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/*
* Copyright (C) 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef ART_COMPILER_OPTIMIZING_ESCAPE_H_
#define ART_COMPILER_OPTIMIZING_ESCAPE_H_
namespace art {
class HInstruction;
/*
* Methods related to escape analysis, i.e. determining whether an object
* allocation is visible outside ('escapes') its immediate method context.
*/
/*
* Performs escape analysis on the given instruction, typically a reference to an
* allocation. The method assigns true to parameter 'is_singleton' if the reference
* is the only name that can refer to its value during the lifetime of the method,
* meaning that the reference is not aliased with something else, is not stored to
* heap memory, and not passed to another method. In addition, the method assigns
* true to parameter 'is_singleton_and_not_returned' if the reference is a singleton
* and not returned to the caller and to parameter 'is_singleton_and_not_deopt_visible'
* if the reference is a singleton and not used as an environment local of an
* HDeoptimize instruction (clients of the final value must run after BCE to ensure
* all such instructions have been introduced already).
*
* Note that being visible to a HDeoptimize instruction does not count for ordinary
* escape analysis, since switching between compiled code and interpreted code keeps
* non escaping references restricted to the lifetime of the method and the thread
* executing it. This property only concerns optimizations that are interested in
* escape analysis with respect to the *compiled* code (such as LSE).
*
* When set, the no_escape function is applied to any use of the allocation instruction
* prior to any built-in escape analysis. This allows clients to define better escape
* analysis in certain case-specific circumstances. If 'no_escape(reference, user)'
* returns true, the user is assumed *not* to cause any escape right away. The return
* value false means the client cannot provide a definite answer and built-in escape
* analysis is applied to the user instead.
*/
void CalculateEscape(HInstruction* reference,
bool (*no_escape)(HInstruction*, HInstruction*),
/*out*/ bool* is_singleton,
/*out*/ bool* is_singleton_and_not_returned,
/*out*/ bool* is_singleton_and_not_deopt_visible);
/*
* Convenience method for testing the singleton and not returned properties at once.
* Callers should be aware that this method invokes the full analysis at each call.
*/
bool DoesNotEscape(HInstruction* reference, bool (*no_escape)(HInstruction*, HInstruction*));
} // namespace art
#endif // ART_COMPILER_OPTIMIZING_ESCAPE_H_
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