From 0d6d72f47661eb7504f9270d74c9e05e792e5f65 Mon Sep 17 00:00:00 2001
From: Daniel Berlin <dberlin@dberlin.org>
Date: Mon, 22 Aug 2016 19:14:30 +0000
Subject: [PATCH] MSSA: Factor out phi node placement

llvm-svn: 279462
---
 include/llvm/Transforms/Utils/MemorySSA.h |  2 ++
 lib/Transforms/Utils/MemorySSA.cpp        | 39 +++++++++++++----------
 2 files changed, 24 insertions(+), 17 deletions(-)

diff --git a/include/llvm/Transforms/Utils/MemorySSA.h b/include/llvm/Transforms/Utils/MemorySSA.h
index 606ecff59c5..3a28b1c915b 100644
--- a/include/llvm/Transforms/Utils/MemorySSA.h
+++ b/include/llvm/Transforms/Utils/MemorySSA.h
@@ -616,6 +616,8 @@ private:
   MemoryAccess *findDominatingDef(BasicBlock *, enum InsertionPlace);
   void removeFromLookups(MemoryAccess *);
 
+  void placePHINodes(const SmallPtrSetImpl<BasicBlock *> &,
+                     const SmallPtrSetImpl<BasicBlock *> &);
   MemoryAccess *renameBlock(BasicBlock *, MemoryAccess *);
   void renamePass(DomTreeNode *, MemoryAccess *IncomingVal,
                   SmallPtrSet<BasicBlock *, 16> &Visited);
diff --git a/lib/Transforms/Utils/MemorySSA.cpp b/lib/Transforms/Utils/MemorySSA.cpp
index af2f954219c..e4acddd969b 100644
--- a/lib/Transforms/Utils/MemorySSA.cpp
+++ b/lib/Transforms/Utils/MemorySSA.cpp
@@ -1459,6 +1459,27 @@ void MemorySSA::OptimizeUses::optimizeUses() {
                         LocStackInfo);
 }
 
+void MemorySSA::placePHINodes(
+    const SmallPtrSetImpl<BasicBlock *> &DefiningBlocks,
+    const SmallPtrSetImpl<BasicBlock *> &LiveInBlocks) {
+  // Determine where our MemoryPhi's should go
+  ForwardIDFCalculator IDFs(*DT);
+  IDFs.setDefiningBlocks(DefiningBlocks);
+  IDFs.setLiveInBlocks(LiveInBlocks);
+  SmallVector<BasicBlock *, 32> IDFBlocks;
+  IDFs.calculate(IDFBlocks);
+
+  // Now place MemoryPhi nodes.
+  for (auto &BB : IDFBlocks) {
+    // Insert phi node
+    AccessList *Accesses = getOrCreateAccessList(BB);
+    MemoryPhi *Phi = new MemoryPhi(BB->getContext(), BB, NextID++);
+    ValueToMemoryAccess[BB] = Phi;
+    // Phi's always are placed at the front of the block.
+    Accesses->push_front(Phi);
+  }
+}
+
 void MemorySSA::buildMemorySSA() {
   // We create an access to represent "live on entry", for things like
   // arguments or users of globals, where the memory they use is defined before
@@ -1528,23 +1549,7 @@ void MemorySSA::buildMemorySSA() {
     // live into it to.
     LiveInBlockWorklist.append(pred_begin(BB), pred_end(BB));
   }
-
-  // Determine where our MemoryPhi's should go
-  ForwardIDFCalculator IDFs(*DT);
-  IDFs.setDefiningBlocks(DefiningBlocks);
-  IDFs.setLiveInBlocks(LiveInBlocks);
-  SmallVector<BasicBlock *, 32> IDFBlocks;
-  IDFs.calculate(IDFBlocks);
-
-  // Now place MemoryPhi nodes.
-  for (auto &BB : IDFBlocks) {
-    // Insert phi node
-    AccessList *Accesses = getOrCreateAccessList(BB);
-    MemoryPhi *Phi = new MemoryPhi(BB->getContext(), BB, NextID++);
-    ValueToMemoryAccess[BB] = Phi;
-    // Phi's always are placed at the front of the block.
-    Accesses->push_front(Phi);
-  }
+  placePHINodes(DefiningBlocks, LiveInBlocks);
 
   // Now do regular SSA renaming on the MemoryDef/MemoryUse. Visited will get
   // filled in with all blocks.