib/Transforms/Scalar/Float2Int.cpp
index c9314229c38..13e46375323 100644
--- a/llvm/lib/Transforms/Scalar/Float2Int.cpp
+++ b/llvm/lib/Transforms/Scalar/Float2Int.cpp
@@ -19,6 +19,7 @@
 #include "llvm/ADT/EquivalenceClasses.h"
 #include "llvm/ADT/MapVector.h"
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/Analysis/AliasAnalysis.h"
 #include "llvm/IR/ConstantRange.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/IRBuilder.h"
@@ -60,6 +61,7 @@ namespace {
     bool runOnFunction(Function &F) override;
     void getAnalysisUsage(AnalysisUsage &AU) const override {
       AU.setPreservesCFG();
+      AU.addPreserved<AliasAnalysis>();
     }
 
     void findRoots(Function &F, SmallPtrSet<Instruction*,8> &Roots);
diff --git a/llvm/lib/Transforms/Scalar/LoopRotation.cpp b/llvm/lib/Transforms/Scalar/LoopRotation.cpp
index a675e1289ba..bf034bc8d19 100644
--- a/llvm/lib/Transforms/Scalar/LoopRotation.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopRotation.cpp
@@ -13,6 +13,7 @@
 
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/AliasAnalysis.h"
 #include "llvm/Analysis/AssumptionCache.h"
 #include "llvm/Analysis/CodeMetrics.h"
 #include "llvm/Analysis/InstructionSimplify.h"
@@ -56,6 +57,7 @@ namespace {
 
     // LCSSA form makes instruction renaming easier.
     void getAnalysisUsage(AnalysisUsage &AU) const override {
+      AU.addPreserved<AliasAnalysis>();
       AU.addRequired<AssumptionCacheTracker>();
       AU.addPreserved<DominatorTreeWrapperPass>();
       AU.addRequired<LoopInfoWrapperPass>();