AliasAnalysis: workaround a bug in the move-only checker

This is a workaround for a bug in the move-only checker: rdar://151841926.
The move-only checker sometimes inserts destroy_addr within read-only static access scopes.
Therefore don't consider static access scopes as immutable scopes.

Author: eeckstein

SwiftCompilerSources/Sources/Optimizer/Analysis/AliasAnalysis.swift

@@ -622,6 +622,14 @@ private enum ImmutableScope {
       if beginAccess.isUnsafe {
         return nil
       }
+
+      // This is a workaround for a bug in the move-only checker: rdar://151841926.
+      // The move-only checker sometimes inserts destroy_addr within read-only static access scopes.
+      // TODO: remove this once the bug is fixed.
+      if beginAccess.isStatic {
+        return nil
+      }
+
       switch beginAccess.accessKind {
       case .read:
         self = .readAccess(beginAccess)

test/SILOptimizer/licm_exclusivity.sil

@@ -153,10 +153,12 @@ bb2:
 // CHECK-LABEL: sil @hoist_access_static : $@convention(thin) () -> () {
 // CHECK: [[GLOBAL:%.*]] = global_addr @globalX : $*X
 // CHECK: [[BEGIN:%.*]] = begin_access [read] [static] [[GLOBAL]] : $*X
-// CHECK-NEXT: load
-// CHECK-NEXT: br bb1
+
+// Currently disabled because of a workaround in AliasAnalysis: rdar://151841926
+// xCHECK-NEXT: load
+// xCHECK-NEXT: br bb1
 // CHECK: apply
-// CHECK-NEXT: cond_br
+// xCHECK-NEXT: cond_br
 // CHECK: bb2
 // CHECK: end_access [[BEGIN]]
 // CHECK-LABEL: } // end sil function 'hoist_access_static'