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Implements a constant interpreter that can deal with basic integer operations. Summary of the features that it includes: * builtin integer values, and builtin integer insts * struct and tuple values, and insts that construct and extract them (necessary to use stdlib integers) * function referencing and application (necessary to call stdlib integer functions) * error handling data structures and logic, for telling you why your value is not evaluatable * metatype values (not necessary for integers, but it's only a few extra lines, so I thought it would be more trouble than it's worth to put them in a separate PR) * conditional branches (ditto)
89 lines
3.1 KiB
C++
89 lines
3.1 KiB
C++
//===--- ConstExpr.h - Constant expression evaluator -----------*- C++ -*-===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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//
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// This defines an interface to evaluate Swift language level constant
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// expressions. Its model is intended to be general and reasonably powerful,
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// with the goal of standardization in a future version of Swift.
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//
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// Constant expressions are functions without side effects that take constant
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// values and return constant values. These constants may be integer, and
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// floating point values. We allow abstractions to be built out of fragile
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// structs and tuples.
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//
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//===----------------------------------------------------------------------===//
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#ifndef SWIFT_SILOPTIMIZER_CONSTEXPR_H
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#define SWIFT_SILOPTIMIZER_CONSTEXPR_H
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#include "swift/Basic/LLVM.h"
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#include "swift/Basic/SourceLoc.h"
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#include "llvm/Support/Allocator.h"
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namespace swift {
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class ApplyInst;
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class ASTContext;
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class Operand;
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class SILInstruction;
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class SILModule;
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class SILNode;
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class SILValue;
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class SymbolicValue;
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enum class UnknownReason;
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/// This class is the main entrypoint for evaluating constant expressions. It
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/// also handles caching of previously computed constexpr results.
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class ConstExprEvaluator {
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/// We store arguments and result values for the cached constexpr calls we
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/// have already analyzed in this ASTContext so that they are available even
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/// after this ConstExprEvaluator is gone.
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ASTContext &astContext;
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/// The current call stack, used for providing accurate diagnostics.
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llvm::SmallVector<SourceLoc, 4> callStack;
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ConstExprEvaluator(const ConstExprEvaluator &) = delete;
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void operator=(const ConstExprEvaluator &) = delete;
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public:
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explicit ConstExprEvaluator(SILModule &m);
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~ConstExprEvaluator();
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ASTContext &getASTContext() { return astContext; }
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void pushCallStack(SourceLoc loc) { callStack.push_back(loc); }
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void popCallStack() {
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assert(!callStack.empty());
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callStack.pop_back();
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}
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const llvm::SmallVector<SourceLoc, 4> &getCallStack() { return callStack; }
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// As SymbolicValue::getUnknown(), but handles passing the call stack and
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// allocator.
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SymbolicValue getUnknown(SILNode *node, UnknownReason reason);
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/// Analyze the specified values to determine if they are constant values.
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/// This is done in code that is not necessarily itself a constexpr
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/// function. The results are added to the results list which is a parallel
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/// structure to the input values.
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///
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/// TODO: Return information about which callees were found to be
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/// constexprs, which would allow the caller to delete dead calls to them
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/// that occur after after folding them.
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void computeConstantValues(ArrayRef<SILValue> values,
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SmallVectorImpl<SymbolicValue> &results);
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};
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} // end namespace swift
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#endif
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