From 2863721f0582b304d37c8b37b92574d246598b18 Mon Sep 17 00:00:00 2001
From: Alina Sbirlea <asbirlea@google.com>
Date: Tue, 20 Aug 2019 22:47:58 +0000
Subject: [PATCH] [MemorySSA] Make Phi cleanups consistent.

Summary:
Make Phi cleanups consistent: remove self as a trivial Phi and
recurse to potentially remove other trivial phis.

Reviewers: george.burgess.iv

Subscribers: Prazek, sanjoy.google, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D66454

llvm-svn: 369466
---
 llvm/include/llvm/Analysis/MemorySSAUpdater.h |  1 +
 llvm/lib/Analysis/MemorySSAUpdater.cpp        | 41 +++++++++++----------------
 2 files changed, 18 insertions(+), 24 deletions(-)

diff --git a/llvm/include/llvm/Analysis/MemorySSAUpdater.h b/llvm/include/llvm/Analysis/MemorySSAUpdater.h
index 872f574..1d34663 100644
--- a/llvm/include/llvm/Analysis/MemorySSAUpdater.h
+++ b/llvm/include/llvm/Analysis/MemorySSAUpdater.h
@@ -275,6 +275,7 @@ private:
   getPreviousDefRecursive(BasicBlock *,
                           DenseMap<BasicBlock *, TrackingVH<MemoryAccess>> &);
   MemoryAccess *recursePhi(MemoryAccess *Phi);
+  MemoryAccess *tryRemoveTrivialPhi(MemoryPhi *Phi);
   template <class RangeType>
   MemoryAccess *tryRemoveTrivialPhi(MemoryPhi *Phi, RangeType &Operands);
   void tryRemoveTrivialPhis(ArrayRef<WeakVH> UpdatedPHIs);
diff --git a/llvm/lib/Analysis/MemorySSAUpdater.cpp b/llvm/lib/Analysis/MemorySSAUpdater.cpp
index e63a9b8..f229e6f 100644
--- a/llvm/lib/Analysis/MemorySSAUpdater.cpp
+++ b/llvm/lib/Analysis/MemorySSAUpdater.cpp
@@ -173,12 +173,9 @@ MemoryAccess *MemorySSAUpdater::recursePhi(MemoryAccess *Phi) {
   TrackingVH<MemoryAccess> Res(Phi);
   SmallVector<TrackingVH<Value>, 8> Uses;
   std::copy(Phi->user_begin(), Phi->user_end(), std::back_inserter(Uses));
-  for (auto &U : Uses) {
-    if (MemoryPhi *UsePhi = dyn_cast<MemoryPhi>(&*U)) {
-      auto OperRange = UsePhi->operands();
-      tryRemoveTrivialPhi(UsePhi, OperRange);
-    }
-  }
+  for (auto &U : Uses)
+    if (MemoryPhi *UsePhi = dyn_cast<MemoryPhi>(&*U))
+      tryRemoveTrivialPhi(UsePhi);
   return Res;
 }
 
@@ -187,6 +184,11 @@ MemoryAccess *MemorySSAUpdater::recursePhi(MemoryAccess *Phi) {
 // argument.
 // IE phi(a, a) or b = phi(a, b) or c = phi(a, a, c)
 // We recursively try to remove them.
+MemoryAccess *MemorySSAUpdater::tryRemoveTrivialPhi(MemoryPhi *Phi) {
+  assert(Phi && "Can only remove concrete Phi.");
+  auto OperRange = Phi->operands();
+  return tryRemoveTrivialPhi(Phi, OperRange);
+}
 template <class RangeType>
 MemoryAccess *MemorySSAUpdater::tryRemoveTrivialPhi(MemoryPhi *Phi,
                                                     RangeType &Operands) {
@@ -490,8 +492,7 @@ void MemorySSAUpdater::fixupDefs(const SmallVectorImpl<WeakVH> &Vars) {
 void MemorySSAUpdater::removeEdge(BasicBlock *From, BasicBlock *To) {
   if (MemoryPhi *MPhi = MSSA->getMemoryAccess(To)) {
     MPhi->unorderedDeleteIncomingBlock(From);
-    if (MPhi->getNumIncomingValues() == 1)
-      removeMemoryAccess(MPhi);
+    tryRemoveTrivialPhi(MPhi);
   }
 }
 
@@ -507,8 +508,7 @@ void MemorySSAUpdater::removeDuplicatePhiEdgesBetween(const BasicBlock *From,
       Found = true;
       return false;
     });
-    if (MPhi->getNumIncomingValues() == 1)
-      removeMemoryAccess(MPhi);
+    tryRemoveTrivialPhi(MPhi);
   }
 }
 
@@ -617,8 +617,7 @@ void MemorySSAUpdater::updatePhisWhenInsertingUniqueBackedgeBlock(
 
   // If NewMPhi is a trivial phi, remove it. Its use in the header MPhi will be
   // replaced with the unique value.
-  if (HasUniqueIncomingValue)
-    removeMemoryAccess(NewMPhi);
+  tryRemoveTrivialPhi(MPhi);
 }
 
 void MemorySSAUpdater::updateForClonedLoop(const LoopBlocksRPO &LoopBlocks,
@@ -1227,8 +1226,7 @@ void MemorySSAUpdater::wireOldPredecessorsToNewImmediatePredecessor(
       return false;
     });
     Phi->addIncoming(NewPhi, New);
-    if (onlySingleValue(NewPhi))
-      removeMemoryAccess(NewPhi);
+    tryRemoveTrivialPhi(NewPhi);
   }
 }
 
@@ -1293,10 +1291,8 @@ void MemorySSAUpdater::removeMemoryAccess(MemoryAccess *MA, bool OptimizePhis) {
     unsigned PhisSize = PhisToOptimize.size();
     while (PhisSize-- > 0)
       if (MemoryPhi *MP =
-              cast_or_null<MemoryPhi>(PhisToOptimize.pop_back_val())) {
-        auto OperRange = MP->operands();
-        tryRemoveTrivialPhi(MP, OperRange);
-      }
+              cast_or_null<MemoryPhi>(PhisToOptimize.pop_back_val()))
+        tryRemoveTrivialPhi(MP);
   }
 }
 
@@ -1310,8 +1306,7 @@ void MemorySSAUpdater::removeBlocks(
       if (!DeadBlocks.count(Succ))
         if (MemoryPhi *MP = MSSA->getMemoryAccess(Succ)) {
           MP->unorderedDeleteIncomingBlock(BB);
-          if (MP->getNumIncomingValues() == 1)
-            removeMemoryAccess(MP);
+          tryRemoveTrivialPhi(MP);
         }
     // Drop all references of all accesses in BB
     if (MemorySSA::AccessList *Acc = MSSA->getWritableBlockAccesses(BB))
@@ -1335,10 +1330,8 @@ void MemorySSAUpdater::removeBlocks(
 
 void MemorySSAUpdater::tryRemoveTrivialPhis(ArrayRef<WeakVH> UpdatedPHIs) {
   for (auto &VH : UpdatedPHIs)
-    if (auto *MPhi = cast_or_null<MemoryPhi>(VH)) {
-      auto OperRange = MPhi->operands();
-      tryRemoveTrivialPhi(MPhi, OperRange);
-    }
+    if (auto *MPhi = cast_or_null<MemoryPhi>(VH))
+      tryRemoveTrivialPhi(MPhi);
 }
 
 void MemorySSAUpdater::changeToUnreachable(const Instruction *I) {
-- 
2.7.4