51a895aded
Introduce llvm::CmpPredicate, an abstraction over a floating-point predicate, and a pack of an integer predicate with samesign information, in order to ease extending large portions of the codebase that take a CmpInst::Predicate to respect the samesign flag. We have chosen to demonstrate the utility of this new abstraction by migrating parts of ValueTracking, InstructionSimplify, and InstCombine from CmpInst::Predicate to llvm::CmpPredicate. There should be no functional changes, as we don't perform any extra optimizations with samesign in this patch, or use CmpPredicate::getMatching. The design approach taken by this patch allows for unaudited callers of APIs that take a llvm::CmpPredicate to silently drop the samesign information; it does not pose a correctness issue, and allows us to migrate the codebase piece-wise.
63 lines
2.3 KiB
C++
63 lines
2.3 KiB
C++
//===- CmpPredicate.h - CmpInst Predicate with samesign information -------===//
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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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// A CmpInst::Predicate with any samesign information (applicable to ICmpInst).
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_IR_CMPPREDICATE_H
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#define LLVM_IR_CMPPREDICATE_H
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#include "llvm/IR/InstrTypes.h"
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namespace llvm {
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/// An abstraction over a floating-point predicate, and a pack of an integer
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/// predicate with samesign information. Some functions in ICmpInst construct
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/// and return this type in place of a Predicate.
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class CmpPredicate {
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CmpInst::Predicate Pred;
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bool HasSameSign;
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public:
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/// Constructed implictly with a either Predicate and samesign information, or
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/// just a Predicate, dropping samesign information.
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CmpPredicate(CmpInst::Predicate Pred, bool HasSameSign = false)
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: Pred(Pred), HasSameSign(HasSameSign) {
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assert(!HasSameSign || CmpInst::isIntPredicate(Pred));
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}
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/// Implictly converts to the underlying Predicate, dropping samesign
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/// information.
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operator CmpInst::Predicate() const { return Pred; }
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/// Query samesign information, for optimizations.
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bool hasSameSign() const { return HasSameSign; }
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/// Compares two CmpPredicates taking samesign into account and returns the
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/// canonicalized CmpPredicate if they match. An alternative to operator==.
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///
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/// For example,
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/// samesign ult + samesign ult -> samesign ult
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/// samesign ult + ult -> ult
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/// samesign ult + slt -> slt
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/// ult + ult -> ult
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/// ult + slt -> std::nullopt
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static std::optional<CmpPredicate> getMatching(CmpPredicate A,
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CmpPredicate B);
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/// An operator== on the underlying Predicate.
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bool operator==(CmpInst::Predicate P) const { return Pred == P; }
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/// There is no operator== defined on CmpPredicate. Use getMatching instead to
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/// get the canonicalized matching CmpPredicate.
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bool operator==(CmpPredicate) const = delete;
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};
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} // namespace llvm
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#endif
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