[Exclusivity] Fix a bug wherein we miss detected a non conflicting in-scope access as conflicting

Author: Joe Shajrawi

lib/SILOptimizer/Transforms/AccessEnforcementOpts.cpp

@@ -637,7 +637,7 @@ void AccessConflictAndMergeAnalysis::visitBeginAccess(
 
       auto &outerAccessInfo = result.getAccessInfo(outerBeginAccess);
       // If there is no potential conflict, leave the outer access mapped.
-      if (!outerAccessInfo.isDistinctFrom(beginAccessInfo))
+      if (outerAccessInfo.isDistinctFrom(beginAccessInfo))
         continue;
 
       LLVM_DEBUG(beginAccessInfo.dump();

test/SILOptimizer/access_enforcement_opts.sil

@@ -1332,7 +1332,7 @@ class RefElemClass {
 // CHECK-NEXT: [[REFY:%.*]] = ref_element_addr %0 : $RefElemClass, #RefElemClass.y
 // CHECK-NEXT: [[BEGINX:%.*]] = begin_access [modify] [dynamic] [[REFX]] : $*BitfieldOne
 // CHECK: end_access [[BEGINX]] : $*BitfieldOne
-// CHECK: [[BEGINY:%.*]] = begin_access [modify] [dynamic] [no_nested_conflict] [[REFY]] : $*Int32
+// CHECK: [[BEGINY:%.*]] = begin_access [modify] [dynamic] [[REFY]] : $*Int32
 // CHECK: [[BEGINX2:%.*]] = begin_access [modify] [dynamic] [no_nested_conflict] [[REFX]] : $*BitfieldOne
 // CHECK-NEXT: end_access [[BEGINX2]] : $*BitfieldOne
 // CHECK-NEXT: end_access [[BEGINY]] : $*Int32
@@ -1358,6 +1358,34 @@ bb0(%0 : $RefElemClass):
   return %10 : $()
 }
 
+class RefElemNoConflictClass {
+  var x : Int32
+  var y : Int32
+  init()
+}
+
+// Checks that we can detect not having a nested conflict in class when we are accessing
+// fields that do no alias
+// CHECK-LABEL: sil @ref_elem_no_alias : $@convention(thin) (RefElemNoConflictClass) -> () {
+// CHECK: [[REFX:%.*]] = ref_element_addr %0 : $RefElemNoConflictClass, #RefElemNoConflictClass.x
+// CHECK-NEXT: [[REFY:%.*]] = ref_element_addr %0 : $RefElemNoConflictClass, #RefElemNoConflictClass.y
+// CHECK: [[BEGINY:%.*]] = begin_access [modify] [dynamic] [no_nested_conflict] [[REFY]] : $*Int32
+// CHECK: [[BEGINX:%.*]] = begin_access [modify] [dynamic] [no_nested_conflict] [[REFX]] : $*Int32
+// CHECK-NEXT: end_access [[BEGINX]] : $*Int32
+// CHECK-NEXT: end_access [[BEGINY]] : $*Int32
+// CHECK-LABEL: } // end sil function 'ref_elem_no_alias'
+sil @ref_elem_no_alias : $@convention(thin) (RefElemNoConflictClass) -> () {
+bb0(%0 : $RefElemNoConflictClass):
+  %x = ref_element_addr %0 : $RefElemNoConflictClass, #RefElemNoConflictClass.x
+  %y = ref_element_addr %0 : $RefElemNoConflictClass, #RefElemNoConflictClass.y
+  %b2 = begin_access [modify] [dynamic] %y : $*Int32
+  %b3 = begin_access [modify] [dynamic] %x : $*Int32
+  end_access %b3 : $*Int32
+  end_access %b2 : $*Int32
+  %10 = tuple ()
+  return %10 : $()
+}
+
 // public func testStronglyConnectedComponent() {
 // During the merge optimization,
 // Check that we don't merge cross strongly component boundaries for now