Get rid of address to pointer conversion in LoopRotate which is present just to avoid the address phi absence assert

Author: meg-gupta

lib/SILOptimizer/LoopTransforms/LoopRotate.cpp

@@ -146,9 +146,7 @@ static void mapOperands(SILInstruction *inst,
 static void updateSSAForUseOfValue(
     SILSSAUpdater &updater, SmallVectorImpl<SILPhiArgument *> &insertedPhis,
     const llvm::DenseMap<ValueBase *, SILValue> &valueMap,
-    SILBasicBlock *Header, SILBasicBlock *EntryCheckBlock, SILValue Res,
-    SmallVectorImpl<std::pair<SILBasicBlock *, unsigned>>
-        &accumulatedAddressPhis) {
+    SILBasicBlock *Header, SILBasicBlock *EntryCheckBlock, SILValue Res) {
   // Find the mapped instruction.
   assert(valueMap.count(Res) && "Expected to find value in map!");
   SILValue MappedValue = valueMap.find(Res)->second;
@@ -178,14 +176,13 @@ static void updateSSAForUseOfValue(
     if (user->getParent() == Header)
       continue;
 
-    assert(user->getParent() != EntryCheckBlock
-           && "The entry check block should dominate the header");
+    assert(user->getParent() != EntryCheckBlock &&
+           "The entry check block should dominate the header");
     updater.rewriteUse(*use);
   }
 
   // Canonicalize inserted phis to avoid extra BB Args and if we find an address
   // phi, stash it so we can handle it after we are done rewriting.
-  bool hasOwnership = Header->getParent()->hasOwnership();
   for (SILPhiArgument *arg : insertedPhis) {
     if (SILValue inst = replaceBBArgWithCast(arg)) {
       arg->replaceAllUsesWith(inst);
@@ -194,30 +191,24 @@ static void updateSSAForUseOfValue(
       // SimplifyCFG deletes the dead BB arg.
       continue;
     }
-
-    // If we didn't simplify and have an address phi, stash the value so we can
-    // fix it up.
-    if (hasOwnership && arg->getType().isAddress())
-      accumulatedAddressPhis.emplace_back(arg->getParent(), arg->getIndex());
   }
 }
 
-static void updateSSAForUseOfInst(
-    SILSSAUpdater &updater, SmallVectorImpl<SILPhiArgument *> &insertedPhis,
-    const llvm::DenseMap<ValueBase *, SILValue> &valueMap,
-    SILBasicBlock *header, SILBasicBlock *entryCheckBlock, SILInstruction *inst,
-    SmallVectorImpl<std::pair<SILBasicBlock *, unsigned>>
-        &accumulatedAddressPhis) {
+static void
+updateSSAForUseOfInst(SILSSAUpdater &updater,
+                      SmallVectorImpl<SILPhiArgument *> &insertedPhis,
+                      const llvm::DenseMap<ValueBase *, SILValue> &valueMap,
+                      SILBasicBlock *header, SILBasicBlock *entryCheckBlock,
+                      SILInstruction *inst) {
   for (auto result : inst->getResults())
     updateSSAForUseOfValue(updater, insertedPhis, valueMap, header,
-                           entryCheckBlock, result, accumulatedAddressPhis);
+                           entryCheckBlock, result);
 }
 
 /// Rewrite the code we just created in the preheader and update SSA form.
 static void rewriteNewLoopEntryCheckBlock(
     SILBasicBlock *header, SILBasicBlock *entryCheckBlock,
     const llvm::DenseMap<ValueBase *, SILValue> &valueMap) {
-  SmallVector<std::pair<SILBasicBlock *, unsigned>, 8> accumulatedAddressPhis;
   SmallVector<SILPhiArgument *, 8> insertedPhis;
   SILSSAUpdater updater(&insertedPhis);
 
@@ -226,7 +217,7 @@ static void rewriteNewLoopEntryCheckBlock(
   for (unsigned i : range(header->getNumArguments())) {
     auto *arg = header->getArguments()[i];
     updateSSAForUseOfValue(updater, insertedPhis, valueMap, header,
-                           entryCheckBlock, arg, accumulatedAddressPhis);
+                           entryCheckBlock, arg);
   }
 
   auto instIter = header->begin();
@@ -235,43 +226,9 @@ static void rewriteNewLoopEntryCheckBlock(
   while (instIter != header->end()) {
     auto &inst = *instIter;
     updateSSAForUseOfInst(updater, insertedPhis, valueMap, header,
-                          entryCheckBlock, &inst, accumulatedAddressPhis);
+                          entryCheckBlock, &inst);
     ++instIter;
   }
-
-  // Then see if any of our phis were address phis. In such a case, rewrite the
-  // address to be a smuggled through raw pointer. We do this late to
-  // conservatively not interfere with the previous code's invariants.
-  //
-  // We also translate the phis into a BasicBlock, Index form so we are careful
-  // with invalidation issues around branches/args.
-  auto rawPointerTy =
-      SILType::getRawPointerType(header->getParent()->getASTContext());
-  auto rawPointerUndef = SILUndef::get(rawPointerTy, header->getModule());
-  auto loc = RegularLocation::getAutoGeneratedLocation();
-  while (!accumulatedAddressPhis.empty()) {
-    SILBasicBlock *block;
-    unsigned argIndex;
-    std::tie(block, argIndex) = accumulatedAddressPhis.pop_back_val();
-    auto *arg = cast<SILPhiArgument>(block->getArgument(argIndex));
-    assert(arg->getType().isAddress() && "Not an address phi?!");
-    for (auto *predBlock : block->getPredecessorBlocks()) {
-      Operand *predUse = arg->getIncomingPhiOperand(predBlock);
-      SILBuilderWithScope builder(predUse->getUser());
-      auto *newIncomingValue =
-          builder.createAddressToPointer(loc, predUse->get(), rawPointerTy);
-      predUse->set(newIncomingValue);
-    }
-    SILBuilderWithScope builder(arg->getNextInstruction());
-    SILType oldArgType = arg->getType();
-    auto *phiShim = builder.createPointerToAddress(
-        loc, rawPointerUndef, oldArgType, true /*isStrict*/,
-        false /*is invariant*/);
-    arg->replaceAllUsesWith(phiShim);
-    SILArgument *newArg = block->replacePhiArgument(
-        argIndex, rawPointerTy, OwnershipKind::None, nullptr);
-    phiShim->setOperand(newArg);
-  }
 }
 
 /// Update the dominator tree after rotating the loop.