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The `assume` attribute is a way to provide additional, arbitrary information to the optimizer. For now, assumptions are restricted to strings which will be accumulated for a function and emitted as comma separated string function attribute. The key of the LLVM-IR function attribute is `llvm.assume`. Similar to `llvm.assume` and `__builtin_assume`, the `assume` attribute provides a user defined assumption to the compiler. A follow up patch will introduce an LLVM-core API to query the assumptions attached to a function. We also expect to add more options, e.g., expression arguments, to the `assume` attribute later on. The `omp [begin] asssumes` pragma will leverage this attribute and expose the functionality in the absence of OpenMP. Reviewed By: aaron.ballman Differential Revision: https://reviews.llvm.org/D91979
51 lines
1.6 KiB
C++
51 lines
1.6 KiB
C++
//===--- Assumptions.h - Assumption handling and organization ---*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// String assumptions that are known to optimization passes should be placed in
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// the KnownAssumptionStrings set. This can be done in various ways, i.a.,
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// via a static KnownAssumptionString object.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_IR_ASSUMPTIONS_H
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#define LLVM_IR_ASSUMPTIONS_H
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#include "llvm/ADT/StringRef.h"
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#include "llvm/ADT/StringSet.h"
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namespace llvm {
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class Function;
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/// The key we use for assumption attributes.
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constexpr StringRef AssumptionAttrKey = "llvm.assume";
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/// A set of known assumption strings that are accepted without warning and
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/// which can be recommended as typo correction.
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extern StringSet<> KnownAssumptionStrings;
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/// Helper that allows to insert a new assumption string in the known assumption
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/// set by creating a (static) object.
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struct KnownAssumptionString {
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KnownAssumptionString(StringRef AssumptionStr)
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: AssumptionStr(AssumptionStr) {
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KnownAssumptionStrings.insert(AssumptionStr);
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}
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operator StringRef() const { return AssumptionStr; }
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private:
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StringRef AssumptionStr;
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};
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/// Return true if \p F has the assumption \p AssumptionStr attached.
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bool hasAssumption(Function &F, const KnownAssumptionString &AssumptionStr);
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} // namespace llvm
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#endif
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