RedundantLoadElimination: don't crash when loading a non-trivial enum which was stored as trivial non-payload case.

rdar://114648847

Author: eeckstein

SwiftCompilerSources/Sources/Optimizer/FunctionPasses/RedundantLoadElimination.swift

@@ -307,10 +307,15 @@ private func shrinkMemoryLifetime(from load: LoadInst, to availableValue: Availa
     case .assign:
       builder.createDestroyAddr(address: availableStore.destination)
       context.erase(instruction: availableStore)
-    case .initialize:
+    case .initialize,
+         // It can be the case that e non-payload case is stored as trivial enum and the enum is loaded as [take], e.g.
+         //   %1 = enum $Optional<Class>, #Optional.none
+         //   store %1 to [trivial] %addr : $*Optional<Class>
+         //   %2 = load [take] %addr : $*Optional<Class>
+         .trivial:
       context.erase(instruction: availableStore)
-    case .trivial, .unqualified:
-      fatalError("store ownership doesn't fit a later load [take]")
+    case .unqualified:
+      fatalError("unqualified store in ossa function?")
     }
     return valueToAdd
   }

test/SILOptimizer/redundant_load_elim_ossa.sil

@@ -1446,3 +1446,19 @@ bb0(%0 : $Builtin.RawPointer, %1 : $A2):
   %30 = tuple(%3 : $A, %20 : $A)
   return %30 : $(A, A)
 }
+
+// CHECK-LABEL: sil [ossa] @store_trivial_load_non_trivial_enum
+// CHECK:         %0 = enum $Optional<B>, #Optional.none!enumelt
+// CHECK-NOT:     store 
+// CHECK-NOT:     load 
+// CHECK:         return %0
+// CHECK-LABEL: } // end sil function 'store_trivial_load_non_trivial_enum'
+sil [ossa] @store_trivial_load_non_trivial_enum : $@convention(thin) () -> @owned Optional<B> {
+bb0:
+  %0 = enum $Optional<B>, #Optional.none!enumelt
+  %1 = alloc_stack $Optional<B>
+  store %0 to [trivial] %1 : $*Optional<B>
+  %3 = load [take] %1 : $*Optional<B>
+  dealloc_stack %1 : $*Optional<B>
+  return %3 : $Optional<B>
+}