Merge pull request #2171 from eeckstein/dead-obj-elim

Bug fixes in DeadObjectElimination

Author: eeckstein

include/swift/SILOptimizer/Utils/Local.h

@@ -270,6 +270,9 @@ class ValueLifetimeAnalysis {
   /// It is assumed that \p Inst is located after the value's definition.
   bool isWithinLifetime(SILInstruction *Inst);
 
+  /// For debug dumping.
+  void dump() const;
+
 private:
 
   /// The value.

lib/SILOptimizer/Transforms/DeadObjectElimination.cpp

@@ -580,15 +580,12 @@ static bool removeAndReleaseArray(SILValue NewArrayValue, bool &CFGChanged) {
     auto *TupleElt = dyn_cast<TupleExtractInst>(Op->getUser());
     if (!TupleElt)
       return false;
-    switch (TupleElt->getFieldNo()) {
-    default:
-      return false;
-    case 0:
+    if (TupleElt->getFieldNo() == 0 && !ArrayDef) {
       ArrayDef = TupleElt;
-      break;
-    case 1:
+    } else if (TupleElt->getFieldNo() == 1 && !StorageAddress) {
       StorageAddress = TupleElt;
-      break;
+    } else {
+      return false;
     }
   }
   if (!ArrayDef)
@@ -623,7 +620,7 @@ static bool removeAndReleaseArray(SILValue NewArrayValue, bool &CFGChanged) {
     return false;
 
   // Find array object lifetime.
-  ValueLifetimeAnalysis VLA(ArrayDef, DeadArray.getAllUsers());
+  ValueLifetimeAnalysis VLA(NewArrayValue, DeadArray.getAllUsers());
 
   // Check that all storage users are in the Array's live blocks.
   for (auto *User : DeadStorage.getAllUsers()) {

lib/SILOptimizer/Utils/Local.cpp

@@ -1240,6 +1240,18 @@ bool ValueLifetimeAnalysis::isWithinLifetime(SILInstruction *Inst) {
   llvm_unreachable("Expected to find use of value in block!");
 }
 
+void ValueLifetimeAnalysis::dump() const {
+  llvm::errs() << "lifetime of def: " << *DefValue;
+  for (SILInstruction *Use : UserSet) {
+    llvm::errs() << "  use: " << *Use;
+  }
+  llvm::errs() << "  live blocks:";
+  for (SILBasicBlock *BB : LiveBlocks) {
+    llvm::errs() << ' ' << BB->getDebugID();
+  }
+  llvm::errs() << '\n';
+}
+
 //===----------------------------------------------------------------------===//
 //                    Casts Optimization and Simplification
 //===----------------------------------------------------------------------===//

test/SILOptimizer/dead_array_elim.sil

@@ -115,6 +115,66 @@ bb2:
   return %18 : $()
 }
 
+// CHECK-LABEL: sil @tuple_extract_in_different_block
+// CHECK: bb0(%0 : $TrivialDestructor):
+// CHECK-NEXT: strong_retain %0
+// CHECK-NEXT: br bb1
+// CHECK: bb1:
+// CHECK-NEXT: strong_release %0
+// CHECK: return
+sil @tuple_extract_in_different_block : $@convention(thin) (@owned TrivialDestructor) -> () {
+bb0(%0 : $TrivialDestructor):
+  %2 = integer_literal $Builtin.Word, 2
+  // function_ref Swift._allocateUninitializedArray <A> (Builtin.Word) -> (Swift.Array<A>, Builtin.RawPointer)
+  %3 = function_ref @allocArray : $@convention(thin) <τ_0_0> (Builtin.Word) -> @owned (Array<τ_0_0>, Builtin.RawPointer)
+  %4 = apply %3<TrivialDestructor>(%2) : $@convention(thin) <τ_0_0> (Builtin.Word) -> @owned (Array<τ_0_0>, Builtin.RawPointer)
+  %6 = tuple_extract %4 : $(Array<TrivialDestructor>, Builtin.RawPointer), 1
+  %7 = pointer_to_address %6 : $Builtin.RawPointer to $*TrivialDestructor
+  strong_retain %0 : $TrivialDestructor
+  store %0 to %7 : $*TrivialDestructor
+  br bb1
+ 
+bb1:
+  %5 = tuple_extract %4 : $(Array<TrivialDestructor>, Builtin.RawPointer), 0
+  %13 = struct_extract %5 : $Array<TrivialDestructor>, #Array._buffer
+  %14 = struct_extract %13 : $_ArrayBuffer<TrivialDestructor>, #_ArrayBuffer._storage
+  %15 = struct_extract %14 : $_BridgeStorage<_ContiguousArrayStorageBase, _NSArrayCore>, #_BridgeStorage.rawValue
+  strong_release %15 : $Builtin.BridgeObject
+  %18 = tuple ()
+  return %18 : $()
+}
+
+
+// CHECK-LABEL: sil @multiple_tuple_extracts
+// CHECK: apply
+// CHECK: store
+// CHECK: load
+// CHECK: strong_release
+// CHECK: return
+sil @multiple_tuple_extracts : $@convention(thin) (@owned TrivialDestructor) -> @owned TrivialDestructor {
+bb0(%0 : $TrivialDestructor):
+  %2 = integer_literal $Builtin.Word, 2
+  // function_ref Swift._allocateUninitializedArray <A> (Builtin.Word) -> (Swift.Array<A>, Builtin.RawPointer)
+  %3 = function_ref @allocArray : $@convention(thin) <τ_0_0> (Builtin.Word) -> @owned (Array<τ_0_0>, Builtin.RawPointer)
+  %4 = apply %3<TrivialDestructor>(%2) : $@convention(thin) <τ_0_0> (Builtin.Word) -> @owned (Array<τ_0_0>, Builtin.RawPointer)
+  %10 = tuple_extract %4 : $(Array<TrivialDestructor>, Builtin.RawPointer), 1
+  %11 = pointer_to_address %10 : $Builtin.RawPointer to $*TrivialDestructor
+  strong_retain %0 : $TrivialDestructor
+  store %0 to %11 : $*TrivialDestructor
+
+  %20 = tuple_extract %4 : $(Array<TrivialDestructor>, Builtin.RawPointer), 1
+  %21 = pointer_to_address %20 : $Builtin.RawPointer to $*TrivialDestructor
+  %22 = load %21 : $*TrivialDestructor
+
+  %12 = tuple_extract %4 : $(Array<TrivialDestructor>, Builtin.RawPointer), 0
+  %13 = struct_extract %12 : $Array<TrivialDestructor>, #Array._buffer
+  %14 = struct_extract %13 : $_ArrayBuffer<TrivialDestructor>, #_ArrayBuffer._storage
+  %15 = struct_extract %14 : $_BridgeStorage<_ContiguousArrayStorageBase, _NSArrayCore>, #_BridgeStorage.rawValue
+  strong_release %15 : $Builtin.BridgeObject
+
+  return %22 : $TrivialDestructor
+}
+
 // CHECK-LABEL: sil @release_dead_array_on_two_branches
 // CHECK: bb0(%0 : $TrivialDestructor, %1 : $TrivialDestructor):
 // CHECK-NEXT: cond_br