SIL: fix APIs for (re)moving instructions

Instructions can only be moved and erased, but never _removed_ from a block.

Author: eeckstein

include/swift/SIL/SILBasicBlock.h

@@ -148,9 +148,10 @@ public SwiftObjectHeader {
 
   void push_back(SILInstruction *I);
   void push_front(SILInstruction *I);
-  void remove(SILInstruction *I);
   void erase(SILInstruction *I);
   void erase(SILInstruction *I, SILModule &module);
+  static void moveInstruction(SILInstruction *inst, SILInstruction *beforeInst);
+  void moveInstructionToFront(SILInstruction *inst);
 
   void eraseAllInstructions(SILModule &module);
 

include/swift/SIL/SILInstruction.h

@@ -376,9 +376,6 @@ class SILInstruction : public llvm::ilist_node<SILInstruction> {
     NumCreatedInstructions++;
   }
 
-  /// This method unlinks 'self' from the containing basic block.
-  void removeFromParent();
-
   ~SILInstruction() {
     NumDeletedInstructions++;
   }

lib/SIL/IR/SILBasicBlock.cpp

@@ -91,10 +91,6 @@ void SILBasicBlock::push_front(SILInstruction *I) {
   InstList.push_front(I);
 }
 
-void SILBasicBlock::remove(SILInstruction *I) {
-  InstList.remove(I);
-}
-
 void SILBasicBlock::eraseAllInstructions(SILModule &module) {
   while (!empty()) {
     erase(&*begin(), module);
@@ -112,6 +108,21 @@ void SILBasicBlock::erase(SILInstruction *I, SILModule &module) {
   module.scheduleForDeletion(I);
 }
 
+void SILBasicBlock::moveInstruction(SILInstruction *inst,
+                                    SILInstruction *beforeInst) {
+  if (inst == beforeInst)
+    return;
+  inst->getParent()->InstList.remove(inst);
+  inst->ParentBB = nullptr;
+  beforeInst->getParent()->insert(beforeInst->getIterator(), inst);
+}
+
+void SILBasicBlock::moveInstructionToFront(SILInstruction *inst) {
+  inst->getParent()->InstList.remove(inst);
+  inst->ParentBB = nullptr;
+  push_front(inst);
+}
+
 /// This method unlinks 'self' from the containing SILFunction and deletes it.
 void SILBasicBlock::eraseFromParent() {
   getParent()->eraseBlock(this);

lib/SIL/IR/SILInstruction.cpp

@@ -103,16 +103,6 @@ transferNodesFromList(llvm::ilist_traits<SILInstruction> &L2,
   ASSERT_IMPLEMENTS_STATIC(CLASS, PARENT, classof, bool(SILNodePointer));
 #include "swift/SIL/SILNodes.def"
 
-void SILInstruction::removeFromParent() {
-#ifndef NDEBUG
-  for (auto result : getResults()) {
-    assert(result->use_empty() && "Uses of SILInstruction remain at deletion.");
-  }
-#endif
-  getParent()->remove(this);
-  ParentBB = nullptr;
-}
-
 /// eraseFromParent - This method unlinks 'self' from the containing basic
 /// block and deletes it.
 ///
@@ -126,18 +116,13 @@ void SILInstruction::eraseFromParent() {
 }
 
 void SILInstruction::moveFront(SILBasicBlock *Block) {
-  getParent()->remove(this);
-  Block->push_front(this);
+  Block->moveInstructionToFront(this);
 }
 
 /// Unlink this instruction from its current basic block and insert it into
 /// the basic block that Later lives in, right before Later.
 void SILInstruction::moveBefore(SILInstruction *Later) {
-  if (this == Later)
-    return;
-
-  getParent()->remove(this);
-  Later->getParent()->insert(Later, this);
+  SILBasicBlock::moveInstruction(this, Later);
 }
 
 /// Unlink this instruction from its current basic block and insert it into

lib/SILOptimizer/Mandatory/AddressLowering.cpp

@@ -3885,8 +3885,7 @@ static void deleteRewrittenInstructions(AddressLoweringState &pass) {
     }
     // willDeleteInstruction was already called for open_existential_value to
     // update the registered type. Carry out the remaining deletion steps.
-    deadInst->getParent()->remove(deadInst);
-    pass.getModule()->scheduleForDeletion(deadInst);
+    deadInst->getParent()->erase(deadInst);
   }
 
   pass.valueStorageMap.clear();