Fix silcombine of inject_enum_addr when we have an empty struct with unreferenceable storage

Author: meg-gupta

lib/SILOptimizer/SILCombiner/SILCombinerMiscVisitors.cpp

@@ -1240,6 +1240,16 @@ SILCombiner::visitInjectEnumAddrInst(InjectEnumAddrInst *IEAI) {
     return nullptr;
   }
 
+  SILType elemType = IEAI->getOperand()->getType().getEnumElementType(
+      IEAI->getElement(), IEAI->getFunction());
+  auto *structDecl = elemType.getStructOrBoundGenericStruct();
+
+  // We cannot create a struct when it has unreferenceable storage.
+  if (elemType.isEmpty(*IEAI->getFunction()) && structDecl &&
+      structDecl->hasUnreferenceableStorage()) {
+    return nullptr;
+  }
+
   // Localize the address access.
   Builder.setInsertionPoint(AI);
   auto *AllocStack = Builder.createAllocStack(DataAddrInst->getLoc(),
@@ -1250,8 +1260,6 @@ SILCombiner::visitInjectEnumAddrInst(InjectEnumAddrInst *IEAI) {
 
   // If it is an empty type, apply may not initialize it.
   // Create an empty value of the empty type and store it to a new local.
-  SILType elemType = IEAI->getOperand()->getType().getEnumElementType(
-      IEAI->getElement(), IEAI->getFunction());
   if (elemType.isEmpty(*IEAI->getFunction())) {
     enumValue = createEmptyAndUndefValue(
         elemType.getObjectType(), &*Builder.getInsertionPoint(),

test/Inputs/clang-importer-sdk/usr/include/ctypes.h

@@ -295,6 +295,8 @@ struct StructWithBitfields {
   unsigned : 11;
 };
 
+union EmptyCUnion {};
+
 typedef struct ModRM {
   unsigned rm: 3;
   unsigned reg: 3;

test/SILOptimizer/sil_combine_enum_addr.sil

@@ -3,14 +3,15 @@
 // RUN:   -emit-module-path=%t/resilient_struct.swiftmodule \
 // RUN:   -module-name=resilient_struct %S/../Inputs/resilient_struct.swift
 
-// RUN: %target-sil-opt -enable-sil-verify-all %s -sil-combine -jumpthread-simplify-cfg -I %t | %FileCheck %s
+// RUN: %target-sil-opt -sdk %clang-importer-sdk-path -enable-sil-verify-all %s -sil-combine -jumpthread-simplify-cfg -I %t | %FileCheck %s
 
 sil_stage canonical
 
 import Builtin
 import Swift
 
 import resilient_struct
+import ctypes
 
 // CHECK-LABEL: sil  @convert_inject_enum_addr_select_enum_addr_into_cond_br : $@convention(thin) (@in Int, @inout _Stdout) -> ()
 // CHECK-NOT: init_existential_addr
@@ -47,7 +48,6 @@ bb2:
   br bb1
 }
 
-
 // CHECK-LABEL: sil  @convert_inject_enum_addr_switch_enum_addr_into_cond_br : $@convention(thin) (@in Int, @inout _Stdout) -> ()
 // CHECK-NOT: init_existential_addr
 // CHECK-NOT: inject_enum_addr
@@ -122,7 +122,6 @@ bb22:
   br bb2
 }
 
-
 class A {
 
 }
@@ -314,10 +313,10 @@ bb3:
 
 sil @no_init_struct : $@convention(thin) () -> (@out ResilientEmptyStruct)
 
-// CHECK-LABEL: sil @test_empty_struct_uninintialized : $@convention(thin) () -> () {
+// CHECK-LABEL: sil @test_empty_struct_uninitialized : $@convention(thin) () -> () {
 // CHECK-NOT: switch_enum_addr
-// CHECK-LABEL: } // end sil function 'test_empty_struct_uninintialized'
-sil @test_empty_struct_uninintialized : $@convention(thin) () -> () {
+// CHECK-LABEL: } // end sil function 'test_empty_struct_uninitialized'
+sil @test_empty_struct_uninitialized : $@convention(thin) () -> () {
 bb0:
   %0 = alloc_stack $Optional<ResilientEmptyStruct>
   %1 = init_enum_data_addr %0 : $*Optional<ResilientEmptyStruct>, #Optional.some!enumelt
@@ -337,3 +336,29 @@ bb3:
   %8 = tuple ()
   return %8 : $()
 }
+
+sil @no_init_c_union : $@convention(thin) () -> (@out EmptyCUnion)
+
+// CHECK-LABEL: sil @test_empty_c_union : $@convention(thin) () -> () {
+// CHECK: inject_enum_addr
+// CHECK-LABEL: } // end sil function 'test_empty_c_union'
+sil @test_empty_c_union : $@convention(thin) () -> () {
+bb0:
+  %0 = alloc_stack $Optional<EmptyCUnion>
+  %1 = init_enum_data_addr %0 : $*Optional<EmptyCUnion>, #Optional.some!enumelt
+  %f = function_ref @no_init_c_union : $@convention(thin) () -> (@out EmptyCUnion)
+  apply %f(%1) : $@convention(thin) () -> (@out EmptyCUnion)
+  inject_enum_addr %0 : $*Optional<EmptyCUnion>, #Optional.some!enumelt
+  switch_enum_addr %0 : $*Optional<EmptyCUnion>, case #Optional.some!enumelt: bb1, case #Optional.none!enumelt: bb2
+
+bb1:
+  br bb3
+
+bb2:
+  br bb3
+
+bb3:
+  dealloc_stack %0 : $*Optional<EmptyCUnion>
+  %8 = tuple ()
+  return %8 : $()
+}