From 97c856a6126f0853dd894cc5f78dfaa574c78540 Mon Sep 17 00:00:00 2001
From: Evgeniy Stepanov <eugeni.stepanov@gmail.com>
Date: Wed, 25 Jun 2014 09:17:21 +0000
Subject: Factor out part of LICM::sink into a helper function.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211678 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Scalar/LICM.cpp | 69 +++++++++++++++++++++++++-----------------
 1 file changed, 41 insertions(+), 28 deletions(-)

diff --git a/lib/Transforms/Scalar/LICM.cpp b/lib/Transforms/Scalar/LICM.cpp
index c16ffdbf64..bc1db37331 100644
--- a/lib/Transforms/Scalar/LICM.cpp
+++ b/lib/Transforms/Scalar/LICM.cpp
@@ -192,6 +192,14 @@ namespace {
                          SmallVectorImpl<BasicBlock*> &ExitBlocks,
                          SmallVectorImpl<Instruction*> &InsertPts,
                          PredIteratorCache &PIC);
+
+    /// \brief Create a copy of the instruction in the exit block and patch up
+    /// SSA.
+    /// PN is a user of I in ExitBlock that can be used to get the number and
+    /// list of predecessors fast.
+    Instruction *CloneInstructionInExitBlock(Instruction &I,
+                                             BasicBlock &ExitBlock,
+                                             PHINode &PN);
   };
 }
 
@@ -531,6 +539,35 @@ bool LICM::isNotUsedInLoop(Instruction &I) {
   return true;
 }
 
+Instruction *LICM::CloneInstructionInExitBlock(Instruction &I,
+                                               BasicBlock &ExitBlock,
+                                               PHINode &PN) {
+  Instruction *New = I.clone();
+  ExitBlock.getInstList().insert(ExitBlock.getFirstInsertionPt(), New);
+  if (!I.getName().empty()) New->setName(I.getName() + ".le");
+
+  // Build LCSSA PHI nodes for any in-loop operands. Note that this is
+  // particularly cheap because we can rip off the PHI node that we're
+  // replacing for the number and blocks of the predecessors.
+  // OPT: If this shows up in a profile, we can instead finish sinking all
+  // invariant instructions, and then walk their operands to re-establish
+  // LCSSA. That will eliminate creating PHI nodes just to nuke them when
+  // sinking bottom-up.
+  for (User::op_iterator OI = New->op_begin(), OE = New->op_end(); OI != OE;
+       ++OI)
+    if (Instruction *OInst = dyn_cast<Instruction>(*OI))
+      if (Loop *OLoop = LI->getLoopFor(OInst->getParent()))
+        if (!OLoop->contains(&PN)) {
+          PHINode *OpPN =
+              PHINode::Create(OInst->getType(), PN.getNumIncomingValues(),
+                              OInst->getName() + ".lcssa", ExitBlock.begin());
+          for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
+            OpPN->addIncoming(OInst, PN.getIncomingBlock(i));
+          *OI = OpPN;
+        }
+  return New;
+}
+
 /// sink - When an instruction is found to only be used outside of the loop,
 /// this function moves it to the exit blocks and patches up SSA form as needed.
 /// This method is guaranteed to remove the original instruction from its
@@ -566,35 +603,11 @@ void LICM::sink(Instruction &I) {
 
     Instruction *New;
     auto It = SunkCopies.find(ExitBlock);
-    if (It != SunkCopies.end()) {
+    if (It != SunkCopies.end())
       New = It->second;
-    } else {
-      New = I.clone();
-      SunkCopies[ExitBlock] = New;
-      ExitBlock->getInstList().insert(ExitBlock->getFirstInsertionPt(), New);
-      if (!I.getName().empty())
-        New->setName(I.getName() + ".le");
-
-      // Build LCSSA PHI nodes for any in-loop operands. Note that this is
-      // particularly cheap because we can rip off the PHI node that we're
-      // replacing for the number and blocks of the predecessors.
-      // OPT: If this shows up in a profile, we can instead finish sinking all
-      // invariant instructions, and then walk their operands to re-establish
-      // LCSSA. That will eliminate creating PHI nodes just to nuke them when
-      // sinking bottom-up.
-      for (User::op_iterator OI = New->op_begin(), OE = New->op_end(); OI != OE;
-           ++OI)
-        if (Instruction *OInst = dyn_cast<Instruction>(*OI))
-          if (Loop *OLoop = LI->getLoopFor(OInst->getParent()))
-            if (!OLoop->contains(PN)) {
-              PHINode *OpPN = PHINode::Create(
-                  OInst->getType(), PN->getNumIncomingValues(),
-                  OInst->getName() + ".lcssa", ExitBlock->begin());
-              for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
-                OpPN->addIncoming(OInst, PN->getIncomingBlock(i));
-              *OI = OpPN;
-            }
-    }
+    else
+      New = SunkCopies[ExitBlock] =
+          CloneInstructionInExitBlock(I, *ExitBlock, *PN);
 
     PN->replaceAllUsesWith(New);
     PN->eraseFromParent();
-- 
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