stdlib: loadUnaligned doesn't need stack protection for it's temporary

rdar://105231457

Author: eeckstein

stdlib/public/core/UnsafeRawPointer.swift

@@ -463,7 +463,7 @@ public struct UnsafeRawPointer: _Pointer {
     as type: T.Type
   ) -> T {
     _debugPrecondition(_isPOD(T.self))
-    return withUnsafeTemporaryAllocation(of: T.self, capacity: 1) {
+    return _withUnprotectedUnsafeTemporaryAllocation(of: T.self, capacity: 1) {
       let temporary = $0.baseAddress._unsafelyUnwrappedUnchecked
       Builtin.int_memcpy_RawPointer_RawPointer_Int64(
         temporary._rawValue,
@@ -1245,7 +1245,7 @@ public struct UnsafeMutableRawPointer: _Pointer {
     as type: T.Type
   ) -> T {
     _debugPrecondition(_isPOD(T.self))
-    return withUnsafeTemporaryAllocation(of: T.self, capacity: 1) {
+    return _withUnprotectedUnsafeTemporaryAllocation(of: T.self, capacity: 1) {
       let temporary = $0.baseAddress._unsafelyUnwrappedUnchecked
       Builtin.int_memcpy_RawPointer_RawPointer_Int64(
         temporary._rawValue,

test/SILOptimizer/stack_protection.sil

@@ -136,17 +136,31 @@ bb0:
   return %4 : $Int64
 }
 
-// CHECK-LABEL: sil [stack_protection] @stack_alloc_builtin_with_3_args
+// CHECK-LABEL: sil [stack_protection] @stack_alloc_builtin
 // CHECK-NOT:     copy_addr
-// CHECK:       } // end sil function 'stack_alloc_builtin_with_3_args'
-sil @stack_alloc_builtin_with_3_args : $@convention(thin) () -> () {
+// CHECK:       } // end sil function 'stack_alloc_builtin'
+sil @stack_alloc_builtin: $@convention(thin) () -> () {
 bb0:
   %0 = integer_literal $Builtin.Word, 8
   %1 = builtin "stackAlloc"(%0 : $Builtin.Word, %0 : $Builtin.Word, %0 : $Builtin.Word) : $Builtin.RawPointer
   %2 = builtin "stackDealloc"(%1 : $Builtin.RawPointer) : $()
   %r = tuple ()
   return %r : $()
 }
+
+// CHECK-LABEL: sil @unprotected_stack_alloc_builtin
+// CHECK-NOT:     copy_addr
+// CHECK:       } // end sil function 'unprotected_stack_alloc_builtin'
+sil @unprotected_stack_alloc_builtin: $@convention(thin) () -> () {
+bb0:
+  %0 = integer_literal $Builtin.Word, 8
+  %1 = integer_literal $Builtin.Int1, 0
+  %2 = builtin "unprotectedStackAlloc"(%0 : $Builtin.Word, %0 : $Builtin.Word, %0 : $Builtin.Word, %1 : $Builtin.Int1) : $Builtin.RawPointer
+  %3 = builtin "stackDealloc"(%2 : $Builtin.RawPointer) : $()
+  %r = tuple ()
+  return %r : $()
+}
+
 // CHECK-LABEL: sil [stack_protection] @function_local_stack_obj
 // CHECK-NOT:     copy_addr
 // CHECK:       } // end sil function 'function_local_stack_obj'

test/SILOptimizer/stack_protection.swift

@@ -111,3 +111,10 @@ public func testWithUnsafeTemporaryAllocation() {
   }
 }
 
+// CHECK-LABEL: sil @$s4test13loadUnalignedySiSVF
+// CHECK-NOT:     copy_addr
+// CHECK:       } // end sil function '$s4test13loadUnalignedySiSVF'
+public func loadUnaligned(_ urp: UnsafeRawPointer) -> Int {
+  return urp.loadUnaligned(as: Int.self)
+}
+