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8707fa7000
Micro-optimization in module file size and loading complexity. No functionality change. Swift SVN r5240
371 lines
12 KiB
C++
371 lines
12 KiB
C++
//===--- BCRecordLayout.h - Convenience wrappers for bitcode ----*- 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 - 2015 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 http://swift.org/LICENSE.txt for license information
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// See http://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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/// \file Convenience wrappers for the LLVM bitcode format and bitstream APIs.
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///
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/// This allows you to use a sort of DSL to declare and use bitcode abbrevs
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/// and records. Example:
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///
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/// \code
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/// using Metadata = BCRecordLayout<
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/// METADATA_ID, // ID
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/// BCFixed<16>, // Module format major version
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/// BCFixed<16>, // Module format minor version
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/// BCBlob // misc. version information
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/// >;
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/// unsigned MetadataAbbrevCode = Metadata::emitAbbrev(Out);
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/// Metadata::emitRecord(Out, ScratchRecord, MetadataAbbrevCode,
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/// VERSION_MAJOR, VERSION_MINOR, extraData);
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/// \endcode
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///
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/// For details on the bitcode format, see
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/// http://llvm.org/docs/BitCodeFormat.html
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///
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//===----------------------------------------------------------------------===//
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#ifndef SWIFT_SERIALIZATION_BCRECORDLAYOUT_H
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#define SWIFT_SERIALIZATION_BCRECORDLAYOUT_H
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#include "swift/Basic/LLVM.h"
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#include "llvm/Bitcode/BitCodes.h"
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#include "llvm/Bitcode/BitstreamWriter.h"
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#include "llvm/Support/MathExtras.h"
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namespace swift {
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namespace serialization {
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namespace impl {
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/// Convenience base for all kinds of bitcode abbreviation fields.
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///
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/// This just defines common properties queried by the metaprogramming.
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template<bool LAST = false>
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class BCField {
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public:
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static const bool MUST_BE_LAST = LAST;
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template<typename T>
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static bool assertValid(const T &data) {}
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};
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} // end namespace impl
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/// Represents a literal operand in a bitcode record.
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///
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/// The value of a literal operand is the same for all instances of the record,
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/// so it is only emitted in the abbreviation definition.
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///
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/// Note that because this uses a compile-time template, you cannot have a
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/// literal operand that is fixed at run-time without dropping down to the
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/// raw LLVM APIs.
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template<uint64_t Value>
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class BCLiteral : public impl::BCField<> {
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public:
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static void emitOp(llvm::BitCodeAbbrev &abbrev) {
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abbrev.Add(llvm::BitCodeAbbrevOp(Value));
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}
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template<typename T>
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static void assertValid(const T &data) {
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assert(data == Value && "data value does not match declared literal value");
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}
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};
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/// Represents a fixed-width value in a bitcode record.
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///
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/// Note that the LLVM bitcode format only supports unsigned values.
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template<uint64_t Width>
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class BCFixed : public impl::BCField<> {
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public:
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static void emitOp(llvm::BitCodeAbbrev &abbrev) {
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abbrev.Add(llvm::BitCodeAbbrevOp(llvm::BitCodeAbbrevOp::Fixed, Width));
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}
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template<typename T>
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static void assertValid(const T &data) {
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assert(data >= 0 && "cannot encode signed integers");
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assert(llvm::isUInt<Width>(data) &&
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"data value does not fit in the given bit width");
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}
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};
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/// Represents a variable-width value in a bitcode record.
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///
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/// The \p Width parameter should include the continuation bit.
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///
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/// Note that the LLVM bitcode format only supports unsigned values.
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template<uint64_t Width>
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class BCVBR : public impl::BCField<> {
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static_assert(Width >= 2, "width does not have room for continuation bit");
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public:
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static void emitOp(llvm::BitCodeAbbrev &abbrev) {
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abbrev.Add(llvm::BitCodeAbbrevOp(llvm::BitCodeAbbrevOp::VBR, Width));
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}
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template<typename T>
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static void assertValid(const T &data) {
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assert(data >= 0 && "cannot encode signed integers");
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}
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};
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/// Represents a character encoded in LLVM's Char6 encoding.
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///
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/// This format is suitable for encoding decimal numbers (without signs or
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/// exponents) and C identifiers (without dollar signs), but not much else.
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///
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/// \sa http://llvm.org/docs/BitCodeFormat.html#char6-encoded-value
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class BCChar6 : public impl::BCField<> {
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public:
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static void emitOp(llvm::BitCodeAbbrev &abbrev) {
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abbrev.Add(llvm::BitCodeAbbrevOp(llvm::BitCodeAbbrevOp::Char6));
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}
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template<typename T>
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static void assertValid(const T &data) {
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assert(llvm::BitCodeAbbrevOp::isChar6(data) && "invalid Char6 data");
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}
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};
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/// Represents an untyped blob of bytes.
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///
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/// If present, this must be the last field in a record.
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class BCBlob : public impl::BCField<true> {
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public:
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static void emitOp(llvm::BitCodeAbbrev &abbrev) {
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abbrev.Add(llvm::BitCodeAbbrevOp(llvm::BitCodeAbbrevOp::Blob));
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}
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};
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/// Represents an array of some other type.
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///
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/// If present, this must be the last field in a record.
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template<typename Element>
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class BCArray : public impl::BCField<true> {
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static_assert(!std::is_same<Element, BCBlob>::value,
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"arrays of blobs are not permitted");
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public:
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static void emitOp(llvm::BitCodeAbbrev &abbrev) {
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abbrev.Add(llvm::BitCodeAbbrevOp(llvm::BitCodeAbbrevOp::Array));
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Element::emitOp(abbrev);
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}
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};
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namespace impl {
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/// Attaches the last field to an abbreviation.
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///
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/// This is the base case for \c emitOps.
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///
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/// \sa BCRecordLayout::emitAbbrev
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template<typename Last>
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static void emitOps(llvm::BitCodeAbbrev &abbrev) {
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Last::emitOp(abbrev);
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}
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/// Attaches fields to an abbreviation.
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///
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/// This is the recursive case for \c emitOps.
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///
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/// \sa BCRecordLayout::emitAbbrev
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template<typename First, typename... Rest>
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static typename std::enable_if<sizeof...(Rest) != 0, void>::type
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emitOps(llvm::BitCodeAbbrev &abbrev) {
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static_assert(!First::MUST_BE_LAST,
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"arrays and blobs may not appear in the middle of a record");
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First::emitOp(abbrev);
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emitOps<Rest...>(abbrev);
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}
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/// Helper class for emitting a scalar element in the middle of a record.
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///
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/// \sa BCRecordLayout::emitRecord
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template<typename First, typename... Fields>
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class BCRecordWriter {
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public:
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template <typename BufferTy, typename FirstData, typename... Data>
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static typename std::enable_if<sizeof...(Fields) != 0, void>::type
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emit(llvm::BitstreamWriter &out, BufferTy &buffer, unsigned abbrCode,
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FirstData data, Data... rest) {
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static_assert(!First::MUST_BE_LAST,
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"arrays and blobs may not appear in the middle of a record");
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First::assertValid(data);
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buffer.push_back(data);
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BCRecordWriter<Fields...>::emit(out, buffer, abbrCode, rest...);
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}
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};
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/// Helper class for emitting a scalar element at the end of a record.
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///
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/// This has a separate implementation because up until now we've only been
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/// \em building the record (into a data buffer), and now we need to hand it
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/// off to the BitstreamWriter to be emitted.
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///
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/// \sa BCRecordLayout::emitRecord
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template<typename Last>
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class BCRecordWriter<Last> {
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template <typename BufferTy, typename LastData>
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static void emit(llvm::BitstreamWriter &out, BufferTy &buffer,
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unsigned abbrCode, LastData data) {
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static_assert(!Last::MUST_BE_LAST,
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"arrays and blobs need special handling");
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Last::assertValid(data);
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buffer.push_back(data);
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out.EmitRecordWithAbbrev(abbrCode, buffer);
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}
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};
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/// Helper class for emitting an array element at the end of a record.
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///
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/// \sa BCRecordLayout::emitRecord
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template<typename EleTy>
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class BCRecordWriter<BCArray<EleTy>> {
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public:
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template <typename BufferTy>
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static void emit(llvm::BitstreamWriter &out, BufferTy &buffer,
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unsigned abbrCode, StringRef arrayData) {
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// FIXME: validate array data.
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out.EmitRecordWithArray(abbrCode, buffer, arrayData);
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}
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template <typename BufferTy, typename ArrayTy>
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static void emit(llvm::BitstreamWriter &out, BufferTy &buffer,
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unsigned abbrCode, const ArrayTy &arrayData) {
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#ifndef NDEBUG
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for (auto &item : arrayData)
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EleTy::assertValid(item);
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#endif
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buffer.reserve(buffer.size() + arrayData.size());
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std::copy(arrayData.begin(), arrayData.end(),
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std::back_inserter(buffer));
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out.EmitRecordWithAbbrev(abbrCode, buffer);
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}
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};
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/// Helper class for emitting a blob element at the end of a record.
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///
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/// \sa BCRecordLayout::emitRecord
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template<>
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class BCRecordWriter<BCBlob> {
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public:
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template <typename BufferTy>
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static void emit(llvm::BitstreamWriter &out, BufferTy &buffer,
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unsigned abbrCode, StringRef blobData) {
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out.EmitRecordWithBlob(abbrCode, buffer, blobData);
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}
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};
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} // end namespace impl
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/// Represents a single bitcode record type.
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///
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/// This class template is meant to be instantiated and then given a name,
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/// so that from then on that name can be used
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template<typename... Fields>
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class BCGenericRecordLayout {
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llvm::BitstreamWriter &Out;
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unsigned AbbrevCode;
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public:
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/// Create a layout and register it with the given bitstream writer.
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explicit BCGenericRecordLayout(llvm::BitstreamWriter &out)
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: Out(out), AbbrevCode(emitAbbrev(out)) {}
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/// Emit a record to the bitstream writer, using the given buffer for scratch
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/// space.
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///
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/// Note that even fixed arguments must be specified here.
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template <typename BufferTy, typename... Data>
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void emit(BufferTy &buffer, unsigned recordID, Data... data) const {
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emitRecord(Out, buffer, AbbrevCode, recordID, data...);
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}
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/// Registers this record's layout with the bitstream reader.
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///
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/// \returns The abbreviation code for the newly-registered record type.
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static unsigned emitAbbrev(llvm::BitstreamWriter &out) {
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auto *abbrev = new llvm::BitCodeAbbrev();
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impl::emitOps<Fields...>(*abbrev);
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return out.EmitAbbrev(abbrev);
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}
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/// Emit a record identified by \p abbrCode to bitstream reader \p out, using
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/// \p buffer for scratch space.
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///
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/// Note that even fixed arguments must be specified here. Currently, arrays
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/// and blobs can only be passed as StringRefs.
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template <typename BufferTy, typename... Data>
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static void emitRecord(llvm::BitstreamWriter &out, BufferTy &buffer,
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unsigned abbrCode, unsigned recordID, Data... data) {
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static_assert(sizeof...(data)+1 <= sizeof...(Fields),
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"Too many record elements");
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static_assert(sizeof...(data)+1 >= sizeof...(Fields),
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"Too few record elements");
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buffer.clear();
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impl::BCRecordWriter<Fields...>::emit(out, buffer, abbrCode, recordID,
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data...);
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}
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};
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template<unsigned RecordCode, typename... Fields>
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class BCRecordLayout : public BCGenericRecordLayout<BCLiteral<RecordCode>,
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Fields...> {
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using Base = BCGenericRecordLayout<BCLiteral<RecordCode>, Fields...>;
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public:
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enum : unsigned {
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/// The record code associated with this layout.
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Code = RecordCode
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};
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/// Create a layout and register it with the given bitstream writer.
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explicit BCRecordLayout(llvm::BitstreamWriter &out) : Base(out) {}
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/// Emit a record to the bitstream writer, using the given buffer for scratch
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/// space.
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///
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/// Note that even fixed arguments must be specified here.
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template <typename BufferTy, typename... Data>
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void emit(BufferTy &buffer, Data... data) const {
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Base::emit(buffer, RecordCode, data...);
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}
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/// Emit a record identified by \p abbrCode to bitstream reader \p out, using
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/// \p buffer for scratch space.
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///
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/// Note that even fixed arguments must be specified here. Currently, arrays
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/// and blobs can only be passed as StringRefs.
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template <typename BufferTy, typename... Data>
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static void emitRecord(llvm::BitstreamWriter &out, BufferTy &buffer,
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unsigned abbrCode, Data... data) {
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Base::emitRecord(out, buffer, abbrCode, RecordCode, data...);
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}
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};
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/// RAII object to pair entering and exiting a sub-block.
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class BCBlockRAII {
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llvm::BitstreamWriter &Writer;
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public:
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BCBlockRAII(llvm::BitstreamWriter &writer, unsigned blockID,
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unsigned abbrevLen)
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: Writer(writer) {
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writer.EnterSubblock(blockID, abbrevLen);
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}
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~BCBlockRAII() {
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Writer.ExitBlock();
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}
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};
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} // end namespace serialization
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} // end namespace swift
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#endif
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