SIL: Promote removeDeadBlock() from SILOptimizer to a method on SILBasicBlock

Author: slavapestov

include/swift/SIL/SILBasicBlock.h

@@ -174,6 +174,9 @@ public SwiftObjectHeader {
   /// This method unlinks 'self' from the containing SILFunction and deletes it.
   void eraseFromParent();
 
+  /// Replaces usages of this block with 'undef's and then deletes it.
+  void removeDeadBlock();
+
   /// Remove all instructions of a SILGlobalVariable's static initializer block.
   void clearStaticInitializerBlock(SILModule &module);
 

include/swift/SILOptimizer/Utils/BasicBlockOptUtils.h

@@ -83,13 +83,6 @@ class NonErrorHandlingBlocks {
   }
 };
 
-/// Remove all instructions in the body of \p bb in safe manner by using
-/// undef.
-void clearBlockBody(SILBasicBlock *bb);
-
-/// Handle the mechanical aspects of removing an unreachable block.
-void removeDeadBlock(SILBasicBlock *bb);
-
 /// Remove all unreachable blocks in a function.
 bool removeUnreachableBlocks(SILFunction &f);
 

lib/SIL/IR/SILBasicBlock.cpp

@@ -127,6 +127,29 @@ void SILBasicBlock::eraseFromParent() {
   getParent()->eraseBlock(this);
 }
 
+/// Handle the mechanical aspects of removing an unreachable block.
+void SILBasicBlock::removeDeadBlock() {
+  for (SILArgument *arg : getArguments()) {
+    arg->replaceAllUsesWithUndef();
+    // To appease the ownership verifier, just set to None.
+    arg->setOwnershipKind(OwnershipKind::None);
+  }
+
+  // Instructions in the dead block may be used by other dead blocks.  Replace
+  // any uses of them with undef values.
+  while (!empty()) {
+    // Grab the last instruction in the bb.
+    auto *inst = &back();
+
+    // Replace any still-remaining uses with undef values and erase.
+    inst->replaceAllUsesOfAllResultsWithUndef();
+    inst->eraseFromParent();
+  }
+
+  // Now that the bb is empty, eliminate it.
+  eraseFromParent();
+}
+
 void SILBasicBlock::cloneArgumentList(SILBasicBlock *Other) {
   assert(Other->isEntry() == isEntry() &&
          "Expected to both blocks to be entries or not");

lib/SILOptimizer/FunctionSignatureTransforms/ExistentialTransform.cpp

@@ -380,7 +380,7 @@ void ExistentialTransform::populateThunkBody() {
   /// Remove original body of F.
   for (auto It = F->begin(), End = F->end(); It != End;) {
     auto *BB = &*It++;
-    removeDeadBlock(BB);
+    BB->removeDeadBlock();
   }
 
   /// Create a basic block and the function arguments.

lib/SILOptimizer/Transforms/SimplifyCFG.cpp

@@ -642,7 +642,7 @@ bool SimplifyCFG::removeIfDead(SILBasicBlock *BB) {
     addToWorklist(S);
 
   LLVM_DEBUG(llvm::dbgs() << "remove dead bb" << BB->getDebugID() << '\n');
-  removeDeadBlock(BB);
+  BB->removeDeadBlock();
   ++NumBlocksDeleted;
   return true;
 }
@@ -1782,7 +1782,7 @@ bool SimplifyCFG::simplifySwitchEnumUnreachableBlocks(SwitchEnumInst *SEI) {
     addToWorklist(SEI->getParent());
     SILBuilderWithScope(SEI).createUnreachable(SEI->getLoc());
     for (auto &succ : SEI->getSuccessors()) {
-      removeDeadBlock(succ.getBB());
+      succ.getBB()->removeDeadBlock();
     }
     SEI->eraseFromParent();
     return true;

lib/SILOptimizer/Utils/BasicBlockOptUtils.cpp

@@ -67,37 +67,6 @@ NonErrorHandlingBlocks::NonErrorHandlingBlocks(SILFunction *function)
   }
 }
 
-/// Remove all instructions in the body of \p bb in safe manner by using
-/// undef.
-void swift::clearBlockBody(SILBasicBlock *bb) {
-
-  for (SILArgument *arg : bb->getArguments()) {
-    arg->replaceAllUsesWithUndef();
-    // To appease the ownership verifier, just set to None.
-    arg->setOwnershipKind(OwnershipKind::None);
-  }
-
-  // Instructions in the dead block may be used by other dead blocks.  Replace
-  // any uses of them with undef values.
-  while (!bb->empty()) {
-    // Grab the last instruction in the bb.
-    auto *inst = &bb->back();
-
-    // Replace any still-remaining uses with undef values and erase.
-    inst->replaceAllUsesOfAllResultsWithUndef();
-    inst->eraseFromParent();
-  }
-}
-
-// Handle the mechanical aspects of removing an unreachable block.
-void swift::removeDeadBlock(SILBasicBlock *bb) {
-  // Clear the body of bb.
-  clearBlockBody(bb);
-
-  // Now that the bb is empty, eliminate it.
-  bb->eraseFromParent();
-}
-
 bool swift::removeUnreachableBlocks(SILFunction &f) {
   ReachableBlocks reachable(&f);
   // Visit all the blocks without doing any extra work.
@@ -109,7 +78,7 @@ bool swift::removeUnreachableBlocks(SILFunction &f) {
   for (auto ii = std::next(f.begin()), end = f.end(); ii != end;) {
     auto *bb = &*ii++;
     if (!reachable.isVisited(bb)) {
-      removeDeadBlock(bb);
+      bb->removeDeadBlock();
       changed = true;
     }
   }