SILCombine: remove the dead alloc_ref peephole optimization

eeckstein · eeckstein · commit d91759daf8e4 · 2023-09-19T15:10:30.000+02:00
It's not needed because dead alloc_refs are removed by the DeadObjectElimination pass
diff --git a/lib/SILOptimizer/SILCombiner/SILCombiner.h b/lib/SILOptimizer/SILCombiner/SILCombiner.h
@@ -253,7 +253,6 @@ class SILCombiner :
   SILInstruction *visitIndexAddrInst(IndexAddrInst *IA);
   bool optimizeStackAllocatedEnum(AllocStackInst *AS);
   SILInstruction *visitAllocStackInst(AllocStackInst *AS);
-  SILInstruction *visitAllocRefInst(AllocRefInst *AR);
   SILInstruction *visitSwitchEnumAddrInst(SwitchEnumAddrInst *SEAI);
   SILInstruction *visitInjectEnumAddrInst(InjectEnumAddrInst *IEAI);
   SILInstruction *visitPointerToAddressInst(PointerToAddressInst *PTAI);
diff --git a/lib/SILOptimizer/SILCombiner/SILCombinerMiscVisitors.cpp b/lib/SILOptimizer/SILCombiner/SILCombinerMiscVisitors.cpp
@@ -745,32 +745,6 @@ SILInstruction *SILCombiner::visitAllocStackInst(AllocStackInst *AS) {
   return eraseInstFromFunction(*AS);
 }
 
-SILInstruction *SILCombiner::visitAllocRefInst(AllocRefInst *AR) {
-  // Check if the only uses are deallocating stack or deallocating.
-  SmallPtrSet<SILInstruction *, 16> ToDelete;
-  bool HasNonRemovableUses = false;
-  for (auto UI = AR->use_begin(), UE = AR->use_end(); UI != UE;) {
-    auto *Op = *UI;
-    ++UI;
-    auto *User = Op->getUser();
-    if (!isa<DeallocRefInst>(User) && !isa<SetDeallocatingInst>(User) &&
-        !isa<FixLifetimeInst>(User) && !isa<DeallocStackRefInst>(User)) {
-      HasNonRemovableUses = true;
-      break;
-    }
-    ToDelete.insert(User);
-  }
-
-  if (HasNonRemovableUses)
-    return nullptr;
-
-  // Remove the instruction and all its uses.
-  for (auto *I : ToDelete)
-    eraseInstFromFunction(*I);
-  eraseInstFromFunction(*AR);
-  return nullptr;
-}
-
 /// Returns the base address if \p val is an index_addr with constant index.
 static SILValue isConstIndexAddr(SILValue val, unsigned &index) {
   auto *IA = dyn_cast<IndexAddrInst>(val);
diff --git a/test/SILOptimizer/sil_combine.sil b/test/SILOptimizer/sil_combine.sil
@@ -2617,20 +2617,6 @@ bb0(%0 : $*B):
   return %2 : $()
 }
 
-// CHECK-LABEL: sil @delete_dead_alloc_ref
-// CHECK: bb0
-// CHECK-NEXT: tuple
-// CHECK-NEXT: return
-sil @delete_dead_alloc_ref : $() -> () {
-bb0:
-  %1 = alloc_ref $B
-  set_deallocating %1 : $B
-  fix_lifetime %1 : $B
-  dealloc_ref %1 : $B
-  %2 = tuple()
-  return %2 : $()
-}
-
 // CHECK-LABEL: sil @delete_dead_alloc_stack2
 // CHECK: bb0
 // CHECK-NEXT: destroy_addr %0
@@ -3521,31 +3507,6 @@ bb0:
 }
 
 
-// CHECK-LABEL: sil @remove_unused_alloc_ref
-// CHECK-NEXT: bb0
-// CHECK-NEXT: %0 = tuple ()
-// CHECK-NEXT: return %0 : $()
-sil @remove_unused_alloc_ref : $@convention(thin) () -> () {
-bb0:
-  %1 = alloc_ref $B
-  dealloc_ref %1 : $B
-  %3 = tuple ()
-  return %3 : $()
-}
-
-// CHECK-LABEL: sil @remove_unused_alloc_ref_stack
-// CHECK-NEXT: bb0
-// CHECK-NEXT: %0 = tuple ()
-// CHECK-NEXT: return %0 : $()
-sil @remove_unused_alloc_ref_stack : $@convention(thin) () -> () {
-bb0:
-  %1 = alloc_ref [stack] $B
-  set_deallocating %1 : $B
-  dealloc_stack_ref %1 : $B
-  %3 = tuple ()
-  return %3 : $()
-}
-
 // Int1_const == x -> x == Int1_const
 // CHECK-LABEL: sil @canonicalize_bool_eq_checks
 sil @canonicalize_bool_eq_checks : $@convention(thin) (Builtin.Int1) -> Builtin.Int1 {
diff --git a/test/SILOptimizer/sil_combine_misc_opts.sil b/test/SILOptimizer/sil_combine_misc_opts.sil
@@ -61,94 +61,6 @@ bb0(%0 : $Klass):
   return %9999 : $()
 }
 
-// Unused alloc-ref elim
-
-// CHECK-LABEL: sil @remove_unused_alloc_ref :
-// CHECK-NOT: alloc_ref
-// CHECK-NOT: dealloc_ref
-// CHECK: } // end sil function 'remove_unused_alloc_ref'
-sil @remove_unused_alloc_ref : $@convention(thin) () -> () {
-bb0:
-  %1 = alloc_ref $Klass
-  dealloc_ref %1 : $Klass
-  %3 = tuple ()
-  return %3 : $()
-}
-
-// CHECK-LABEL: sil [ossa] @remove_unused_alloc_ref_ossa :
-// CHECK-NOT: alloc_ref
-// CHECK-NOT: dealloc_ref
-// CHECK: } // end sil function 'remove_unused_alloc_ref_ossa'
-sil [ossa] @remove_unused_alloc_ref_ossa : $@convention(thin) () -> () {
-bb0:
-  %1 = alloc_ref $Klass
-  dealloc_ref %1 : $Klass
-  %3 = tuple ()
-  return %3 : $()
-}
-
-// CHECK-LABEL: sil @remove_unused_alloc_ref_stack :
-// CHECK-NOT: alloc_ref
-// CHECK-NOT: set_deallocating
-// CHECK-NOT: dealloc_ref
-// CHECK: } // end sil function 'remove_unused_alloc_ref_stack'
-sil @remove_unused_alloc_ref_stack : $@convention(thin) () -> () {
-bb0:
-  %1 = alloc_ref [stack] $Klass
-  set_deallocating %1 : $Klass
-  dealloc_stack_ref %1 : $Klass
-  %3 = tuple ()
-  return %3 : $()
-}
-
-// CHECK-LABEL: sil [ossa] @remove_unused_alloc_ref_stack_ossa :
-// CHECK-NOT: alloc_ref
-// CHECK-NOT: set_deallocating
-// CHECK-NOT: dealloc_ref
-// CHECK: } // end sil function 'remove_unused_alloc_ref_stack_ossa'
-sil [ossa] @remove_unused_alloc_ref_stack_ossa : $@convention(thin) () -> () {
-bb0:
-  %1 = alloc_ref [stack] $Klass
-  set_deallocating %1 : $Klass
-  dealloc_ref %1 : $Klass
-  dealloc_stack_ref %1 : $Klass
-  %3 = tuple ()
-  return %3 : $()
-}
-
-// CHECK-LABEL: sil @remove_unused_alloc_ref_fixlifetime :
-// CHECK-NOT: alloc_ref
-// CHECK-NOT: set_deallocating
-// CHECK-NOT: dealloc_ref
-// CHECK-NOT: fix_lifetime
-// CHECK: } // end sil function 'remove_unused_alloc_ref_fixlifetime'
-sil @remove_unused_alloc_ref_fixlifetime : $@convention(thin) () -> () {
-bb0:
-  %1 = alloc_ref [stack] $Klass
-  set_deallocating %1 : $Klass
-  fix_lifetime %1 : $Klass
-  dealloc_stack_ref %1 : $Klass
-  %3 = tuple ()
-  return %3 : $()
-}
-
-// CHECK-LABEL: sil [ossa] @remove_unused_alloc_ref_fixlifetime_ossa :
-// CHECK-NOT: alloc_ref
-// CHECK-NOT: set_deallocating
-// CHECK-NOT: dealloc_ref
-// CHECK-NOT: fix_lifetime
-// CHECK: } // end sil function 'remove_unused_alloc_ref_fixlifetime_ossa'
-sil [ossa] @remove_unused_alloc_ref_fixlifetime_ossa : $@convention(thin) () -> () {
-bb0:
-  %1 = alloc_ref [stack] $Klass
-  set_deallocating %1 : $Klass
-  fix_lifetime %1 : $Klass
-  dealloc_ref %1 : $Klass
-  dealloc_stack_ref %1 : $Klass
-  %3 = tuple ()
-  return %3 : $()
-}
-
 // We should have a single load [copy] here.
 //
 // CHECK-LABEL: sil [ossa] @remove_loadcopy_with_only_destroy_users : $@convention(thin) (@in_guaranteed Builtin.NativeObject) -> () {
diff --git a/test/SILOptimizer/sil_combine_ossa.sil b/test/SILOptimizer/sil_combine_ossa.sil
@@ -3194,21 +3194,6 @@ bb0(%0 : $*B):
   return %2 : $()
 }
 
-// CHECK-LABEL: sil [ossa] @delete_dead_alloc_ref :
-// CHECK: bb0
-// CHECK-NEXT: tuple
-// CHECK-NEXT: return
-// CHECK: } // end sil function 'delete_dead_alloc_ref'
-sil [ossa] @delete_dead_alloc_ref : $() -> () {
-bb0:
-  %1 = alloc_ref $B
-  set_deallocating %1 : $B
-  fix_lifetime %1 : $B
-  dealloc_ref %1 : $B
-  %2 = tuple()
-  return %2 : $()
-}
-
 // CHECK-LABEL: sil [ossa] @delete_dead_alloc_stack2
 // XHECK: bb0
 // XHECK-NEXT: destroy_addr %0
@@ -4044,33 +4029,6 @@ bb0:
   return %9 : $AnyObject
 }
 
-
-// CHECK-LABEL: sil [ossa] @remove_unused_alloc_ref
-// CHECK-NEXT: bb0
-// CHECK-NEXT: %0 = tuple ()
-// CHECK-NEXT: return %0 : $()
-sil [ossa] @remove_unused_alloc_ref : $@convention(thin) () -> () {
-bb0:
-  %1 = alloc_ref $B
-  dealloc_ref %1 : $B
-  %3 = tuple ()
-  return %3 : $()
-}
-
-// CHECK-LABEL: sil [ossa] @remove_unused_alloc_ref_stack
-// CHECK-NEXT: bb0
-// CHECK-NEXT: %0 = tuple ()
-// CHECK-NEXT: return %0 : $()
-sil [ossa] @remove_unused_alloc_ref_stack : $@convention(thin) () -> () {
-bb0:
-  %1 = alloc_ref [stack] $B
-  set_deallocating %1 : $B
-  dealloc_ref %1 : $B
-  dealloc_stack_ref %1 : $B
-  %3 = tuple ()
-  return %3 : $()
-}
-
 // Int1_const == x -> x == Int1_const
 // CHECK-LABEL: sil [ossa] @canonicalize_bool_eq_checks :
 // CHECK: builtin "cmp_eq_Int1"(%0 : $Builtin.Int1, %1 :
