From 1bf0915d7a50a12c46b4e42a6e5336fa1f3e5f7f Mon Sep 17 00:00:00 2001
From: Sanjay Patel <spatel@rotateright.com>
Date: Tue, 29 Aug 2017 14:07:48 +0000
Subject: [PATCH] [Instruction] add moveAfter() convenience function; NFCI

As suggested in D37121, here's a wrapper for removeFromParent() + insertAfter(),
but implemented using moveBefore() for symmetry/efficiency.

Differential Revision: https://reviews.llvm.org/D37239


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@312001 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/IR/Instruction.h              |  4 ++++
 lib/CodeGen/AtomicExpandPass.cpp           | 10 ++--------
 lib/CodeGen/CodeGenPrepare.cpp             |  9 +++------
 lib/IR/Instruction.cpp                     |  4 ++++
 lib/Transforms/Vectorize/SLPVectorizer.cpp |  3 +--
 5 files changed, 14 insertions(+), 16 deletions(-)

diff --git a/include/llvm/IR/Instruction.h b/include/llvm/IR/Instruction.h
index 8dc02111b86..0cf8003423f 100644
--- a/include/llvm/IR/Instruction.h
+++ b/include/llvm/IR/Instruction.h
@@ -113,6 +113,10 @@ public:
   /// \pre I is a valid iterator into BB.
   void moveBefore(BasicBlock &BB, SymbolTableList<Instruction>::iterator I);
 
+  /// Unlink this instruction from its current basic block and insert it into
+  /// the basic block that MovePos lives in, right after MovePos.
+  void moveAfter(Instruction *MovePos);
+
   //===--------------------------------------------------------------------===//
   // Subclass classification.
   //===--------------------------------------------------------------------===//
diff --git a/lib/CodeGen/AtomicExpandPass.cpp b/lib/CodeGen/AtomicExpandPass.cpp
index aa9c8e94d08..9d1f94a8a43 100644
--- a/lib/CodeGen/AtomicExpandPass.cpp
+++ b/lib/CodeGen/AtomicExpandPass.cpp
@@ -320,16 +320,10 @@ bool AtomicExpand::bracketInstWithFences(Instruction *I, AtomicOrdering Order) {
   auto LeadingFence = TLI->emitLeadingFence(Builder, I, Order);
 
   auto TrailingFence = TLI->emitTrailingFence(Builder, I, Order);
-  // The trailing fence is emitted before the instruction instead of after
-  // because there is no easy way of setting Builder insertion point after
-  // an instruction. So we must erase it from the BB, and insert it back
-  // in the right place.
   // We have a guard here because not every atomic operation generates a
   // trailing fence.
-  if (TrailingFence) {
-    TrailingFence->removeFromParent();
-    TrailingFence->insertAfter(I);
-  }
+  if (TrailingFence)
+    TrailingFence->moveAfter(I);
 
   return (LeadingFence || TrailingFence);
 }
diff --git a/lib/CodeGen/CodeGenPrepare.cpp b/lib/CodeGen/CodeGenPrepare.cpp
index 03ef8985210..1250d025fbc 100644
--- a/lib/CodeGen/CodeGenPrepare.cpp
+++ b/lib/CodeGen/CodeGenPrepare.cpp
@@ -3586,9 +3586,8 @@ Value *TypePromotionHelper::promoteOperandForOther(
     // Create the truncate now.
     Value *Trunc = TPT.createTrunc(Ext, ExtOpnd->getType());
     if (Instruction *ITrunc = dyn_cast<Instruction>(Trunc)) {
-      ITrunc->removeFromParent();
       // Insert it just after the definition.
-      ITrunc->insertAfter(ExtOpnd);
+      ITrunc->moveAfter(ExtOpnd);
       if (Truncs)
         Truncs->push_back(ITrunc);
     }
@@ -4943,8 +4942,7 @@ bool CodeGenPrepare::optimizeExt(Instruction *&Inst) {
     assert(LI && ExtFedByLoad && "Expect a valid load and extension");
     TPT.commit();
     // Move the extend into the same block as the load
-    ExtFedByLoad->removeFromParent();
-    ExtFedByLoad->insertAfter(LI);
+    ExtFedByLoad->moveAfter(LI);
     // CGP does not check if the zext would be speculatively executed when moved
     // to the same basic block as the load. Preserving its original location
     // would pessimize the debugging experience, as well as negatively impact
@@ -5936,8 +5934,7 @@ void VectorPromoteHelper::promoteImpl(Instruction *ToBePromoted) {
                        "this?");
     ToBePromoted->setOperand(U.getOperandNo(), NewVal);
   }
-  Transition->removeFromParent();
-  Transition->insertAfter(ToBePromoted);
+  Transition->moveAfter(ToBePromoted);
   Transition->setOperand(getTransitionOriginalValueIdx(), ToBePromoted);
 }
 
diff --git a/lib/IR/Instruction.cpp b/lib/IR/Instruction.cpp
index 365cb019aec..ceb521c4c48 100644
--- a/lib/IR/Instruction.cpp
+++ b/lib/IR/Instruction.cpp
@@ -89,6 +89,10 @@ void Instruction::moveBefore(Instruction *MovePos) {
   moveBefore(*MovePos->getParent(), MovePos->getIterator());
 }
 
+void Instruction::moveAfter(Instruction *MovePos) {
+  moveBefore(*MovePos->getParent(), ++MovePos->getIterator());
+}
+
 void Instruction::moveBefore(BasicBlock &BB,
                              SymbolTableList<Instruction>::iterator I) {
   assert(I == BB.end() || I->getParent() == &BB);
diff --git a/lib/Transforms/Vectorize/SLPVectorizer.cpp b/lib/Transforms/Vectorize/SLPVectorizer.cpp
index d8da03ae2a9..1f530cbb5d2 100644
--- a/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ b/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -4467,8 +4467,7 @@ bool SLPVectorizerPass::tryToVectorizeList(ArrayRef<Value *> VL, BoUpSLP &R,
                 cast<Instruction>(Builder.CreateExtractElement(
                     VectorizedRoot, Builder.getInt32(VecIdx++)));
             I->setOperand(1, Extract);
-            I->removeFromParent();
-            I->insertAfter(Extract);
+            I->moveAfter(Extract);
             InsertAfter = I;
           }
         }
-- 
2.50.1