RawSILInstLowering: Don't insert an access scope for assign_or_init if there is already one.

This avoids inserting a dynamic access check when the parent is static (and therefore can be statically enforced).

Author: eeckstein

lib/SILOptimizer/Mandatory/RawSILInstLowering.cpp

@@ -290,13 +290,20 @@ lowerAssignOrInitInstruction(SILBuilderWithScope &b,
       auto isRefSelf = selfValue->getType().getASTType()->mayHaveSuperclass();
 
       SILValue selfRef;
+      bool needInsertEndAccess = false;
       if (isRefSelf) {
         selfRef = b.emitBeginBorrowOperation(loc, selfValue);
+      } else if (isa<BeginAccessInst>(selfValue)) {
+        // Don't insert an access scope if there is already one. This avoids
+        // inserting a dynamic access check when the parent is static (and therefore
+        // can be statically enforced).
+        selfRef = selfValue;
       } else {
         selfRef = b.createBeginAccess(loc, selfValue, SILAccessKind::Modify,
                                       SILAccessEnforcement::Dynamic,
                                       /*noNestedConflict=*/false,
                                       /*fromBuiltin=*/false);
+        needInsertEndAccess = true;
       }
 
       auto emitFieldReference = [&](VarDecl *field,
@@ -341,7 +348,7 @@ lowerAssignOrInitInstruction(SILBuilderWithScope &b,
       if (isRefSelf) {
         if (selfRef != selfValue)
           b.emitEndBorrowOperation(loc, selfRef);
-      } else {
+      } else if (needInsertEndAccess) {
         b.createEndAccess(loc, selfRef, /*aborted=*/false);
       }
 

test/SILOptimizer/init_accessors.sil

@@ -39,9 +39,9 @@ bb0(%0 : $Int, %1 : $*Test):
 }
 
 // CHECK-LABEL: sil hidden [ossa] @$s14init_accessors4TestV1vACSi_tcfC : $@convention(method) (Int, @thin Test.Type) -> Test
+// CHECK: [[SELF_REF:%.*]] = begin_access [modify] [unknown] [[SELF:%.*]] : $*Test
 // CHECK: [[INIT_REF:%.*]] = function_ref @$s14init_accessors4TestV1xSivi : $@convention(thin) (Int) -> @out Int
-// CHECK: [[SELF_REF:%.*]] = begin_access [modify] [dynamic] [[SELF:%.*]] : $*Test
-// CHECK-NEXT: [[FIELD_REF:%.*]] = struct_element_addr [[SELF_REF]] : $*Test, #Test._x
+// CHECK: [[FIELD_REF:%.*]] = struct_element_addr [[SELF_REF]] : $*Test, #Test._x
 // CHECK-NEXT: {{.*}} = apply [[INIT_REF]]([[FIELD_REF]], %0) : $@convention(thin) (Int) -> @out Int
 sil hidden [ossa] @$s14init_accessors4TestV1vACSi_tcfC : $@convention(method) (Int, @thin Test.Type) -> Test {
 bb0(%0 : $Int, %1 : $@thin Test.Type):

test/SILOptimizer/init_accessors.swift

@@ -41,10 +41,11 @@ struct TestInit {
   }
 
   // CHECK-LABEL: sil hidden [ossa] @$s14init_accessors8TestInitV1x1yACSi_SitcfC : $@convention(method) (Int, Int, @thin TestInit.Type) -> TestInit
+  // CHECK: end_access
+  // CHECK: [[SELF_VALUE:%.*]] = begin_access [modify] [static] {{.*}} : $*TestInit
   // CHECK: // function_ref TestInit.point.init
   // CHECK-NEXT: [[INIT_ACCESSOR_FN:%.*]] = function_ref @$s14init_accessors8TestInitV5pointSi_Sitvi : $@convention(thin) (Int, Int, @inout Int, @thin TestInit.Type) -> (@out Int, @out (Int, Int))
   // CHECK-NEXT: [[INIT_ACCESSOR:%.*]] = partial_apply [callee_guaranteed] [on_stack] [[INIT_ACCESSOR_FN]](%2) : $@convention(thin) (Int, Int, @inout Int, @thin TestInit.Type) -> (@out Int, @out (Int, Int))
-  // CHECK: [[SELF_VALUE:%.*]] = begin_access [modify] [dynamic] {{.*}} : $*TestInit
   // CHECK: [[Y_REF:%.*]] = struct_element_addr [[SELF_VALUE]] : $*TestInit, #TestInit.y
   // CHECK-NEXT: [[FULL_REF:%.*]] = struct_element_addr [[SELF_VALUE]] : $*TestInit, #TestInit.full
   // CHECK-NEXT: ([[X_VAL:%.*]], [[Y_VAL:%.*]]) = destructure_tuple {{.*}} : $(Int, Int)
@@ -71,10 +72,13 @@ struct TestSetter {
   }
 
   // CHECK-LABEL: sil hidden [ossa] @$s14init_accessors10TestSetterV1x1yACSi_SitcfC : $@convention(method) (Int, Int, @thin TestSetter.Type) -> TestSetter
+  // CHECK: [[AS:%.*]] = alloc_stack
+  // CHECK: end_access
+  // CHECK: end_access
+  // CHECK: [[SELF:%.*]] = begin_access [modify] [static] [[AS]] : $*TestSetter
   // CHECK: [[INIT_ACCESSOR_FN:%.*]] = function_ref @$s14init_accessors10TestSetterV5pointSi_Sitvi : $@convention(thin) (Int, Int, @inout Int, @inout Int, @thin TestSetter.Type) -> ()
   // CHECK: [[INIT_ACCESSOR:%.*]] = partial_apply [callee_guaranteed] [on_stack] [[INIT_ACCESSOR_FN]](%2) : $@convention(thin) (Int, Int, @inout Int, @inout Int, @thin TestSetter.Type) -> ()
-  // CHECK: [[SELF:%.*]] = begin_access [modify] [dynamic] %14 : $*TestSetter
-  // CHECK-NEXT: ([[X:%.*]], [[Y:%.*]]) = destructure_tuple {{.*}} : $(Int, Int)
+  // CHECK:      ([[X:%.*]], [[Y:%.*]]) = destructure_tuple {{.*}} : $(Int, Int)
   // CHECK-NEXT: [[X_REF:%.*]] = struct_element_addr [[SELF]] : $*TestSetter, #TestSetter.x
   // CHECK-NEXT: [[Y_REF:%.*]] = struct_element_addr [[SELF]] : $*TestSetter, #TestSetter.y
   // CHECK-NEXT: {{.*}} = apply [[INIT_ACCESSOR]]([[X]], [[Y]], [[X_REF]], [[Y_REF]]) : $@noescape @callee_guaranteed (Int, Int, @inout Int, @inout Int) -> ()
@@ -204,17 +208,18 @@ struct TestNoInitAndInit {
 
   // CHECK-LABEL: sil hidden [ossa] @$s14init_accessors013TestNoInitAndE0V1x1yACSi_SitcfC : $@convention(method) (Int, Int, @thin TestNoInitAndInit.Type) -> TestNoInitAndInit
   //
+  // CHECK: end_access
+  // CHECK: [[SELF_REF:%.*]] = begin_access [modify] [static] {{.*}} : $*TestNoInitAndInit
   // CHECK: [[INIT_REF_FN:%.*]] = function_ref @$s14init_accessors013TestNoInitAndE0V6pointXSivi : $@convention(thin) (Int, @inout Int, @thin TestNoInitAndInit.Type) -> ()
   // CHECK: [[INIT_REF:%.*]] = partial_apply [callee_guaranteed] [on_stack] [[INIT_REF_FN]](%2) : $@convention(thin) (Int, @inout Int, @thin TestNoInitAndInit.Type) -> ()
-  // CHECK: [[SELF_REF:%.*]] = begin_access [modify] [dynamic] {{.*}} : $*TestNoInitAndInit
-  // CHECK-NEXT: [[X_REF:%.*]] = struct_element_addr [[SELF_REF]] : $*TestNoInitAndInit, #TestNoInitAndInit.x
+  // CHECK:      [[X_REF:%.*]] = struct_element_addr [[SELF_REF]] : $*TestNoInitAndInit, #TestNoInitAndInit.x
   // CHECK-NEXT: {{.*}} = apply [[INIT_REF]](%0, [[X_REF]]) : $@noescape @callee_guaranteed (Int, @inout Int) -> ()
   // CHECK-NEXT: end_access [[SELF_REF]] : $*TestNoInitAndInit
   //
+  // CHECK: [[SELF_REF:%.*]] = begin_access [modify] [static] {{.*}} : $*TestNoInitAndInit
   // CHECK: [[INIT_REF_FN:%.*]] = function_ref @$s14init_accessors013TestNoInitAndE0V6pointYSivi : $@convention(thin) (Int, @thin TestNoInitAndInit.Type) -> @out Int
   // CHECK: [[INIT_REF:%.*]] = partial_apply [callee_guaranteed] [on_stack] [[INIT_REF_FN]](%2) : $@convention(thin) (Int, @thin TestNoInitAndInit.Type) -> @out Int
-  // CHECK: [[SELF_REF:%.*]] = begin_access [modify] [dynamic] {{.*}} : $*TestNoInitAndInit
-  // CHECK-NEXT: [[Y_REF:%.*]] = struct_element_addr [[SELF_REF]] : $*TestNoInitAndInit, #TestNoInitAndInit.y
+  // CHECK:      [[Y_REF:%.*]] = struct_element_addr [[SELF_REF]] : $*TestNoInitAndInit, #TestNoInitAndInit.y
   // CHECK-NEXT: {{.*}} = apply [[INIT_REF]]([[Y_REF]], %1) : $@noescape @callee_guaranteed (Int) -> @out Int
   // CHECK-NEXT: end_access [[SELF_REF]] : $*TestNoInitAndInit
   init(x: Int, y: Int) {