SimplifyGlobalValue: handle fix_lifetime instruction

Author: eeckstein

SwiftCompilerSources/Sources/Optimizer/InstructionPasses/SimplifyGlobalValue.swift

@@ -37,22 +37,20 @@ let simplifyGlobalValuePass = InstructionPass<GlobalValueInst>(
 private func checkUsers(of val: Value, users: inout Stack<Instruction>) -> Bool {
   for use in val.uses {
     let user = use.instruction
-    if user is RefCountingInst || user is DebugValueInst {
-      users.push(user)
-      continue
-    }
-    if let upCast = user as? UpcastInst {
-      if !checkUsers(of: upCast, users: &users) {
+    switch user {
+      case is RefCountingInst, is DebugValueInst, is FixLifetimeInst:
+        users.push(user)
+      case let upCast as UpcastInst:
+        if !checkUsers(of: upCast, users: &users) {
+          return false
+        }
+      case is RefElementAddrInst, is RefTailAddrInst:
+        // Projection instructions don't access the object header, so they don't
+        // prevent deleting reference counting instructions.
+        break
+      default:
         return false
-      }
-      continue
-    }
-    // Projection instructions don't access the object header, so they don't
-    // prevent deleting reference counting instructions.
-    if user is RefElementAddrInst || user is RefTailAddrInst {
-      continue
     }
-    return false
   }
   return true
 }

test/SILOptimizer/sil_combine_cow.sil renamed to test/SILOptimizer/sil_combine_inst_passes.sil

@@ -104,3 +104,26 @@ bb0:
   return %t : $(Builtin.Int1, Builtin.BridgeObject)
 }
 
+sil_global private @outlined_global : $_ContiguousArrayStorage<Int>
+
+// CHECK-LABEL: sil @remove_arc_of_global_value
+// CHECK-NOT:   retain
+// CHECK-NOT:   release
+// CHECK-NOT:   fix_lifetime
+// CHECK-NOT:   debug_value
+// CHECK:     } // end sil function 'remove_arc_of_global_value'
+sil @remove_arc_of_global_value : $@convention(thin) () -> Int {
+bb0:
+  %0 = global_value @outlined_global : $_ContiguousArrayStorage<Int>
+  strong_retain %0 : $_ContiguousArrayStorage<Int>
+  debug_value %0 : $_ContiguousArrayStorage<Int>, let, name "x"
+  %2 = upcast %0 : $_ContiguousArrayStorage<Int> to $__ContiguousArrayStorageBase
+  strong_retain %2 : $__ContiguousArrayStorageBase
+  %13 = ref_tail_addr [immutable] %2 : $__ContiguousArrayStorageBase, $Int
+  %16 = load %13 : $*Int
+  fix_lifetime %0 : $_ContiguousArrayStorage<Int>
+  strong_release %2 : $__ContiguousArrayStorageBase
+  strong_release %0 : $_ContiguousArrayStorage<Int>
+  return %16 : $Int
+}
+