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