Merge pull request #35731 from meg-gupta/rlefixes

Fix lifetime of intermediate phis created by the SSAUpdater for RLE

Author: meg-gupta

include/swift/SILOptimizer/Utils/InstOptUtils.h

@@ -703,6 +703,10 @@ makeCopiedValueAvailable(SILValue value, SILBasicBlock *inBlock);
 SILValue
 makeNewValueAvailable(SILValue value, SILBasicBlock *inBlock);
 
+/// Given an ssa value \p value, create destroy_values at leaking blocks
+void endLifetimeAtLeakingBlocks(SILValue value,
+                                ArrayRef<SILBasicBlock *> userBBs);
+
 /// Given a forwarding instruction, eliminate it if all of its users are debug
 /// instructions and ownership uses.
 bool tryEliminateOnlyOwnershipUsedForwardingInst(

include/swift/SILOptimizer/Utils/LoadStoreOptUtils.h

@@ -271,7 +271,9 @@ class LSValue : public LSBase {
       Res = makeCopiedValueAvailable(Res, Inst->getParent());
       Builder.emitEndBorrowOperation(InsertPt->getLoc(), Val);
       // Insert a destroy on the Base
-      SILBuilderWithScope(Inst).emitDestroyValueOperation(Inst->getLoc(), Base);
+      SILBuilderWithScope builder(Inst);
+      builder.emitDestroyValueOperation(
+          RegularLocation::getAutoGeneratedLocation(), Base);
     }
     return Res;
   }

lib/SILOptimizer/Transforms/RedundantLoadElimination.cpp

@@ -1342,11 +1342,26 @@ SILValue RLEContext::computePredecessorLocationValue(SILBasicBlock *BB,
           .getObjectType(),
       Values[0].second.getOwnershipKind());
 
+  SmallVector<SILPhiArgument *, 8> insertedPhis;
+  Updater.setInsertedPhis(&insertedPhis);
+
   for (auto V : Values) {
     Updater.addAvailableValue(V.first, V.second);
   }
 
   auto Val = Updater.getValueInMiddleOfBlock(BB);
+
+  for (auto *phi : insertedPhis) {
+    if (phi == Val) {
+      continue;
+    }
+    // Fix lifetime of intermediate phis
+    SmallVector<SILBasicBlock *, 4> userBBs;
+    for (auto use : phi->getUses()) {
+      userBBs.push_back(use->getParentBlock());
+    }
+    endLifetimeAtLeakingBlocks(phi, userBBs);
+  }
   return makeNewValueAvailable(Val, BB);
 }
 

lib/SILOptimizer/Utils/InstOptUtils.cpp

@@ -1983,8 +1983,9 @@ SILValue swift::makeCopiedValueAvailable(SILValue value, SILBasicBlock *inBlock)
     return value;
 
   auto insertPt = getInsertAfterPoint(value).getValue();
-  auto *copy =
-      SILBuilderWithScope(insertPt).createCopyValue(insertPt->getLoc(), value);
+  SILBuilderWithScope builder(insertPt);
+  auto *copy = builder.createCopyValue(
+      RegularLocation::getAutoGeneratedLocation(), value);
 
   return makeNewValueAvailable(copy, inBlock);
 }
@@ -2009,13 +2010,15 @@ SILValue swift::makeNewValueAvailable(SILValue value, SILBasicBlock *inBlock) {
         assert(loopBlock == inBlock);
         auto front = loopBlock->begin();
         SILBuilderWithScope newBuilder(front);
-        controlEqCopy = newBuilder.createCopyValue(front->getLoc(), value);
+        controlEqCopy = newBuilder.createCopyValue(
+            RegularLocation::getAutoGeneratedLocation(), value);
       },
       [&](SILBasicBlock *postDomBlock) {
         // Insert a destroy_value in the leaking block
         auto front = postDomBlock->begin();
         SILBuilderWithScope newBuilder(front);
-        newBuilder.createDestroyValue(front->getLoc(), value);
+        newBuilder.createDestroyValue(
+            RegularLocation::getAutoGeneratedLocation(), value);
       });
 
   return controlEqCopy ? controlEqCopy : value;
@@ -2057,3 +2060,22 @@ bool swift::tryEliminateOnlyOwnershipUsedForwardingInst(
   callbacks.deleteInst(forwardingInst);
   return true;
 }
+
+void swift::endLifetimeAtLeakingBlocks(SILValue value,
+                                       ArrayRef<SILBasicBlock *> uses) {
+  if (!value->getFunction()->hasOwnership())
+    return;
+
+  if (value.getOwnershipKind() != OwnershipKind::Owned)
+    return;
+
+  findJointPostDominatingSet(
+      value->getParentBlock(), uses, [&](SILBasicBlock *loopBlock) {},
+      [&](SILBasicBlock *postDomBlock) {
+        // Insert a destroy_value in the leaking block
+        auto front = postDomBlock->begin();
+        SILBuilderWithScope newBuilder(front);
+        newBuilder.createDestroyValue(
+            RegularLocation::getAutoGeneratedLocation(), value);
+      });
+}

test/SILOptimizer/redundant_load_elim_ossa_complex.sil

@@ -771,3 +771,50 @@ bb7:
   return %val1 : $Klass
 }
 
+// CHECK-LABEL: @rle_fixlifetimeof_intermediate_phis :
+// CHECK: load
+// CHECK-NOT: load
+// CHECK-LABEL: end sil function 'rle_fixlifetimeof_intermediate_phis'
+sil [ossa] @rle_fixlifetimeof_intermediate_phis : $@convention(thin) (@in NonTrivialStruct, @owned Klass, @owned Klass) -> @owned Klass {
+bb0(%0 : $*NonTrivialStruct, %1 : @owned $Klass, %2 : @owned $Klass):
+  %ele = struct_element_addr %0 : $*NonTrivialStruct, #NonTrivialStruct.val
+  %val1 = load [copy] %ele : $*Klass
+  cond_br undef, bb1, bb2
+
+bb1:
+  store %2 to [assign] %ele : $*Klass
+  br bb3
+
+bb2:
+  destroy_value %2 : $Klass
+  br bb3
+
+bb3:
+  cond_br undef, bb4, bb8
+
+bb4:
+  cond_br undef, bb5, bb6
+
+bb5:
+  %val2 = load [copy] %ele : $*Klass
+  destroy_value %val2 : $Klass
+  store %1 to [assign] %ele : $*Klass
+  br bb7
+
+bb6:
+  destroy_value %1 : $Klass
+  br bb7
+
+bb7:
+  br bb9
+
+bb8:
+  destroy_value %1 : $Klass
+  br bb9
+
+bb9:
+  %val3 = load [take] %ele : $*Klass
+  destroy_value %val3 : $Klass
+  return %val1 : $Klass
+}
+